Search

Research has shown the large effect that occupants have on buildings' performance. Uncertainties related to the actual energy consumption of buildings increase the risks for the investments in low carbon technologies. Monitoring building occupancy can potentially decrease these uncertainties by providing more information about the occupants and their behaviour. The objective of the investigation is to establish an approach to inform the design process (e.g. building simulation) by addressing the complexity of occupants behaviour. The approach integrates information on occupants' behaviour and attitudes regarding energy use and indoor conditions to determine the requirements for building simulation and energy calculations. This paper presents the results of two monitoring campaigns in which the approach was employed. The monitoring campaigns focused on two owner-inhabited apartments in Spain and three social rental dwellings in The Netherlands. The results have given first insights of the power of the methodology to obtain detailed and understandable data on the occupancy patterns. This investigation highlighted the importance socio-economical status and attitudes towards energy conservation on occupants' behaviour in residential buildings. The methods described in this paper can be readily used to develop occupancy and heating profiles for monitored households to be used in building simulation programs. [ABSTRACT FROM AUTHOR]

Occupants account for a significant impact on building performance through their interactions with zone level building components. Empirically-derived occupant models, despite their potential to represent occupants’ impact in building performance simulation (BPS), have minimal penetration in design and code compliance processes. Instead, occupants are represented with static schedules or simple deterministic triggers. The objective of this paper is to better understand the influence of assumptions made in representing occupant interactions with building components over a BPS model's energy use and comfort predictions, as well as their ability to promote better design decisions. To this end, the energy and daylight performance of a generic perimeter office space in Ottawa, Canada were evaluated using a set of comprehensive performance metrics. Results indicate that representing dynamic occupant–building interactions lead to different energy predictions from the static schedules. The maximum difference in the total electricity use was for window-to-wall area ratios (WWR) of 20%, which was about 30% higher with the stochastic cases than the blind-open static cases. WWR 60% and 40% generally yielded the lowest lighting electricity use with the static and stochastic cases, respectively. This paper emphasizes the importance of incorporating empirically-derived dynamic occupant models for simulation-aided design and code compliance. [ABSTRACT FROM AUTHOR]

In a hybrid cooling system, an indirect evaporative cooling (IEC) unit is installed before an air handling unit to pre-cool the incoming fresh air, in order to reduce the energy consumption of the air-conditioning system. When the system is applied in humid regions, as the dew point temperature of the fresh air is higher, condensation will probably occur in the dry channels of IEC unit. However, the model of IEC unit considering condensation had been seldom studied, which would become an obstacle in predicting the performance of the hybrid system. In order to evaluate its energy saving potential precisely, the paper aims to establish a short-cut model for predicting the annual performance of the hybrid cooling system considering condensation in IEC unit. This paper firstly presents the analytical models for IEC under non-condensation, totally condensation and partially condensation states and proposed a method for judging the three states as well. The models were validated by the published data from literatures. The validated model was then incorporated with TRNSYS for predicting the performance of an IEC hybrid cooling system in a wet market in Hong Kong and the annual simulation results were validated by a field measurement with good agreement. [ABSTRACT FROM AUTHOR]

Highlights • The weighted average values of thermal energy consumption (oil and natural gas) for space heating, as of 2011, of the complete stock of buildings in Greece used as primary residences (insulated or not, single-dwellings or apartments), is estimated to 60.9 up to 130.1 KWh·m−2·year−1. • The mean actual thermal energy consumption for space heating of residential buildings is much lower than that evaluated based on HDHs or the method of Hellenic Building Energy Performance Regulation (REPB), according to European Directive 31/2010. • The implementation of the Hellenic regulation for building energy performance (REPB) imposed the improvement of thermal protection of the building envelope and the performance of the electrical and mechanical systems. • Applying the REPB minimum requirements on thermal protection reduce the space heating loads of residential buildings in all climate zones by 63% to 70%. The compliance of existing residential buildings to the minimum requirements of the REPB could result to about 24.4 TWh of savings in space heating energy annually. • The benefits of any National Regulation on Building Energy Performance should be examined on the basis of expected lower actual energy consumption. Abstract This paper presents the energy, the technical and the environmental characteristics of residential buildings in Greece, as well as their potential for energy conservation, based on their actual energy consumption data. The technical characteristics of residential buildings related to their energy performance (insulation, type of openings, system for space heating and cooling, etc.), the actual energy use (kWh.m−2.year−1) and the environmental factors (kgCO₂.m−2.year−1) related to energy consumption, are some of the parameters of this survey. The average annual specific energy consumption of residential buildings in Greece was 112 kWh·m−2·year−1 in 2014, the 6th lower consumption among the 28 European member states (EU-28) in which the average residential building energy consumption is of about 158.8 kWh·m−2·year−1. The potential of space heating energy conservation for Greek residential buildings was estimated, based on (i) the 2011 heating energy consumption data and (ii) the percentages of space heating energy conservation, calculated by analysing 144 different types of residential buildings, having various geometric and technical characteristics, such as the A/V ratio (envelope area to volume of building), the heating degree hours (HDHs) and various occupancy profiles. The resulting average actual energy consumption is much lower than that calculated using Heating Degree Hours (HDHs) or the method of Hellenic Building Energy Performance Regulation (REPB). Almost 45% of these buildings were built before 1980, without any thermal insulation or double glazing. The compliance of these buildings to the minimum requirements of the REPB (related to thermal insulation and the efficiency of their electromechanical systems), could result to about 24.4 TWh of savings in space heating energy annually, i.e. to about 32–175 kWh·m−2·year−1, depending on the climate zone that corresponds to 8.5–46.2 kgCO₂·m−2·year−1 reduction. [ABSTRACT FROM AUTHOR]

Abstract Convenience stores are known to have higher Energy Use Intensities (EUIs) than most other commercial building types. However, convenience store energy performance analyses have not been systematically investigated. Moreover, current national convenience store benchmarks are inconsistent from one data base to another due to lack of relevant energy data. This paper assesses the energy performance of more than five hundred convenience stores in the same fleet in Eastern United States. The investigation aims to establish benchmarks for convenience stores with and without gasoline pumping stations. The main factors influencing the actual convenience store building energy use were determined. Multiple regression models were developed to find relationships between annual energy consumption per unit area and gross floor area, customer transaction count, building operating year, etc. The statistically characterized results are meant to serve as a reference data set in comparing the whole-building energy performance index for buildings of similar functionality. The statistical correlation analyses can strengthen the robust prediction of energy performance in convenience stores, enabling proper assessment of energy conservation measurements (ECMs) for convenience store operations, as well as guiding additional such energy performance studies. [ABSTRACT FROM AUTHOR]

Abstract: This paper aims to study the various parameters that affect the energy performance of commercial buildings in Singapore. The parameters are diverse, ranging from characteristics of construction of the walls and windows, to the various system settings and types within the building. Building energy performance is measured via two key indexes, namely, the Envelope Thermal Transfer Value (ETTV) and the annual cooling energy requirement (E c). Parameters related to these two indexes are identified. An additional parameter, the solar absorptance of the wall, is further incorporated to calibrate the ETTV equation. A relative ranking on the functional parameters of ETTV has been performed to evaluate their effectiveness in lowering the ETTV of buildings. In addition, the impact of using cladding on ETTV is also studied. A correlation for E c, expressed in the form of a simple linear equation, has been developed. This correlation accounts for the internal building loads, envelope loads, operating schedules and efficiency of the cooling equipment. Finally, ETTV and E c have been employed to study the effects of chiller over-sizing and ventilation rates on building cooling energy. In the pursuit for better energy-efficient buildings, the approach presented in this paper contributes to the construct of sustainable energy-efficient built-environment. [Copyright &y& Elsevier]

The application of retrofit actions to existing building stocks can improve the energy performance of the residential sector. In this context, particular attention should be given to historical buildings, which represent a large part of the Italian building stock. To improve the energy performance of them, adequate retrofit actions must be applied. Many studies and regulations have focused on identifying the best refurbishment measures. However, the selection of these measures is difficult due to restrictive regulations, which are dictated by the Ministry of Cultural Heritage and Activities, high retrofit costs, and variable climate zones. Thus, energy renovations in Italian buildings are not simple, and it is very difficult to find generic solutions that can be applied to buildings across the entire territory. In this paper, the authors investigated the most common retrofit solutions used in Italy, focusing in particular on the energy performance of historical building envelopes. First, energy performance analyses were conducted for two typical base cases in four different Italian cities using TRNSYS software, and some common retrofit measures were analysed. In some cases, the results showed Primary Energy saving of 44.6% (sample A) and 56.7% (sample B). Furthermore, these were used to identify different energy and economic impacts associated with the same refurbishment measures in different climatic contexts, highlighting the non-existence of a generic solution suitable for all regions or countries. [ABSTRACT FROM AUTHOR]

A great number of low carbon technologies have been developed in the last decades. The use of such technologies promises good indoor environment for the building's occupants, lower energy consumption and carbon emissions. However, there are uncertainties related to payback periods and usability constraints of low carbon technologies. In addition, past and current research has shown differences between the expected and the actual performance of buildings, both in terms of energy consumption and indoor comfort. For a better understanding of differences between expected and actual performance of buildings, it is necessary to investigate the energy consumption, the behaviour of the occupants and their interaction with new technologies, and the resulting indoor comfort. Monitoring building performance can help to reduce the uncertainties related to the building performance of buildings. This paper presents an overview and classification of data collection methods to monitor the energy consumption, thermal comfort of occupants and the operation of buildings in use. Data collection methods and techniques are categorised and linked to specific methods to evaluate building performance and recommendations are made to set up building monitoring research. By identifying the most effective methods to monitor buildings, this research aims at embedding performance monitoring in standard practice. [ABSTRACT FROM AUTHOR]

Building energy assessment methods, used in a regulatory context, impose a calculation procedure under restricted and predefined conditions to check preset energy performance levels. Standardized boundary conditions and input data are implemented allowing for objective evaluation of various building designs. Focusing on school buildings in particular, these specific boundary conditions are however often inaccurate or even unavailable. Therefore, throughout this paper, typical school characteristics and their uncertainty are studied. The impact on the energy demand calculations is then demonstrated in an uncertainty analysis using the Monte Carlo analysis method combined with the Latin Hypercube sampling technique. A sensitivity analysis, using the elementary effect method of Morris, reveals the set point temperature, load and users’ profiles of lighting and equipment in class rooms as the most dominant input parameters on which additional surveys and questioning are focused to determine possible inaccuracies and to define, where necessary, new, more realistic boundary conditions. As a final result, a list of representative boundary conditions for Flemish schools is determined which can be used directly or can be converted into averaged input data for simplified calculation methods. [ABSTRACT FROM AUTHOR]

• A precise framework is presented, facilitating a reliable data acquisition. • UAS enable fast & automated data acquisition to assess building's energy performance. • Data storage using BIM facilitates consistent assessment of energy performance. The following paper presents a framework for an assessment of energy performance of buildings based on the identification of physical parameters characterizing a building regarding its thermal behavior. Data acquisition within this framework is performed primarily by using UAS, equipped with RGB-camera and thermography-camera for a simultaneous application during the flight. To ensure a reproducible flight for the parallel acquisition of thermography and RGB data, a flight path automatically computed from a basic three-dimensional model is used. An estimation of U-value is applied to the thermography data obtained, allowing the derivation of a probable material set of the investigated structure. The framework also proposes suitable data models for data storage and management to act as a foundation for all algorithmic components, including numerical assessment of energy performance of buildings. Conclusively the framework is applied on a school building illustrating the previously defined methods. The validation of the Building Performance Simulation (BPS) performed within this framework shows an oscillation of Mean Bias Error (MBE) for the heat demand between −6.4% and 6.3%. [ABSTRACT FROM AUTHOR]

Abstract: The architectural design variables which most influence the energy performance of a building are the envelope materials, shape and window areas. As these start to be defined in the early design stages, designers require simple tools to obtain information about the energy performance of the building for the design variations being considered at this phase. The shape factor is one of those tools, but it fails to correlate with energy demand in the presence of important solar gains. This paper presents a new design indicator of energy performance for residential buildings, the Envelope-Related Energy Demand (ERED), which aims to overcome the shortcomings of the shape factor while maintaining a reasonable simplicity of use. The inputs to ERED are areas of envelope elements (floor, walls, roofs and windows), U-values of envelope materials, solar heat gain coefficients (SHGC) of windows and site related parameters, concerning temperature and solar irradiation. ERED was validated against detailed simulation results of 8000 hypothetical residential buildings, varying in envelope shape, window areas and materials. Results show that there is a strong correlation between ERED and simulated energy demand. These results confirm the adequacy of ERED to assist design decisions in early stages of the design process. [Copyright &y& Elsevier]

Abstract: An archetypal simulation model of office building representing variability in UK office building stock by parameterising built form, construction elements, occupancy/usage and operational/control strategy has been developed thus enabling detailed energy performance simulation to be used for stock modelling and parametric studies. The paper discusses the building characteristics needed to be considered for energy performance simulation, their values, and how they can be used in parametric studies. These parameters include built forms, fabrics (including thermal mass and insulation positioning), glazing percentages and characteristics, daylight and solar control measures and activity and operational related parameters (heating and cooling set points, ventilation rate, occupancy density and metabolic rate, equipment and lighting gain). The default parameter values suggested for the archetypal simulation model reflect typical existing and currently proposed UK office building stock. An archetypal model, combined with parametric studies, can be used in assessing energy performance of building stock and evaluating adaptation/retrofitting strategies. [Copyright &y& Elsevier]

Abstract: This paper presents the results of a recent research effort to collect and analyze data pertaining to traditional bath buildings (“hammams”) in Egypt, Turkey, Morocco, Syria, and Algeria. Thereby, the energy performance of and the thermal comfort conditions in five such buildings were studied. Moreover, empirically calibrated building performance simulation models of a number of objects were generated in order to predict the consequences of alternative thermal retrofit measures. The results provide the opportunity for an objective assessment of the actual energy and indoor environmental performance of these buildings. [Copyright &y& Elsevier]

Abstract: The building''s energy performance is the result not only of material and component performances, but also of the way the components are interconnected. Concerning windows, their energy performance, which is usually evaluated by using the glass and frame heat transfer coefficients and the linear heat transfer coefficients of the glazing spacer, depends also on the frame installation. In this paper the entity of thermal losses due to the frame installation has been evaluated in terms of linear thermal transmittance calculated in accordance with the standard EN ISO 10211:2007 using THERM 5.2. The analysis of thermal bridges between a wooden frame window installed into two different kinds of external clay block walls has been carried out. The linear thermal transmittances have been calculated for three cases regarding the position (external, internal, and intermediate) and three concerning the insulation of the hole perimeter (non insulated, insulated and with insulation over fixed frame). The impact of the window installation on thermal losses has been estimated and its dependence on different sizes has been evaluated. A new graphical representation has been suggested. The frame position and the configuration of the window hole insulation result to have a relevant impact on the overall thermal performance of the considered window. [Copyright &y& Elsevier]

Abstract: This paper presents the development of an energy efficient window frame made of a glass fibre reinforced polyester (GFRP) material. Three frame proposals were considered. The energy and structural performances of the frames were calculated and compared with wooden and aluminium reference frames. In order to estimate performances, detailed thermal calculations were performed in four successive steps including solar energy and light transmittance in addition to heat loss and supplemented with a simplified structural calculation of frame load capacity and deflection. Based on these calculations, we carried out an analysis of the potential energy savings of the frame. The calculations for a reference office building showed that the heating demand was considerably lower with a window made of GFRP than with the reference frames. It was found that GFRP is suitable for window frames, and windows made of this material are highly competitive in their contribution to the energy savings. A rational product development method was followed, and the process clearly identified the objectives of the investigation and set out the appropriate way to attain them. Using simple rational development methods, a well-defined and effective window was achieved smoothly and quickly, as is illustrated in the case study. [ABSTRACT FROM AUTHOR]

Abstract: The energy performance of buildings has become increasingly important in the general strive to reduce the overall energy use, which is manifested in the Energy Performance of Buildings Directive launched by the European Union. An important first step is of course to identify and address buildings that have an energy saving potential. In order to achieve this, robust methods for evaluation as well as reliable energy key figures are needed. For a large majority of multifamily buildings in Sweden the available data of the energy use originates from the property holder. Unfortunately, the data is often limited to the energy that the property holder is responsible for. Thus, information from the tenants about their household electricity use, indoor temperatures, number of residents, etc., is missing. In this paper an evaluation was conducted on monthly consumption data registered by the property holders for over 100 multifamily buildings/real estates in Sweden. The used approach, based on the energy signature method, was developed for evaluating the energy performance of multifamily buildings in terms of the overall heat loss coefficient, K tot. To compensate for the missing data, different assumed consumption profiles have been used. The results shows that although the obtained value of K tot for an individual building is rather sensitive to the assumed consumption profiles of household electricity, the sensitivity is reduced if the evaluation is made in relative and not absolute terms. Thus, the use of consumption profiles could be a successful way to circumvent the present lack of a detailed knowledge of a buildings total energy use. In addition, an evaluation in relative terms instead of absolute values is also more correct, since available data in almost all cases does not support the determination of the true value of K tot. The use of an average consumption profile instead of a detailed knowledge is of course not desirable, but for fairly large buildings such an approach could be successful. [Copyright &y& Elsevier]

[Display omitted] For almost two decades, the Zero Energy Buildings (ZEB) standard has epitomized a commitment to the high energy performance of buildings. Nevertheless, the applicability of ZEB in hot climates is currently limited and furthermore, in light of the current limitations of traditional building energy modeling methods, new methods are necessary to effectively evaluate the energy balance potential of larger districts. To help bridge this gap, this paper introduces solar-based (both sun-hours and solar irradiation) and geometry-based prediction metrics to be used in optimization studies to evaluate the impact of urban morphology on the energy balance of residential blocks in hot urban contexts. These prediction metrics are derived from the simulated energy performance of 1,944 parametric variations of residential blocks in Tel Aviv. In a regression analysis, these metrics recorded high correlation with energy demand, energy supply and the balance between them. To test the applicability of these metrics for optimization, the RBFMOpt method is employed in a multi-objective optimization study of the energy supply and demand of a nine-block residential district in Tel Aviv. Detailed energy simulations are performed for the best non-dominated results from the solar and geometric optimization studies and compared to the non-dominated results from a full energy optimization run. The results indicate that these metrics - the solar and geometric area-weighted exposure and shading indices - can serve as effective energy performance indicators to inform early-stage morphological decisions making. This workflow promotes urban energy optimization towards more harmonized energy supply and demand driven approaches. [ABSTRACT FROM AUTHOR]

The energy performance gap in buildings is a well-known phenomenon. However, its actual definition and extent is dependent on the baseline used for defining the gap. In this paper a calibration-based methodology is used to identify and validate the root causes of the performance gap. Following analysis of the performance of four case studies in the UK, from different building sectors, cross sectoral learnings that are applicable in the wider industry context are uncovered. Through the model calibration process and in the overall performance assessment, Indoor Environmental Quality (IEQ) parameters have been used to improve the robustness of validation of the calibrated models and to highlight the interrelationship of energy and IEQ. The study shows the importance of contractual accountability to minimise performance issues, building a case for having IEQ in energy performance contracts to manage the trade-offs of IEQ against energy performance that leads to unintended health consequences for the occupants. [ABSTRACT FROM AUTHOR]