Academic literature on the topic 'Building performance gap'

Occupant behaviour is a key factor in the energy consumption and performance of a building. However, it is difficult to model and simulate hence there is often a mismatch between the predicted and actual performance of a new or refurbished buildings and surprising variations in the consumptions of similar and identical buildings. Although environmental conditions affect people significantly, there are also non-environmental factors including how well employers manage people and how well dwelling occupants understand their controls. Rarely are these factors considered in building performance, especially commercial buildings. Poor management can lead to varying degrees of occupant maladaptation. Maladaptation taken here to mean behaviour patterns that are detrimental to the optimal functioning of the building. This paper proposes a novel concept for designers that examines the worst possible energy performance gap (“extreme” scenario testing) where the theoretical occupants do their best to make the building consume as much energy as possible. The novel concept is called “maxmaladaptation”. By considering maxmaladaptation, designers can attempt to reduce it, so reducing the energy gap. This paper briefly reviews the energy gap and social psychology and its contribution to understanding energy consumption with some examples, underlying the concept of maxmaladaptation. Practical application: Building energy performance gaps often exist because predicted design consumptions are often less than actual consumptions due to the occupants not behaving as designers expect. Using the concept of maxmaladaptation, an extreme scenario of maximum energy use by occupants, designers can design buildings to avoid unexpected energy consumption. Often the influences of occupant behaviour are not considered in detail. Social psychology gives an insight into non-environmental factors that can cause maladaptation, a constituent of maxmaladaptation.

Abstract The energy consumption in the world due to economic development, rising population, and technological developments is growing, which has led to an increase in global warming. Therefore, there is a strong need to develop new strategies to reduce energy consumption. Buildings account for about 40% of global energy consumption. Since occupancy time in residential buildings is longer than in commercial and office buildings, residential buildings have a more significant impact on energy consumption. Due to this issue, efforts are being made to optimize energy consumption in residential buildings. Evaluating the performance of a building through building certificates that include as-designed and in-operation is essential for improving energy efficiency. Building energy simulations must be performed before construction to ensure that energy consumption in buildings is acceptable. However, it is observed that the energy consumption of the building after construction is higher than what was designed. This difference is defined as the energy performance gap, which indicates extra energy consumption or failure to comply with energy standards in the operation of the building. There are several reasons for the increased energy consumption of an operating building compared to the designed model. So far, studies have been conducted to determine the factors affecting the energy performance gap, but it is necessary to analyze these studies comprehensively. This article investigates the causes of energy performance gaps and ways to reduce this difference through a comprehensive literature review study. In this way, it is possible to achieve solutions in the building certification criteria that minimize the difference in energy consumption between the as-designed model and the in-operation mode of the building. This article can help decision-makers select the certificate that best fits their purposes.

As a result of an increasing demand for energy-efficient buildings with a better experience of user comfort, the built environment sector needs to consider the prediction of building energy performance, which during the design phase, is achieved when a building is handed over and used. There is, however, significant evidence that shows that buildings do not perform as anticipated. This discrepancy is commonly described as the ‘energy performance gap’. Building energy audit and post occupancy evaluation (POE) are among the most efficient processes to identify and reduce the energy performance gap and improve indoor environmental quality by observing, monitoring, and the documentation of in-use buildings’ operating performance. In this study, a case study of UAE university buildings’ energy audit, POE, and dynamic simulation were carried out to first, identify factors of the dynamic energy performance gap, and then to identify the utility of the strategy for reducing the gap. Furthermore, the building energy audit data and POE were applied in order to validate and calibrate a dynamic simulation model. This research demonstrated that the case study building’s systems were not operating as designed and almost a quarter of the cooling energy was wasted due to the fault of the building facility management of the mechanical systems. The more research findings were discussed in the paper.

Energy supply, the increasing demands for energy, climate change, and the imperative to reduce greenhouse gas emissions must be considered in designing buildings. In order to design energy-efficient buildings, there should be accurate information about the thermal performance of the building. The thermal simulation readings should be precise. Its precision will also have a definite indication of the operational energy costs enabling the likelihood of conserving more energy used in building operations and reducing the greenhouse effect that is a result of emissions of greenhouse gases. Energy-efficient buildings are vital as they reduce the consumption of energy in and allow sustainable development. Erecting such buildings will require correct and realistic prediction of the buildings performance when subjected to a wide variety of harsh weather conditions in order to have a view of the impact of all the physical elements that influence the thermal performance. The behavior of the occupants also influences the thermal performance of a building. To achieve this, energy assessment instruments are used to accurately forecast the buildings thermal performance. This paper critically reviews energy rating methods for housing and the limitations of assessment systems.

One of the most discussed issues in the design community is the performance gap. In this research, we investigate for the first time whether part of the gap might be caused by the modelling literacy of design teams. A total of 108 building modellers were asked to comment on the importance of obtaining and using accurate values for 21 common modelling input variables, from U-values to occupancy schedules when using dynamic simulation to estimate annual energy demand. The questioning was based on a real building for which high-resolution energy, occupancy and temperature data were recorded. A sensitivity analysis was then conducted using a model of the building (based on the measured data) by perturbing one parameter in each simulation. The effect of each perturbation on the annual energy consumption given by the model was found and a ranked list generated. The order of this list was then compared to that given by the modellers for the same changes in the parameters. A correlation analysis indicated little correlation between which variables were thought to be important by the modellers and which proved to be objectively important. k-means cluster analysis identified subgroups of modellers and showed that 25% of the people tested were making judgements that appeared worse than a person responding at random. Follow-up checks showed that higher level qualifications, or having many years of experience in modelling, did not improve the accuracy of people’s predictions. In addition, there was no correlation between modellers, with many ranking some parameters as important that others thought irrelevant. Using a three-part definition of literacy, it is concluded that this sample of modellers, and by implication the population of building modellers, cannot be considered modelling literate. This indicates a new cause of the performance gap. The results suggest a need and an opportunity for both industry and universities to increase their efforts with respect to building physics education, and if this is done, a part of the performance gap could be rapidly closed. Practical application: In any commercial simulation, the modeller will have to decide which parameters must be included and which might be ignored due to lack of time and/or data, and how much any approximations might perturb the results. In this paper, the judgment of 108 modellers was compared against each other. The results show that the internal mental models of thermal modellers disagree with one another, and disagree with the results of a validated thermal model. The lessons learnt will be of great utility to modellers, and those educating the next generation of modellers.

Measurement campaigns have shown major discrepancies in buildings energy performance between planned energy demand and real energy consumption, while nowadays most of the newly constructed offices buildings are equipped with BMS systems, integrating a more or less extended measurement layer providing large amounts of data. The HIT2GAP project has developed a new generation of building monitoring and control tools based on advanced data treatment techniques allowing new approaches to assess building energy performance data, getting a better understanding of building’s behaviour and hence a better performance. From a strong research layer on data, HIT2GAP solution builds on existing measurement and control tools that are embedded into a new software platform for performance optimization. The HIT2GAP solution is applied as a novel intelligent layer offering new capability of the existing BMS systems and offering the management stakeholders opportunities for services with a novel added value. Applying the solutions to groups of buildings also allows to test energy demand vs. local production management modules. This solution is being tested in various pilot sites across Europe. HIT2GAP work has been carried out with a permanent concern about market exploitation of the solutions developed within the project. This paper will present the project solution in detail and showcase the achievement so far in the real case demo sites.

Internationally, buildings are a major contributor to carbon emissions. Despite significant advances in the technology and construction of energy-efficient buildings, in many cases a performance gap between designed and actual performance exists. While much research has investigated the drivers of the building energy performance gap – both static and transient– there has been considerably less research into the total performance gap, defined here as performance gaps in building energy use, occupant satisfaction and Indoor Environmental Quality parameters such as thermal comfort and air quality which may impact on occupant health and wellbeing. This paper presents a meta-analysis of building performance data from buildings in the UK and China – selected due to their contrasting development environments – which illustrate the presence of and complexities of evaluating total performance gaps in both countries. The data demonstrate the need for (1) high end-use, spatial granularity and temporal resolution data for both energy and Indoor Environmental Quality, and (2) developing methodologies that allow meaningful comparisons between buildings internationally to facilitate learning from successful building design, construction methodologies and policy environments internationally. Using performance data from a UK building, a potential forward path is illustrated with the objective of developing a framework to evaluate total building performance. Practical application: While much research has examined building energy performance gaps, Indoor Environmental Quality and occupant satisfaction gaps are rarely included despite their relationship to energy. We use a meta-analysis of energy, indoor environmental quality, and occupant satisfaction data from buildings in the UK and China to illustrating the presence of and complexities of evaluating total performance gaps for buildings in the two countries, and the need for high resolution dynamic buildings data and novel methodologies for comparison between buildings across different contexts. Illustrative case studies are used to demonstrate potential future directions for evaluating ‘total’ building performance.

Increasing studies imply that predicted energy performance of buildings significantly deviates from actual measured energy use. This so-called "performance gap" may undermine one's confidence in energy-efficient buildings, and thereby the role of building energy efficiency in the national carbon reduction plan. Closing the performance gap becomes a daunting challenge for the involved professions, stimulating them to reflect on how to investigate and better understand the size, origins, and extent of the gap. The energy performance gap underlines the lack of prediction capability of current building energy models. Specifically, existing predictions are predominantly deterministic, providing point estimation over the future quantity or event of interest. It, thus, largely ignores the error and noise inherent in an uncertain future of building energy consumption. To overcome this, the thesis turns to a thriving area in engineering statistics that focuses on computation-based uncertainty quantification. The work provides theories and models that enable probabilistic prediction over future energy consumption, forming the basis of risk assessment in decision-making. Uncertainties that affect the wide variety of interacting systems in buildings are organized into five scales (meteorology - urban - building - systems - occupants). At each level both model form and input parameter uncertainty are characterized with probability, involving statistical modeling and parameter distributional analysis. The quantification of uncertainty at different system scales is accomplished using the network of collaborators established through an NSF-funded research project. The bottom-up uncertainty quantification approach, which deals with meta uncertainty, is fundamental for generic application of uncertainty analysis across different types of buildings, under different urban climate conditions, and in different usage scenarios. Probabilistic predictions are evaluated by two criteria: coverage and sharpness. The goal of probabilistic prediction is to maximize the sharpness of the predictive distributions subject to the coverage of the realized values. The method is evaluated on a set of buildings on the Georgia Tech campus. The energy consumption of each building is monitored in most cases by a collection of hourly sub-metered consumption data. This research shows that a good match of probabilistic predictions and the real building energy consumption in operation is achievable. Results from the six case buildings show that using the best point estimations of the probabilistic predictions reduces the mean absolute error (MAE) from 44% to 15% and the root mean squared error (RMSE) from 49% to 18% in total annual cooling energy consumption. As for monthly cooling energy consumption, the MAE decreases from 44% to 21% and the RMSE decreases from 53% to 28%. More importantly, the entire probability distributions are statistically verified at annual level of building energy predictions. Based on uncertainty and sensitivity analysis applied to these buildings, the thesis concludes that the proposed method significantly reduces the magnitude and effectively infers the origins of the building energy performance gap.

This study aims at a preliminary characterization of system operation uncertainty. It bases this on an analysis of the energy consumption of 6 existing buildings on the Georgia Tech campus. The analysis is speculative in nature.

The building sector is responsible for almost a quarter of the total carbon dioxide emissions. The urgency to reduce the emissions is reflected in the stricter guidelines which have been set all over the world. To reduce the building sector’s emissions the energy consumption need to be reduced, which can be done in two ways: building new energy efficient buildings or retrofitting of current buildings. Due to the life expectancy of current building stock the largest savings before 2030 will be made through retrofits. For this reliable computational tools are required, and currently there is a gap between the predicted and actual performance of retrofitted buildings. This thesis is going to look into how the computational method is contributing to the performance gap. A building at the RMIT campus in Melbourne, Australia, which is going to be retrofitted through retrofits designed by Siemens, is used. A thermal simulation model of the building was built, and tuned to reflect the pre-retrofit building, and compared against the measured energy performance of the building. The retrofits were then implemented in the simulation model and the gap in the predictions between the simpler computational method used by Siemens in designing the retrofits, and the extensive simulation model was compared. The gap between the computational methods were analysed in order to see how Siemens calculation method contribute to the performance gap. The conclusions which have been drawn are that the simulation model is reflecting the energy use of the building well considering the access of data available during the study. Especially the electricity use is reflected well both in the total annual use, approximately 4 % gap to measured value, and the monthly variation over the year. The total natural gas use is under predicting the annual use, approximately 40 % gap to the measured value, but shows a good correlation to the monthly variation. The electricity use is relatively stable in the simulation model, where the natural gas was sensitive for direct changes to the heating system. The input parameters which have the largest impact in the electricity use are internal gain profiles and the electrical internal gains energy use. Siemens calculation method are contributing to the performance gap through the lack of interaction between the different retrofits, the light retrofit have a noticeable impact on the heating and cooling system of the building. To only use one single period in the regression models can also easily lead to incorrect predictions. The strength of the simulation model is its ability to see the retrofits influence on each other and the possibility for scenario analysis.
Byggnadssektorn är ansvarig för nästan en fjärdedel av de totala globala koldioxidutsläppen. Viljan att minska utsläppen kan ses i de allt striktare riktlinjer som sätts över hela världen. För att reducera utsläppen finns det två sätt: bygga nya energieffektiva byggnader eller ombyggnation av nuvarande byggnader. Livslängden på nuvarande byggnadsbestånd innebär att de största besparingarna innan 2030 kommer att ske inom ombyggnationer. För detta krävs tillförlitliga verktyg, och i nuläget finns det ett gap mellan byggnaders förutspådda och verkliga energiprestanda. I denna examensuppsatts kommer beräkningsmetodens inflytande över detta gap att undersökas. En byggnad på RMIT:s campus i Melbourne, Australien, som kommer att undergå en ombyggnation som designats av Siemens har använts. En termisk simuleringsmodell av byggnaden skapades och avstämdes mot den verkliga byggnaden, och jämfördes mot uppmätta värden av byggnadens energiprestanda. Ombyggnationerna var sedan implementerade och skillnaden mellan den förutspådda prestandan av byggnaden, genom den omfattande simuleringsmodellen och den enklare beräkningsmetoden som användes av Siemens, jämfördes. Genom att analysera gapet mellan de olika beräkningsmetoderna kunde slutsatser dras angående hur de kan bidra till gapet i energiprestanda. Slutsatserna från arbetet är att simuleringsmodellen ger en bra bild av energianvändningen av byggnaden, med hänsyn till informationen som varit tillänglig. Byggnadens totala uppmätta elektricitetsanvändning är speciellt väl överrensstämmande med simuleringsmodellens resultat både i den årliga användningen, ca 4 % skillnad från uppmätta värden, och variationen över ett år. Den totala användningen av naturgas enligt simuleringsmodellen är under de uppmätta värdena med en skillnad på ca 40 %, men med en god överrensstämmelse med den årliga variationen. Användningen av elektricitet i modellen är relativt stabil, användningen av naturgas är känslig för direkta ändringar till uppvärmningssystemet. Inputparametrarna som har störst inverkan på elanvändningen är interna, energiproducerande och konsumerande, enheters användningsprofil (PC, personer, ljus m.m.), el konsumtion, och latenta samt sensibla värme. Siemens beräkningsmetod bidrar till gapet mellan förutspådda och verkliga energiprestanda genom brist på samverkan mellan de olika delarna i ombyggnationen. Ombyggnationen som innebär uppgradering av byggnadens belysning innebär exempelvis märkbara skillnader i byggnadens uppvärmnings- och kylsystem. Användningen av endast en period i skapandet av regressionsmodeller för att förutspå vattenkokarnas och kylarnas användning leder även till en missledande framtida energiproduktion. Styrkan i simuleringsmodellen är möjligheten till samverkan mellan olika ombyggnationer påverkan på varandra samt möjligheten till scenarioanalys.

There is widespread acceptance of the need to reduce energy consumption within the built environment. Despite this, there are often large discrepancies between the energy performance aspiration and operational reality of modern buildings. The application of existing mitigation measures appears to be piecemeal and lacks a whole-system approach to the problem. This Engineering Doctorate aims to identify common reasons for performance discrepancies and develop a methodology for risk mitigation. Existing literature was reviewed in detail to identify individual factors contributing to the risk of a building failing to meet performance aspirations. Risk factors thus identified were assembled into a taxonomy that forms the basis of a methodology for identifying and evaluating performance risk. A detailed case study was used to investigate performance at whole-building and sub-system levels. A probabilistic approach to estimating system energy consumption was also developed to provide a simple and workable improvement to industry best practice. Analysis of monitoring data revealed that, even after accounting for the absence of unregulated loads in the design estimates, annual operational energy consumption was over twice the design figure. A significant part of this discrepancy was due to the space heating sub-system, which used more than four times its estimated energy consumption, and the domestic hot water sub-system, which used more than twice. These discrepancies were the result of whole-system lifecycle risk factors ranging from design decisions and construction project management to occupant behaviour and staff training. Application of the probabilistic technique to the estimate of domestic hot water consumption revealed that the discrepancies observed could be predicted given the uncertainties in the design assumptions. The risk taxonomy was used to identify factors present in the results of the qualitative case study evaluation. This work has built on practical building evaluation techniques to develop a new way of evaluating both the uncertainty in energy performance estimates and the presence of lifecycle performance risks. These techniques form a risk management methodology that can be applied usefully throughout the project lifecycle.

The UK Government has placed the need to reduce national energy demands and carbon emissions at the forefront of the political agenda, with a commitment made to meet EU targets of 20% reductions in greenhouse gas emissions and primary energy consumption, alongside a 20% improvement in overall energy efficiency, across all EU Member States, by 2020. Building performance has been identified as a key area where significant progress towards meeting these ambitions can be made. It is fundamental to ensure that the building fabric of a property functions correctly in order to achieve high levels of thermal effectiveness, which should result in lower energy demands and carbon emissions. However, research to date shows that a gap exists between predicted and actual performance levels. This research utilises the dwelling Heat Loss Coefficient (HLC) as a common output in design stage and post-construction evaluation techniques, that can be used to compare predicted and measured fabric performance. The Standard Assessment Procedure (SAP), coheating tests, air pressure tests and thermal imaging are used to evaluate in-situ buildings. Sensitivity analysis and controlled conditions experiments are utilised in order to investigate the reliability of the assessment techniques used. The key findings from the study include the demonstration, through novel coheating test, that post-installation mechanically ventilated heat recovery (MVHR) system efficiency levels can have a pronounced effect on the measured HLC, and, in conjunction with use of assumed theoretical efficiency levels, can cause divergence in theoretical and measured data of 10-15%. This can largely be resolved through correct design, installation and commissioning. Environmental conditions, both notional and site-specific, can also cause divergence in the HLC data, including wind speed (15%) and solar gains (10-26%). In addition, it has been shown that, when considering thermal bridging values, inaccurate calculation at the design-stage and poor attention to detail during construction could cause underperformance in this element by up to 50%. This is of significance as there are currently no mandatory procedures to assess post-construction compliance with thermal bridging levels specified within the UK Building Regulations.

There is a need to reduce unsustainable use of fossil fuels. Increased usage of renewable energy by combined use of photovoltaic solar panels (PV) with battery storage is one way. Another way is to increase awareness of energy usage and reduce the energy performance gap by building energy-efficient buildings. Buildings have a long lifetime and high energy usage will have an impact for a long time. Barriers, drivers and non-energy benefits (NEBs) for investments in battery storage in photovoltaic systems (PV) in the context of farmers in Sweden with PV systems was investigated by a questionnaire study. The questionnaire was sent to farmers in Sweden who already have photovoltaics installed and about 100 persons answered, a response rate of 59%. Among the drivers for investments in battery storage in PV systems in agriculture it was found that the highest-ranked driver, i.e., to use a larger part of the electricity produced oneself, turns out to be the highest priority for grid owners seeking to reduce the need for extensive investments in the grid. The primary NEBs found were the possibility to become more independent of grid electricity. A method for the building process, called ByggaE, which aims to reduce the energy performance gap, has been developed and described. The method is based on two main processes with activities. Documents that support the activities can be found and stored in the energy documentation, a digital map structure. The two main processes are: The client’s activity to formulate requirements and ways to verify these requirements. The main process for other actors is to identify, handle and follow up risks or critical parts. An overall relation between the energy efficiency gap and the energy performance gap has been identified. Realistic assumptions and follow-up related to the assumptions are found to be important to reduce both the energy efficiency gap and the energy performance gap.
För att uppnå klimatmålen är det nödvändigt att minska den ohållbara användningen av fossila bränslen. Ett sätt är att öka användning av förnybar energi genom att kombinera solel med batterilager. Ett annat sätt är att öka medvetenheten om energianvändningen med dess negativa påverkan på miljön och uppfylla energikraven för nya byggnader bättre. Eftersom byggnader har lång livslängd ger onödigt hög energianvändning påverkan under lång tid.   Hinder, drivkrafter och andra icke energirelaterade fördelar med att investera i batterilager till solel har undersökts i en enkätstudie bland svenska lantbruk. Det kom in 100 svar från lantbrukare som har solel, vilket motsvarar en svarsfrekvens på 59 %. Den viktigaste drivkraften för att investera i batterilager till solelanläggningen är en högre egenanvändning av el. Detta visade sig också vara högst prioriterat av elnätsägare för att minska behovet av kostsamma investeringar i elnätet. Den största icke energirelaterade fördelen med batterilager är större oberoende av elnätet.   En kvalitetsäkringsmetod för byggprocessen har utvecklats och beskrivits. Syftet med metoden, som kallas ByggaE, är att minska skillnaden mellan verklig energianvändning och energikrav i nya byggnader. Metoden bygger på två huvudprocesser med aktiviteter. Beställarens huvudprocess är att formulera krav och metoder att kontrollera och följa upp dessa krav. De andra aktörernas huvudprocess är att identifiera, hantera och följa upp risker eller kritiska moment som kan påverka energianvändningen. Dokument som stödjer aktiviteterna lagras i en digital mappstruktur.   Det är viktigt med realistiska antaganden och uppföljning som relaterar till dessa antaganden för att fler lönsamma energieffektiviseringsåtgärder ska bli genomförda och för att de energiprestanda som krävs eller förväntas ska bli uppfyllda.

The market shift towards high-performance buildings has been brought into question by growing concerns about the actual energy efficiency of these projects. Research studies have been pointing increasingly to performance gaps between the predicted (or modelled) and actual (or measured) energy consumption of certified ‘green’ buildings. Discussions about reasons for performance gaps have been recurring in the building industry and research alike. This thesis investigates the energy performance gap of three high-performance LEED-certified buildings in British Columbia: the Centre for Interactive Research on Sustainability (CIRS), the Jim Pattison Centre of Excellence in Sustainable Building Technology and Renewable Energy Conversation (JPCE) and the District Education Centre (DEC). For each case study, an energy performance evaluation reveals differences between modelled and measured energy consumption. Based on an extensive literature review, the reasons for identified performance gaps are explored through expert interviews with key stakeholders that were involved in the design, construction or operation of each of these projects. The energy performance evaluation reveals significant performance gaps in all three case studies, with one project out-performing and two under-performing the design predictions. The research highlights a lack of consistent metered-energy data at the system level. Based on these findings this study attempts to evaluate key sources of performance issues, in the context of the three case-study buildings. It shows that performance-gap reasons indicated in the literature occurred at all phases of the building lifecycle: starting at the planning/design and modelling phase, through the construction, commissioning and handover phases, to the building operation and occupancy phase. The results suggest that performance gaps are closely related to shortcomings in energy design concepts, development procedures, and operational practices that were applied in the three buildings. The research emphasizes the importance of creating a greater transparency of development procedures and collaborative approaches to successfully design, build and operate high-performance buildings. The challenges faced by project teams to integrate innovative technologies calls for robust design solutions and methodologies that can be easily translated into implementation strategies and operation procedures that meet building management capacities.
Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate

Bridging the gap between the predicted and actual energy performance of buildings is necessary to increase the energy performance of existing buildings and achieve the European Union’s energy efficiency targets in the “2030 climate & energy framework”. Construction is considered the sector with the most potential for energy saving. Specifically, buildings space heating has considerable potential for energy saving. Thermal transmittance is the fundamental parameter to characterise the heat losses of building envelopes. However, several research authors evidenced that assumptions regarding heat loss from a home pre-retrofit and post-retrofit were incorrect. In this sense, accurate on-site measurements are necessary to provide information on the actual thermal transmittance of façades. The purpose of this thesis is to contribute to reduce the energy performance gap of residential buildings. Therefore, the aim of the thesis is to enhance the accuracy of in situ measurements of the actual thermal transmittance of façades of existing residential buildings using the heat flux meter method to ensure successful decision-making during the energy renovation processes of existing buildings, and to confirm energy performance strategies for new nearly zero-energy buildings. The analysis of testing parameters for the in situ measurement process of the thermal transmittance are not fully specified by the standard ISO used extensively. Relating to calculation methods to conduct research on the thermal behaviour of façades, the standardised average method is widely used by authors. Very few initiatives used the standardised dynamic method because it is more complex than the average method. This research assesses the implications of using the different standardised calculation methods in order to verify which best fits theoretical values. Moreover, the usability of the standardised dynamic method is promoted and facilitated through a calculation procedure, defining a programmed spreadsheet accessible to practitioners. The dissertation proposes a classification system of façades to facilitate the selection of façades to conduct a systematic analysis of the thermal performance of façades in the housing sector. The classification of façades of existing residential buildings for subsequent analysis is based on the characterization of the opaque part of façades. The dissertation continues with the exploration of the boundaries of the requirements for using the standardised heat flow meter method to refine the testing conditions in low U-value façades. Façades with low thermal transmittance values are increasingly promoted due to comply with Directive 2010/31/EC targets. However, as several researchers shown, conducting accurate in situ measurement of low thermal transmittance façades is a challenging task. Investigating the limits of application of the HFM method for the in situ measurement of U-values in low thermal transmittance façades would allow to ensure compliance with policies to transition the existing building stock to nearly zero-energy buildings, and to confirm energy performance strategies for new nearly zero-energy buildings. To enhance the usability of the heat flux meter method, the dissertation compares different criteria for determining conditions for stopping the test during in situ experimental campaigns when measuring the thermal transmittance of existing buildings’ façades using the heat flow meter method. This will help to reduce practitioners’ uncertainty about the duration of experimental campaigns for obtaining accurate actual thermal transmittance of existing buildings’ façades. The dissertation concludes by outlining the main contributions of this research. The subjects that were raised during the research undertaken although they could not be addressed are commented and proposed as future work.
Reduir la diferència entre el rendiment energètic previst i real dels edificis és necessari per tal d’augmentar el rendiment energètic dels edificis existents i assolir els objectius sobre eficiència energètica de la Unió Europea en el “Marc sobre clima i energia per al 2030”. La construcció és considerada el sector amb més potencial d'estalvi energètic. Concretament, el condicionament tèrmic dels edificis mitjançant calefacció té un potencial d'estalvi energètic considerable. La transmitància tèrmica és el paràmetre fonamental per caracteritzar les pèrdues de calor a través de les envolvents de l’edifici. Tanmateix, diversos investigadors han demostrat que les hipòtesis sobre la pèrdua de calor dels edificis abans i després d’una rehabilitació no són correctes. En aquest sentit, es fa necessari realitzar mesures in situ amb elevada precisió per proporcionar informació sobre la transmitància tèrmica real de les façanes. El propòsit d’aquesta tesi és contribuir a reduir la bretxa del rendiment energètic en els edificis residencials. Per això, l'objectiu d'aquesta dissertació és millorar la precisió en la realització de mesures in situ de la transmitància tèrmica real de les façanes dels edificis residencials existents usant el mètode estandarditzat del mesurador de flux de calor (HFM), per assegurar l'èxit en la presa de decisions durant els processos de renovació energètica dels edificis existents i confirmar estratègies d'eficiència energètica per a nous edificis de consum d’energia quasi nul. L'anàlisi dels paràmetres d’assaig per a la mesura in situ de la transmitància tèrmica no està totalment especificada en l'estàndard ISO utilitzat extensivament. Pel que fa als procediments de càlcul, el mètode que s’utilitza de forma més àmplia pels investigadors és el mètode de mitjanes. Poques iniciatives utilitzen el mètode dinàmic degut a la seva complexitat. La investigació avalua les implicacions d'utilitzar els diferents mètodes de càlcul estandarditzats per verificar quin s’ajusta millor als valors teòrics de referència. A més, es fomenta i facilita la usabilitat del mètode dinàmic estandarditzat mitjançant un procediment de càlcul, definint un full de càlcul programat accessible per als professionals. La dissertació proposa un sistema de classificació de façanes per facilitar la selecció de façanes per a la seva posterior anàlisi del rendiment tèrmic de les façanes del sector de l'habitatge. La classificació de façanes d'edificis residencials existents es basa en la caracterització de la part opaca de les façanes. La dissertació continua explorant els límits dels requisits per a la utilització del mètode HFM per a refinar les condicions d’assaig en les façanes amb baixa transmitància tèrmica. Aquestes façanes es promouen cada vegada més per tal de complir amb els objectius de la Directiva 2010/31/CE. Tot i així, diversos investigadors han demostrat que realitzar mesures in situ precises en aquest tipus de façanes és un repte. Investigar els límits d'aplicació del mètode HFM per a la mesura in situ de la transmitància tèrmica en façanes amb baixa transmitància tèrmica permetrà assegurar el compliment de les polítiques de transició d'edificis existents a edificis de consum energètic quasi nul (nZEB), i confirmar estratègies d'eficiència energètica per a nous edificis nZEB. Per millorar la usabilitat del mètode HFM, aquesta tesi analitza diferents criteris per a determinar les condicions d’aturada de l’assaig durant les campanyes experimentals per mesurar in situ la transmitància tèrmica de les façanes. Els resultats ajudaran a reduir la incertesa sobre la durada de les campanyes experimentals per obtenir una transmitància tèrmica real precisa de les façanes dels edificis existents. La tesi conclou resumint les principals aportacions d'aquesta investigació. Els temes que s’han plantejat durant la investigació realitzada, i que no s'ha pogut abordar, es comenten i es proposen com a línies de treball futures

Within the European framework, most of residential buildings do not satisfy the minimum thermal specifications. In fact, the renovation rate across the EU is estimated at 1% per year. To fulfil with the goals stated by European Directives 2010/31/EU and 2012/27/EU, it is necessary to ensure a minimum energy performance gap. From a thorough literature review, it was detected that the thermal behavior of a building is often underestimated or neglected during its construction and operation stages. For this reason, an accurate non-destructive testing (NDT) should be required, improving the shortcomings given by the current modelling tools and diagnostic techniques. The purpose of this thesis was to develop a method for determining in-situ the thermal behavior of façades under steady-state conditions using quantitative internal infrared thermography (IRT). After drawing up a numerical model to estimate the thermal transmittance (U-value) as a key parameter of the built quality, the dissertation continued with a validation process that was executed in two typical Spanish walls from different construction periods. This allowed: (i) refining the proposed method; (ii) exploring the boundaries conditions; (iii) assessing the influence of tabulated values set by international standards for wall emissivity and convective heat transfer coefficients among other aspects. The results revealed lower deviations related to the theoretical U-values (1.24 to 3.97%) for test durations of 2-3 hours. Furthermore, the results demonstrated that the use of tabulated values might entail high deviations (40%) in heavy multi-leaf walls with low U-values. Broadly, construction project documents for existing buildings, especially the oldest ones, are not available. Hence, this method may provide information about the building envelope for future refurbishment. In the case of new buildings, the method might allow the thermal behaviour of building façades to be checked according to the design parameters. Despite this, a subsequent literature review highlighted that a gap in the standardization of this method for in-situ building diagnostics is still to fill. Considering this aspect, three studies were developed in order to enhance the applicability of the quantitative internal IRT within the construction industry field. Firstly, the most influential operating conditions were analyzed through an experimental room with a heavy single-leaf wall tested under a wide temperature difference range (3.8 < DT < 21ºC). Secondly, this dissertation performed tests in a public housing stock comprised of four unoccupied buildings (without electric and heating systems in operation), to assess the influence of non-transient thermophysical properties of the wall (i.e. heat capacity per unit of area) on the accuracy of the method. Thirdly, a data-processing method based on U-value time series analysis was proposed and validated through six building façades with heavy multi-leaf walls. The aim was to find a common criterion for stopping the test when it is not necessary more data to obtain a reliable result. Having investigated the aspects mentioned above, it can be extrapolated that: (i) the optimum temperature difference range is found to be between 7 and 16ºC; (ii) the variance in the thermal transmittance could mainly be predicted by changes in the outer air temperature; (iii) the quantitative internal IRT is more accurate in heavy multi-leaf walls with high heat capacities per unit of area, reaching maximum deviations of 0.20%; (iv) the test might be executed in only 30 minutes; (v) the method could allow the assessment of aspects related to the determination of U-value of unoccupied buildings for DT under 10ºC, especially in Spain or European countries with a Mediterranean climate where these test conditions might represent a limitation. Hence, the decision-making could be streamlined in real built environments, increasing the European renovation rate in the mid-term.
Dins el Marc Europeu, la majoria dels edificis residencials no satisfan les especificacions tèrmiques mínimes. De fet, la taxa de renovació a Europa és estimada en 1% anual. Per complir amb els objectius de les Directives Europees 2010/31/UE i 2012/27/UE, és necessari assegurar una bretxa energètica mínima. A partir d'un estat de l'art exhaustiu, es va detectar que el comportament tèrmic d'un edifici sovint és subestimat o negligit durant les etapes de construcció i operació. Per aquest motiu, una prova no destructiva i precisa hauria de ser requerida, per tal de millorar les deficiències donades per les actuals eines de modelització i diagnosi d'edificis. El propòsit de la tesi era desenvolupar un mètode per determinar in-situ el comportament tèrmic de les façanes sota condicions estacionàries mitjançant la termografia quantitativa interna (IRT). Després d'elaborar un model numèric per estimar la transmitància tèrmica (U-value) com a paràmetre clau de la qualitat construïda, la dissertació va continuar amb un procés de validació executat en dues parets típiques espanyoles de diferents períodes de construcció. Això va permetre: (i) refinar el mètode proposat; (ii) explorar les condicions de contorn; (iii) avaluar la influència dels valors tabulats establerts per les normatives internacionals per l'emissivitat de la paret i els coeficients de transferència de calor per convecció. Els resultats van revelar baixes desviacions respecte als valors teòrics de transmitància tèrmica (1.24 a 3.97%) per duracions de test entre 2 i 3 hores. A més a més, els resultats van demostrar que l’ús de valors tabulats podria implicar altes desviacions (40%) en parets compostes. En general, els projectes de construcció d'edificis existents antics no estan disponibles. Per tant, aquest mètode podria proporcionar informació sobre la façana per futures rehabilitacions. En el cas d’edificis nous, el mètode podria permetre verificar el comportament tèrmic de les parets d’acord amb els paràmetres de disseny. Malgrat això, una revisió bibliogràfica posterior va posar de manifest que encara hi ha una bretxa en la estandardització d’aquest mètode per la diagnosi in-situ. Considerant aquest aspecte, es van desenvolupar tres estudis per tal de millorar l’aplicabilitat de la termografia quantitativa interna dins el camp de la indústria de la construcció. En primer lloc, es va analitzar la influència de les condicions operatives en la determinació de la transmitància tèrmica mesurada a través duna cambra experimental amb una façana simple sota un ampli rang de diferència de temperatura (3.8 < DT < 21ºC). En segon lloc, es van dur a terme tests en un parc d’habitatges públics constituïts per quatre pisos desocupats (sense sistemes elèctrics ni de calefacció en funcionament), amb la finalitat d’analitzar la influència de les propietats termofísiques no transitòries (ex. la capacitat de calor per unitat d’àrea) en la precisió del mètode. En tercer lloc, es va proposar i validar un mètode de processat de dades basat en l’anàlisi de sèries de temps de la U-value mitjançant sis parets compostes. L’objectiu era trobar un criteri comú per aturar la prova quan no són necessàries més dades per obtenir un resultat fiable. Havent investigat els aspectes mencionats anteriorment, es pot extrapolar que: (i) el gradient de temperatura òptim es troba entre 7 i 16ºC; (ii) la variància en la transmitància tèrmica podria ser principalment atribuïda a canvis en la temperatura ambient de l’aire exterior; (iii) la IRT quantitativa interna és més acurada en parets compostes amb altes capacitats de calor per unitat d’àrea, aconseguint unes desviacions màximes del 0.20%; (iv) el test podria ser executat en només 30 minuts; (v) el mètode podria permetre l’avaluació d’aspectes relacionats amb la determinació de la U-value en edificis desocupats per T sota 10ºC, especialment a Espanya o països europeus amb un clima mediterrani on aquestes condicions de test podrien representar una limitació. Per tant, la presa de decisions es podria simplificar en entorns construïts reals. De fet, aquesta recerca podria conduir a una millor execució del procés de rehabilitació en edificis que s’espera que tinguin deficiències l’any 2050, augmentant així la taxa de renovació europea a mig termini. La dissertació conclou resumint les principals aportacions d’aquesta investigació. Els temes que s’han plantejat durant la recerca realitzada, i que no es van poder abordar, es comenten i es proposen com a línies de treball futures.

This Engineering Doctorate aims to understand the factors that generate variability in small power consumption in commercial office buildings in order to generate more representative, building specific estimates of energy consumption. Current energy modelling practices in England are heavily focussed on simplified calculations for compliance with Building Regulations, which exclude numerous sources of energy use such as small power. When considered, estimates of small power consumption are often based on historic benchmarks, which fail to capture the significant variability of this end-use, as well as the dynamic nature of office environments. Six interrelated studies are presented in this thesis resulting in three contributions to existing theory and practice. The first contribution consists of new monitored data of energy consumption and power demand profiles for individual small power equipment in use in contemporary office buildings. These were used to inform a critical review of existing benchmarks widely used by designers in the UK. In addition, monthly and annual small power consumption data for different tenants occupying similar buildings demonstrated variations of up to 73%. The second contribution consists of a cross-disciplinary investigation into the factors influencing small power consumption. A study based on the Theory of Planned Behaviour demonstrated that perceived behavioural control may account for 17% of the variation in electricity use by different tenants. A subsequent monitoring study at the equipment level identified that user attitudes and actions may have a greater impact on variations in energy consumption than job requirements or computer specification alone. The third contribution consists of two predictive models for estimating small power demand and energy consumption in office buildings. Outputs from both models were validated and demonstrated a good correlation between predictions and monitored data. This research also led to the development and publication of industry guidance on how to stimate operational energy use at the design stage.

<p>Since the dawn of civilization, timber has been a primary material for achieving great structural engineering feats. Yet during the late 19th century and most of the 20th century it lost currency as a preferred material for construction of large and tall multi-storey building superstructures. This Structural Engineering Document (SED) addresses a reawakening of interest in timber and timber-based products as primary con-struction materials for relatively tall, multi-storey buildings. Emphasis throughout is on holistically addressing various aspects of performance of complete systems, reflecting that major gaps in knowhow relate to design concepts rather than technical information about timber as a material. Special con-sideration is given to structural form, fire vulnerability, and durability aspects for attaining desired building performance over lifespans that can be centuries long.</p>

AbstractThis chapter discusses the organizational and occupational dimensions of resilience in temporary organizing contexts and how these contribute to sustained reliable performance. When dealing with issues related to high levels of safety in complex settings, longstanding organizations with strong organizational routines are often described as the most appropriate forms of organizing. However, temporary forms of organizing are developing and little is known on how actors engaged in such contexts can enhance and sustain resilience when facing uncertainty in safety-critical contexts. This chapter addresses this gap in the literature by demonstrating that temporary organizations, such as project-based ones, can also deal with major safety issues, and that temporary forms of organizing can help complex projects to be efficiently and safely carried out. We examine this proposition by studying the case of an inter-organizational and safety-critical project: the construction by a shipyard of a series of ships. Looking at the meso-level, i.e. the occupational groups involved in the project, we show how temporary forms of organizing and occupational groups together contribute to the resilience of the whole project. We highlight that the ability of the project to coordinate temporary organizing forms is key in achieving (safe) performance.

AbstractAquaponics’ potential to transform urban food production has been documented in a rapid increase of academic research and public interest in the field. To translate this publicity into real-world impact, the creation of commercial farms and their relationship to the urban environment have to be further examined. This research has to bridge the gap between existing literature on growing system performance and urban metabolic flows by considering the built form of aquaponic farms. To assess the potential for urban integration of aquaponics, existing case studies are classified by the typology of their building enclosure, with the two main categories being greenhouses and indoor environments. This classification allows for some assumptions about the farms’ performance in their context, but a more in-depth life cycle assessment (LCA) is necessary to evaluate different configurations. The LCA approach is presented as a way to inventory design criteria and respective strategies which can influence the environmental impact of aquaponic systems in the context of urban built environments.

AbstractThe influence of urban density on household electricity consumption is still scarcely investigated, despite the growing attention to building energy performance and the electrification of heating systems advocated at the European level. While the positive correlation between urban sprawl developments and the increasing of marginal costs of public infrastructures, services, amenities, public, and private transports are known, there has been little research on the relationship between urban form and electricity consumption in residential building stock. The present work aims to contribute to filling the gap in the existing literature, presenting the early results of ongoing research on the role of urban form in the household electricity consumption in Italy and, consequently, the related energy costs. The building typology and, in general, the structure of urban dwellings, is crucial to forecasting the electricity requirements, taking into account single housing units and their spatial composition in multi-family homes and neighborhoods. After a brief literature review on the topic, the contribution presents empirical research on the electricity consumption at the municipal level in 140 Italian cities, analyzing the diverse consumption patterns under different conditions of urban density to verify whether there exists a significant statistical correlation between them. The analysis confirms that there is a statistically negative correlation between urban density and the log of electricity consumption, even if its incidence is very limited. Further investigation may highlight whether there exists a threshold for which this relationship would be reversed, explaining the higher electricity consumption in dense metropolitan areas.

AbstractThe project BIM4EEB aims also to develop digital tools to support the design, procurement, installation, post-renovation operation, user feedback and profiling of building automation systems for HVAC. This helps supporting decision making, interaction with tenants and owners during the design, construction, and post-renovation operation phases. The development of the tools will be underpinned by a sound methodological approach. Work will include considerations of interoperability with Smart City technology of automation systems for HVAC. Specific objectives will be related to the development of the following software tools: A software component supporting the automatic generation of the layout for control systems emphasising on user preferences and including constraint checking of BAC-topologies against selected building codes. Data and information stored in BIM models are used to generate the initial recommendations and constraints and to deliver the final installation instructions. A software component allowing the seamless specification and evaluation of user comfort and systems performance. The underpinning information model will merge data sources from BIM (dimensional data) and BAC (factual data). An energy-refurbishment assessment tool, for bridging the gap between commercial simulators and the BIM management system. A user-profiling component allowing to compare expectations of tenants and owners regarding comfort and systems’ performance against monitored parameters. The results of this software component can be used in the pre- and post-renovation phases to update the content of BIM systems and thus to improve their accuracy and to reduce efforts for data acquisition and verification.

AbstractLegacy systems are business-critical software systems whose failure can have a significant impact on the business. Yet, their maintenance and adaption to changed requirements consume a considerable amount of the total software development costs. Frequently, domain experts and developers involved in the original development are not available anymore, making it difficult to adapt a legacy system without introducing bugs or unwanted behavior. This results in a dilemma: businesses are reluctant to change a working system, while at the same time struggling with its high maintenance costs. We propose the concept of Structured Software Reengineering replacing the ad hoc forward engineering part of a reengineering process with the application of behavior-preserving, proven-correct transformations improving nonfunctional program properties. Such transformations preserve valuable business logic while improving properties such as maintainability, performance, or portability to new platforms. Manually encoding and proving such transformations for industrial programming languages, for example, in interactive proof assistants, is a major challenge requiring deep expert knowledge. Existing frameworks for automatically proving transformation rules have limited expressiveness and are restricted to particular target applications such as compilation or peep-hole optimizations. We present Abstract Execution, a specification and verification framework for statement-based program transformation rules on JAVA programs building on symbolic execution. Abstract Execution supports universal quantification over statements or expressions and addresses properties about the (big-step) behavior of programs. Since this class of properties is useful for a plethora of applications, Abstract Execution bridges the gap between expressiveness and automation. In many cases, fully automatic proofs are in possible. We explain REFINITY, a workbench for modeling and proving statement-level JAVA transformation rules, and discuss our applications of Abstract Execution to code refactoring, cost analysis of program transformations, and transformations reshaping programs for the application of parallel design patterns.

This paper explores the use of new tools for the creation of novel methods of identifying faults in building energy performance remotely. With the rise in availability of interval utility data and the proliferation of machine learning processes, new methods are arising which promise to bridge the gap between architects, engineers, auditors, operators, and utility personnel. Utility use information, viewed with sufficient granularity, can offer a sort of “genome, ”that is a set of “genes” which are unique to a given building and can be decoded to provide information about the building’s performance. The applications of algorithms to a large data set of these “genomes” can identify patterns across many buildings, providing the opportunity for identifying mechanical faults in a much larger sample of buildings that could previously be evaluated using traditional methods.

The United States is well known for the birthplace of tall buildings in the world since the nineteenth century. The trend continued across all continents and in 1940, Europe developed its first tall building of over 100 meters in Genoa, Italy. Building codes, technological development, energy crisis, etc. have all influenced the built environment in different ways, a very visible sign of such impacts can be seen in high rise buildings not only on their architectural style but also on their performance. Different studies worldwide investigate energy performance of modern high-rise buildings; however, evolution of such buildings is rarely considered; energy performance of different high-rise buildings’ generations is seldom investigated and compared. To close a gap this study aims to make a closer look of how technological developments and energy crisis affected high-rise buildings in Europe with a focus on their energy performance.

In this report, we have evaluated the performance of nearly 40 global climate models (GCMs) participating in Phase 6 of the Coupled Model Intercomparison Project (CMIP6). The focus is on the northern European area, but the ability to simulate southern European and global climate is discussed as well. Model evaluation was started with a technical control; completely unrealistic values in the GCM output files were identified by seeking the absolute minimum and maximum values. In this stage, one GCM was rejected totally, and furthermore individual output files from two other GCMs. In evaluating the remaining GCMs, the primary tool was the Model Climate Performance Index (MCPI) that combines RMS errors calculated for the different climate variables into one index. The index takes into account both the seasonal and spatial variations in climatological means. Here, MCPI was calculated for the period 1981—2010 by comparing GCM output with the ERA-Interim reanalyses. Climate variables explored in the evaluation were the surface air temperature, precipitation, sea level air pressure and incoming solar radiation at the surface. Besides MCPI, we studied RMS errors in the seasonal course of the spatial means by examining each climate variable separately. Furthermore, the evaluation procedure considered model performance in simulating past trends in the global-mean temperature, the compatibility of future responses to different greenhouse-gas scenarios and the number of available scenario runs. Daily minimum and maximum temperatures were likewise explored in a qualitative sense, but owing to the non-existence of data from multiple GCMs, these variables were not incorporated in the quantitative validation. Four of the 37 GCMs that had passed the initial technical check were regarded as wholly unusable for scenario calculations: in two GCMs the responses to the different greenhouse gas scenarios were contradictory and in two other GCMs data were missing from one of the four key climate variables. Moreover, to reduce inter-GCM dependencies, no more than two variants of any individual GCM were included; this led to an abandonment of one GCM. The remaining 32 GCMs were divided into three quality classes according to the assessed performance. The users of model data can utilize this grading to select a subset of GCMs to be used in elaborating climate projections for Finland or adjacent areas. Annual-mean temperature and precipitation projections for Finland proved to be nearly identical regardless of whether they were derived from the entire ensemble or by ignoring models that had obtained the lowest scores. Solar radiation projections were somewhat more sensitive.

1.1 Macroeconomic summary Economic recovery has consistently outperformed the technical staff’s expectations following a steep decline in activity in the second quarter of 2020. At the same time, total and core inflation rates have fallen and remain at low levels, suggesting that a significant element of the reactivation of Colombia’s economy has been related to recovery in potential GDP. This would support the technical staff’s diagnosis of weak aggregate demand and ample excess capacity. The most recently available data on 2020 growth suggests a contraction in economic activity of 6.8%, lower than estimates from January’s Monetary Policy Report (-7.2%). High-frequency indicators suggest that economic performance was significantly more dynamic than expected in January, despite mobility restrictions and quarantine measures. This has also come amid declines in total and core inflation, the latter of which was below January projections if controlling for certain relative price changes. This suggests that the unexpected strength of recent growth contains elements of demand, and that excess capacity, while significant, could be lower than previously estimated. Nevertheless, uncertainty over the measurement of excess capacity continues to be unusually high and marked both by variations in the way different economic sectors and spending components have been affected by the pandemic, and by uneven price behavior. The size of excess capacity, and in particular the evolution of the pandemic in forthcoming quarters, constitute substantial risks to the macroeconomic forecast presented in this report. Despite the unexpected strength of the recovery, the technical staff continues to project ample excess capacity that is expected to remain on the forecast horizon, alongside core inflation that will likely remain below the target. Domestic demand remains below 2019 levels amid unusually significant uncertainty over the size of excess capacity in the economy. High national unemployment (14.6% for February 2021) reflects a loose labor market, while observed total and core inflation continue to be below 2%. Inflationary pressures from the exchange rate are expected to continue to be low, with relatively little pass-through on inflation. This would be compatible with a negative output gap. Excess productive capacity and the expectation of core inflation below the 3% target on the forecast horizon provide a basis for an expansive monetary policy posture. The technical staff’s assessment of certain shocks and their expected effects on the economy, as well as the presence of several sources of uncertainty and related assumptions about their potential macroeconomic impacts, remain a feature of this report. The coronavirus pandemic, in particular, continues to affect the public health environment, and the reopening of Colombia’s economy remains incomplete. The technical staff’s assessment is that the COVID-19 shock has affected both aggregate demand and supply, but that the impact on demand has been deeper and more persistent. Given this persistence, the central forecast accounts for a gradual tightening of the output gap in the absence of new waves of contagion, and as vaccination campaigns progress. The central forecast continues to include an expected increase of total and core inflation rates in the second quarter of 2021, alongside the lapse of the temporary price relief measures put in place in 2020. Additional COVID-19 outbreaks (of uncertain duration and intensity) represent a significant risk factor that could affect these projections. Additionally, the forecast continues to include an upward trend in sovereign risk premiums, reflected by higher levels of public debt that in the wake of the pandemic are likely to persist on the forecast horizon, even in the context of a fiscal adjustment. At the same time, the projection accounts for the shortterm effects on private domestic demand from a fiscal adjustment along the lines of the one currently being proposed by the national government. This would be compatible with a gradual recovery of private domestic demand in 2022. The size and characteristics of the fiscal adjustment that is ultimately implemented, as well as the corresponding market response, represent another source of forecast uncertainty. Newly available information offers evidence of the potential for significant changes to the macroeconomic scenario, though without altering the general diagnosis described above. The most recent data on inflation, growth, fiscal policy, and international financial conditions suggests a more dynamic economy than previously expected. However, a third wave of the pandemic has delayed the re-opening of Colombia’s economy and brought with it a deceleration in economic activity. Detailed descriptions of these considerations and subsequent changes to the macroeconomic forecast are presented below. The expected annual decline in GDP (-0.3%) in the first quarter of 2021 appears to have been less pronounced than projected in January (-4.8%). Partial closures in January to address a second wave of COVID-19 appear to have had a less significant negative impact on the economy than previously estimated. This is reflected in figures related to mobility, energy demand, industry and retail sales, foreign trade, commercial transactions from selected banks, and the national statistics agency’s (DANE) economic tracking indicator (ISE). Output is now expected to have declined annually in the first quarter by 0.3%. Private consumption likely continued to recover, registering levels somewhat above those from the previous year, while public consumption likely increased significantly. While a recovery in investment in both housing and in other buildings and structures is expected, overall investment levels in this case likely continued to be low, and gross fixed capital formation is expected to continue to show significant annual declines. Imports likely recovered to again outpace exports, though both are expected to register significant annual declines. Economic activity that outpaced projections, an increase in oil prices and other export products, and an expected increase in public spending this year account for the upward revision to the 2021 growth forecast (from 4.6% with a range between 2% and 6% in January, to 6.0% with a range between 3% and 7% in April). As a result, the output gap is expected to be smaller and to tighten more rapidly than projected in the previous report, though it is still expected to remain in negative territory on the forecast horizon. Wide forecast intervals reflect the fact that the future evolution of the COVID-19 pandemic remains a significant source of uncertainty on these projections. The delay in the recovery of economic activity as a result of the resurgence of COVID-19 in the first quarter appears to have been less significant than projected in the January report. The central forecast scenario expects this improved performance to continue in 2021 alongside increased consumer and business confidence. Low real interest rates and an active credit supply would also support this dynamic, and the overall conditions would be expected to spur a recovery in consumption and investment. Increased growth in public spending and public works based on the national government’s spending plan (Plan Financiero del Gobierno) are other factors to consider. Additionally, an expected recovery in global demand and higher projected prices for oil and coffee would further contribute to improved external revenues and would favor investment, in particular in the oil sector. Given the above, the technical staff’s 2021 growth forecast has been revised upward from 4.6% in January (range from 2% to 6%) to 6.0% in April (range from 3% to 7%). These projections account for the potential for the third wave of COVID-19 to have a larger and more persistent effect on the economy than the previous wave, while also supposing that there will not be any additional significant waves of the pandemic and that mobility restrictions will be relaxed as a result. Economic growth in 2022 is expected to be 3%, with a range between 1% and 5%. This figure would be lower than projected in the January report (3.6% with a range between 2% and 6%), due to a higher base of comparison given the upward revision to expected GDP in 2021. This forecast also takes into account the likely effects on private demand of a fiscal adjustment of the size currently being proposed by the national government, and which would come into effect in 2022. Excess in productive capacity is now expected to be lower than estimated in January but continues to be significant and affected by high levels of uncertainty, as reflected in the wide forecast intervals. The possibility of new waves of the virus (of uncertain intensity and duration) represents a significant downward risk to projected GDP growth, and is signaled by the lower limits of the ranges provided in this report. Inflation (1.51%) and inflation excluding food and regulated items (0.94%) declined in March compared to December, continuing below the 3% target. The decline in inflation in this period was below projections, explained in large part by unanticipated increases in the costs of certain foods (3.92%) and regulated items (1.52%). An increase in international food and shipping prices, increased foreign demand for beef, and specific upward pressures on perishable food supplies appear to explain a lower-than-expected deceleration in the consumer price index (CPI) for foods. An unexpected increase in regulated items prices came amid unanticipated increases in international fuel prices, on some utilities rates, and for regulated education prices. The decline in annual inflation excluding food and regulated items between December and March was in line with projections from January, though this included downward pressure from a significant reduction in telecommunications rates due to the imminent entry of a new operator. When controlling for the effects of this relative price change, inflation excluding food and regulated items exceeds levels forecast in the previous report. Within this indicator of core inflation, the CPI for goods (1.05%) accelerated due to a reversion of the effects of the VAT-free day in November, which was largely accounted for in February, and possibly by the transmission of a recent depreciation of the peso on domestic prices for certain items (electric and household appliances). For their part, services prices decelerated and showed the lowest rate of annual growth (0.89%) among the large consumer baskets in the CPI. Within the services basket, the annual change in rental prices continued to decline, while those services that continue to experience the most significant restrictions on returning to normal operations (tourism, cinemas, nightlife, etc.) continued to register significant price declines. As previously mentioned, telephone rates also fell significantly due to increased competition in the market. Total inflation is expected to continue to be affected by ample excesses in productive capacity for the remainder of 2021 and 2022, though less so than projected in January. As a result, convergence to the inflation target is now expected to be somewhat faster than estimated in the previous report, assuming the absence of significant additional outbreaks of COVID-19. The technical staff’s year-end inflation projections for 2021 and 2022 have increased, suggesting figures around 3% due largely to variation in food and regulated items prices. The projection for inflation excluding food and regulated items also increased, but remains below 3%. Price relief measures on indirect taxes implemented in 2020 are expected to lapse in the second quarter of 2021, generating a one-off effect on prices and temporarily affecting inflation excluding food and regulated items. However, indexation to low levels of past inflation, weak demand, and ample excess productive capacity are expected to keep core inflation below the target, near 2.3% at the end of 2021 (previously 2.1%). The reversion in 2021 of the effects of some price relief measures on utility rates from 2020 should lead to an increase in the CPI for regulated items in the second half of this year. Annual price changes are now expected to be higher than estimated in the January report due to an increased expected path for fuel prices and unanticipated increases in regulated education prices. The projection for the CPI for foods has increased compared to the previous report, taking into account certain factors that were not anticipated in January (a less favorable agricultural cycle, increased pressure from international prices, and transport costs). Given the above, year-end annual inflation for 2021 and 2022 is now expected to be 3% and 2.8%, respectively, which would be above projections from January (2.3% and 2,7%). For its part, expected inflation based on analyst surveys suggests year-end inflation in 2021 and 2022 of 2.8% and 3.1%, respectively. There remains significant uncertainty surrounding the inflation forecasts included in this report due to several factors: 1) the evolution of the pandemic; 2) the difficulty in evaluating the size and persistence of excess productive capacity; 3) the timing and manner in which price relief measures will lapse; and 4) the future behavior of food prices. Projected 2021 growth in foreign demand (4.4% to 5.2%) and the supposed average oil price (USD 53 to USD 61 per Brent benchmark barrel) were both revised upward. An increase in long-term international interest rates has been reflected in a depreciation of the peso and could result in relatively tighter external financial conditions for emerging market economies, including Colombia. Average growth among Colombia’s trade partners was greater than expected in the fourth quarter of 2020. This, together with a sizable fiscal stimulus approved in the United States and the onset of a massive global vaccination campaign, largely explains the projected increase in foreign demand growth in 2021. The resilience of the goods market in the face of global crisis and an expected normalization in international trade are additional factors. These considerations and the expected continuation of a gradual reduction of mobility restrictions abroad suggest that Colombia’s trade partners could grow on average by 5.2% in 2021 and around 3.4% in 2022. The improved prospects for global economic growth have led to an increase in current and expected oil prices. Production interruptions due to a heavy winter, reduced inventories, and increased supply restrictions instituted by producing countries have also contributed to the increase. Meanwhile, market forecasts and recent Federal Reserve pronouncements suggest that the benchmark interest rate in the U.S. will remain stable for the next two years. Nevertheless, a significant increase in public spending in the country has fostered expectations for greater growth and inflation, as well as increased uncertainty over the moment in which a normalization of monetary policy might begin. This has been reflected in an increase in long-term interest rates. In this context, emerging market economies in the region, including Colombia, have registered increases in sovereign risk premiums and long-term domestic interest rates, and a depreciation of local currencies against the dollar. Recent outbreaks of COVID-19 in several of these economies; limits on vaccine supply and the slow pace of immunization campaigns in some countries; a significant increase in public debt; and tensions between the United States and China, among other factors, all add to a high level of uncertainty surrounding interest rate spreads, external financing conditions, and the future performance of risk premiums. The impact that this environment could have on the exchange rate and on domestic financing conditions represent risks to the macroeconomic and monetary policy forecasts. Domestic financial conditions continue to favor recovery in economic activity. The transmission of reductions to the policy interest rate on credit rates has been significant. The banking portfolio continues to recover amid circumstances that have affected both the supply and demand for loans, and in which some credit risks have materialized. Preferential and ordinary commercial interest rates have fallen to a similar degree as the benchmark interest rate. As is generally the case, this transmission has come at a slower pace for consumer credit rates, and has been further delayed in the case of mortgage rates. Commercial credit levels stabilized above pre-pandemic levels in March, following an increase resulting from significant liquidity requirements for businesses in the second quarter of 2020. The consumer credit portfolio continued to recover and has now surpassed February 2020 levels, though overall growth in the portfolio remains low. At the same time, portfolio projections and default indicators have increased, and credit establishment earnings have come down. Despite this, credit disbursements continue to recover and solvency indicators remain well above regulatory minimums. 1.2 Monetary policy decision In its meetings in March and April the BDBR left the benchmark interest rate unchanged at 1.75%.

The project was originally aimed at investigating and developing new efficient methods for cost effective removal of ammonia (NH₃) and hydrogen sulfide (H₂S) from Concentrated Animal Feeding Operations (CAFO), in particular broiler and laying houses (NH₃) and hog houses (H₂S). In both cases, the principal idea was to design and operate a dedicated air collection system that would be used for the treatment of the gases, and that would work independently from the general ventilation system. The advantages envisaged: (1) if collected at a point close to the source of generation, pollutants would arrive at the treatment system at higher concentrations; (2) the air in the vicinity of the animals would be cleaner, a fact that would promote animal growth rates; and (3) collection efficiency would be improved and adverse environmental impact reduced. For practical reasons, the project was divided in two: one effort concentrated on NH₃₍g₎ removal from chicken houses and another on H₂S₍g₎ removal from hog houses. NH₃₍g₎ removal: a novel approach was developed to reduce ammonia emissions from CAFOs in general, and poultry houses in particular. Air sucked by the dedicated air capturing system from close to the litter was shown to have NH₃₍g₎ concentrations an order of magnitude higher than at the vents of the ventilation system. The NH₃₍g₎ rich waste air was conveyed to an acidic (0<pH<~5) bubble column reactor where NH₃ was converted to NH₄⁺. The reactor operated in batch mode, starting at pH 0 and was switched to a new acidic absorption solution just before NH₃₍g₎ breakthrough occurred, at pH ~5. Experiments with a wide range of NH₃₍g₎ concentrations showed that the absorption efficiency was practically 100% throughout the process as long as the face velocity was below 4 cm/s. The potential advantages of the method include high absorption efficiency, lower NH₃₍g₎ concentrations in the vicinity of the birds, generation of a valuable product and the separation between the ventilation and ammonia treatment systems. A small scale pilot operation conducted for 5 weeks in a broiler house showed the approach to be technically feasible. H₂S₍g₎ removal: The main goal of this part was to develop a specific treatment process for minimizing H₂S₍g₎ emissions from hog houses. The proposed process consists of three units: In the 1ˢᵗ H₂S₍g₎ is absorbed into an acidic (pH<2) ferric iron solution and oxidized by Fe(III) to S⁰ in a bubble column reactor. In parallel, Fe(III) is reduced to Fe(II). In the 2ⁿᵈ unit Fe(II) is bio-oxidized back to Fe(III) by Acidithiobacillus ferrooxidans (AF).In the 3ʳᵈ unit S⁰ is separated from solution in a gravity settler. The work focused on three sub-processes: the kinetics of H₂S absorption into a ferric solution at low pH, the kinetics of Fe²⁺ oxidation by AF and the factors that affect ferric iron precipitation (a main obstacle for a continuous operation of the process) under the operational conditions. H₂S removal efficiency was found higher at a higher Fe(III) concentration and also higher for higher H₂S₍g₎ concentrations and lower flow rates of the treated air. The rate limiting step of the H₂S reactive absorption was found to be the chemical reaction rather than the transition from gas to liquid phase. H₂S₍g₎ removal efficiency of >95% was recorded with Fe(III) concentration of 9 g/L using typical AFO air compositions. The 2ⁿᵈ part of the work focused on kinetics of Fe(II) oxidation by AF. A new lab technique was developed for determining the kinetic equation and kinetic parameters (KS, Kₚ and mₘₐₓ) for the bacteria. The 3ʳᵈ part focused on iron oxide precipitation under the operational conditions. It was found that at lower pH (1.5) jarosite accumulation is slower and that the performance of the AF at this pH was sufficient for successive operation of the proposed process at the H₂S fluxes predicted from AFOs. A laboratory-scale test was carried out at Purdue University on the use of the integrated system for simultaneous hydrogen sulfide removal from a H₂S bubble column filled with ferric sulfate solution and biological regeneration of ferric ions in a packed column immobilized with enriched AFbacteria. Results demonstrated the technical feasibility of the integrated system for H₂S removal and simultaneous biological regeneration of Fe(III) for potential continuous treatment of H₂S released from CAFO. NH₃ and H₂S gradient measurements at egg layer and swine barns were conducted in winter and summer at Purdue. Results showed high potential to concentrate NH₃ and H₂S in hog buildings, and NH₃ in layer houses. H₂S emissions from layer houses were too low for a significant gradient. An NH₃ capturing system was designed and tested in a 100-chicken broiler room. Five bell-type collecting devices were installed over the litter to collect NH₃ emissions. While the air extraction system moved only 10% of the total room ventilation airflow rate, the fraction of total ammonia removed was 18%, because of the higher concentration air taken from near the litter. The system demonstrated the potential to reduce emissions from broiler facilities and to concentrate the NH₃ effluent for use in an emission control system. In summary, the project laid a solid foundation for the implementation of both processes, and also resulted in a significant scientific contribution related to AF kinetic studies and ferrous analytical measurements.

Prefabricated modular steel (PFMS) construction is a more efficient and safe method of constructing a high-quality building with less waste material and labour dependency than traditional steel construction. It is indeed critical to have a precise and valuable intermodular joining system that allows for efficient load transfer, safe handling, and optimal use of modular units' strength. Thus, the purpose of this study was to develop joints using tension bolts and solid tenons welded into the gusset plate (GP). These joints ensured rigid and secure connectivity in both horizontal and vertical directions for the modular units. Using the three-dimensional (3D) finite element (FE) analysis software ABAQUS, the study investigated the nonlinear lateral structural performance of the joint and two-storey modular steel building (MSB). The solid element FE models of joints were then simplified by introducing connectors and beam elements to enhance computational efficiency. Numerous parameters indicated that column tenons were important in determining the joint's structural performance. Moreover, with a standard deviation (SD) of 0.025, the developed connectors and beam element models accurately predicted the structural behaviour of the joints. As a result of their simplification, these joints demonstrated effective load distribution, seismic performance, and ductility while reducing computational time, effort, and complexity. The validity of the FE analysis was then determined by comparing the results to the thirteen joint bending tests performed in the reference.

This report maps the African landscape of Open Science – with a focus on Open Data as a sub-set of Open Science. Data to inform the landscape study were collected through a variety of methods, including surveys, desk research, engagement with a community of practice, networking with stakeholders, participation in conferences, case study presentations, and workshops hosted. Although the majority of African countries (35 of 54) demonstrates commitment to science through its investment in research and development (R&D), academies of science, ministries of science and technology, policies, recognition of research, and participation in the Science Granting Councils Initiative (SGCI), the following countries demonstrate the highest commitment and political willingness to invest in science: Botswana, Ethiopia, Kenya, Senegal, South Africa, Tanzania, and Uganda. In addition to existing policies in Science, Technology and Innovation (STI), the following countries have made progress towards Open Data policies: Botswana, Kenya, Madagascar, Mauritius, South Africa and Uganda. Only two African countries (Kenya and South Africa) at this stage contribute 0.8% of its GDP (Gross Domestic Product) to R&D (Research and Development), which is the closest to the AU’s (African Union’s) suggested 1%. Countries such as Lesotho and Madagascar ranked as 0%, while the R&D expenditure for 24 African countries is unknown. In addition to this, science globally has become fully dependent on stable ICT (Information and Communication Technologies) infrastructure, which includes connectivity/bandwidth, high performance computing facilities and data services. This is especially applicable since countries globally are finding themselves in the midst of the 4th Industrial Revolution (4IR), which is not only “about” data, but which “is” data. According to an article1 by Alan Marcus (2015) (Senior Director, Head of Information Technology and Telecommunications Industries, World Economic Forum), “At its core, data represents a post-industrial opportunity. Its uses have unprecedented complexity, velocity and global reach. As digital communications become ubiquitous, data will rule in a world where nearly everyone and everything is connected in real time. That will require a highly reliable, secure and available infrastructure at its core, and innovation at the edge.” Every industry is affected as part of this revolution – also science. An important component of the digital transformation is “trust” – people must be able to trust that governments and all other industries (including the science sector), adequately handle and protect their data. This requires accountability on a global level, and digital industries must embrace the change and go for a higher standard of protection. “This will reassure consumers and citizens, benefitting the whole digital economy”, says Marcus. A stable and secure information and communication technologies (ICT) infrastructure – currently provided by the National Research and Education Networks (NRENs) – is key to advance collaboration in science. The AfricaConnect2 project (AfricaConnect (2012–2014) and AfricaConnect2 (2016–2018)) through establishing connectivity between National Research and Education Networks (NRENs), is planning to roll out AfricaConnect3 by the end of 2019. The concern however is that selected African governments (with the exception of a few countries such as South Africa, Mozambique, Ethiopia and others) have low awareness of the impact the Internet has today on all societal levels, how much ICT (and the 4th Industrial Revolution) have affected research, and the added value an NREN can bring to higher education and research in addressing the respective needs, which is far more complex than simply providing connectivity. Apart from more commitment and investment in R&D, African governments – to become and remain part of the 4th Industrial Revolution – have no option other than to acknowledge and commit to the role NRENs play in advancing science towards addressing the SDG (Sustainable Development Goals). For successful collaboration and direction, it is fundamental that policies within one country are aligned with one another. Alignment on continental level is crucial for the future Pan-African African Open Science Platform to be successful. Both the HIPSSA ((Harmonization of ICT Policies in Sub-Saharan Africa)3 project and WATRA (the West Africa Telecommunications Regulators Assembly)4, have made progress towards the regulation of the telecom sector, and in particular of bottlenecks which curb the development of competition among ISPs. A study under HIPSSA identified potential bottlenecks in access at an affordable price to the international capacity of submarine cables and suggested means and tools used by regulators to remedy them. Work on the recommended measures and making them operational continues in collaboration with WATRA. In addition to sufficient bandwidth and connectivity, high-performance computing facilities and services in support of data sharing are also required. The South African National Integrated Cyberinfrastructure System5 (NICIS) has made great progress in planning and setting up a cyberinfrastructure ecosystem in support of collaborative science and data sharing. The regional Southern African Development Community6 (SADC) Cyber-infrastructure Framework provides a valuable roadmap towards high-speed Internet, developing human capacity and skills in ICT technologies, high- performance computing and more. The following countries have been identified as having high-performance computing facilities, some as a result of the Square Kilometre Array7 (SKA) partnership: Botswana, Ghana, Kenya, Madagascar, Mozambique, Mauritius, Namibia, South Africa, Tunisia, and Zambia. More and more NRENs – especially the Level 6 NRENs 8 (Algeria, Egypt, Kenya, South Africa, and recently Zambia) – are exploring offering additional services; also in support of data sharing and transfer. The following NRENs already allow for running data-intensive applications and sharing of high-end computing assets, bio-modelling and computation on high-performance/ supercomputers: KENET (Kenya), TENET (South Africa), RENU (Uganda), ZAMREN (Zambia), EUN (Egypt) and ARN (Algeria). Fifteen higher education training institutions from eight African countries (Botswana, Benin, Kenya, Nigeria, Rwanda, South Africa, Sudan, and Tanzania) have been identified as offering formal courses on data science. In addition to formal degrees, a number of international short courses have been developed and free international online courses are also available as an option to build capacity and integrate as part of curricula. The small number of higher education or research intensive institutions offering data science is however insufficient, and there is a desperate need for more training in data science. The CODATA-RDA Schools of Research Data Science aim at addressing the continental need for foundational data skills across all disciplines, along with training conducted by The Carpentries 9 programme (specifically Data Carpentry 10 ). Thus far, CODATA-RDA schools in collaboration with AOSP, integrating content from Data Carpentry, were presented in Rwanda (in 2018), and during17-29 June 2019, in Ethiopia. Awareness regarding Open Science (including Open Data) is evident through the 12 Open Science-related Open Access/Open Data/Open Science declarations and agreements endorsed or signed by African governments; 200 Open Access journals from Africa registered on the Directory of Open Access Journals (DOAJ); 174 Open Access institutional research repositories registered on openDOAR (Directory of Open Access Repositories); 33 Open Access/Open Science policies registered on ROARMAP (Registry of Open Access Repository Mandates and Policies); 24 data repositories registered with the Registry of Data Repositories (re3data.org) (although the pilot project identified 66 research data repositories); and one data repository assigned the CoreTrustSeal. Although this is a start, far more needs to be done to align African data curation and research practices with global standards. Funding to conduct research remains a challenge. African researchers mostly fund their own research, and there are little incentives for them to make their research and accompanying data sets openly accessible. Funding and peer recognition, along with an enabling research environment conducive for research, are regarded as major incentives. The landscape report concludes with a number of concerns towards sharing research data openly, as well as challenges in terms of Open Data policy, ICT infrastructure supportive of data sharing, capacity building, lack of skills, and the need for incentives. Although great progress has been made in terms of Open Science and Open Data practices, more awareness needs to be created and further advocacy efforts are required for buy-in from African governments. A federated African Open Science Platform (AOSP) will not only encourage more collaboration among researchers in addressing the SDGs, but it will also benefit the many stakeholders identified as part of the pilot phase. The time is now, for governments in Africa, to acknowledge the important role of science in general, but specifically Open Science and Open Data, through developing and aligning the relevant policies, investing in an ICT infrastructure conducive for data sharing through committing funding to making NRENs financially sustainable, incentivising open research practices by scientists, and creating opportunities for more scientists and stakeholders across all disciplines to be trained in data management.