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Highlights • A pre and post renovation energy use analysis of almost 90,000 renovated dwellings. • The (p)rebound effects explain only partly disappointing energy renovation results. • Effectiveness of renovations are dependent on state of building prior to renovation. • Effectiveness of renovations are dependent on type of occupant. • Deep renovations often save less energy than expected but are the most effective. Abstract Energy renovations often result in lower energy savings than expected. Therefore, in this study we investigate nearly 90,000 renovated dwellings in the Netherlands with pre and post renovation data of actual and calculated energy consumption. One of the main additions of this paper, compared to previous studies on thermal renovation, is that it only takes dwellings into account with the same occupants before and after renovation, using a large longitudinal dataset. Overall this paper shows new insights towards the influence of the energy efficiency state of a building prior to energy renovation, the type of building, the number of occupants, the income level of the occupants and the occupancy time on the actual energy savings, the energy saving gap and on the probability of lower energy savings than expected. We also investigate if the influence is different per type of thermal renovation measure. Some of the findings are: it is impossible to conclude which single thermal renovation measure is the most effective because this is dependent on the energy efficiency of the building prior to the energy renovation, type of building, income level and occupancy; occupants with a high income save more energy than occupants with low income; dwellings with employed occupants benefit more from improved building installations than dwellings occupied by unemployed occupants; The prebound and rebound effects are only part of the explanations for lower than expected energy savings; Deep renovations result more often in lower than expected energy savings than single renovation measures but nevertheless they result in the highest average energy saving compared to other thermal renovation measures. The results could be used for more realistic expectations of the energy reduction achieved by thermal renovations, which is important for (amongst others) policy makers, clients and contractors who make use of energy performance contracting, home owners, landlords and (social) housing associations and as a starting point to improve the energy calculation method. [ABSTRACT FROM AUTHOR]

Abstract The current rollout of smart meters for gas and electricity, both in the UK and internationally, will help suppliers to better forecast demand and supply accurate bills to consumers. However, even with an in-home display (IHD), the benefits of a smart meter to a domestic customer are limited by the so-called 'double invisibility' of energy [1] and the standardisation of IHD design for an imagined home 'micro-resource manager' [2]. Furthermore, low-income households may be limited in the benefits they can reap from such systems; already living within a tight budget, suggestions for further energy-related cost savings may be detrimental to their health and wellbeing. This makes it important that the impact of actions taken to save energy is communicated. This can be done using indoor environmental measures, including carbon dioxide, relative humidity and temperature, as part of an integrated meter and sensor system (IMSS) and an associated IHD or digital application. Such a system gives users the ability to make informed decisions about their energy use and indoor environmental health. This paper explores the potential barriers to implementing an IMSS in practice. It explains how an IMSS was designed, based on a review of meter and sensor systems; details the process is taken to trial the IMSS in 19 social housing properties in the English Midlands; and makes recommendations for a larger scale rollout of IMSSs. The paper also reviews current progress in cloud storage and security as relevant to IMSSs and smart metering. [ABSTRACT FROM AUTHOR]

Hospitals present a widely recognized margin for energy conservation due to their elevated final energy use intensity. Specifically, operating rooms are among the functional areas with greatest energy demand in hospitals, given the stringent indoor conditions for patients and surgical staff. However, energy efficiency in surgical facilities has traditionally been overlooked by the scientific literature in favor of guaranteeing adequate air quality conditions. This paper assesses the potential energy savings that could be achieved in a surgical suite in a Spanish hospital by lowering the current ventilation rates to the lowest energy-demanding values recommended by the proper Spanish standard and other international codes. Likewise, the paper assesses the actual hygrothermal and ventilation conditions in the suite based on the results of a continuous monitoring campaign performed for a period of 12 days. Simulations undertaken with a dynamic energy model specifically developed and calibrated for this work revealed that the average energy intensity of the suite is 1021 kWh/m 2 /year (1685 kWh/m 2 /year for operating rooms), with 80% of the total annual thermal demand corresponding to periods of inactivity. In addition, energy savings between 40% and 80% are possible while complying with both national and international standards. [ABSTRACT FROM AUTHOR]

Green construction is gaining foothold among professionals, decision makers and the broader public. However, its success depends on a clear minded analysis of its pros and cons based on critical assessment, including cost-benefit analysis. This paper makes a first attempt at such an analysis of some of the first green sustainable schools in Israel. It deals with a limited sample available, as well as diverse rating systems which the different architects have chosen to comply with. By identifying and isolating the “green premium” of those schools which are comparable, and by analyzing actual direct benefits for the schools through energy and water bills (23% and 24% lower consumption respectively per year), the paper concludes that for the time being the payback period of green schools in Israel may prove counterproductive and prohibitive if calculated only on the basis of these two direct and immediate benefits. However, including in the analysis additional benefits, e.g. staff satisfaction (included in this paper), student achievements, user and broader public health issues and other public benefits (not included in this paper) can change the cost-benefit analysis outcome significantly. [ABSTRACT FROM AUTHOR]

Recently there has been growing interest in regenerative evaporative coolers (REC), which can reduce the temperature of the supply air to below the wet-bulb of intake air and approach its dew-point. In this paper, we designed, fabricated and experimentally tested a counter-flow REC in laboratory. The REC’s core heat and mass exchanger was fabricated using stacked sheets composed of high wicking evaporation (wickability of available materials was measured) and waterproof aluminium materials. The developed REC system has a much higher cooling performance compared to conventional indirect evaporative cooler. However, the decision to use the REC for China buildings depends on a dedicated evaluation of the net energy saved against the capital expended. Such an evaluation requires the hourly-based data on the availability of cooling capacity provided by the REC for various climates. The paper used an experiment-based method to estimate the cooling capacity and energy savings provided by the proposed REC for China’s various climates. By using the experimental results and regional hourly-based weather data, the energy saving potential of the REC against an equivalent-sized mechanical air conditioner alone was analysed. The results indicate that, for all selected regions, the REC could reduce 53–100% of cooling load and 13–58% of electrical energy consumption annually. [ABSTRACT FROM AUTHOR]

[Display omitted] • Present a comprehensive review of building electricity profile models. • Distinguish the differences of building electricity profile and prediction models. • Categorize the statistical and bottom-up models for electricity use profiles. • Investigate the validation metrics in accordance with the modeling methods. • Discuss the key future perspectives of building electricity profile analysis. The building sector contributes significantly to overall energy consumption and carbon emissions. Improving renewable energy utilization in buildings is of considerable importance for their carbon neutrality. Electricity is expected to become the major form of final energy consumption in buildings; as such, understanding the features of building electricity use profiles is pivotal for building energy system design and city-scale electricity distribution network planning. This study reviews the current status and future challenges of building electricity use profile models. The paper distinguishes between electricity use profile models and electricity use prediction models. Then it comprehensively reviews current research papers, focusing on four aspects, including the temporal and spatial distribution of datasets, the distinction between statistical and bottom-up modeling methods, mathematical and engineering domain validation metrics, and applications in building energy system design and energy policy making. Key perspectives for future research are discussed in the paper, including the temporal scales of models, the aggregation of electricity use profiles, occupant-driven environment-interactive model structures, as well as the fit-for-purpose model evaluation. This is intended to inform and inspire future research on building electricity use profiles, improve the in-depth understanding and quantitative descriptions of building electricity use, and support the design of future building systems and energy distribution networks. [ABSTRACT FROM AUTHOR]

Facing the challage of energy conservation and emission reduction in the building sector, most energy saving strategies of central heating only focus on the performance improvement of building envelope, ignoring the impact of energy use behavior. This paper proposed a building energy conservation strategy based on energy use behavior analysis, which provides a perspective for in-depth exploration of building energy conservation. After investigating a typical university in the northern China, the energy use behaviors were characterized and two different DeST energy consumption models before or after considering energy use behavior were established. By comparing the results calculated by these two models, the impact of energy use behavior analysis on building energy consumption was quantitatively analyzed. The results show that the heating energy consumption and carbon emission can be reduced by 23.28% and 23% respectively through the proposed strategy based on energy use behavior. Therefore, the analysis of energy use behavior can provide a theoretical basis for heating operators to make decisions on energy supply regulation. With central cooling and heating further popularizing in the future, the research methodology of this paper has more extensive reference value for energy conservation and emission reduction strategies in the building sector. [ABSTRACT FROM AUTHOR]

This paper presents the concept of a sensible heat Electric Thermal Storage (ETS) system dedicated to household central heating. ETS is the technology of converting off-peak electricity into heat and using it in household heating 24 h a day. An ETS system is comprised of electric heating elements which are embedded within a high-density solid matrix. Since the thermal energy is stored in the solid matrix during off-peak hours and is discharged during peak hours, it results in significant savings in the household heating cost. A numerical model is developed to analyze the performance of the ETS unit, the central component of the presented system. The energy conservation equations for the solid matrix and air domains are formulated. Solid matrix is modeled as a porous medium, where radial heat conduction is neglected. The governing system of differential equations with boundary and initial conditions is solved using the Finite Volume Method. The developed model allows determining the air temperature at the outlet of the Electric Thermal Storage unit. Despite the simplified assumptions considered in the numerical model formulation, a good coincidence of the computation results with experimental data is reached. The heating system proposed in the paper meets the air quality requirements imposed by the environmental regulations and is an efficient and environmentally friendly heating systems for residential buildings. [ABSTRACT FROM AUTHOR]

Global trends in reapplication of wood re-application and wood-based products, used as construction and architectural coating materials, are present not only because of esthetic, artistic and design requirements or tradition and nature-based inspiration, but also because wood adapts to modern trends in sustainable development. This paper presents traditional influence on application of wood as a façade cladding element in modern architecture of Serbia and provides the analyses of functional and design potentials of wood as an element of ventilated façade systems and its influence on energy efficiency. The objective of this research was to provide a more detailed insight into potentials and limitations of the application of wood and wood-based products, as façade cladding elements used for construction and reconstruction of architectural objects, in the climate conditions of Belgrade (Serbia) as well as to point out certain suggestions about improving their energy efficiency characteristics. The paper presents the examples of various methods of applying wood and wood-based products as elements of façade cladding in modern architecture of Belgrade. The main focus is put on an object that underwent different refurbishment methods and façade system alterations in order to meet the requirements of energy saving. [ABSTRACT FROM AUTHOR]

The variable differential pressure (DP) set-point control strategy has become the main energy-saving measure for central air conditioning water system variable volume adjustment. In optimal operation control, it is critical to use the right reference object to implement global, accurate, and online control. In mainland China, the most unfavorable loop is typically used as the reference object for variable DP set-point control in the majority of cases of variable volume air conditioning system adjustment. However, its concept and feasibility require further clarification. First, this paper analyzes the difference in the characteristics of a most unfavorable loop under air conditioning design work conditions versus under operational conditions. Under design operational conditions, the referenced most unfavorable hydraulic loop only reflects the distribution of the pipe network's hydraulic characteristics, whereas under system operational conditions, the variable volume adjustment strategy should be chosen according to each user's load requirement, i.e., a most unfavorable thermodynamic loop. Then, this paper provides definitions of the most unfavorable thermodynamic loop and online identification method and proposes a variable DP set-point optimal reset strategy based on the maximum valve position loop's optimal reset valve position domain and best valve position domain. Finally, the variable DP set-point control of a primary pump variable volume air conditioning water system in an industrial factory is used as an example to conduct a test studying 6 variable DP or constant DP control strategies, including the method proposed in this paper. The test results show that the most unfavorable loop-based variable DP control strategy saves 47–58% water pump power consumption (up to 985 kWh electric power consumption per day) when compared with the conventional variable DP control strategy, whereas the most unfavorable thermodynamic loop-based variable DP control strategy is more advantageous in ensuring the overall cooling energy supply for each user. [ABSTRACT FROM AUTHOR]

This paper studies how human activity affects energy consumption and how such activity can be leveraged from electricity meter data. Using 15-minute interval data and applying the methods introduced in this paper, it is possible to identify in which days there was human activity and extract daily routines from such data. This type of insight into the way people consume energy helps understanding energy use at a deeper level, and realise where significant energy savings can be made. [ABSTRACT FROM AUTHOR]

In China, the population is expected to continue to grow together with construction of new buildings. Consequently, the energy demand required by the building sector will inevitably rise. This paper focuses on the Chinese residential sector and describes the structure by using the EfB—energy for buildings model. Using this tool it is possible to simulate the trend of the energy demand until 2030. A range of different scenarios – at national and regional level – is presented and discussed, including government plans and the application of some proposed recommendations. The analysis suggests that the energy consumption in this sector will not stop its growth and in 2030 it will comprise between 9500 and 14,000 PJ. Meaningful energy savings can be achieved with the introduction of more aggressive policies and behavioural change. Many difficulties have been faced in this work because of the complexity and rapid evolution of the Country; anyway, it can be considered as a starting point for future research. Among further improvements, the paper suggests the introduction of a more complete description of the building types, the association of the floor area evolution to the construction sector activity and the inclusion of economic and environmental evaluations. [ABSTRACT FROM AUTHOR]

In a privatized global marketplace, innovation is a key driver of sustainable development and national competitiveness. Here we report on an innovative new fully building-integrated thermal solar panel concept that is patented and currently being readied for commercialization. The paper outlines the French regulatory landscape governing the deployment of thermal solar panels in France, and thus the need for countries like France to develop new building-integrated solar power meeting “building-envelope” integration requirements for protected areas. We go on to introduce the new as-developed system, its physical modelling via a finite element analysis model constructed using an electric circuit analogy, and the results achieved on a detached home retrofitted with this system and trialled for a 12-month period. This paper leads out of COST – European Cooperation Science and Technology – framework action TU 1205 “Building Integration of Solar Thermal Systems”. [ABSTRACT FROM AUTHOR]

This paper summarises the results of a study to identify and quantify the potential impact of measures and policies to reduce the energy consumption of air conditioning in European countries over a 10-year period. The market penetration of air conditioning in Europe has increased steadily over several decades. On a “business as usual” basis, its energy consumption would increase by over 50% by 2020. Measures to restrict this increase are therefore important, but the savings potential straddles several overlapping areas which are subject to different constraints including those imposed by the replacement rates of systems and products, and the refurbishment rates of existing buildings. This work reported in this paper is based on the use of information from a variety of sources in a highly disaggregated model to assess the “realisable” savings over a 10-year period, taking into account relevant constraints. The paper summarises results at a European level, focussing on those cases that generate the greatest realisable savings. Savings are possible in three areas: improved equipment and system efficiency, reduced cooling loads, and more effective operation. The cases that offer the largest savings provide the basis for recommendations for policy measures, often using existing policy instruments. In addition, areas where further work is needed are identified. More detailed results and information about the study and additional recommendations can be found at http://www.bre.co.uk/searchresults.jsp?category=5&q=energy+management [1] . [ABSTRACT FROM AUTHOR]

In this paper, a mathematical model is formulated to quantify the social impact an individual has on his/her community when he/she performs any energy efficiency project and transmits that information to his/her neighbours. This model is called the expected power savings model; it combines direct and indirect expected power savings of the energy efficiency project for each individual within the network. The indirect savings are quantified through the social interactions people in the network. The example used in this paper illustrates the effectiveness of the model by identifying the households who should have free solar water heaters installed in their residential houses based on their influence through interactions in their community. Two case studies are considered in this paper, single and multiple sources case studies. In the multiple source case study, the results show that it is not necessarily the people with the highest connections who provide the maximum expected power savings. [ABSTRACT FROM AUTHOR]

This paper considers energy conservation practices in Qatar with special emphasis on commercial buildings. Energy conservation approaches are classified into five main areas and an Energy Conservation Matrix (ECM) database for buildings is developed. The ECM maps the energy conservation techniques/technologies to models versus their application domain. Three scenarios (building envelope design, change in customer behavior, and consideration of renewable energy supply) are analyzed to study different alternatives for efficiency improvement. The analysis is done in a case hotel. The analysis shows that, the energy conservation potential of using envelope redesign for the case study is about 7.5% while conservation through behavior change ranges between 2.74% and 15.80%. The conserved energy potential ranges between 10% and 24.12% of the site energy in the combinatorial scenario that integrated envelope design alternatives with customer behavior change. The renewable energy (RE) scenario conserves energy, indirectly, by using green energies generated from renewable sources. The output shows that due to changes as per the three scenarios, total CO 2 emissions of the building are also reduced. The analysis shows that adoption of 30% RE alternative can reduce emissions by about 27% with respect to the reference scenario. It is believed that the scenarios developed in this paper and the results obtained will motivate the designers to consider alternative designs or redesigns in the large scale commercial buildings. [ABSTRACT FROM AUTHOR]

• Operating time of SMEs is estimated using a SOM and hourly demand data. • The estimated operating time is used for hourly AC demand disaggregation. • The average errors of yearly AC demand estimation are better than 10%. • Hourly disaggregation highlights season and time period of AC demand peaks. Despite the growing penetration of smart meters and energy management systems in recent years, few tools have been proposed for energy demand data analysis and visualization to promote energy conservation in small- and medium-sized enterprises (SMEs). In this paper, we propose a new method consisting of operating time estimation and simplified disaggregation based only on the SME's hourly electricity demand data and actual outdoor temperature data. The method first estimates the operating time using a self-organizing map, which categorizes the hourly data as operating, half-operating, or non-operating time and eliminates manual parameter adjustment that requires user trial and error. Then, using the estimated operating time, our simplified disaggregation method estimates hourly air conditioning (AC) demand considering the variation in each office's temperature at which air conditioners are switched on. The method was evaluated using a public business energy management system dataset from Japan, and the average errors of yearly AC demand estimation were better than 10%. The outputs of the proposed method may provide information that is more relevant, reliable, and specific to each customer and efficiently promote energy conservation measures in SMEs. [ABSTRACT FROM AUTHOR]

• The data requirements of quota methods are summarized, and a city-scale database containing 670 credible government office buildings is established. • By comparing the processes, the results and applicability, the selection basis of quota methods under different conditions is refined. • A flow chart of the formulation process and method selection of city-level building energy consumption quotas is constructed. • It is proposed that special attention should be paid to the outliers, and the characteristics of outliers in Chongqing are summarized. Energy consumption quota policies are effective management measures to promote energy conservation and emission reduction in China. Cities need to choose an appropriate method to formulate local energy consumption quota standards. This paper is based on the data of 670 government office buildings in Chongqing and the selected quantile method (QM), quota-level method (QLM) and multiple linear regression (MLR) method, which are widely used in the formulation of city-level energy quotas. By comparing their interpretability, evaluation, consistency and stability, the application conditions and applicability of each method are summarized. MLR has the strongest explanatory power but the highest requirements for the technology and information dimensions. The QLM is more explanatory and stable than the QM and is more suitable for the initial stage of energy quota management. When using the QLM, we should consider scientific classifications and reasonable quota levels. Special attention should be given to "outliers" with abnormal evaluations of the quota results. The outliers in Chongqing are characterized as buildings that have been used for more than 10 years and have an area of less than 5000 m2. Finally, this paper constructed a flow chart of the formulation process and method selection to help policymakers better understand how to choose the most appropriate method and identify inefficient buildings. [ABSTRACT FROM AUTHOR]

• This study presents a comprehensive review on fan-use rates and effects in practice. • The main trigger of fan-use is a warm environment rather than building types. • Using fans elevates neutral temperature averages by 3 K in real buildings. • More than 15% air-conditioning-use rate is reduced by fan-use in buildings. • 3-K temperature extension is achieved by using fans for productivity not decreasing. This paper is a literature review of field studies on fan-use rates and their effects on thermal comfort, energy conservation, and human productivity. In the assessed literature, fans are more popular in Asia, and more used in mixed-mode (MM) and naturally ventilated (NV) buildings than in air-conditioned (AC) buildings. On the basis of collected fan-use models, probit regression models of fan-use rates and ambient environments were obtained and indicate that the essential trigger of fan-use is a warm environment rather than building types. This result helps us to understand the control behaviors and comfort requirements of occupants. Also, fans could provide benefits in three aspects: widening neutral temperatures, saving energy, and improving occupants' productivity. First, using fans in buildings elevates the neutral temperature and the upper limit of neutral zone (0.5 thermal sensation scale) averages by about 3 K in ranges from 25.7°C to 28.7°C and 27.5°C to 30.7°C, respectively. Second, fan-use reduces AC-use rates in MM buildings in summer. The regression models based on the collected AC-use rate models illustrate that, on average, AC-use is expected to be reduced by about 15% in summer when fans are used. Third, providing occupants access to fans could improve occupants' productivity. Based on the limited data available, a 3-K temperature extension is achieved by fans ensuring productivity not decreasing. This review could shed some light on the extension of the neutral temperature range, predictions of MM buildings' energy consumptions, and methods to enhance productivity. Additionally, this review suggests some valuable directions for future research on fans. [ABSTRACT FROM AUTHOR]

Abstract Heating energy conservation is an important part of China's energy conservation strategy. China's coal-fired heating is reducing and heating energy conservation policy is enhancing but not in a significant manner. This paper aims to figure out the actual realization of Chinese governments' ex ante expectations towards energy conservation policy in the heating industry. A trans-log production function is established incorporating asymmetric energy price decomposition and seemingly unrelated regression method is adopted to estimate the own-price and cross-price elasticity of factor input demands of the heating industry, then the direct energy rebound effect is estimated within China's heating industry. The results indicate that the actual energy-saving effect of the heating industry in China only realizes 60.04% of the theoretical energy-saving goal. Energy rebound in the heating industry in China is not only influenced by technical progress but also influenced by its state-owned monopoly status. [ABSTRACT FROM AUTHOR]

Highlights • Thermal quadrupoles formalism is applied for modelling transient heat transfers in building walls with a semi-infinite assumption. • Front face response curves of multi-layered walls are analysed to estimate the thermal properties of the wall. • Experiments are carried out on two classical multi-layered building walls using artificial thermal excitations. • The proposed method reduces the evaluation time less than 10 hours. Abstract Thermal performances of building walls are significant for energy conservation. However, very few non-destructive evaluation methods exist to quantitatively diagnose the building walls in situ due to the walls' large thickness. Moreover, most of the existing methods are inconvenient to implement in situ and take a long characterization time. This paper studies transient heat transfer to estimate the wall's thermal properties based on the thermal quadrupoles modelling. Semi-infinite boundary condition is assumed at the rear face of the wall. With this assumption, only the front face response of the wall is considered. The evaluation time is then effectively reduced within a few hours, and the diagnosis in situ is simplified without the measurement on the rear face of the wall. Experiments are carried out on two traditional multi-layered building wall cases using heating lamps. With the measured surface temperatures and heat fluxes, the unit-pulse response and unit-step response at the front surface of the investigated wall are reconstructed through a deconvolution approach and a TSVD (Truncated Singular Value Decomposition) inversion. The unit-step response curve is directly characterized by the thermal resistance, thermal effusivity and heat capacity of the wall, thus allowing us to estimate the wall properties. The characterization time for the two cases is less than 10 hours. [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 Energy Management and Information Systems are a family of analytics technologies that include energy information systems, fault detection and diagnostics (FDD), and automated system optimization tools. Such systems have the potential to enable buildings to meet energy management goals of reducing total energy consumption and cost. Most current market offerings use data-driven and rule-based analytics. However, the use of physics-based models in the analytics offers potential improvements by providing an accurate estimation of outputs based on representation of the physical principles governing the building system behaviors. This also permits the use of design stage models to inform commissioning and operation. This paper describes the development and testing of a hybrid data-driven and physics model-based operational tool for energy efficiency in central cooling plants. The tool offers FDD functionality, setpoint optimization, and visualization of key performance parameters. It was demonstrated at a university campus in the mixed-humid ASHRAE Climate Zone 4A. Key performance metrics that were analyzed include plant electricity use reduction, plant model calibration, and system economics. Annual simulations indicate the tool can provide electricity savings of greater than 10% for approximately six months of the year, mainly during the winter season when wet bulb temperatures are low, though only 1.38% savings for the entire year. Additionally, over a 4-day period in April, recommended optimal setpoints were implemented, resulting in 17% savings versus metered baseline consumption. With respect to model calibration, the difference between model-predicted and measured parameters was less than 10% for 90% of data points acquired for three of six chillers, and for each ten cooling towers. Finally, the tool users reported that satisfaction with the capabilities was equal to or better than that with the preexisting BAS system. [ABSTRACT FROM AUTHOR]

Highlights • Providing a critical review of office building energy management based on occupancy monitoring and modeling, and HVAC and lighting control strategies. • Proposing a roadmap towards cognitive building management. Abstract Buildings are responsible for a large portion of global energy consumption. Therefore, a detailed investigation towards a more effective energy performance of buildings is needed. Building energy performance is mature in terms of parameters related to the buildings' physical characteristics, and their attributes are easily collectable. However, the poor ability of emulating reality pertinent to time-dependent parameters, such as occupancy parameters, may result in large discrepancies between estimated and actual energy consumption. Although efforts are being made to minimize energy waste in buildings by applying different control strategies based on occupancy information, new practices should be examined to achieve fully smart buildings by providing more realistic occupancy models to reflect their energy usage. This paper provides a comprehensive review of the methods for collection and application of occupancy-related parameters affecting total building energy consumption. Different occupancy-based control strategies are investigated with emphasis on heating, ventilation, and air conditioning (HVAC) and lighting systems. The advantages and limitations of existing methods are outlined to identify the gaps for future research. [ABSTRACT FROM AUTHOR]

Highlights • An experimental rig to evaluate the thermal performance of roofs in the field is presented. • Eight roofs with trapezoidal shape, built in reduced scale, were simultaneously evaluated. • Heat flows, temperature and thermal resistance were verified during the tests. • Measured values were compared with results obtained through computer simulations. • There was good agreement between the results obtained with the rig and through computer simulations. Abstract Reducing the thermal gain through the roof is one of the best approaches to decreasing energy consumption and to providing thermal comfort to the users of residential or commercial single-story buildings. In this context, this paper describes an experimental test rig for use in the field, which was employed to simultaneously evaluate the thermal performance of eight roofs in reduced scale in the city of Florianópolis, Santa Catarina State, southern Brazil. The experimental test rig is comprised of a temperature-controlled environment over which the roofs were constructed. All roofs have a trapezoidal air cavity with the same dimensions, in order to carry out the calibration of the test rig. In the calibration tests, the surface temperatures, the heat flow in the roofs and the thermal resistance for the upward and downward directions of heat flow were investigated. Furthermore, computer simulations and measurements of a roof with real dimensions were also carried out in order to verify whether the experimental test rig could provide results compatible with those obtained in a real situation. The calibration results show good agreement between the results obtained for the eight roofs, with a maximum variation of 8.7% in the thermal resistance values. On comparing the values for the thermal resistance obtained with the experimental test rig and the computer simulation, there were differences of 11.7% for the upward direction and 26.1% for the downward direction of heat flow. In relation to the comparison of the results obtained between the experimental test rig and the measurement values for the roof with real dimensions, the differences were 5.6% for the upward and 34.3% for the downward heat flow. [ABSTRACT FROM AUTHOR]

Highlights • The first city-level building energy efficiency benchmarking system for China. • A model considering the influence of operation parameters on energy consumption. • A systematic methodology of building energy benchmarking is proposed. • The model is a valuable analysis support tool for building energy managers. Abstract The city-level public building energy efficiency benchmarking system has an important guiding value for building energy-saving work, especially for Beijing, with its high energy-consumption density and both long heating and air-conditioning periods. This paper analyzed the characteristics of large-scale office buildings in Beijing and gives a detailed description of the process of establishing a public building energy efficiency benchmarking system for large-scale office buildings in Beijing, China, including data investigation and verification, Energy Usage Intensity(EUI) calculation, determining independent and dependent variables, developing and testing the benchmarking model, and deriving the benchmarking rating table. Then the first city-level public office building energy efficiency benchmarking system in China is established based on 88 large-scale office buildings in Beijing. The results showed that the model's performance index R2 is 0.667 and gives a good representation. The process has a strong potential for replication for other cities in China and even for a national energy-consumption evaluation system. [ABSTRACT FROM AUTHOR]

Highlights • Non-intrusive techniques are proposed to infer occupancy from existing HVAC sensors. • Reheat energy use is reduced by more than 38% with better nighttime setback schedules. • Derived a comprehensive set of candidate anomalous zones using unsupervised learning. • Proposed approach can be readily applied to any commercial building with a BMS. Abstract The Heating Ventilation and Air Conditioning (HVAC) system of commercial buildings traditionally runs on a fixed schedule that does not take occupancy into account despite its huge variation over space and time, thereby wasting a lot of energy in conditioning empty or partially-occupied spaces. Occupancy information is essential to eliminate wasteful energy use with imperceptible impact on building operations and human comfort. This paper investigates the application of non-intrusive techniques to obtain a rough estimate of occupancy from coarse-grained measurements of sensors that are commonly available through the building management system. Various static and adaptive energy-efficient schedules are developed based on this approximate knowledge of occupancy at the level of individual zones. Our experiments in three large commercial buildings confirm that the proposed techniques can uncover the recurring occupancy pattern of the zones, and schedules that incorporate these occupancy patterns can achieve more than 38% reduction in reheat energy consumption while maintaining indoor thermal comfort. [ABSTRACT FROM AUTHOR]

Abstract Parallel fan-powered terminal units (FPTUs) are widely considered more energy efficient compared with series FPTUs because of the intermittent terminal unit fan operation. Recent studies found that the energy savings potential of parallel FPTUs may be overestimated due to the primary air leakage through the backdraft dampers when terminal unit fans are not operating. However, the lack of an effective modeling approach in building simulation programs has prevented the thorough investigation of how the primary air leakage from parallel FPTUs affects the energy consumption of variable air volume (VAV) systems. In this paper, a modeling approach was developed and implemented in EnergyPlus using the Energy Management System (EMS) for the comparative analysis of energy impact of primary air leakage from parallel FPTUs. A series of building energy simulations were also conducted at four air leakage levels under five different U.S. climates. Although the percentage energy increases caused by the primary air leakage vary with local climates and leakage levels, simulation results show consistent increases in the energy consumption of central cooling coil, central supply fan, and FPTU supplemental heating throughout all the climates as the air leakage level increases. Compared with series FPTUs, the energy savings potential of parallel units significantly decreases as air leakage level increases. At the highest air leakage level of 15% simulated in this study, series FPTUs may use less energy than parallel FPTUs. [ABSTRACT FROM AUTHOR]

Highlights • A methodology to assess fan energy savings when improving ductwork. • The methodology is based on EN 16798-5-1. • Simulations are compared with measured results on an experimental ventilation system. Abstract This paper proposes a methodology to assess fan energy savings when improving ductwork airtightness. This methodology builds on standard EN 16798-5-1:2017. Unlike the classical ``cube law'', it considers pressure drops at air terminal devices separately from the pressure drops in the rest of the system. The calculation tool based on this methodology: (a) gives the fan energy use before and after airtightness improvements with various inputs depending on the initial state; (b) indicates whether or not the required airflow rates are met at the air terminal devices; (c) gives a range of energy savings assuming, on the one hand, perfect fan adjustment, no errors in input data and constant fan efficiency, and on the other hand, safe-side estimates of deviations from these assumptions. Using experimental data from an earlier study on a full scale ductwork built in a laboratory, the tool gives results in good agreement with measured energy savings (within 7 percentage points). With ideal pressure adjustment and when required airflow rates were met before tightening, the maximum fan energy savings by tightening the ductwork from 1.5 times Class A to Class C reaches 51% according to the tool versus 46% according to measurement data. [ABSTRACT FROM AUTHOR]

Facility managers and occupants can have a significant influence on the energy consumed in buildings through their operation of various building systems. Acknowledging this energy-saving potential, researchers have turned to building energy modeling to quantify the impact of human actions and operation patterns on building performance and propose energy conservation strategies. However, a review of the current literature reveals consistent shortcomings related to the: (1) implementation and validation of the simulated strategies; (2) availability of granular data on occupants’ characteristics and their working conditions; (3) consideration of the building's urban context (e.g., shading effects from neighboring buildings); and (4) implications for low-energy buildings subjected to extreme climate conditions. This paper presents an integrated data collection, energy modeling, and analysis framework to evaluate and apply operation-focused energy saving strategies in commercial buildings. The framework is supported by contextual data covering the building's design, occupants, and urban context. It is validated through a case study on a low-energy design building in Abu Dhabi, UAE. Energy savings of 24.4% are observed in the studied building following the implementation of simple operation strategies that do not require any capital investment nor affect the comfort and wellbeing of building occupants. [ABSTRACT FROM AUTHOR]

To reduce global greenhouse gas emissions associated with building energy use, owners of large building portfolios such as university campuses frequently rely on building energy models (BEM) to better understand potential costs and benefits of retrofits. Model development workflows that are designed for individual buildings require a level of effort that would be time and cost prohibitive to apply to such campuses which often include hundreds of diverse-use buildings. While smaller campuses can effectively utilize the traditional BEM approach to study retrofit scenarios, this option is therefore not feasible for larger campuses. Large universities have instead utilized a combination of statistical and spreadsheet models which may not fully capture the unique architectural features, programmatic requirements, and systems configurations of individual campus buildings. With the goal of overcoming these limitations, two separate urban energy models, that employed considerably different methodologies, were developed for the campus of the Massachusetts Institute of Technology to evaluate future energy scenarios with an appreciably smaller effort vis-à-vis developing building-by-building energy models. This study reviews these two models with regards to their setup and calibration effort, ability to model individual building energy use, and the accuracy in predicted savings from implementing a variety of retrofitting measures. The paper identifies both models’ strengths and limitations and suggests best practice procedures for administrators of other campuses interested in undergoing a similar exercise. [ABSTRACT FROM AUTHOR]

Housing Stock Energy Models (HSEMs) play a determinant role in the study of strategies to decarbonise the UK housing stock. Over the past three decades, a range of national HSEMs have been developed and deployed to estimate the energy demand of the 27 million dwellings that comprise the UK housing stock. However, despite ongoing improvements in the fidelity of both modelling strategies and calibration data, their longevity, usability and reliability have been compromised by a lack of modularity and openness in the underlying algorithms and calibration data sets. To address these shortfalls, a new open and modular platform for the dynamic simulation of national (in the first instance, the UK) housing stocks has been developed—the Energy Hub (EnHub) . This paper describes EnHub’s architecture, its underlying rationale, the datasets it employs, its current scope, examples of its application, and plans for its further development. In this we pay particular attention to the systematic identification of housing archetypes and their corresponding attributes to represent the stock. The scenarios we analyse in our initial applications of EnHub, based on these archetypes, focus on improvements to housing fabric, the efficiency of lights and appliances and of the related behavioural practices of their users. In this we consider a perfect uptake scenario and a conditional (partial) uptake scenario. Results from the disaggregation of energy use throughout the stock for the baseline case and for our scenarios indicate that improvements to solid wall and loft thermal performance are particularly effective, as are reductions in infiltration. Improvements in lights and appliances and reductions in the intensity of their use are largely counteracted by increases in heating demand. Housing archetypes that offer the greatest potential savings are apartments and detached dwellings, owing to their relatively high surface area to volume ratio; in particular for pre-1919 and inter-war epochs. [ABSTRACT FROM AUTHOR]

India is running 11% peak demand as well as short of electrical energy which is the cause of poor grid availability at many sits in India. This motivates the consumer to install their own captive power plant in the building to improve reliability of electricity building. The photovoltaic system cost is rapidly decreasing day by day as well as it is the pollution free source of electricity it is popularity choice of residential consumers. The electronics loads (DC appliances) are increasing in the building. The PV system is also a source of DC power. Therefore, the integration of the DC appliances as well as PV system to the traditional AC distribution system forced to introduce the DC–AC and AC–DC converters at the PV system and appliances. Which decrease the system efficiency, reliability and system capital cost. In this paper, the comparison analysis of the distribution structures (i) Traditional system: AC distribution system with AC compatible appliances (conventional), (ii) Hybrid system: AC distribution system with DC compatible a appliances (high efficient) and (iii) DC system: DC distribution system with DC compatible appliances. The simulation results of this study shows that DC system in the building shows high efficiency and small capital cost as compared to the traditional as well as hybrid system. It is also need small number of AC–DC–sAC conversion stages. [ABSTRACT FROM AUTHOR]

The energy consumption in a multi-chiller system is very significant and its consumption will be increased by inappropriate operating of the chillers. Accordingly, the economic dispatch in multi-chiller systems becomes an important issue for saving energy. Such issue is known as optimal chiller loading, which is solved by applying different optimization methods. This study employs exchange market algorithm to obtain optimal set points of the economic dispatch problem on chiller plants, which is inspired by trading the shares on a stock market. Exchange market algorithm is proposed for solving continuous non-linear optimization problems and it is comprised of two searching and two absorbing operators. The decision variable of the optimal chiller loading is partial load ratio of each chiller and the objective function of the optimal chiller loading problem is minimizing the power consumption while satisfying the cooling demand. This paper adopts three case studies to evaluate the performance of exchange market algorithm and compares it with other optimization methods applied on the optimal chiller loading problem. Results show that exchange market algorithm is an efficient method for solving optimal chiller loading problem in chiller plants, and is adaptable for usage in air-conditioning systems. In addition, the comparison results show that the exchange market algorithm provides better solutions than previous optimization methods applied on the optimal chiller loading method in terms of convergence speed and total consumption of electrical energy. [ABSTRACT FROM AUTHOR]

This paper proposes a ventilated window with a phase change material (PCM) heat exchanger as a new window application. In summer, night ventilation mode is operated to discharge energy stored in PCM by the ambient cold air, which can be reloaded again, when ventilation pre-cooled air is provided. Numerical model is built and verified by full-scale experiment to evaluate the PCM ventilation system. The nonlinear properties and hysteresis of PCM are set in the model. The conclusion is that the configuration optimization should be based on different climates. In the case study in Copenhagen, the heat exchanger with 10 mm plate thickness is optimized. It can cool down the ventilated air 6.5 °C on average in 3.9 h pre-cooling effective time with 3.19 MJ/day energy saving. The material cost saving is 16.87% compared to 20 mm plate thickness which has similar discharged heat amount. Nevertheless, the heat exchanger with 5 mm plate thickness has a faster thermal response and a higher cost saving ability, which is good for the climate when the period of outdoor air temperature suitable for night ventilation in a day is short. [ABSTRACT FROM AUTHOR]

Dynamic pricing is an effective way to induce the customers to change their electricity usage patterns, critical peak pricing (CPP) event shows a great potential to reduce the peak demand and enhance the grid reliability. This paper investigates performances of the CPP experiment across aggregated group-level of electricity customers covering 16 commercial, 15 office and 50 residential objectives in the Kitakyushu Smart Community demonstration project. A data-based approach to the comparisons of electricity demand curves and distributions among time of use (TOU) and CPP events. Result confirms the differences in price-based responsiveness across types of customer, there is demand shaping effect during the CPP event period by adjusting the electricity price at 30-min interval. The power saving effects were obviously confirmed in residential and commercial sectors under CPP event program. A multiple linear regression model is used to examine the response effectiveness and weigh the influencing factors of the fixed time for the dynamic pricing scheme. For the no-residential part, the electricity consumption strongly depends on the variations in temperature, commercial consumer tends to respond more to the changes of electricity price than office sector. The residential customer shows a promising potential for load reduction corresponding the increasing electricity price. However, the effects depend on the preferences of residential customers to change their power usage pattern at real time of the CPP event period. [ABSTRACT FROM AUTHOR]

Heat recovery devices can help ventilation systems conserve energy; However, they cause a pressure drop in the system, and hence the system incurs an electricity consumption. In the present paper, the maximum allowable pressure drop of the recovery units is achieved from thermodynamic and economic points of view. The novelty of the research is that, unlike the existing criterion which does not differ for different cities, the introduced criteria can be calculated for each city with individual weather, economic, power plants, and energy conditions. Although the methods presented to calculate the criteria consider a broad range of effective parameters, there is no need to use complex energy simulation methods. Moreover, for each city, four types of criteria are introduced, which allows the city authorities to choose the best ones according to their city conditions, and then calculate the chosen criteria by the data of the city. In order to gain the criteria, modified enthalpy-hours and bin method variables are introduced to calculate sensible and latent energy consumption due to ventilation. The criteria are numerically calculated for Kerman city in Iran, and the results show that the recovery type and the chosen viewpoint has a considerable effect on the allowable pressure drop. The sensitivity of the results to different variables is analyzed in the end. [ABSTRACT FROM AUTHOR]

The demand for improving the energy performance of buildings located in the historic districts of cities is as high as the current demand in other city districts. The need to reduce energy consumption and improve the comfort of inhabitants is compounded by the need to preserve an environment of heritage value. The selection of rehabilitation strategies at urban scale offers significant benefits, but makes the process long and costly. Therefore, methods or tools are necessary to establish a rapid assessment that facilitates strategic decision making and a deeper analysis of a reduced number of alternatives. This paper describes a method that supports decision making regarding the suitability of Energy Conservation Measures (ECMs) in historic districts at early stages. The method considers the improvement of the energy performance of buildings as a positive impact, balanced with the negative impacts that the implementation of ECMs could produce. A CityGML-based urban model allows the automation of a multi-scale assessment for different ECMs and provides possible global energy demand reductions. This method, combined with an economic evaluation, can be used by decision makers for large-scale energy retrofitting. The applicability of the method is demonstrated through implementation in the historic city of Santiago de Compostela. [ABSTRACT FROM AUTHOR]

This paper presents the methodological approach and findings of a simulation study of advanced energy conservation, generation and management technologies applied to two case study dwellings in the UK, so as to achieve net zero energy (NZE) target that includes a reduction of net regulated energy (HVAC) to 0 kWh/m 2 per year and energy generation of at least 50 kWh/m 2 per year. The performance of the dwellings are also tested for a change in energy use and risk of summertime overheating in future climates in the short (2030s), medium (2050s) and long term (2080s). The findings indicate that to meet the NZE targets, regulated loads need to reduce by about half (over current Building Regulations) with community (rather than building-level) renewables playing a major role. It is also found that the NZE targets, given current regulations, are not particularly difficult to achieve in design with regard to energy efficiency but are highly expectant with regard to renewable energy. Further, summertime overheating is projected to be a risk for net zero energy dwellings by the 2050s. Despite this the regulated energy use of both dwellings is projected to reduce by 11 kWh/m 2 /yr, accompanied by a small increase in renewable generation (2 kWh/m 2 /yr). [ABSTRACT FROM AUTHOR]

Australia’s commercial building stock exceeds 134 million m 2 of net lettable area, with retail buildings contributing 35% to this sector’s energy use. The energy intensity of retail buildings in hotter climates is higher than the national average, as is the energy intensity of smaller buildings (under 1500 m 2 ) that are not considered ‘high-end’ commercial properties. Little attention has been paid to improving the energy efficiency of these types of buildings through regulation (for new buildings) or through market mechanisms (for retrofitting). As many of these buildings are single storey ‘warehouse’ type buildings, their predominant heat load comes through the roof, and thus are well suited to benefit from cool roof technology. Despite this, there remains a deficiency in quantifying the benefit of such technology in the context of single-storey retail buildings in Australia. This paper reports on an experimentally validated numerical study aimed at addressing this deficiency. Results show that application of cool roof technology to a warehouse type building in a subtropical environment increases the energy efficiency by shifting space temperature towards the design set point (21–23 °C), and thus reducing cooling energy demand. This study also indicates an energy saving every month with the application of cool roof, with the largest saving in hotter months and no heating penalty in cooler months. Application of cool roof technology on warehouse style buildings across Australian buildings indicates energy savings can be achieved in all broad Australian climatic zones, with the greatest energy reduction associated with tropical, subtropical and desert environments. [ABSTRACT FROM AUTHOR]

With the ageing of population in Europe, the housing stock needs to meet the demands of older occupants, including an increasing demand for energy efficiency. As collective entities, Dutch social housing associations are among the frontrunners in achieving the energy and comfort goals of the European Union and the national government. This paper presents a number of case studies from the domain of social housing for older people from The Netherlands. The cases presented focus on the baseline conditions, the interventions conducted, the financial aspects and the involvement of stakeholders. Implications and recommendations for the design and retrofitting of housing, as well as the process of improving energy efficiency and comfort in practice, are discussed on a supranational level. [ABSTRACT FROM AUTHOR]

This paper investigates application potential of the maisotsenko cycle (M-Cycle) evaporative air coolers in air conditioning systems in moderate climate (Poland is used as an example). Cross-flow M-Cycle heat and mass exchanger (HMX) was chosen as the most representative unit for this type of application. Analysis is based on the computer simulations performed during the peak day in summer (day when the highest cooling loads occur) and assumptions used in Polish standards for air conditioning systems. The obtained results show that evaporative cooling through Maisotsenko cycle has high application potential and allows to generate significant energy savings in compare to the systems equipped with standard heat recovery devices. The most favorable application for the M-Cycle in moderate climate is displacement ventilation, where proposed unit is able to cover almost all energy required by the air conditioning system. [ABSTRACT FROM AUTHOR]

Air source heat pump (ASHP) has been widely applied to many parts of the world due to its simple structure and low initial cost. To save energy consumed for spacing heating and enhance the indoor thermal environment, improving the performances of ASHP has become one of the research focus in the relevant field. Currently, the most conventional heating terminal of ASHP system for spacing heating is finned tube heat exchanger coupled with air fan, which may cause strong draught sensation and dry eye problem and make users feel uncomfortable during convective heating. On the other hand, radiant heating is attracting more and more attention due to its comfortable indoor thermal environment. In this paper, a novel radiant-convective heating terminal was presented and coupled into an ASHP system. Both the operating characteristics and heating performances of the novel system were experimentally investigated. The experimental results showed that the novel system took about 28 min to enter a steady operating stage, during which the radiant panel surface temperature and outlet air temperature for the novel heating terminal, and COP of the novel system were 40.9 °C, 32.1 °C, and 3.11, respectively, under a standard heating condition. In addition, all parameters mentioned above saw a linear increase when the outdoor air temperature increased from −4.0 to 10.0 °C, and their respective rising rates were 0.41 °C, 0.28 °C and 0.04 per increased outdoor air temperature. Furthermore, the experimental results also demonstrated that adjusting the indoor air flow rate could effectively allocate the amount of heat generated by different heat transfer modes, which may have significant effects on the indoor thermal environment. [ABSTRACT FROM AUTHOR]

This paper examines the effectiveness of coelostat daylighting systems for enhancing the indoor visual environment of open-plan offices. A coelostat consists of a movable mirror capable of tracking the sun and a fixed second mirror, which, acting together, create a single beam of sunlight for daylighting. A series of computer simulations were carried out using TracePro and Radiance where the relevant IES output (polar candela distribution plots) of the former was exported to the latter for photometric analyses. The results reveal that coelostat daylighting systems can significantly enhance not only the visual environment but also the energy efficiency when sufficient daylight is introduced by simultaneously applying side and top daylighting (ST) schemes. When only daylight admitted through windows is considered, daylight availability varies from 0.12% (at 10 a.m., summer solstice) to 3.19% (at 12 p.m., winter solstice). In contrast, the highest daylight availability of 3.41% is observed at 12 p.m. on the day of the winter solstice when side and top lighting are considered in addition to daylight admitted through windows. Electricity savings of 1.78 kWh are estimated over a period of one hour around noon, that is, a half an hour before and after noon. A comparison between the on-site measured data and simulated values showed that they were in good agreement, confirming the reliability of the computer modeling developed in this work. The approach described here could be extended to analyze daylighting performance of buildings with similar solar features, such as light wells. [ABSTRACT FROM AUTHOR]

Thermally activated building system (TABS) is a hydronic cooling system, in which cold water is circulated through pipes embedded in the building structure to remove the heat from the indoor space. This paper proposes a hybrid passive cooling system, in which TABS is integrated with a cooling tower. The performance of this integrated system greatly depends on the climatic conditions of the geographical area. Hence, the feasibility of the proposed system to provide thermal comfort in twelve Indian cities spread over five different climatic regions is investigated using COMSOL Multiphysics. Different cooling scenarios like Roof and Floor cooled TABS (RF) and All Surfaces cooled TABS (AS) are compared. The proposed system performs well in arid and semi-arid regions, and the RF scenario is sufficient to achieve thermal comfort. The system is able to reduce the indoor operative temperature by 14 °C for the arid climatic conditions of Jaipur. In the other three regions, i.e., humid subtropical, tropical wet and dry and tropical wet regions, the performance of the proposed system is relatively low and the AS scenario is required to achieve thermal comfort. [ABSTRACT FROM AUTHOR]

This paper aims to analyse the changes that the new Hellenic Regulation on the Energy Performance of Buildings (REPB) has brought to the Hellenic residential buildings, which is in line with the European Directive 2010/31/EC. These changes refer to construction techniques, construction costs and energy performance. Our assessment is based on the numerical analysis of two typical residential buildings, a single and a multi-one. Both buildings were studied according to the requirements set before and after the application of the REPB for all (four in total) climate zones of Greece. The cost for implementing the two regulations was evaluated, as was also the energy consumption cost. Based on these costs we estimated the operating costs for heating, cooling and domestic hot water of the two buildings of this study. The implementation of the REPB significantly reduced the required heating loads for space heating in all climate zones by 37%–48% for both building types; this is mainly attributed to the improvement of the thermal properties of the building envelope and the improved energy performance of the electromechanical systems. The required cooling load was low and the implementation of the REPB did not change it significantly. Significant energy savings, in the range of 51%–58% were also achieved by installing flat plate solar collectors for Domestic Hot Water heating. [ABSTRACT FROM AUTHOR]

Based on an analysis of building processes to date, this paper proposes two ways to make Building Information Modelling (BIM) and with it complex building processes less expensive and more reliable. First, existing experience with building processes that include building-integrated solar systems is analysed, as they are one example for buildings with high energy-saving goals. Based on the analysis, the authors propose to include a new property set and functions in machine code in the next version of the Industry Foundation Classes (IFC). For the machine-code functions, several formats are proposed and the advantages and disadvantages of the proposed IFC extensions are discussed. For simple conventional building components, the existing IFC version 4 seems appropriate. Buildings with innovations that add complexity to the building process can profit most by the savings generated by exchanging machine-code functions. In building processes to date, much information is not shared because of proprietary matters. Functions in machine code can provide the necessary confidentiality so that more capabilities can be exchanged between the stakeholders. Models based on machine-code functions can be updated much faster than detailed models with many parameters. With machine-code functions, advantage can be taken of the greater accuracy of detailed models, as long as they are fast and easy to use. The modularity of the functions stimulates competition between alternative approaches, which makes simulation models less expensive. Finally, exchanging a closed, validated simulation model in machine code introduces a much lower risk of error than exporting and importing complex simulation models. [ABSTRACT FROM AUTHOR]

This paper presents a lighting control system based on natural light monitoring and on occupancy control, characterized by installation easiness, even for existing plants, and cheapness. The system is based on a smart control unit and lighting control devices that can be directly mounted on the lamps in series connection. The installation is noninvasive and does not require any changes in the wiring system, since the communication between each lamp and the control system is realized by means of a 2.4 GHz wireless protocol. The system functionality is ensured with any lamps, also with non-dimmable ones. Tests and functionality verifications on the system were performed in laboratory, proving the applicability to real cases and performances that are comparable to the ones achievable with dimmable LED lamps, but with a significant cost saving. Hypothesizing the application of the proposed system and of different control technologies and strategies to a real academic classroom case study, different lighting scenarios have been simulated. Obtained results allow quantifying the effects in terms of energy consumption and CO 2 emissions relative to such scenarios, achieving up to 69.6% of energy saving and 30.5% of CO 2 emissions avoided. From an economic point of view, the comparison between the proposed control system and commercial systems shows a shorter PayBack Period, from 9 to 5 years. [ABSTRACT FROM AUTHOR]

Building energy models are widely used to estimate or predict the average energy consumption of a building. However, they only provide approximate figures with significant uncertainties. Particular uses such as energy performance guarantee require more reliable results in order to set suitable contracts. For this purpose, uncertainty quantification can be used to support modeling phase and results interpretation. The aim of this paper is to present a comprehensive methodology applied to an office building. First, sensitivity analysis allows users to identify and prioritize the most influential inputs of their model. Non-influential inputs can then be fixed to their nominal values, without impacting the results. The remaining set of parameters makes it possible to assess quantitative measures such as Sobol’ indices which give useful information on the model variance. Different methods are suitable for such calculations but generally rely on specific sample design. Meta-model reduction based on Polynomial Chaos Expansion can be used as a post-processing method and appears to be the best compromise between accuracy and computation time for our case study. This approach also involves the use of probability density function and cumulative distribution to calculate confidence intervals and probability to exceed a threshold value. At last, the importance of using adjustment variables to take into account time-varying parameters is also discussed. [ABSTRACT FROM AUTHOR]

• A new urban building energy modeling tool-AutoBPS was developed. • AutoBPS calculated urban building energy demands, analyzed energy retrofit and rooftop PV potential via EnergyPlus. • AutoBPS automatically generated multi-zone models, considering shading from surrounding buildings. • A downtown district of 3633 buildings in Changsha, China, was simulated to demonstrate the tool's features. • All three energy conservation measures and PV installation could save 38.6% of total energy demand. China has promised to peak carbon emissions by 2030 and become carbon neutral before 2060. Achieving this target requires actions from all sectors, especially the building sector, which accounts for 33 % of the total energy consumption in China. Within this scenario, this paper introduces a new urban building energy modeling tool, Automated Building Performance Simulation (AutoBPS), to calculate urban building energy demands and to analyze energy retrofit and rooftop photovoltaic (PV) potential. AutoBPS uses a building-by-building approach to automatically generate multi-zone (one zone per floor) models based on the city building dataset, considering the shading effect by surrounding buildings. The tool simulates building energy use and PV generation via EnergyPlus. A downtown district of 3633 buildings in Changsha, China, was selected as a case study to demonstrate the features of the tool. Firstly, annual baseline energy uses of 1793 GWh were simulated by inputting Geographic Information System (GIS) data. Then, different energy conservation measures (covering envelope, lighting, cooling system upgrade, etc.) and roof PV generation systems were adopted to explore energy saving potential. The results showed that the window upgrade was the most energy-efficient individual measure for residential buildings, while the lighting upgrade was that one for commercial buildings. Altogether three measures could save 2.7 ∼ 30.7 % of annual site energy use intensity per building. The total energy demand could be reduced by 18.5 % by combining all measures and saved by 38.6 % when PV installation was added. AutoBPS can be easily applied to other cities, supporting urban energy efficiency plans for carbon reduction goal implementation. [ABSTRACT FROM AUTHOR]