Dissertations / Theses on the topic 'Building Heating and Cooling'

Current research studies show that building heating, cooling and ventilation energy consumption account for nearly 40% of the total building energy use in the U.S. The potential for saving energy through building control systems varies from 5% to 20% based on recent market surveys. In addition, building control affects environmental performances such as thermal, visual, air quality, etc., and occupancy such as working productivity and comfort. Building control has been proven to be important both in design and operation stages. Building control design and operation need consistent and reliable static and dynamic information from multiple resources. Static information includes building geometry, construction and HVAC equipment. Dynamic information includes zone environmental performance, occupancy and outside weather information during operation.. At the same time, model-based predicted control can help to optimize energy use while maintaining indoor set-point temperature when occupied. Unfortunately, several issues in the current approach of building control design and operation impede achieving this goal. These issues include: a) dynamic information data such as real-time on-site weather (e.g., temperature, wind speed and solar radiation) and occupancy (number of occupants and occupancy duration in the space) are not readily available; b) a comprehensive building energy model is not fully integrated into advanced control for accuracy and robustness; c) real-time implementation of indoor air temperature control are rare. This dissertation aims to investigate and solve these issues based on an integrated building control approach. This dissertation introduces and illustrates a method for integrated building heating, cooling and ventilation control to reduce energy consumption and maintain indoor temperature set-point, based on the prediction of occupant behavior patterns and weather conditions. Advanced machine learning methods including Adaptive Gaussian Process, Hidden Markov Model, Episode Discovery and Semi-Markov Model are modified and implemented into this dissertation. A nonlinear Model Predictive Control (NMPC) is designed and implemented in real-time based on Dynamic Programming. The experiment test-bed is setup in the Solar Decathlon House (2005), with over 100 sensor points measuring indoor environmental parameters such as temperature, relative humidity, CO2, lighting, motion and acoustics, and power consumption for electrical plugs, HVAC and lighting. The outdoor environmental parameters, such as temperature, relative humidity, CO2, global horizontal solar radiation and wind speed, are measured by the on-site weather station. The designed controller is implemented through LabVIEW. The experiments are carried out for two continuous months in the heating season and for a week in cooling season. The results show that there is a 26% measured energy reduction in the heating season compared with the scheduled temperature set-points, and 17.8% energy reduction in the cooling season. Further simulation-based results show that with tighter building façade, the cooling energy reduction could reach 20%. Overall, the heating, cooling and ventilation energy reduction could reach nearly 50% based on this integrated control approach for the entire heating/cooling testing periods compared to the conventional scheduled temperature set-point.

The heating and cooling requirements after a shutdown period of the heating ventilating and air conditioning (HVAC) systems in buildings are studied through an analytical model. The parameters affecting the preconditioning and storage loads which are of particular importance are identified. A mathematical computer model is developed to facilitate the analysis of the shutdown loads. Zones are grouped in terms of heavy, medium and light weight construction for the study. For a specified zone, the ratio of the inside surface area to the outside exposed area, A(s)/A(w), is an important parameter in predicting the additional loads resulting from system shutdown. The computer model is validated with known computer programs, namely DOE-2, BLAST, and DARE-P. A simplification to the model is proved to be adequate for the study. The zones with similar weight characteristics and the same A(s)/A(w) ratio, prove to have the same temperature profiles during the shutdown period, provided that they are at the same ambient conditions. Design guidance and procedures for predicting the preconditioning and storage loads using the models are developed. In addition, the use of DOE-2 and ASHRAE weighting factor method for shutdown load predictions is demonstrated for generic and custom applications.

Heating, Ventilation, and Air Conditioning (HVAC) systems are responsible for a substantial share of the energy consumed in commercial buildings. Energy used by HVAC systems has increased over the years due to its broader application in response to the growing demand for better thermal comfort within the built environment. While existing case studies demonstrate the energy saving potential of efficient HVAC operation, there is a lack of studies quantifying energy savings from optimal operation of HVAC systems when considering indoor environmental conditions. This research aims to improve the performance of HVAC systems by optimizing its energy consumption without compromising indoor environmental conditions. The concept of maintaining indoor environmental conditions poses new challenges to the optimal operation of HVAC systems. While the primary objective of ensuring optimal operation is to minimize energy consumption, controlling the indoor environmental parameters, e.g., temperature, humidity, the level of carbon dioxide (CO2), and volatile organic compounds (VOCs) to remain within the acceptable range imposes excess energy use. These two conflicting objectives constitute a multi-variable constrained optimization problem that has been solved using a particle swarm algorithm (PSO). A real-time predictive model has been developed for individual indoor environmental parameters and HVAC energy consumption using Nonlinear Autoregressive Exogenous (NARX) neural network (NN). During model development, efforts have been paid to optimize the performance of the model in terms of complexity, prediction results, and ease of application to a real system. The proposed predictive models are then optimized to provide an optimal control setting for HVAC systems taking into account seasonal variations. An extensive case study analysis has been performed in a real commercial building to demonstrate the effectiveness of developing predictive models and evaluating the relevance of integrating indoor air quality (IAQ) within the optimization problem. Results show that it is possible to minimize 7.8% energy consumption from HVAC systems without compromising indoor environmental conditions. This study demonstrates that the proposed optimal control settings maintain the indoor environment within the acceptable limit of thermal comfort conditions (indoor air temperature between 19.60 to 28.20C and indoor air humidity between 30 to 65 %RH as per ASHRAE Standard 55-2017) and air quality (CO2 ≤ 800 ppm and VOC ≤ 1000ppm as per Australian Standard AS 1668.2 2016). The outcomes of this research will act as a guideline for energy management practices, not only for energy efficient building design and retrofitting but also for building energy performance analysis. This research provides insight into the aspects that affect the performance of predictive models for indoor temperature. The proposed feature selection approach establishes its efficacy to determine salient and independent input parameters without compromising prediction performance. The application of this approach will minimize the measurement and data storing cost of variables. Further, using fewer numbers of input parameters in the model will reduce the computational cost and time. Thus, the proposed model establishes its applicability in a real system for a more extended period of advanced prediction. In addition, the need to better account for building-occupant interactions as an important step to maintain a healthy indoor environment has been recognized through evaluating a real-life demand control (DCV) system. Lastly, the proposed optimization approach, where four defined environmental parameters are considered simultaneously presents a new outlook within the HVAC control system by eliminating the unseen interface between thermal comfort and IAQ. Overall, this unexploited potential to simultaneously improve the performance of HVAC systems and indoor environmental conditions drives the discussion on reconsidering the set-point configuration standards of HVAC in commercial buildings, either as part of individual building retrofit planning or as part of building regulatory applications.

International Energy Agency Solar Heating & Cooling (IEA SHC) programme states the fact that space/water heating and cooling demand account for over 75% of the energy consumed in single and multi-family homes. Solar energy technology can meet up to 100% of this demand depending on the size of the system, storage capacity, the heat load and the region’s climate. Solar thermal collectors are particular type of heat extracting devices that convert solar radiation into thermal energy through a transport medium or flowing fluid. Although hybrid PV/T or thermal-alone systems offer some advantages to improve the solar heat utilisation, there are a few technical challenges found in these systems in practice that prevented wide-scale applications. These technical drawbacks include being expensive to make and install, inability of switching already-built photovoltaic (PV) systems into PV/T systems, architectural design etc. The aims of this project, therefore, were to investigate roof integrated solar thermal roof collectors that properly blend into surrounding thus avoiding ‘add on’ appearance and having a dual function (heat absorption and roofing). Another objective was to address the inherent technical pitfalls and practical limitations of conventional solar thermal collectors by bringing unique, inexpensive, maintenance free and easily adaptable solutions. Thus, in this innovative research, unique and simple building integrated solar thermal roof collectors have been developed for heating & cooling applications. The roof systems which mainly based on low cost and structurally unique polyethylene heat exchanger are relatively cost effective, competitive and developed by primarily exploiting components and techniques widely available on the market. The following objectives have been independently achieved via evaluating three aspects of investigations as following: • Investigation on the performance of poly heat exchanger underneath PV units • Investigation on the performance of a Building Integrated PV/T Roof ‘Invisible’ Collector combined with a liquid desiccant enhanced indirect evaporative cooling system • Investigation on the build-up and performance test of a novel ‘Sandwich’ solar thermal roof for heat pump operation These works have been assessed by means of computer simulation, laboratory and field experimental work and have been demonstrated adequately. The key findings from the study confirm the potential of the examined technology, and elucidate the specific conclusions for the practice of such systems. The analysis showed that water temperature within the poly heat exchanger loop underneath PV units could reach up to 36°C and the system would achieve up to 20.25% overall thermal efficiency. Techno-economic analysis was carried out by applying the Life Cycle Cost (LCC) method. Evaluations showed that the estimated annual energy savings of the overall system was 10.3 MWh/year and the cost of power generation was found to be £0.0622 per kWh. The heat exchanger loop was coupled with a liquid desiccant enhanced indirect evaporative cooling unit and experimental results indicated that the proposed system could supply about 3 kW of heating and 5.2 kW of cooling power. Lastly, the results from test of a novel solar thermal collector for heat pump operation presented that the difference in water temperature could reach up to 18°C while maximum thermal efficiency found to be 26%. Coefficient Performance of the heat pump (COPHP) and overall system (COPSYS) averages were attained as COPHP=3.01 and COPSYS=2.29, respectively. An economic analysis pointed a minimum payback period of about 3 years for the system.

The aim of the study was to evaluate the long-term environmental performance effectiveness of heating and cooling systems between ‘sustainable’ and conventional office buildings. The key research question that this study tried to answear is, ‘To what extent do sustainable office buildings remain sustainable in the long run?’ On this basis, two hypotheses (HP) were tested:  HP1: Sustainable buildings remain sustainable in the long run.  HP2: Current indicators fulfil the role for determining long term sustainability. From the sustainability point of view, this study focused only on the environmental aspect. The word ‘sustainable’ has been used for identifying office buildings where environmental aspects have been taken into consideration through sustainability approaches. In order to address the first hypothesis, initially this study used a case study comparison approach to compare ‘sustainable’ with conventional office buildings, by comparing building design and heating-cooling system characteristics. This helped to raise understanding of the environmental characteristics that classify an office building as sustainable. Two case studies were used:  The first case study comparison consists of a new ‘sustainable’ BREEAM excellent certified office building from 2009 and a conventional office building from the 1960s that had no refurbishments.  The second case study comparison consists of a refurbished ‘sustainable’ BREEAM excellent certified office building compared to a conventional office building from the 1950s that had an upgrade in the heating system. The study then focused on assessing the current environmental performance of heating and cooling between the case study buildings. Therefore Post Occupancy Evaluation (POE) methods were used including site visits, interviews, recording of heating and cooling systems, collection of heating-cooling consumption data, conducting thermographic surveys, applying Heating Degree Data (HDD) Evaluation and undertaking Life Cycle Assessment (LCA). LCA has played a key role in evaluating the long run environmental performance of heating and cooling systems. The LCA evaluated two performance indicators: a) energy consumption of heating and cooling for 2 years of operation and b) the raw-material consumption of heating and cooling system production. Further, hypothetical long run scenarios were developed to consider the consequences of the existing operational and embodied raw-material emissions in the long run. Sensitivity LCA analysis was also used in order to evaluate the environmental impacts of alternative scenarios of different low/zero carbon technologies if they were installed in the case study buildings. Uncertainty analysis was used to assess the significance of uncertainty in the data evaluated. The key outcome of this study was the need for developing a new Sustainability Indicator that can be used to support environment decision making in evaluating the long run environmental performance of heating and cooling systems in office buildings. The new indicator brings together all the research methods used in this study by developing further the existing energy indicator already integrated in existing Sustainable Assessment Methods (SAMs) and by developing a new indicator for raw-materials of heating and cooling systems. Suggestions for their integration on existing SAMs are also discussed. Finally the study ends with key conclusions and suggestions for further research.

This thesis investigates the design of domestic glazed spaces in the United Kingdom, by studying the effect of a range of variables on the thermal properties of glazed spaces, in order to achieve a thermally comfortable environment while minimising the use of energy for heating and cooling. Earlier research work on domestic glazed spaces has concentrated on optimising the design of the space as a mechanism for reducing the space heating load of the parent house. Computer based dynamic thermal simulation is used in this study as the method of assessment and the variables tested are; glazing type, orientation and the degree of integration of the glazed space with the parent building. Unshaded, unventilated, and unheated, glazed spaces were found to be thermally comfortable for only a quarter to a third of the hours of possible use whatever the form, orientation or glazing type. Generally the higher the insulating value of the glazing the fewer the number of comfortable hours for all orientations and arrangements, due to discomfort being caused by high temperatures, even though the weather data used for the simulations only rose above 27'C for 25 hours during the course of the year. Further studies showed that significant reductions in the number of hours experiencing high temperatures could be achieved by the use of buoyancy driven ventilation. The studies indicated that glazed spaces integrated into the house plan tended to experience high temperatures for long periods but that the peak temperatures were much lower than those experienced for shorter periods in the exposed spaces. The effect of ventilation on overheating was therefore more marked in the integral than in the exposed glazed spaces. A study of the effects of roof shading blinds indicated that internal blinds had minimal effect in reducing high temperatures. External blinds had a greater effect than ventilation and a combination of external roof blinds and ventilation appears to provide the best strategy for the control of high temperatures. Studies on space heating loads for the houses and glazed spaces indicated wide variations in the heating loads of the glazed spaces depending predominantly on the insulating properties of the glazing. In terms of the reduction in the space heating load for the parent house, the thermal simulation results predict very little change due to the presence of the glazed space. A study on the effect of increasing the thermal storage properties of the floor construction of the glazed spaces, by substituting a clay tile finish for the original thin carpet layer, in order to reduce high temperatures proved inconclusive with minimal changes in the number of comfortable hours experienced. An investigation of thermal comfort during the Winter indicated that low surface temperatures did not reduce resultant temperatures below the lower limit of the comfortable range in the glazed spaces, during the heated period.

The aim of this thesis is to study the energy performance of a building integrated heating and cooling system. The research objectives are to investigate the system operating characters, to develop mathematical models for the heating and cooling systems, to demonstrate the technologies experimentally, to identify the best designs for a combined system and to investigate the cost effectiveness of the system. The main components of the systems are the aluminium plate façade and the building wall behind it, these form a plenum between them and the air is then heated or cooled as it flows through this plenum. Mathematical models were developed based on the energy balance equations and solved by matrix inversion method. These models were then validated with experimental results. The experiments were carried out in the laboratory with a facade area of 2m2. Two designs of facade were tested, i.e. flat and transpired plates. Results showed that the transpired design gave better thermal performance; the system efficiency for the flat plate was only about 30%, whereas it was about 85% for the transpired plate. On the other hand, a cooling system with double plenums was found to be better than a single plenum. Thus, a transpired plate with two plenums was identified as the best design for space heating and cooling. The cooling efficiency was nearly 2.0 even at low solar radiation intensity. A simulation study was carried out by assuming a 40m2 of façade was installed on an office building in London. The yearly energy saving was estimated as 10,877kWh, which is equivalent to 5,874kgCO2/year of emission avoidance. The system is calculated to cost about £70/m2, and for a discount rate of 5% and 30 years of lifetime, the payback period for this system would be less than a years.

Increased consciousness of the environmental problems has aroused people’s interest of renewable energy systems, especially the application of green features in buildings. The demand for air conditioning / cooling in domestic and non-domestic buildings is rising throughout the world; this increases the reliance on conventional fuels and the global warming effect from greenhouse gas emissions. Passive cooling and energy efficient design can substantially reduce reliance on fuel based heating and cooling. Passive and Hybrid Downdraught Cooling, in different forms, is now technically viable in many parts of the world. This has been established through a combination of research projects. In some hot arid regions, a major part of the energy consumed consists of air-conditioning requirements. Alternative methods, using passive cooling techniques, can assist in reducing the conventional energy consumption in buildings. Evaporative cooling, which can be tracked back several hundreds of years in ancient Egypt and Persia [1–3], is one of the most effective strategies, because of the enormous latent heat needed for evaporation of water. Green features are architectural features used to mitigate migration of various air-borne pollutants and transmission of air from outside to indoor environment in an advantageous way [9]. The reduction of fossil fuel consumption and the associated decrease in greenhouse gas emissions are vital to combat global warming and this can be accomplished, in part, by the use of natural ventilation. To assess the performance of several innovative cooling systems devices and to develop improved models for more established technology, quantitative measurement of output was necessary. This was achieved in this study by the development of simply constructed low energy cooling systems which were calibrated by the innovative use of wind and water as a source. These devices were found to be consistent and accurate in measuring the temperature and cooling load from a number of devices. There were some problems in the original evaporative units. Therefore, a number of modifications have to be made to enhance the systems performance. The novel Windcatcher – PEC cooling system was assessed and different cooling loads were achieved.

Modern development in many Third World countries in the hot regions of the world,, have been accompanied by the construction of highly energy-wasteful buildings. The interiors of these buildings have to be mechanically airconditioned in order to achieve thermal-comfort conditions. The consequence of this, has been the rapid increase in electricity-generating plant capacity to match demand (of which, for example at present in Oman, more than 70% nationally is used for air-conditioning modern, energyinefficient buildings). The aim of this work was to find the most suitable way of stabilising or even reducing the electricity demand in a country like Oman. The first step taken to achieve this aim, was to study and draw out lessons from the vernacular architecture of the different climatic regions in Oman. This has been followed by a literature survey that looks at passive and active natural cooling techniques for buildings in hot climates. Mathematical models were then developed to analyze and compare those passive techniques that are most suitable for an environment like that of Oman. Different ways of reducing the heat gain through the roof were investigated and compared. These include the addition of insulation, shading, air-cooling of the roof when the ambient air temperature is lower than that of the roof, and roof ponds. Roof ponds were found to be the most effective of those techniques analyzed. An improved design of the roof pond (the Water Diode roof pond) that eliminates the need for covering the roof pond during the day and uncovering it at night, was suggested and analyzed. The analysis showed promising results. Mathematical models were also developed to analyze and compare dif f erent ways of reducing the heat gain through the walls. These included the use of closed cavities, naturally ventilated cavities, the addition of insulation, and the effect of using brick as compared to concrete block. The analysis suggested that the combination of a Water Diode roof pond and insulated brick wall construction will reduce the heat gain through the envelope of a single room by more than 90%, when compared to a room with un-insulated roof and single-leaf concrete block walls. An empirical validation of the mathematical models was conducted. The results showed a good agreement between the actual and predicted values. An economical analysis of the commonly used roof and wall constructions in Oman, was also conducted. This compared the life-cycle cost of nine different construction techniques, with eight different airconditioning schedules. The result of this analysis showed a clear advantage of using roof insulation, reflective double glazing, and insulated walls with brick outer-leaf and concrete block inner-leaf.

With a nation-wide aim toward reducing operational energy costs in buildings, it is important to understand the dynamics of controlled heating, cooling, and air circulation of an individual room, the "One-Room Model Problem." By understanding how one most efficiently regulates a room's climate, one can use this knowledge to help develop overall best-practice power reduction strategies. A key toward effectively analyzing the "One-Room Model Problem" is to understand the capabilities and limitations of existing commercial tools designed for similar problems. In this thesis we develop methodology to link commercial Computational Fluid Dynamics (CFD) software COMSOL with standard computational mathematics software MATLAB, and design controllers that apply inlet airflow and heating or cooling to a room and investigate their effects. First, an appropriate continuum model, the Boussinesq System, is described within the framework of this problem. Next, abstract and weak formulations of the problem are described and tied to a Finite Element Method (FEM) approximation as implemented in the interface between COMSOL and MATLAB. A methodology is developed to design Linear Quadratic Regulator (LQR) controllers and associated functional gains in MATLAB which can be implemented in COMSOL. These "closed-loop" methods are then tested numerically in COMSOL and compared against "open-loop" and average state closed-loop controllers.
Ph. D.

The basic issue of this thesis concerns one of the fundamental problems of the future of our society: How to meet the energy requirements for a large and growing world population while preserving our environment? This question is important for the world and the answers are complex and interwoven.Conventional energy sources, fossil and fissile, are polluting in the present and in the future: they erode the environment and their resources are limited. Renewable energy (hydro, wind, solar, geothermal) constitutes a minimum of pollution in the different energy systems. The technologies for using renewable energy are well known though further development and progress are made. This development also requires behavioural change, adaptation, and above all political will. The transition from an economy based on fossil energy to an economy based on renewable energy appears necessary for the protection of the environment. The cost of renewable energy is often represented as an obstacle but remains competitive in the long run.The development and availability of renewable energy, which varies because of its spatial and temporal distribution, require an adaptation of lifestyle, habits, habitat design (passive bioclimatic houses), urban planning and transportation.The focus of this thesis was to apply renewable energy in an area with hot summers and cold winter, a climate like that in the northwest of Algeria. In order to provide improved comfort in the buildings and also economic development in this area, the energy demand for heating and cooling was analyzed in the ancient city of Tlemcen. To supply domestic hot water and space heating, water must be simultaneously available at two different temperature levels. Cold water temperature, close to that of the atmosphere, and hot water between 50 and 60°C. An interesting feature of the preparation of hot water is the small variation of requirements during the year, unlike that to heating. The preparation of hot water is one of the preferred applications of solar energy in the building for several reasons. For this reason an experimental study of the thermal behaviour of a domestic hot water storage tank was undertaken. The phenomena that affect the thermal behaviour of tank especially the coupling between the solar collector and storage tank was studied. This study included concentrating solar collector in which optical fibers were used to transport the energy to the storage tank. Another technology was introduced and developed for the heating and cooling of buildings in the desert involving an existing ancient irrigation system called Fouggara. The novel idea is to use the Fouggara as an air conditioner by pumping ambient air through this underground system. Then air at a temperature of about 21°C would be supplied to the building for heating in the winter and cooling in the summer. This study shows the feasibility of using this ancient irrigation system of Fouggara and contributes to reducing and eliminating the energy demand for heating and cooling buildings in the Sahara desert.

Godkänd; 2011; 20110920 (sofama)

Standing column wells (SCWs) have the potential to deliver much higher rates of heat transfer to geothermal heating and cooling systems in buildings via heat pumps than conventional vertical borehole heat exchange arrays. Its open-end column design with porous casing along the borehole (depending on the formation) encourages the flow of groundwater from the rock’s porous matrix into the well or the opposite way according to the hydraulic gradients. This approach induces a further heat transfer mechanism in addition to the conduction: it is advection. Advection induced by the groundwater movement due to the hydraulic gradient and the action of the well pump causes warmer water (in winter) and cooler (in summer) to be drawn into the well thus increasing heat transfer capacity. This is beneficial for SCWs to offer much higher heat transfer performance than other conventional approaches. The development of a numerical model for clusters of standing column wells is described in this thesis. The model is three-dimensional, dynamic and solves the governing equations using a finite volume discretisation scheme with a fully implicit algorithm. The slower acting field equations are solved using a wider time interval than that used for the faster acting well equations and the two sets of equations are coupled through the field equation source terms. A groundwater bleed feature is incorporated. The model has been validated thermally and hydraulically using existing field data. Two test cases have been applied to reveal the advantages of using SCWs in UK conditions, competing with the conventional closed-loop system of vertical borehole heat exchangers. The results of the applications suggest that SCWs can deliver substantially higher rates of heat transfer than conventional closed-loop borehole heat exchanger arrays, typically up to 250Wm-1, especially when groundwater bleed is operational. The results also confirm that a bleeding operation can offer up to 2.2K improvement (reduction) in the outlet well water temperature in summer and (increase) in the well water temperature in winter. Investigation results on borehole diameter confirm that a larger well borehole diameter would offer improved heat transfer performance in some cases, according to the relative change of the heat transfer coefficient. Analysis of borehole to borehole spacing seems to suggest that 5m is the most effective spacing of the three different spacing choices for this type of application. The results also show that SCW installation in London Clay performs less well than Magnesian Limestone and Old Red Sandstone; the latter two seem to be appropriate formation types to work with this type of application. The advantage of adopting multiple well arrangements (SCW clusters) over the use of single wells has also been confirmed. The important practical consequence of this is that far less geotechnical drilling is needed as the required borehole depth reduces substantially under multiple well arrangements. The results gathered from three different buildings also reveal that the balance between heating and cooling demands appears to have less impact on the mean formation temperature change than the large cooling application, which is beneficial to maintain a steady system performance over a long period of time. The results also suggest that the impact on the rock formation was very dominant in the first few years but it declined towards the end of the 5 year analysis period used in this work. The results from the CO2 emission analysis demonstrate that an annual carbon emission reduction of up to 46% can be achieved by using the geothermal system with SCWs instead of the conventional system consisting of a gas-fired condensing boiler and a conventional aircooled chiller. They also confirm that the balance between heating and cooling demands has a substantial impact on the carbon saving delivered by this technology.

The work presented in this thesis investigates design, computer modelling and testing a sub-wet bulb temperature evaporative cooling system for space air conditioning in buildings. The context of this evaporative cooling technology design is specifically targeted at locations with a hot and dry climate such as that prevailing in most regions of Middle East countries. The focus of this technology is to address the ever-escalating energy consumption in buildings for space cooling using mechanical vapour compression air conditioning systems. In this work, two evaporative cooling configurations both based on sub-wet bulb temperature principle have been studied. Furthermore, in these designs, it was sought to adopt porous ceramic materials as wet media for the evaporative cooler and as building element and use of heat pipes as heat transfer devices. In the first test rig, the prototype system uses porous ceramic materials as part of a functioning building wall element. Experimental and modelling results were obtained for ambient inlet air dry bulb temperature of 30 and 35oC, relative humidity ranging from 35% to 55% and intake air velocity less than 2 (m/s). It was found that the design achieved sub-wet bulb air temperature conditions and a maximum cooling capacity approaching 242 W/m2 of exposed ceramic material wet surface area. The wet bulb effectiveness of the system was higher than unity. The second design exploits the high thermal conductivity of heat pipes to be integrated as an effective heat transfer device with wet porous ceramic flat panels for evaporative cooling. The thermal performance of the prototype was presented and the computer model was validated using laboratory tests at temperatures of 30 and 35oC and relative humidity ranging from 35% to 55%. It was found that at airflow rates of 0.0031kg/s, inlet dry-bulb temperature of 35oC and relative humidity of 35%, the supply air could be cooled to below the inlet air wet bulb temperature and achieve a maximum cooling capacity of about 206 W/m2 of wet ceramic surface area. It was shown that the computer model and experimental tests are largely in good agreement. Finally, a brief case study on direct evaporative cooling thermal performance and environmental impact was conducted as part of a field trip study conducted on an existing large scale installation in Mina Valley, Saudi Arabia. It was found that the evaporative cooling systems used for space cooling in pilgrims’ accommodations and in train stations could reduce energy consumption by as much as 75% and cut carbon dioxide emission by 78% compared to traditional vapour compression systems. This demonstrates strongly that in a region with a hot and dry climate such as Mina Valley, evaporative cooling systems can be an environmentally friendly and energy-efficient cooling system compared to conventional vapour compression systems.

Sectoral energy consumption analyses clearly indicate that building sector plays a key role in global energy consumption, which is almost 40% in developed countries. Among the building services; conventional heating, ventilation and air conditioning (HVAC) systems have the greatest percentage in total energy consumption of buildings. According to the latest research, HVAC is responsible for around 40% of total building energy consumption and 16% of total global energy consumption. In this respect, decisive measures need to be taken to mitigate the energy consumption due to HVAC. The research carried out within the scope of this thesis covers innovative heating, cooling and ventilation technologies for low-carbon buildings. The novel technologies developed are introduced and investigated both theoretically and experimentally. The results indicate that optimised HVAC systems with waste heat recovery have a significant potential to mitigate energy consumed in buildings, thus to halt carbon emissions. Especially plate-type roof waste heat recovery units are very attractive for the said hybrid applications with a thermal efficiency greater than 88%. The said systems are also promising in terms of overall coefficient of performance (COP). The average COP of plate-type roof waste heat recovery unit is determined to be about 4.5, which is incomparable with those of conventional ventilation systems. Preheating performance of fresh air in winter season is found to be remarkable. Comprehensive in- situ tests clearly reveal that the temperature rise in fresh air is found to be around 7 °C. Plate-type roof waste heat recovery units also provide thermal comfort conditions for occupants. Indoor CCE concentration is observed to be varying from 350 to 400 ppm which is very appropriate in term of air quality. In addition, average relative humidity is found to be 57%, which is in the desired range according to the latest building standards. Desiccant-based evaporative cooling systems are capable of providing Abstract desired indoor environments for occupants as well as having considerably high COP ranges. An average of 5.3 °C reduction is achieved in supply air temperature by utilising those systems as well as having relative humidity distribution in thermal comfort range. The dehumidification effectiveness is found to be 63.7%, which is desirable and promising. The desiccant-based evaporative cooling system has a great potential to mitigate cooling demand of buildings not only in hot arid but also in temperate humid climates.

The UK building stock accounts for about half of all energy consumed in the UK. A large portion of the energy is consumed by nondomestic buildings. Offices and retail are the most energy intensive typologies within the nondomestic building sector, typically accounting for over 50% of the nondomestic buildings’ total energy consumption. Heating, ventilating and air conditioning (HVAC) systems are the largest energy end use in the nondomestic sector, with energy consumption close to 50% of total energy consumption. Different HVAC systems have different energy requirements when responding to the same building heating and cooling demands. On the other hand, building heating and cooling demands depend on various parameters such as building fabrics, glazing ratio, building form, occupancy pattern, and many others. HVAC system energy requirements and building energy demands can be determined by mathematical modelling. A widely accepted approach among building professionals is to use building energy simulation tools such as EnergyPlus, IES, DOE2, etc. which can analyse in detail building energy consumption. However, preparing and running simulations in such tools is usually very complicated, time consuming and costly. Their complexity has been identified as the biggest obstacle. Adequate alternatives to complex building energy simulation tools are regression models which can provide results in an easier and faster way. This research deals with the development of regression models that enable the selection of HVAC systems for office buildings. In addition, the models are able to predict annual heating, cooling and auxiliary energy requirements of different HVAC systems as a function of office building heating and cooling demands. For the first part of the data set development used for the regression analysis, a data set of office building simulation archetypes was developed. The four most typical built forms (open plan sidelit, cellular sidelit, artificially lit open plan and composite sidelit cellular around artificially lit open plan built form) were coupled with five types of building fabric and three levels of glazing ratio. Furthermore, two measures of reducing solar heat gains were considered as well as implementation of daylight control. Also, building orientation was included in the analysis. In total 3840 different office buildings were then further coupled with five different HVAC systems: variable air volume system; constant air volume system; fan coil system with dedicated air; chilled ceiling system with embedded pipes, dedicated air and radiator heating; and chilled ceiling system with exposed aluminium panels, dedicated air and radiator heating. The total number of models simulated in EnergyPlus, in order to develop the input database for regression analysis, was 23,040. The results clearly indicate that it is possible to form a reliable judgement about each different HVAC system’s heating, cooling and auxiliary energy requirements based only on office building heating and cooling demands. High coefficients of determination of the proposed regression models show that HVAC system requirements can be predicted with high accuracy. The lowest coefficient of determination among cooling regression models was 0.94 in the case of the CAV system. HVAC system heating energy requirement regression models had a coefficient of determination above 0.96. The auxiliary energy requirement models had a coefficient of determination above 0.95, except in the case of chilled ceiling systems where the coefficient of determination was around 0.87. This research demonstrates that simplified regression models can be used to provide design decisions for the office building HVAC systems studied. Such models allow more rapid determination of HVAC systems energy requirements without the need for time-consuming (hence expensive) reconfigurations and runs of the simulation program.

An emerging category of energy systems, consisting of power generation equipment coupled with thermally-activated components, has evolved as Cooling, Heating, and Power (CHP). The application of CHP systems to buildings has developed into a new paradigm ? Cooling, Heating, and Power for Buildings (CHP-B). This instructional module has been developed to introduce undergraduate engineering students to CHP-B. In the typical ME curriculum, a number of courses could contain topics related to CHP. Thermodynamics, heat transfer, thermal systems design, heat and power, alternate energy systems, and HVAC courses are appropriate for CHP topics. However, the types of material needed for this mix of courses vary. In thermodynamics, basic problems involving a CHP flavor are needed, but in an alternate energy systems course much more CHP detail and content would be required. This series of lectures on CHP-B contains both a stand-alone CHP treatment and a compilation of problems/exercises.

Transient modelling of heat fluxes and temperatures in structures was conducted to examine the effect of various characteristics on the temperature response during unusual operating and extreme weather conditions. The analytical model was validated using published experimental data and numerical results from well-known computer codes. The effect of including radiation heat transfer between interior surfaces, using the Mean Radiative Temperature method, on the temperature response was investigated and found to be negligible for a typical commercial building and a house during winter and summer power outages. The effect of thermal mass in the interior and exterior walls on the inside temperature drift after an HVAC system cutoff or a power outage was presented. The inside air temperature response curve is presented for different wall (exterior or interior) constructions of buildings. The effect of insulation position in exterior walls was also shown for several R values. The effect of exterior wall emissivity, sky temperature, outside vertical convective coefficient, furnishings, and ground temperature on the interior temperature response during winter and summer power outages were examined for buildings. The effect of infiltration on the temperature drift in buildings was investigated during winter and summer power outages. Restarting the HVAC after the power outage was examined during both seasons for typical buildings. Outside temperature profiles exceeding the 97.5 design temperature criterion were used to study the effect of extreme weather on the interior temperature of buildings with the HVAC system operating.
Ph. D.

New climate change projections for the UK were published by the United Kingdom Climate Impacts Programme in 2009. They form the 5th and most comprehensive set of predictions of climate change developed for the UK to date. As one of main products of UK Climate Projections 2009 (UKCP09), the Weather Generator, can generate a set of daily and hourly future weather variables at different time periods (2020s to 2080s) and carbon emission scenarios (low, medium and high) on a 5 km grid scale. In a radical departure from previous methods, the 2009 Projections are statistical-probabilistic in nature. A tool has been developed in Matlab to generate future Test Reference Year (TRY) and Design Reference Years (DRY) weather files from these Projections and the results were verified against results from alternative tools produced by Manchester University and Exeter University as well as with CIBSE’s Future Weather Years (FWYs) which are based on earlier (4th generation) climate change scenarios and are currently used by practitioners. The Northumbria tool is computationally efficient and can extract a single Test Reference Year and 2 Design Reference Years from 3000 years of raw data in less than 6 minutes on a typical modern PC. It uses an established ISO method for generating Test Reference Year data and an alternative method of constructing future Design Reference Years data is proposed. Fifteen different buildings have been identified according to alternative usage, thermal insulation, user activity and construction details. Besides these variants, the buildings were chosen specifically because they either exist, or have received planning consent and so represent ‘real’ UK building examples. Two investigations were then carried out based on the 15 case study buildings. The first involved applying TRYs generated for London, Manchester and Edinburgh for a variety of carbon emission scenarios at time horizons of 2030, 2050 and 2080. The TRYs were developed into a weather data format readable by the EnergyPlus energy simulation program to simulate summertime internal comfort (operative) temperatures, cooling demands and winter heating demands. All results were compared with a control data set of nominally current weather data, together with the same results produced using the alternative weather data generators of Manchester University, Exeter University and the CIBSE FWYs. Results revealed a good agreement between the various methods and show that significant increases in internal summer operative temperatures in non-air-conditioned buildings can be expected as time advances through this century, as well as increased air conditioning cooling energy demands and small reductions in winter heating energy demand. The second investigation involved generating time series of design internal peak summertime operative temperatures, design cooling demands and design winter heating demands for the same conditions as the first investigation. The results were then used to develop a simplified estimation method to predict future design cooling loads using multiple regressions fitting to selected data from the DRY simulation inputs and outputs. The simplified estimation method forms a useful tool for estimating how future cooling design loads in buildings are likely to evolve over time. It also provides a basis for designers and practitioners to determine how buildings constructed today will need to be adapted through life to cope with climate change.

In order to replace a conventional air-conditioner (AC) based on vapour compression technology that directly has high global warming potential and also currently consumes the most fossil fuel primary energy in building sector of tropical countries for generating thermal comfort on sleeping purpose, other alternative green space cooling technologies, as thermoelectric cooling (TEC), has to be improved to have same performance with AC. This research aims to develop and investigate a performance of Solar-powered Thermoelectric Radiant Cooling (STRC) system, as the combination of TEC and radiant cooling (RC) that is well known in its low energy consumption advantage. The studies were conducted through calculations, CFD simulations, system performance simulations and experiments. The results of optimum STRC system design was proved to provide better thermal and air quality performances, while the result in energy performance was depended on the TEC’s COP and vapour condensation prevention. After novel developing of TEC’s cooling channel with combined helical and an oblique fin to induce effective secondary flows that highly reduced the TEC’s hot side temperature in this research, the COP was able to increase up to 175%. Meanwhile, a novel bio-inspired combined superhydrophobic and hydrophobic coating on RC panel were able to competently repel most condensed water droplets, leaving just tiny droplets that was hard to be seen by naked eye. Finally, the COP of STRC system from house model experiment in 1:100 scales under hot and high humid climate was as high as 2.1 that helped STRC to consume electricity 34% less than AC system. Along with other benefits, as no working fluid, noise-free and low maintenance needs, the return of investment (ROI) was studied to be only 5-6 years when being operated with grid electricity and 17-18 years with PV panel generated electricity.

Thermal performance of the solar thermal systems are estimated using numerical methods and software since the solar processes are transitient in nature been driven by time dependent forcing functions and loads. The system components are defined with mathematical relationships that describe how components function. They are based on first principles (energy balances, mass balances, rate equations and equilibrium relationships) at one extreme or empirical curve fits to operating data from specific machines such as absorption chillers. The component models are programed i.e. they represent written subroutines which are simultaneously solved with the executive program. In this thesis for executive program is chosen TRNSYS containing library with solar thermal system component models. Validation of the TRNSYS components models is performed i.e. the simulation results are compared with experimental measurements.With the simulations are determined the long-term system performance i.e. data are obtained for the energy consumption, solar fraction, collector efficiency also it is performed parametric analysis to determine the influence of specific parameters like collector area, tilt and orientation, mass flow rate etc. to the system performance. In this thesis are considered only the residential buildings.

The heating and air-conditioning energy demand of skyscrapers with atria between buildings is explored. Radiation, conduction, convection, and ventilation were evaluated to determine annual heating and cooling energy demands for a 100-building city located in Provo, Utah. Spreadsheets models were developed and calibrated with a computational fluid dynamics model. Three spreadsheet model cases were examined: a baseline no-atrium case, a conditioned atrium case, and an unconditioned atrium case. The energy demands and atrium temperatures were compared between the different cases. The research concludes that atria can be used between buildings to reduce the heating and cooling energy demands. The exposed surface area of the city was reduced by 73.7%. This resulted in a 49.7% reduction in heating and cooling energy consumption for the unconditioned atrium case and a 16.0% reduction in energy consumption for the conditioned atrium case.

In this study, energy conservation potential of appropriate passive cooling and basic heat avoidance strategies were investigated for hot and humid climates. Within this framework, thermal behavior of a case study building that is situated in Cyprus was assessed by collecting temperature and relative humidity data from various rooms of the building during certain days in August. Then, by using feasible simulation strategies of the software tool Summer-Building, the effectiveness of passive cooling measures in reducing energy consumption were examined, for summer months. In this context, the case study building was re-evaluated by applying natural ventilation, night ventilation and ground cooling strategies as well as solar control and shading devices as overhangs and side fins. Consequently, based on the results of the evaluation model, it was found that the proposed passive cooling strategies and basic heat avoidance concepts could provide more than 50 % energy conservation, relative to the completely air conditioned reference building, between 1-15 August 2007.

La reducció del consum energètic dels sistemes de calefacció i refrigeració dels edificis és un repte fonamental per assolir els objectius marcats per l’Horitzó 2020. Noves aplicacions d'emmagatzematge d'energia tèrmica en edificis es mostren prometedores per reduir aquest elevat consum energètic. Un dels objectius d'aquesta tesi doctoral és revisar les aplicacions passives i actives d'emmagatzematge d'energia que es troben en la literatura, especialment aquelles que utilitzen materials de canvi de fase (PCM). En aplicacions passives els requeriments de confort i les condicions climàtiques són els principals paràmetres que s’han tingut en compte fins ara. Per això s'estudia la influència de càrregues internes en el aplicacions passives de PCM. D'altra banda, es presenta un sistema innovador que actua com una unitat d'emmagatzematge tèrmic i alhora com un sistema de calefacció i refrigeració. El rendiment tèrmic d'aquest sistema es testeja sota condicions reals i s'avalua el seu potencial de reducció del consum d'energia.
La reducción del consumo energético de calefacción y refrigeración de los edificios es un reto para lograr los objetivos marcados por el Horizonte 2020. Nuevas aplicaciones de almacenamiento de energía térmica en edificios se muestran prometedoras para reducir este elevado consumo energético. Uno de los objetivos de esta tesis doctoral es revisar aplicaciones pasivas y activas de almacenamiento de energía que se encuentran en la literatura, especialmente aquellas con materiales de cambio de fase (PCM). En aplicaciones pasivas los requerimientos de confort y las condiciones climáticas son los principales parámetros que se han tenido en cuenta hasta ahora. Se estudia la influencia de cargas internas en aplicaciones pasivas de PCM. También, se presenta un sistema innovador que actúa como una unidad de almacenamiento térmico y como calefacción y refrigeración. El rendimiento térmico de este sistema se testea bajo condiciones reales y evalúa su potencial de reducción del consumo energético.
Reducing the energy consumption of heating and cooling systems of buildings is a key challenge to achieve the targets set for the Horizon 2020. New applications of thermal energy storage in buildings are promising to reduce the high energy consumption. One of the objectives of this PhD is to review passive and active applications of thermal energy storage in buildings found in the literature, especially those that use phase change materials (PCM). In passive applications comfort requirements and climatic conditions are the main parameters that have been considered so far. For this study, the influence of internal loads has been taken into account in passive PCM applications. Moreover, an innovative system which acts as a storage unit and a heating and cooling supply is presented. The thermal performance of this system is studied and the potential in reducing the energy consumption of heating and cooling is evaluated.

[EN] In a context of global warming concern and global energy policies, in which heating and cooling systems in buildings account for a significant amount of the global energy consumption, ground source heat pump (GSHP) systems are widely considered as being among the most efficient and comfortable heating and cooling renewable technologies currently available. Nevertheless, both an optimal design of components and an optimal operation of the system as a whole become crucial so that these systems can have a significant contribution to the attenuation of the global energy problem. The overall objective of this PhD dissertation is to perform the control and energy optimization of an experimental GSHP system installed at the Universitat Politècnica de València, making the control system adaptive to the thermal demand of the building and to the climate conditions. For that purpose, different control strategies are proposed, described, developed, implemented and tested in the system. The optimization of any system requires a comprehensive study of its behaviour, by means of a thorough analysis of all the variables and parameters implied on its performance. Therefore, the first step is to analyse the short-term performance of the system, but also the long-term performance based on the experimental data collected at the installation. Second and prior to developing any optimization strategies, it is important to analyse the optimal configuration of the system according to the objectives targeted. This objective includes the study of the best location for the temperature control sensor and the buffer tank, as well as an adequate size for this buffer tank. Finally, once the behaviour of the system has been fully understood, the components of the system are the most efficient according to the possibilities of the research work and they have been connected adequately, the final objective is to develop control and optimization strategies which optimize the operation of the experimental GSHP system. These strategies target the control of the heat pump compressor, but also and more importantly, the energy optimization of the complete system. The focus is not in optimizing the performance of each individual component, but in optimizing the energy performance of the system working as a whole. In this direction, a first approach which combined a temperature compensation strategy and the variation of the frequency of the water circulation pumps, and hence the flow rate, as a function of the thermal load of the building, was first attempted. The application of this first approach resulted in significant energy savings, but also in a lack of user comfort in some of the offices under extreme weather conditions during summer. Consequently, the control and optimization methodology has been upgraded in a global algorithm (which is the final result of this PhD thesis) which couples both strategies in order to ensure the user comfort while keeping significant energy savings. In brief, this PhD work provides a comprehensive experimental study for the energy optimization of a GSHP system for both cooling and heating operation. Experimental results for a one-year operation period demonstrate important energy savings when compared to the standard control operation, up to 35% in the summer season and 53% in the winter season, while keeping the user comfort.
[ES] En un contexto de creciente preocupación por el calentamiento global y de políticas energéticas internacionales, en el cual los sistemas de climatización en edificios representan una parte importante del consumo energético global, los sistemas de bomba de calor geotérmica están ampliamente considerados como una de las tecnologias de climatización de espacios más eficientes disponibles en la actualidad. Sin embargo, tanto un buen diseño de los componentes como una óptima operación del sistema son de vital importancia para que estos sistemas puedan contribuir de manera significativa a atenuar el problema energético global. El objetivo general de esta tesis doctoral es el control y la optimización energética de una instalación experimental de bomba de calor geotérmica construida en la Universitat Politècnica de València, haciendo que el sistema de control se adapte a la demanda térmica del edificio y a las condiciones climatológicas. Para ello, se proponen diferentes estrategias de control, las cuáles son descritas, desarrolladas, implementadas y evaluadas a lo largo de este trabajo de investigación. La optimización de cualquier sistema requiere un amplio estudio de su comportamiento, analizando concienzudamente todas las variables y parámetros implicados en su funcionamiento. Por tanto, el primer paso llevado a cabo es el análisis de los días típicos de funcionamiento de la instalación, pero también su comportamiento a más largo plazo, a partir de los datos experimentales recogidos. En segundo lugar, y como paso previo al desarrollo de las estrategias de optimización, es importante analizar la configuración óptima del sistema de acuerdo con los objetivos perseguidos. Este objetivo incluye el estudio de la posición del sensor de temperatura empleado para el control y del depósito de inercia, así como el dimensionamiento adecuado de este depósito. Finalmente, una vez se ha analizado en profundidad el funcionamiento del sistema, los componentes del mismo son lo más eficientes posible, y éstos han sido conectados de manera adecuada, el objetivo final es el desarrollo de estrategias de control y optimización energética que optimicen la operación de la instalación experimental de bomba de calor geotérmica. Estas estrategias se dirigen principalmente a la optimización del sistema completo. El objetivo no es optimizar el funcionamiento de cada componente de manera individual, sino optimizar el comportamiento energético del sistema trabajando como un todo. En este sentido, se desarrolló una primera metodología que combinaba la compensación de la temperatura de consigna de la bomba de calor en función de la temperatura ambiente exterior, y la variación de la frecuencia de las bombas de circulación (y por tanto el caudal de agua) en función de la carga térmica del edificio. La aplicación de esta primera estrategia resultó en una importante mejora del rendimiento energético, pero también en la pérdida de confort en algunas de las oficinas climatizadas cuando las condiciones climatológicas eran extremas durante el verano. En consecuencia, la metodología de control y optimización desarrollada fue mejorada dando como resultado un algoritmo global de optimización energética (que es el resultado final de esta tesis), el cual acopla ambas estrategias anteriores de manera que se cumpla el confort del usuario y se mantenga un ahorro de energía significativo. En resumen, esta tesis doctoral proporciona un estudio experimental exhaustivo de la optimización energética de un sistema de bomba de calor geotérmica para la climatización de un edificio de oficinas. Los resultados experimentales para un año completo de funcionamiento del sistema muestran un ahorro de energía significativo en comparación con el modo de control de referencia, hasta un 35% en modo refrigeración y un 53% en modo calefacción, a la vez que se mantiene el confort de los usuarios.
[CAT] En un context de creixent preocupació per l'escalfament global i de polítiques energètiques internacionals, en el qual els sistemes de climatització en edificis representen una part important del consum energètic global, els sistemes de bomba de calor geotèrmica estan amplament considerats com una de les tecnologies de climatització més eficients disponibles en la actualitat pel que fa a la climatització d'espais. No obstant això, tant un bon disseny dels components com una operació òptima del sistema són de vital importància per tal que aquests sistemes puguen contribuir de manera significativa a atenuar el problema energètic global. L'objectiu general d'aquesta tesi doctoral és el control i l'optimització energètica d'una instal·lació experimental de bomba de calor geotèrmica construïda a la Universitat Politècnica de València, fent que el sistema de control s'adapte a la demanda tèrmica de l'edifici i a les condicions climatològiques. Amb aquest objectiu, es proposen diferents estratègies de control, les quals són descrites, desenvolupades, implementades i avaluades al llarg d'aquest treball d'investigació. L'optimització de qualsevol sistema requereix un ampli estudi del seu comportament, analitzant conscienciosament totes les variables i paràmetres implicats en el seu funcionament. Per tant, el primer pas duit a terme és l'anàlisi dels dies típics de funcionament de la instal·lació, però també el seu comportament a més llarg termini, a partir de les dades experimentals recollides. En segon lloc, i com pas previ al desenvolupament de les estratègies d'optimització, és important analitzar la configuració òptima del sistema d'acord als objectius perseguits. Aquest objectiu inclou l'estudi de la posició del sensor de temperatura emprat pel control i del dipòsit d'inèrcia, així com el correcte dimensionament d'aquest dipòsit. Finalment, una vegada s'ha analitzat en profunditat el funcionament del sistema, els components d'aquest són el més eficients possible, i han sigut connectats de manera adequada, l'objectiu final és el desenvolupament d'estratègies de control i optimització energètica les quals optimitzen l'operació de la instal·lació experimental de bomba de calor geotèrmica. Aquestes estratègies es dirigeixen principalment a l'optimització del sistema complet. L'objectiu no és optimitzar el funcionament de cada component de manera aïllada, sinó més bé optimitzar el comportament energètic del sistema treballant com un tot. En aquest sentit, es va desenvolupar una primera metodologia que combinava la compensació de la temperatura de consigna de la bomba de calor en funció de la temperatura ambient exterior, i la variació de la freqüència de les bombes de circulació (i per tant del cabdal d'aigua) en funció de la càrrega tèrmica de l'edifici. L'aplicació d'aquest primer apropament va resultar en una important millora del rendiment energètic, però també en la pèrdua de confort en algunes de les oficines climatitzades quan les condicions climatològiques eren extremes durant l'estiu. En conseqüència, la metodologia de control i optimització desenvolupada va ser millorada resultant en un algoritme global d'optimització energètica (resultat principal d'aquesta tesi), el qual acobla ambdues estratègies anteriors de manera que es complisca el confort de l'usuari i es mantinga un important estalvi d'energia. En resum, aquesta tesi doctoral proporciona un estudi experimental exhaustiu de l'optimit\-zació energètica d'un sistema de bomba de calor geotèrmica per la climatització d'un edifici d'oficines. Els resultats experimentals per un any complet de funcionament del sistema mostren un estalvi d'energia significatiu en comparació amb el mode de control de referencia, fins un 35% en mode refrigeració i un 53% en mode calefacció, a la vegada que es manté el confort dels usuaris.
Cervera Vázquez, J. (2016). Control and energy optimization of ground source heat pump systems for heating and cooling in buildings [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/66748
TESIS

The primary purpose of the current research was to implement a numerical model to investigate the interactions between the energy consumption in Heating, Ventilating, and Air Conditioning (HVAC) systems and occupants’ thermal comfort in commercial buildings. A numerical model was developed to perform a thermal analysis of a single zone and simultaneously investigate its occupants’ thermal sensations as a non-linear function of the thermal environmental (i.e. temperature, thermal radiation, humidity, and air speed) and personal factors (i.e. activity and clothing). The zone thermal analyses and thermal comfort calculations were carried out by applying the heat balance method and current thermal comfort standard (ASHRAE STANDARD 55-2004) respectively. The model was then validated and applied on a single generic zone, representing the perimeter office spaces of the Centre for Interactive Research on Sustainability (CIRS), to investigate the impacts of variation in occupants’ behaviors, building’s envelope, HVAC system, and climate on both energy consumption and thermal comfort. Regarding the large number of parameters involved, the initial summer and winter screening analyses were carried out to determine the measures that their impacts on the energy and/or thermal comfort were most significant. These analyses showed that, without any incremental cost, the energy consumption in both new and existing buildings may significantly be reduced with a broader range of setpoints, adaptive clothing for the occupants, and higher air exchange rate over the cooling season. The effects of these measures as well as their combination on the zone thermal performance were then studied in more detail with the whole year analyses. These analyses suggest that with the modest increase in the averaged occupants’ thermal dissatisfaction, the combination scenario can notably reduce the total annual energy consumption of the baseline zone. Considering the global warming and the life of a building, the impacts of climate change on the whole year modeling results were also investigated for the year 2050. According to these analyses, global warming reduced the energy consumption for both the baseline and combination scenario, thanks to the moderate and cold climate of Vancouver.

La integración de sistemas de fotovoltaicos/térmicos (PV/T) y un eficiente aire acondicionado en los edificios permite el suministro de calefacción, refrigeración y electricidad con una reducción de las emisiones de efecto invernadero. Las configuraciones de integración de: a) sistemas fotovoltaicos (PV) con enfriadores eléctricos refrigerados por aire y sistemas de bombas de calor aire-agua; b) sistemas fotovoltaicos/térmicos (PV/T) basados en aire con sistemas de bomba de calor aire-agua; y c) Los sistemas fotovoltaicos/térmicos de baja concentración (LCPV/T) con enfriadores de compresión y absorción tienen un gran potencial para aumentar la proporción de electricidad fotovoltaica in situ. La flexibilidad de incorporar energía LCPV/T para la red bidireccional de baja temperatura en distritos urbanos reduce las pérdidas térmicas y proporciona edificios de productores y consumidores (prosumidores). En comparación con la configuración típica del enfriador de compresión integrado fotovoltaico, la configuración propuesta de LCPV/T junto con los enfriadores de compresión y absorción reduce el período de recuperación en un 10-40% en el edificio de cajas en El Cairo. Sustituir la conexión a la red de agua del campus por el uso de bomba de calor reversible reduce en un 15-30% el coste operativo de refrigeración y calefacción en el edificio de cajas en España.
The integration of photovoltaic/thermal (PV/T) and efficient air conditioning systems into buildings allows the provision of heating, cooling and electricity with a reduction in greenhouse emissions. The integration configurations of: a) photovoltaic (PV) systems with air-cooled electric chillers and air-to-water heat pump (HP) systems; b) air-based PV/T systems with air-to-water HP systems; c) Low concentrated photovoltaic/thermal systems (LCPV/T) with compression and absorption chillers; and d) LCPV/T coupled with water-to-water HP have a great potential in boosting the share of onsite PV-electricity. The flexibility of incorporating LCPV/T energy for the bidirectional low temperature network in urban districts reduces thermal losses and provides producer and consumer (prosumer) buildings. In comparison to the typical configuration of PV integrated compression chiller, the proposed configuration of LCPV/T coupled with the compression and absorption chillers reduces the payback period by 10-40% in the case building in Cairo. Substituting the connection to the campus water network with the use of reversible

This study presents the complete design of a photovoltaic system in commercial buildings. PV installation for Multiarena was primary used for internal consumption, rest of production will be sent according intentions in grid. Project presents theoretical demand calculations for building consumptions. According to the theoretical calculations numerical study has been provided by software Indoor Climate and Energy program. Detailed electric optimization strategy can be founded in project description, as well as the sizing of the photovoltaic installation and economic and financial issues related to it. Study presents several models for photovoltaic system and their economic analysis. Environmental issues can be founded at the end of the study.

Els edificis suposen una part molt significant del consum energètic i de les emissions de CO2 a nivell global. Resoldre aquest problema requereix de la implementació de tecnologies d'eficiència energètica i de la integració d'energies renovables. En aquest context, els mur radiants són una tecnologia capaç d'afrontar aquests reptes. La avaluació del potencial d'aquest sistema s'ha dut a terme amb la experimentació d'una caseta amb murs radiant connectada a un sistema geotèrmic. Els resultats mostren la capacitat del sistema per reduir el consum energètic i desplaçar el pics de demanda, destacant també la sensibilitat als paràmetres de control. Les dades experimentals han servit per desenvolupar un model numèric del mur radiant, el qual s'ha fet servir per un estudi paramètric dels paràmetres de disseny. Finalment, aquest s'ha integrat a un model d'una habitació per estudiar diferents conceptes de control que maximitzin l'aprofitament de la producció d'uns panells fotovoltaics.
Los edificios suponen una fracción significativa del consumo energético y de emisiones de CO2 globales. Resolver este problema requiere implementar tecnologías de eficiencia energética e integrar energías renovables. En este contexto, los muros radiantes son una tecnología capaz de lidiar con estos retos. La evaluación del potencial del sistema se ha llevado a cabo con la experimentación de un cubículo con muros radiantes conectados a un sistema geotérmico. Los resultados muestran la capacidad del sistema para reducir el consumo energético y desplazar los picos de demanda, destacando también la sensibilidad a los parámetros de control. Los datos experimentales sirvieron para desarrollar un modelo numérico del muro radiante, el cual se ha usado para un estudio paramétrico de los parámetros de diseño. Finalmente, este se ha integrado a un modelo de cubículo para estudiar diferentes conceptos de control que maximicen el aprovechamiento de la producción de unos paneles fotovoltaicos.
Buildings represent a significant fraction of the global energy use and CO2 emissions. Solving this issue require the implementation of energy efficiency technologies and the integration of renewable energies. In this context, radiant walls are a technology capable of dealing with these challenges. The evaluation of this system was carried out with the experimentation of a radiant wall cubicle coupled to a geothermal system. The results showed the capability of the system for reducing the energy and shifting the peak loads, highlighting the sensitivity to control parameters. The experimental data was used for the development of a numerical model of the radiant wall, which was used in a parametric study of the design parameters. Finally, the numeric model was integrated in a cubicle model in order to study different control concepts that maximized the use of the energy produced by photovoltaic panels.

Office buildings are responsible for a significant amount of energy usage and CO2 emissions, undesirable because of resource depletion and/or climate change. A possible strategy for reducing energy consumption and hence CO2 emissions might be to specify high performance facades since they should reduce heat losses in cold conditions and conductive heat gains in hot conditions. This project reports on an investigation on energy demand and CO2 emissions in office buildings incorporating facades with U-values between 1.2 to 2.6 W/m2K and g-values between 0.3 to 0.5, in four locations: London, Hong Kong, Caribou and Abu Dhabi which experience, respectively, cool, sub-tropical, cold and hot climates. Other variables considered include office orientation, long working hours, low internal gains and climate change. Energy demand was calculated using a steady-state method and the dynamic simulation tool, EDSL Tas. The results show that low U-value facades can reduce both annual energy demand and CO2 emissions in locations with predominantly cold or predominantly hot environments such as those found in Caribou and Abu Dhabi. In Hong Kong U-value has a marginal effect on energy usage but savings can be achieved by specifying low g-value facades. In London, low U-value facades only decrease annual energy demand if internal gains are also low. However, reducing energy use does not necessarily reduce CO2 emissions and if this is the goal a second strategy which emerges is to select facades which minimise energy demand when solar irradiations are low and maximising the use of, for example, solar energy and air/ground source heat pumps at other times. The work further suggests that Building Regulations should include a lower limit on U-value, a higher set point temperature in winter and more guidance on internal heat gains if energy use and CO2 emissions are to be reduced in the UK.

Energy usage in buildings is a main contributor to CO2 emissions and in order for the EU to reach the 2050 goal of carbon-neutrality, there is a great need to improve the energy efficiency in buildings, particularly commercial buildings that often are substantially overdesigned. Excess margins in the design process of building services result in an oversizing of these systems which has great environmental impacts, divided up as the operational and embodied carbon footprints. The heating and cooling system of an NHS Hospital in southern England was studied and modelled in order to identify whether the system was overdesigned and to quantify the oversizing’s carbon footprint, which was the aim of the study. The cooling system of the NHS Hospital was determined potentially oversized and the focus of the thesis was therefore on the cooling system. It included the chillers that provide cooling, and the associated adiabatic coolers that provide heat rejection, as well as the affiliated pumps. The carbon footprint of this system was quantified, based on the operational energy use, the current grid carbon factor, environmental performance evaluations of units, observations and assumptions, and its cooling capacity was compared to the demand of the hospital. An optimised alternative was developed through analysis of the current system and its capacity, and the demand at the site, as well as based on the learnings of the background research. The system was designed to consist of smaller chillers and a reduced pumping system, to more correctly match the cooling demand. The optimised system was also modelled, its capacity compared to the demand, and its carbon footprint quantified. A future estimation of the two systems’ carbon footprints was calculated for year 2035, based on a projected grid carbon factor. The systems’ setups and carbon footprints were then compared for the current and projected scenarios, and the results discussed, also in regard to mitigation strategies that could lead to a reduction of oversizing and lower the environmental impacts. The results indicate that the yearly carbon footprint difference for the current scenario was approximately 539 tonnes CO2 eq, which was 43% greater than the optimised system’s carbon footprint. Whereas the yearly difference for the projected scenario was estimated to approximately 562 tonnes CO2eq, which was 752% greater than the optimised system’s carbon footprint in a possible future. This demonstrates the great environmental impact caused by the oversizing of cooling systems. The current system’s embodied carbon footprint was estimated to 3.3% of the total carbon footprint for the current scenario, and 4.8% for the projected scenario. Whereas the optimised system’s embodied carbon footprint was estimated to 1.5% for the current scenario, and 8.6% for the projected scenario. This demonstrates the large share of the embodied carbon footprint of the current, oversized system, compared to the optimised system that is sized more correctly for the cooling demand. Furthermore, it shows the anticipated raised proportion of the embodied carbon footprint of a product or system’s total future carbon footprint, since it increases for both the systems with time. The elevated share of the embodied carbon footprint in the future raises the need to address this factor and make it a priority. The key to a correctly sized system that meets the demand was determined to be precise calculations of the requirements and the elimination of excess margins that lack quantifiable justification. This results in an improved environmental performance where the system operates at its optimum level. The stakeholders’ involvement and influence throughout a transparent design process with clear communication, and incentives that provide financial aid to appropriately sized systems, as well as environmental impact evaluations of products, among others, are essential factors with major influence on the outcome. These elements are considered crucial for the reduction of the excess carbon footprint caused by the oversizing of building service systems.
Byggnaders energianvändning är en markant bidragande faktor till koldioxidutsläppen, och för att EU ska kunna nå målet att vara klimatneutral år 2050 finns det ett stort behov av att förbättra energieffektiviteten i byggnader, särskilt kommersiella byggnader som ofta är väsentligt överdesignade. Överskottsmarginaler i designprocessen av byggnadstjänster resulterar i en överdimensionering, som har en enorm miljöpåverkan, vilken delas upp som det operativa och det inneslutna klimatavtrycket. Studiens syfte var att studera och modellera värme- och kylsystemet på ett sjukhus i södra England för att identifiera om systemet var överdimensionerat, och för att kvantifiera dess klimatavtryck. Sjukhusets kylsystem bedömdes vara potentiellt överdimensionerat och studiens fokus var därför på kylsystemet. Det inkluderade kylarna som ger kylning och de anknutna adiabatiska kylarna som ger värmebortförsel, samt de tillhörande pumparna. Klimatavtrycket för systemet kvantifierades, baserat på den operativa energianvändningen, den nuvarande koldioxidfaktorn för elnätet, miljöutvärderingar av enheter, observationer och antaganden, och dess kylkapacitet jämfördes med sjukhusets behov. Ett optimerat alternativ utvecklades genom analys av det nuvarande systemet och dess kapacitet, och behovet på platsen, samt baserat på lärdomarna i litteraturforskningen. Systemet var utformat för att bestå av mindre kylare och ett reducerat pumpsystem för att bättre matcha kylbehovet. Även det optimerade systemet modellerades, dess kapacitet jämfördes med behovet, och dess klimatavtryck kvantifierades. En framtida uppskattning av de två systemens klimatavtryck beräknades för år 2035, baserat på en prognostiserad koldioxidfaktor för elnätet. Systemens uppsättningar och klimatavtryck jämfördes för de nuvarande och framtida scenarierna, resultaten diskuterades sedan, även med avseende på mildringsstrategier som kan leda till en reducering av överdimensionering och minskad miljöpåverkan. Resultaten indikerar att den årliga skillnaden i klimatavtrycket för det nuvarande scenariot var cirka 539 ton koldioxidekvivalenter, vilket var 43% större än det optimerade systemets klimatavtryck. Medan den årliga skillnaden i klimatavtrycket för det framtida scenariot uppskattades till cirka 562 ton koldioxidekvivalenter, vilket var 752% större än det optimerade systemets klimatavtryck i en eventuell framtid. Detta visar på den stora miljöpåverkan som orsakas av överdimensionerade kylsystem. Det nuvarande systemets inneslutna klimatavtryck beräknades till 3.3% av det totala klimatavtrycket för det nuvarande scenariot, och 4.8% för det framtida scenariot. Medan det optimerade systemets inneslutna klimatavtryck för det nuvarande scenariot var 1.5%, och 8.6% för det framtida scenariot. Detta demonstrerar den stora andelen inneslutet klimatavtryck i det nuvarande systemet, jämfört med det optimerade systemet som är bättre anpassat för kylbehovet. Dessutom visar det som förväntat den ökade andelen inneslutet klimatavtryck för en produkts eller ett systems totala klimatavtryck i framtiden, eftersom båda systemens inneslutna klimatavtryck visade på en framtida ökning. Den framtida ökade andelen inneslutet klimatavtryck väcker behovet av att itu med denna växande faktor och göra den till en prioritering. Nyckeln till ett system med korrekt storlek, vars kapacitet möter behovet, bestämdes vara exakta beräkningar av kraven och frånvaron av överskottsmarginaler som saknar kvantifierbar motivering. Detta resulterar i en förbättrad miljöprestanda där systemet fungerar på sin optimala nivå. Berörda parters engagemang och inflytande genom en transparent designprocess med tydlig kommunikation, och incitament som ger ekonomiskt stöd till system av korrekt dimensionering, samt miljökonsekvensbedömningar av produkter, är några av de viktigaste faktorerna med stort inflytande på slutresultatet. Dessa element bedöms vara avgörande för att minska överskottet av klimatavtrycket som orsakas av en överdimensionering av byggnadstjänster.

In this Thesis Project, the creation of a Low Energy building was examined in order to investigate how complex was to select the suitable parameters and systems of the dwelling, aiming to achieve the lowest possible energy consumption in one year period. All the technologies implemented into the system intended to be as energy efficient and profitable as possible. Another objective of this study was also to present the potential of the system to produce a part of the consumed energy, through renewable energy sources, approaching by this way also the standards of a Zero Energy Building. Firstly, the floor plan of the 150 m2 detached house, was drawn in the designing program AutoCAD. In continuation, this 2D floor plan was imported into the simulation program as well as all the initial input data so as for the Base model of the building to be created For the analysis of the building, the Simulation Program IDA ICE 4.7 was used. Gradually, alternations and adjustments were made into the Base model. Different models were created planning to analyze their results and conclude to the proper solution. All the simulations run for one year time period in order to present the total energy usage, system’s losses and demands in each case. In addition, as for the current study, the location of the construction was Athens, all building’s characteristics were chosen to comply with the Greek Regulation for Low Energy Buildings. Finally, through the procedure followed after having accomplished a series of simulations, the final annually energy demands managed to be within the required limits.

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Energy assessment in buildings is an essential topic in order to achieve the set goals for energy efficiency. This thesis investigated the energy consumption in various scenarios in Husmuttern’s buildings. Different purposes (school and apartment), locations (Spain and Sweden) and materials combinations are modelled and analysed. The models were created in the building performance simulation tool IDA ICE. After the yearly energy demand results were obtained they were processed and analysed. Then several factors were changed in the model in order to investigate different impacts in the energy consumption of the building, such as the overall heat transfer, hot water consumption, windows and doors. Also, PV panels were installed in the model to obtain the potential penetration of renewable energy in the buildings. The results showed the different consumption in the buildings depending on the purpose and location, and the impact of the changed factors in the overall energy consumption. The change of windows to more efficient ones showed that the apartments improve their consumption more than the schools, especially in when the Spanish location is considered. This case also had the biggest possible change when the hot water demand is varied. Whereas if the door was the changed, the Swedish apartment has the most possible improvement.

The thesis deals with the analysis of the properties of the external and internal environment of the buildings, the possibilities of heating and cooling. The emphasis is mainly on the energy intensity and the impact of weather conditions on the building temperature during the year. The model created by UPPAAL SMC describes the behavior of heating and cooling during the year and identifies the energy demand of the given building. The building model itself can be partially modified using the built-in user interface.

Low-emissivity (low-E) window films are designed to improve the energy performance of windows and prevent indoor overheating by solar radiation. These films can be applied to different types of glazing units without the need for changing the whole window. This characteristic offers the possibility to improve the energy performance of the window of old and historic buildings for which preservation regulations say windows should remain more or less unchanged. This research aims to figure out to what extent a low-E window film can improve thermal comfort and energy performance of an old three-storey historic stone building in the cold climate of Mid-Sweden. In this research, first, with help of the simulation software “IDA ICE”, the entire building was modelled without window films in a one-year simulation. Second step was to add the low-E window films (3M Thinsulate Climate Control 75 (CC75)) to all the windows and repeat the simulation. Comparison between the results of the two cases revealed an improvement in energy use reduction as well as the thermal comfort when applying the films. For the application of the window films, a cost analysis using payback method was carried out which showed a long- time payback period. Although an investment with a long-time payback period is considered as a disadvantage, for historic buildings with very strict retrofit regulations specially when it comes to the building’s facades, application of the low-emissivity window films for better energy performance and thermal comfort is among the recommendable measures, but not necessarily the best.

O trabalho apresenta uma análise térmica e energética de uma edificação localizada na zona bioclimática 1, que compreende as cidades mais frias do Brasil. A análise foi desenvolvida com o auxílio do programa de simulação dinâmica de edificações EnergyPlus em que foi determinado o consumo anual de energia elétrica de toda a edificação existente, bem como o consumo do sistema HVAC (Aquecimento, Ventilação e Ar Condicionado) do tipo split com ciclo reverso. O sistema HVAC existente representa 42% do consumo total de energia elétrica da edificação sendo que o aquecimento totaliza 89% do consumo do sistema HVAC. A avaliação do conforto térmico dos ambientes climatizados da edificação foi realizada tendo como referência as zonas de conforto de inverno e de verão definidas pela ASHRAE Standard 55-2004. Os ambientes apresentaram um percentual de 7,6 % a 33% das horas de operação do sistema HVAC fora da zona de conforto térmico de inverno da ASHRAE, considerando somente a temperatura operativa. A partir dos resultados da simulação da edificação existente foram propostas modificações na envoltória e o uso de um sistema de ar condicionado com tecnologia VRF (fluxo de refrigerante variável) a fim de reduzir o consumo de energia pelo HVAC e o número de horas desconfortáveis. A utilização de vidros duplos de maior transmissividade, superfícies com cores de maior absortividade solar, lã de vidro nas paredes externas e internas duplas e placas de EPS (Poliestireno Expandido) no piso da edificação, apresentaram ótimos resultados, reduzindo o consumo total de energia elétrica em 18,2% e o consumo do sistema HVAC passou a representar apenas 29,6% do total de energia da edificação. Após o aprimoramento da edificação foram selecionadas, a partir de catálogos de fabricantes, as máquinas com tecnologia VRF que atendessem a máxima carga térmica entre os dias de projeto ou arquivo climático sob determinadas condições. Os resultados obtidos com o sistema VRF apresentaram uma redução de 32,8% sobre o consumo de energia do sistema de HVAC e de 9,3 % sobre o consumo total de energia elétrica da edificação quando comparado com um ar condicionado tradicional do tipo split. Com a melhoria na envoltória e o uso da tecnologia VRF para climatização o percentual de horas fora das zonas de conforto da ASHRAE foram menores que os 4% estabelecido pela norma, quando considerado a temperatura operativa. O sistema VRF foi simulado adaptando o módulo de simulação de serpentinas de expansão direta com compressores de velocidade variável, do EnergyPlus, para quatro faixas de capacidades distintas do compressor (60%, 80%, 100% e 120%) e para cada faixa foram inseridas as correlações de desempenho da capacidade e potência elétrica de aquecimento e refrigeração para diferentes condições de operação. Nas simulações foram considerados a perda de desempenho e o consumo elétrico para a operação de degelo com ciclo reverso para temperaturas externas inferiores a 7º C. As simulações com o sistema VRF acoplado a edificação comprovam a capacidade de economizar energia elétrica, além de apresentar o menor custo especifico da energia para aquecimento em relação aos sistemas radiantes.
This dissertation presents the thermal and energetic analysis of a building located in the bioclimatic zone 01, which comprises the coldness regions of Brazil. The analysis was developed using the software for dynamic simulation of buildings called EnergyPlus, where was determined the annual consumption of electricity throughout the existing building as well as the consumption with lighting, electrical equipments and the HVAC system. The existing HVAC system represents 42% of total consumption and the heating corresponds to 89% of the total energy consumption of the HVAC system. The evaluation of thermal comfort zones of building were conducted with reference to the comfort zones of winter and summer from the ASHRAE Standard 55-2004. The thermal zones presented a percentage in the range of 7.6% to 33% of occupation hours outside the boundaries of ASHRAE thermal comfort zone (winter) evaluating the operating temperature. Based on simulation results of the existing building, changes were proposed in the envelope and in the use of a heat pump air conditioning system with VRF technology (variable refrigerant flow) to reduce the energy consumption of the HVAC and the number of hours outside the comfort zone. The use of double layers glasses with high transmissivity and surfaces colored with high solar absorption, wool glass in the external and double internal walls and EPS sheets on the building floor, presented excellent results. The modification of the envelope decreased 18.2 % in the total consumption of electricity and the HVAC system represents only 29.6% of the total energy of the building. After the building improvement was selected from catalogs of manufacturers, machines with VRF technology that could meet the maximum heat load between design days or weather file. The results obtained with the VRF system showed a 32.8% reduction on energy consumption of HVAC system and 9.3% about the total consumption of electricity of the building compared to a traditional heat pump air conditioning system with single speed compressor. With the improvement in the envelope and the use of VRF system the percentage of hours outside the ASHRAE comfort zones were lower than the 4% target set by the standard. The VRF system was modeled from model: Multi-Speed Electric DX Air Coil, of the EnergyPlus, for four different capacities of the compressor (60, 80, 100 and 120%) and for each capacity range were included the performance correlation of heating and cooling capacity, the correlations of electrical power heating and cooling for different condition of operate and correlation of the fraction of part load operation for each machine selected. As the study was conducted to the cooler regions of Brazil, defrost was considered in the simulation with reverse cycle for operating temperatures below 7°C. The heating energy with heat pump VRF presents lower specific cost compared to radiant systems like radiant floor and radiators.

The aim of this study was to investigate the passive and active parameters affecting energy efficiency of two office buildings with sun spaces, namely the MATPUM Building and the Solar Building on the Middle East Technical University (METU) Campus, Ankara and the effect of sun spaces on temperature patterns within mentioned buildings. Both buildings were oriented in the same direction, namely south. However, the location and the type of the sunspaces differed from each other. The sun space in the MATPUM Building is an atrium which has southerly glazed faç
ade. On the other hand, the sun space in the Solar Building is an enclosed conservatory which has southerly glazed faç
ades and roof. The effect of sun spaces on temperature patterns within case study buildings was determined by collecting internal temperature and humidity data from different locations within the buildings and external temperature and humidity data on certain days of the week from May to August and October and November. Data loggers were used to collect these data. The collected data was then compared for the two buildings and also for the different months. In conclusion, more heat gain resulting in temperature increase inside the buildings was obtained in conservatories when compared to the atria which have glazed faç
ade instead of glazed roof. This was also proved by the analysis of variance method which was used for the comparison of temperature data of two buildings

The thermal quality of the contemporary building tends to be deteriorated due to aesthetic and economic considerations. Cheap materials which are thermally inappropriate are still rising in new buildings. Actually, the architectural design has been changed. Hence, the orientation is poorly investigated. The interior height of the new buildings is defectively compared to those of traditional houses. In addition, the patio is replaced by a corridor and different parts have already become communicating. Accordingly, the heating and cooling space becomes more and more important. The traditional dwelling, in fact, has a bioclimatic architecture which provides naturally minimal comfort. In our work, we tend to exploit the REVIT software in the residential building simulation in Tunisia and to optimize the modern housing model. Following the REVIT validation of the obtained results and comparing them to TRNSYS and SPREADSHEET ASHRAE, we have already relied on them to assess both housing models (contemporary and traditional). Using REVIT, the evaluation results show that traditional housing are more efficient than contemporary ones particularly during summer period. Then, we optimize the modern models making use of the passive strategies of traditional bioclimatic architecture and the improvement measures in the previous investigations. Numerous tests have been generated applying REVIT software in order to determine various models of contemporary housing which are able to be integrated into the Mediterranean climate. In fact, these tests indicate that REVIT efficiency is based on RTS method in thermal simulation of residential buildings.
La qualité thermique des bâtiments modernes a une tendance à se détériorer en raison de considérations esthétiques et économiques. L'utilisation de matériaux de construction de bon marché et thermiquement inappropriées ne cesse d'augmenter dans les nouvelles constructions. À l'heure actuelle, la conception architecturale a changé. L'orientation est peu étudiée, la hauteur intérieure des nouveaux locaux est faible comparée à celle de la maison traditionnelle et le patio est remplacé par un couloir. Les différentes parties sont devenues communicantes. Ainsi, l'espace de chauffage et de refroidissement devient plus important. L'habitation traditionnelle tunisienne présente une architecture bioclimatique qui permet de fournir un confort minimal naturellement. Notre travail vise à exploiter le REVIT dans la simulation des bâtiments résidentiels en Tunisie et d'optimiser le modèle d'habitat moderne. Après validation des résultats obtenus par REVIT, comparés à ceux de TRNSYS et SPREADSHEET ASHRAE, nous l'avons, tout d'abord, exploité pour évaluer les deux modèles d'habitats (traditionnels et contemporains). Les résultats d'évaluation, en utilisant REVIT, montrent que l'habitat traditionnel sont plus efficaces que celui moderne particulièrement en période estivale. Par la suite, nous avons optimisé le modèle de maisons contemporaines, en utilisant en premier lieu, les stratégies passives de l'architecture bioclimatique traditionnelle, et en second lieu, en utilisant les mesures d'amélioration utilisées dans des études antérieures. Afin, de déterminer une variante de modèle d'habitat contemporain thermiquement optimal et qui s'intègre dans le climat méditerranéen, plusieurs tests sont générés en utilisant REVIT. Ces tests montrent l'efficacité de ce dernier qui se base sur la méthode RTS dans la simulation thermique des bâtiments résidentiels.

Dissertação submetida como requisito parcial para obtenção do grau de Mestre em Engenharia Eletrotécnica e de Computadores – Ramo das Energias Renováveis e Sistemas de Potência
Uma das maiores inquietações mundiais atuais está diretamente relacionada com a tomada de consciência de que é insustentável a população mundial continuar a utilizar recursos energéticos de origem meramente fóssil. Sendo assumido de uma forma generalizada que os edifícios são os maiores responsáveis por uma enorme parte do consumo da energia mundial, tornou-se evidente a necessidade de desenvolver meios para que os consumos de energia se tornem mais reduzidos. Neste contexto surgiu o conceito Nearly Zero Energy Buildings (NZEB) – Edifício de balanço energético quase zero. Esta ideia tem vindo a ser cada vez mais divulgada, representando uma das mais recentes tentativas levadas a cabo pela União Europeia (EU) para que o consumo energético de origem meramente fóssil nos edifícios seja reduzido. Este trabalho divide-se em três grandes blocos. Numa primeira fase, suporte teórico com recurso a várias leituras e consultas bibliográficas realizadas, serão abordadas temáticas afetas ao consumo de energia no Mundo, na Europa e mais concretamente, em Portugal. Neste contexto, serão abordados os conteúdos ligados aos documentos legislativos mais significativos que regulam a área da eficiência energética nos edifícios e será efetuada uma clarificação pormenorizada do conceito NZEB. No seguimento desta análise será abordado um caso real de um edifício existente. Para a sua análise e posteriores propostas de medidas no sentido de atingir o conceito NZEB, estabelece-se a construção do modelo de análise, onde é formulado o problema, definidos os objetivos do estudo e as hipóteses de trabalho; indicando-se o método escolhido, o procedimento de recolha de dados, os instrumentos utilizados e as características do meio onde se realiza a investigação. Proceder-se-á à descrição do edifício em estudo, à análise dos dados obtidos e à exposição de conteúdos afetos a diversas técnicas de melhorias, a diferentes tipos de soluções inovadoras e a um conjunto de estratégias, que poderão no contexto de uma reabilitação de um edifício proporcionar uma melhoria do seu desempenho energético.
Nowadays one of the world's greatest concerns is directly related to the understanding that it is impossible for the world population to continue consuming energy resources of pure fossil origin as a first option. It is generally assumed that buildings account for a large part of the world's energy consumption and therefore it is generally accepted that energy consumption must be reduced. It is in this context that the concept Nearly Zero Energy Buildings (NZEB) arises. This idea has become increasingly popular, representing one of the most recent attempts of the European Union (EU) to reduce energy of pure fossil origin consumption in buildings. This work is divided into three major blocks. The first phase will be a theoretical support in which several summaries of bibliographical consultations will be presented, several themes related to the consumption of energy in the World, in Europe and, more specifically, in Portugal will be approached. In this context, content related to the most significant legislative documents regulating the area of energy efficiency in buildings will be addressed and a detailed clarification of the NZEB concept will be addressed. This analysis will be centred in a real case of an existing building. For its analysis and subsequent proposals to try to achieve a NZEB building, it will be developed an analysis model, from which the problem will be formulated, the objectives of the present study and the working hypotheses will be defined; the method, the data collection procedure, the instruments used and the characteristics of the environment where the research is carried out will also be mentioned. A description of the building under study, the analysis of the data obtained and the proposal of various improvement techniques, different types of innovative solutions and a set of strategies will be carried out. In the context of a rehabilitation these solutions may surely improve energy performance.

This thesis provides heat pump usage in heating mode, heating of potable water or cooling mode. The heat pump is connected with photovoltaic power plant. The main aim of this study is to create photovoltaic system connected with heat pump and present the results of an energetic and economic evaluation. The theoretical part describes principle function heat pumps, photovoltaic power plants and components. The study provides as well a description of heating systems with a heat pump used for space heating or cooling. In the practical part of this thesis was performed calculation of energy consumption in a building. Based on this data, has been selected a suitable heat pump. To reduce the energy consumption was designed a hybrid photovoltaic power plant with a battery accumulation. Utilization of electric energy from photovoltaic system was calculated. Solutions provide the option of the energy flow analysis in specific interval. Results are summarized in the energetic and economic evaluation. The proposed solution can be applied for reconstruction or construction of a new building, focused on usage of renewable resources and emissions reduction.

The aim of this diploma thesis is to understand the functioning of heating and cooling systems in an administrative building built in passive standard using a renewable energy source. The thesis includes theoretical findings of heat pumps and designing the heating systems. The experimental part contains an analysis of working of heating and cooling systems in selected rooms in assigned building, which includes an experimental measurement of selected quantities and a thermographic measurement. In the last part of the thesis a comparison of measured and simulated values using simulation software was done.

Purpose: The building sector accounts for 40 % of the total energy consumption in Sweden today, and the largest proportion is consumed during the operating phase. From the year 2020 and onwards, all new buildings should be erected as zero-emissionbuildings. The building’s design can reduce energy demands, but the current legal requirements do not favour energy-efficient designs. This study focuses on the design’s importance for the energy efficiency of buildings, i.e., energy-saving design. The impact of specific measures is difficult to calculate due to the complexity of reality. This study aims to highlight the measures that could reduce energy consumption in commercial buildings. Method: In order to provide answers to the issues stated in the report and to achieve the objective of the study, case studies are being conducted investigating three commercial buildings where deliberate decisions were made to use energy-reducing measures. Results and conclusions are based on qualitative interviews and literature studies. Findings: The energy-reducing design measures found to be of most importance used in the studied buildings are the form factor, the window portion and the thermal storage capacity. Moreover, significant savings are possible by carefully consider how solar energy can be limited or used in the building. Generally, buildings tends to become more technical, therefore technical knowledge early in the process is important to reach a good result. Economic incentives and clear objectives with right focus are also important for optimizing a building’s energy performance. The wording and the requirement levels in the Swedish building regulations highly controls the construction of energy efficient buildings. Implications: This study shows how energy efficient design is made today and provides an indication of what can be done and what should be prioritized. By imposing requirements on consumed energy instead of bought, energy efficient design could be favoured. Furthermore, this study suggests that a balance between windows, façade and solar shading are important energy-reducing measures. Regardless of selected energyreducing measures, a good performance is essential. Finally, this study shows that a methodical use of existing knowledge and technology makes a difference. Limitations: A lifecycle approach provides an overall picture of a building’s energy consumption. However, this study is based on the energy consumption during the operating phase. The result of this study does not take economic or aesthetic factors into account. This study is a comparative case study and is based on few but carefully matched cases. The selected cases are commercial buildings where deliberate decisions were made to use energy-reducing measures.