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• Automatic MiC envelopes and layout generation by a novel SSG-MOO method. • Multi-objective optimization formulation for passive MiC design. • A pilot MiC study in Hong Kong produced 5 selected Pareto optima out of 625. • Up to 0.42% energy savings and 9.71% spatial daylight autonomy improvement against the baseline. • A multi-level analysis of results and design strategies for practitioners. Modular-integrated Construction (MiC) is an emerging construction technique promoted in the building sector for high productivity and low waste emission in the construction phase; yet, the standardized modules also bring new challenges, such as balancing passive energy efficiency and spatial daylight autonomy, to the operational phase. This paper proposes a Symmetric Skeleton Grammar-based Multi-Objective Optimization (SSG-MOO) method to formulate parametric MiC envelopes and detailed layout, with the two objective functions being energy efficiency and interior daylight performance in the operational phase. Pareto optima of the SSG-MOO, computed by the Non-dominated Sorting Genetic Algorithm II, are generally verified and analyzed in three levels, i.e., MOO's solution space, SSG layout, and MiC design parameters. A case study of MiC residential building in Hong Kong demonstrated the SSG-MOO method through five new passive MiC designs (i.e., spatial reorganization of three architectural modules, and parameter tuning of the envelops and corridors), achieving up to 0.42% energy savings and 9.71% spatial daylight autonomy improvement compared to the baseline design. The contribution of this paper is two-fold, including a novel and sound SSG-MOO formulation for parametric MiC designs, and offering time-efficient and evidence-based design tactics for MiC designers and industrial practitioners to push boundaries of MiC. [ABSTRACT FROM AUTHOR]

• The impact of insulation moisture ingress and thermal bypass are investigated. • 2D computational fluid dynamics is used to simulate thermal bypass in buildings. • Moisture ingress can increase thermal transmittance by a factor of ∼2.2. • Thermal bypass can increase thermal transmittance by a factor of ∼3.5. • Insulation detailing and installation can significantly impact heat loss in buildings. Improving the performance of buildings is a key part of the global effort to limit greenhouse gas emissions and reduce energy consumption. Reducing the designed thermal transmittance of building envelopes through the addition of insulation is one of the primary measures adopted in many nations aiming to address the building sector. In theory, these globally adopted measures to improve design should result in considerable energy savings. The reality however is different. And a mismatch between design and in-use performance has been widely cited. This performance gap is extensively attributed to changes in occupant behaviour – the rebound effect. Considerably less research has investigated technical performance gap rationale. This paper aims to address this literature gap by investigating two technical reasons why design and in-use performance might differ; namely: i) moisture presence in the building's insulation and ii) thermal bypass of the insulation system. The study uses a combination of thermal resistance analogies and computational fluid dynamics, to ascertain the extent to which compromised insulation would impact the performance of building envelopes. An increase in envelope heat loss results in an increase in a building's energy consumption, and hence its associated greenhouse gas emissions. The study concluded that, in extreme cases, the presence of moisture in the insulation layers can increase the thermal transmittance of highly insulated envelopes by a factor of 2.2, while closed- and open-loop thermal bypass can increase it by a factor of 3.5 and 3.7 respectively. Although these might be considered extreme cases, the results align with findings from several past studies that quantified the gap between in-situ and design thermal transmittance. The results suggest that, while ensuring building envelopes are designed with adequate levels of insulation is important, ensuring that the insulation is adequately installed is potentially of equal importance. [ABSTRACT FROM AUTHOR]

The growing awareness of climate change is constantly moving the attention of designers and policymakers from typical and current scenarios to future layouts. This new approach introduces a degree of uncertainty that should be accounted in the building design process. The multitude of possible scenarios suggests considering dynamic system that can adapt themselves to unpredicted operating conditions. The aim of this study is to test a new approach and a new flexibility metric analysing the behaviour of a high-performance dynamic internal curtain in current and future scenarios. The first part of the paper focuses on the optimization of the dynamic system in the current scenario; this preliminary analysis represents the traditional design approach and is considered the baseline for all the comparisons. Hence, defining a matrix of likely scenarios, this paper explores the behaviour of three different selected control strategies – always off (i.e., no curtain), fixed control, optimized control – in the different scenarios considering possible variations of i) climate, ii) urban context, iii) internal loads, and iv) building use. The main outcomes of the research are, on the one hand, the comparisons of the control strategies and the benefits of the dynamic system and, on the other hand, the definition of a new metric that can properly describe the flexibility of the building systems with reference to the future scenarios analysed. This metric is based on six classes – which describe the statistical distribution of the energy consumptions of all the scenarios simulated in the matrix – and an index called Energy Flexibility Index (EFI) that quantifies the flexibility of the technology considered. The case study analysed highlights how implementing a dynamic shading system, considering the same building use, can increase the EFI of nearly 21% for non-optimized control strategy and up to 23% when optimized. While changing the building use in residential reduces these values respectively, to 6% and 7%. [ABSTRACT FROM AUTHOR]

Forecast uncertainties pose a considerable challenge to the success of model predictive control (MPC) in buildings. Numerous possibilities for considering forecast uncertainties in MPCs are available, but an in-depth comparison is lacking. This paper compares two main approaches to consider uncertainties: robust and stochastic MPC. They are benchmarked against a deterministic MPC and an MPC with perfect forecast. The MPCs utilize a holistic building model to reflect modern smart homes that include photovoltaic power generation and storage, thermally controlled loads, and smart appliances. Real-world data are used to identify the thermal building model. The performance of the various controllers is investigated under three levels of uncertainty for two building models with different envelope performance. For the highly insulated building, the deterministic MPC achieves satisfactory thermal comfort when the forecast error is medium or low, but the thermal comfort is compromised for high forecast errors. In the poorly insulated building, thermal comfort is compromised at medium and high forecast errors. Compared to the deterministic MPC, the robust MPC increases the electricity cost by up to 4.5% and provides complete temperature constraint satisfaction while the stochastic MPC increases the electricity cost by less than 1% and fulfills the thermal comfort requirements. [ABSTRACT FROM AUTHOR]

[Display omitted] • The paper offers an overview of the implementation of key building energy efficiency requirements in Member States. • The renovation rate has to further increase to achieve zero-emission buildings. • The EU building stock has the potential to achieve a remarkable 94% reduction in direct greenhouse gas emissions by 2050. • Member States strongly rely on renewable technologies deployment for achieving climate neutrality. • Average energy performance level of Nearly-Zero Energy Buildings (NZEB) lags behind EU benchmarks. The European Union (EU) is accelerating its clean energy transition in order to reach climate neutrality in 2050 through targeted policies, with the Energy Performance of Buildings Directive (EPBD) playing a pivotal role in reducing buildings energy consumption. This study evaluates the progress of EU Member States in implementing the EPBD requirements, focusing on Long-Term Renovation Strategies (LTRS), Nearly-Zero Energy Buildings (NZEB), Energy Performance Certificates (EPC), and technical building system inspections. Harmonized data enable cross-country comparisons, revealing trends across climatic zones and assessing policy impacts at the EU level. Aligning renovations with 2020 LTRS could cut greenhouse gas emissions by 35% by 2030 and 94% by 2050. Despite the well-established status of NZEB, their energy performance lags behind EU benchmarks in all climatic zones. Moreover, diverse EPC methodologies complicate in-depth comparisons, yet nearly 70% of EU certification schemes define energy classes based on an energy indicator. Finally, over 75% of Member States implemented heating and cooling system inspection schemes, but few assess their impacts. While progress towards a highly energy-efficient building stock is evident, challenges persist. Member States must intensify efforts, especially in increasing the renovation rate with the aim of achieving zero-emission buildings. The recast EPBD, nearing adoption, will assist Member States by imposing enhanced requirements for building decarbonisation. This effort holds potential to unlock co-benefits, including climate change mitigation, energy resilience, and improved life quality. [ABSTRACT FROM AUTHOR]

Energy efficiency standards for household appliances have been adopted in many countries to mitigate negative externalities, reduce emissions, and save energy. Using Chinese provincial-level panel data from 2008 to 2018, this paper builds a difference-in-difference model to examine the mechanism by which energy-efficiency upgrades in China's air conditioners affect urban household electricity usage. The results show that the upgrades have brought about an obvious reverse effect, with urban household electricity usage increasing rather than decreasing. Reducing the unit costs of energy service has enhanced residents' sensitivity to cooling demand. Driven by the substitution and income effects, urban residents may increase the intensity and frequency of their AC use. Additionally, this reverse effect is heterogeneously dependent on the family size and urban residents' age structure rather than their educational level. When families are larger and have more children, the reverse effect is more pronounced. This paper's findings provide useful recommendations for policy-makers to formulate policies that are synergistic with energy efficiency standards for household appliances. [ABSTRACT FROM AUTHOR]

Energy consumption of lift systems is one key issue in modern high-rise buildings, drawing property owners' attention and accounting for 6% of total electricity consumption by end-use in Hong Kong. A Benchmarking Energy Performance Indicator (BEPI), , measured in J.kg−1.m−1 and proposed by the first author of this paper for lift installations is mentioned in the Technical Guidelines of the Building Energy Code , as one emerging good engineering practice. BEPI is a fair parameter for comparing energy performance of lifts irrespective of their brand, model, travel, speed, capacity and control. It considers energy performance due to both the motor drive efficiency and traffic control intelligence. However, one main obstacle to make it statutory is the lacking of a generic monitor able to retrieve three sets of real time data (normally unavailable on an existing lift) to compute the BEPI, namely energy consumption, instantaneous car load and traveling distance, and to collect ample data statistically reliable enough to determine an acceptable threshold value. This paper describes the development of a proof-of-concept prototype BEPI monitor by giving full technical details on the rationale and history of development, the hardware components, software framework, and updated numerical results of one implementation inside the headquarters of Electrical & Mechanical Services Department (EMSD) of HKSAR. Experiences in installing and calibrating those external sensors that make the whole system non-disturbing to normal lift operation, as well as the procedures in computing the BEPI, are discussed in greater details. It has been shown that the BEPI is traffic dependent but the weekly average of it is relatively stable, confirming it may be robust enough for benchmarking purpose. The solution described in this paper may help roll out the monitoring of BEPI for all lifts inside and outside Hong Kong. [ABSTRACT FROM AUTHOR]

[Display omitted] • nZEBs in Eastern Europe lack carbon neutrality metrics and targets. • Performance requirements for nZEBs in Eastern Europe are presented. • Eastern Europe needs strategy and local governance for nZEB market penetration. • EPCs require major reform, and effective monitoring of nZEB performance is needed. • The cost-optimality calculation method must be adopted to ensure cost-effective market uptake. The European Unions' ambition for the construction sector is to be carbon neutral by 2030 for new construction. Since 2021, all new buildings in the EU should have been constructed as nearly zero-energy buildings (nZEB). However, Eastern European countries struggle to implement the 2018 Energy Performance of Building Directive recast requirements. Next to the economic challenges, equally essential factors hinder renovating the existing residential building stock and adding newly constructed high-performance buildings sourced primarily from renewable energy sources. Therefore, this study provides a cross-study to identify the barriers to nZEB implementation in ten Eastern European countries, including Bulgaria, Croatia, Czechia, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, and Slovakia. The study was conducted between 2019 and 2021 and provides an overview of prospects for nZEB in Eastern Europe. The study examines the challenges of nZEB plans faced in those countries and provides constructive recommendations. The regulations and definitions regarding nZEB energy performance, cooling and heating energy demand, thermal comfort, onsite renewables, and construction quality were analyzed. Results show that most Eastern European countries are unprepared to comply with the EPBD guidelines and cost-optimality approach. The paper ranks each country and recommends specific measures to refine the nZEB definitions. The paper provides a thorough comparative assessment and benchmarking of select EU geography that can help shift the identified gaps into opportunities for the future development of climate-neutral high-performance buildings. [ABSTRACT FROM AUTHOR]

• Five different energy efficiency alternatives for the building were studied. • A ground-source heat pump and solar PV usually provide the highest profitability. • A household battery has become profitable at the 2022 electricity price. • Dimensioning of a solar PV system massively depends on the electricity price level. • At the 2022 electricity price level, the array-to-inverter ratio can be up to 4.9. Buildings and the construction sector make up about a third of the final energy consumption and energy-related carbon dioxide emissions, offering a significant potential for emission reductions. This paper investigates the conversion of a Nordic oil-heated townhouse into a carbon-neutral one. Five different energy efficiency (EE) alternatives including, for example, different heat pump types and their dimensioning are studied. The electricity demand of the EE alternatives is aimed to be covered as cost-effectively as possible with an on-grid system based on solar photovoltaics (PV) and a battery energy storage system (BESS). The cost-optimal dimensioning of the components is based on the 30-year life cycle cost (LCC), and the work is carried out using an hourly level simulation model developed in MATLAB. To maximize the profitability of the BESS, an intelligent control algorithm based on linear programming is implemented based on a day-ahead electricity spot price for the years 2020–2022 and "perfectly" forecasted power demand and generation data. The data used in the simulation consist of measured electricity consumption, simulated heat generation based on annual oil consumption, and simulated solar PV power generation. It was observed that an about 60% partial-power-dimensioned ground source heat pump together with a solar PV system provides almost always the lowest LCC. However, the BESS was shown to be profitable at the current investment costs for the first time at the 2022 electricity prices, enabling a capacity of 210–230 kWh. On average, the cost-optimized on-grid electricity system was found to reduce the 30-year life cycle costs by 6%, 20%, and 85% with the electricity prices of 2020, 2021, and 2022, respectively. When the price of electricity is exceptionally high, it may be justified to implement more extensive energy efficiency improvements, such as additional insulation of the building envelope. Nevertheless, the impact on the life cycle costs is marginal. In addition, the cost-optimized solar PV capacity has increased more than sevenfold between 2020 and 2022. [ABSTRACT FROM AUTHOR]

The low energy efficiency of the European building stock is both a social and environmental issue. However, plans and studies on energy retrofitting interventions do not usually evaluate the impact of these measures on households' energy affordability. This paper analyses and compares the effect of alternative retrofitting strategies on thermal energy services' affordability in Spanish vulnerable households. This analysis was carried out by applying the Required Thermal Energy Expenditure model proposed in previous studies to several 2030 residential building stock scenarios, setting 2020 as a baseline. Therefore, this work proposes a methodological approach to assess the impact of the considered energy efficiency interventions on energy poverty in winter (WEP) and summer (SEP) and carries out both a 'social cost' and a cost-benefit analysis. The dwelling's thermal-enclosure retrofitting stands out as a very WEP-reduction and social-cost effective measure. Instead, replacing old thermal systems with more efficient ones would have a higher impact on SEP. Combining both kinds of retrofitting measures could reduce heating and cooling required expenditures by, respectively, 49% and 59%, and decrease the WEP and SEP share, correspondingly, by 35% and 63%. These results might inform policymakers to enhance the targeting and design of energy efficiency programs. [ABSTRACT FROM AUTHOR]

• The new solution for the façade integrated photovoltaic system, En-ActivETICS was proposed and described in detail, including technical recommendations. • The calibrated numerical model was used to determine hygrothermal performance and identify the most crucial issues of En-ActivETICS. • The positive effect of PCM and diffusion channels was revealed based on a numerical study using calibrated thermoelectrical and hygrothermal models. • The En-ActivETICS was investigated considering local climatic and economic conditions among 38 European countries. • The roadmap 2030 for the En-ActivETICS advancement was developed and presented. The main goal of the European building market transformation regards the reduction of CO 2 emissions and energy demand in the built environment towards net zero carbon buildings. This drives research and building practice to search for economically justified solutions that contribute to achieving these objectives. The work presented in this paper is concerned with the technological and economic context. The original solution of photovoltaic integration with the external thermal insulation composite system named the En-ActivETICS was developed, tested and analysed. The energy potential of the En-ActivETICS across Europe, considering south oriented façade is from 88.3 to 195.8 kWh/(m2⋅a), with the efficiency of solar energy conversion of around 13–14%. The problem of system overheating was solved by applying PCM mortar beside the PV panel, which allowed to keep the PV temperature below 70 °C. The risk of moisture load (from driven rain or water vapour condensation) was avoided by diffusion channels pressed in the mortar. Furthermore, the economic analysis of system implementation in Europe is also promising. Considering the availability of solar energy and electricity prices around Europe the payback time of the En-ActivETICS varies between 12 and 44 years for analysed countries. According to the presented roadmap for the En-ActivETICS advancement a payback period of <10 years is possible with a maximum cost of the system <275 EUR/m2 and electricity price >0.25 EUR/kWh. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has significantly affected people's behavioral patterns and schedules because of stay-at-home orders and a reduction of social interactions. Therefore, the shape of electrical loads associated with residential buildings has also changed. In this paper, we quantify the changes and perform a detailed analysis on how the load shapes have changed, and we make potential recommendations for utilities to handle peak load and demand response. Our analysis incorporates data from before and after the onset of the COVID-19 pandemic, from an Alabama Power Smart Neighborhood with energy-efficient/smart devices, using around 40 advanced metering infrastructure data points. This paper highlights the energy usage pattern changes between weekdays and weekends pre– and post–COVID-19 pandemic times. The weekend usage patterns look similar pre– and post–COVID-19 pandemic, but weekday patterns show significant changes. We also compare energy use of the Smart Neighborhood with a traditional neighborhood to better understand how energy-efficient/smart devices can provide energy savings, especially because of increased work-from-home situations. HVAC and water heating remain the largest consumers of electricity in residential homes, and our findings indicate an even further increase in energy use by these systems. [ABSTRACT FROM AUTHOR]

This paper evaluates through experimental testing a prototype of switchable insulated shading (SIS) systems suitable for windows to optimize solar heat gains in order to maintain indoor thermal comfort. Specifically, the paper describes a laboratory testing procedure and measurement results for SHGC values specific to various SIS designs and operation settings using a box calorimeter set-up. The SIS prototype can modulate continuously its optical and thermal properties including U-value and SHGC using rotating insulation layers controlled through an actuator to a specific slate angle setting. The results of the experimental testing confirm that SHGC value for the SIS prototype is correlated to the slate angle of the insulated layers. This correlation remains applicable for any SIS insulation thickness. The measured data are used to assess the potential energy efficiency benefits from SIS when applied to windows for US homes. In particular, a prototypical housing unit located in three US cities is considered to evaluate the energy efficiency potential for switchable opaque insulated shading systems. The results indicate that SIS systems can achieve up to 8.3%, 11.3%, and 11.4% in annual HVAC energy consumption compared to no-shading cases for dwellings located in Golden, CO (representing a cold climate), Phoenix, AZ (representing a hot climate), and San Francisco, CA (representing a mild climate), respectively. [ABSTRACT FROM AUTHOR]

This paper proposes a distributed feedback-based optimization method, based on the principles of approximate dynamic programming, aiming for the optimal management and energy efficient operation of grid connected buildings. Modern building management faces multiple challenges, aiming for, energy efficiency, RES integration, EV operation, cost reduction and of course user comfort. Therefore, this paper adopts a multi-criterion cost objective, where minimum energy costs are required without sacrificing user preferences and satisfaction. Different type of loads are presented, including both thermostatically controllable loads (simulated and modelled in Energy Plus), and controllable electric vehicles (EV) and energy storage systems (ESS). Extensive simulations showcase the effectiveness of the proposed method introducing comparisons with different strategies by exploiting renewable energy integration, varying pricing tariffs and the stored energy of EVs and ESS units. A robustness evaluation of the proposed method is presented, validating the performance under different conditions. Finally, the paper demonstrates that the proposed strategy can be utilized for the management of real-world problems and buildings. [ABSTRACT FROM AUTHOR]

[Display omitted] The school building sector has a pivotal role to play in the transition to a low carbon UK economy. School buildings are responsible for 15% of the country's public sector carbon emissions, with space heating currently making up the largest proportion of energy use and associated costs in schools. Children spend a large part of their waking life in school buildings. There is substantial evidence that poor indoor air quality and thermal discomfort can have detrimental impacts on the performance, wellbeing and health of schoolchildren and school staff. Maintaining high indoor environmental quality whilst reducing energy demand and carbon emissions in schools is challenging due to the unique operational characteristics of school environments, e.g. high and intermittent occupancy densities or changes in occupancy patterns throughout the year. Furthermore, existing data show that 81% of the school building stock in England was constructed before 1976. Challenges facing the ageing school building stock may be exacerbated in the context of ongoing and future climate change. In recent decades, building stock modelling has been widely used to quantify and evaluate the current and future energy and indoor environmental quality performance of large numbers of buildings at the neighbourhood, city, regional or national level. Building stock models commonly use building archetypes, which aim to represent the diversity of building stocks through frequently occurring building typologies. The aim of this paper is to introduce the Data dRiven Engine for Archetype Models of Schools (DREAMS), a novel, data-driven, archetype-based school building stock modelling framework. DREAMS enables the detailed representation of the school building stock in England through the statistical analysis of two large scale and highly detailed databases provided by the UK Government: (i) the Property Data Survey Programme (PDSP) from the Department for Education (DfE), and (ii) Display Energy Certificates (DEC). In this paper, the development of 168 building archetypes representing 9,551 primary schools in England is presented. The energy consumption of the English primary school building stock was modelled for a typical year under the current climate using the widely tested and applied building performance software EnergyPlus. For the purposes of modelling validation, the DREAMS space heating demand predictions were compared against average measured energy consumption of the schools that were represented by each archetype. It was demonstrated that the simulated fossil-thermal energy consumption of a typical primary school in England was only 7% higher than measured energy consumption (139 kWh/m2/y simulated, compared to 130 kWh/m2/y measured). The building stock model performs better at predicting the energy performance of naturally ventilated buildings, which constitute 97% of the stock, than that of mechanically ventilated ones. The framework has also shown capabilities in predicting energy consumption on a more localised scale. The London primary school building stock was examined as a case study. School building stock modelling frameworks such as DREAMS can be powerful tools that aid decision-makers to quantify and evaluate the impact of a wide range of building stock-level policies, energy efficiency interventions and climate change scenarios on school energy and indoor environmental performance. [ABSTRACT FROM AUTHOR]

• A comprehensive review of urban building energy modeling approaches and methods. • Generalized UBEM frameworks are needed to account for application-specific models. • UBEM domain requires integration with GIS, BIM and cloud-based computing platforms. • Advanced data-driven methods are promising techniques to model building stocks. The world has witnessed a significant population shift to urban areas over the past few decades. Urban areas account for about two-thirds of the world's total primary energy consumption, of which the urban building sector constitutes a significant proportion approximately 40%. Stakeholders such as urban planners and policy makers face substantial challenges when targeting sustainable energy and climate goals related to the buildings' sector, i.e. to reduce energy use and associated emissions. Urban energy modeling is one possible solution that leverages limited resources to estimate building energy use and support appropriate policy formation. Over the past few years, there have been only a few review studies on urban building energy modeling approaches. These studies lack an in-depth discussion of the challenges and future research opportunities related to data-driven, reduced-order, and simulation-based modeling methods. This paper proposes Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis of approaches, methods and tools used for urban building energy modeling. Furthermore, this paper proposes a generalized framework based on existing literature for different urban energy modeling methods. The aim of this study is to assist urban planners and energy policymakers when choosing appropriate methods to develop and implement in-depth sustainable building energy planning and analysis projects based on limited available resources. [ABSTRACT FROM AUTHOR]

[Display omitted] • Impacts of reverse cycle air-conditioners (RCACs) during summer are examined. • Wellbeing impacts are studied via a survey of 283 Australian public housing tenants. • Positive and significant impacts on measures of health and housing suitability are found. • Households with RCACs increased summertime electricity expenditure by about A$40. • There is no significant impact on subjective reporting of energy bill stress. Heating and cooling upgrades can have important implications for energy bills and thermal comfort in public housing. However, more could be known about the specific impacts of such upgrades, including on tenant wellbeing. This paper examines upgrades delivered to public housing properties in the Australian Capital Territory, focusing on effects in summer. We analyze impacts of replacing existing heaters with energy-efficient reverse cycle air-conditioners (RCACs). The principal research question is: by how much does access to indoor cooling increase wellbeing among public housing tenants? The analysis is based on a survey of 283 residents carried out in March–April 2021. We use factor analysis followed by linear regressions and an instrumental variable approach. Positive and significant impacts are found on measures of health and housing suitability, including the reported ability of residents to concentrate. Households with RCACs increased their summertime electricity bills by around A$40 relative to control households, although we find no significant impact on subjective reporting of energy bill stress. The study is among the first to apply rigorous econometric techniques to examine causal impacts of indoor cooling in residential settings. [ABSTRACT FROM AUTHOR]

Providing the occupants with tailored feedback on their energy consumptions can be an effective method to help the users to adopt energy-efficient behaviours. However, in specific contexts such as the social housing, this may be challenging, due to the peculiarities and the economic constraints of the end-users, which make them vulnerable and needing a proper design of the information. Nevertheless, there is a lack of detailed studies in the literature analysing the effects of personalized energy feedback on the space heating consumption and the indoor air temperatures in the social housing sector. This paper aims to evaluate the effects on space heating consumption and indoor air temperature of a personalized feedback campaign delivered in three social housing buildings consisting of 27 apartments in Mediterranean climate. To this end, a personalized feedback campaign was designed and developed, providing for the use of disaggregated energy consumption indicators to show the location of excessive thermal energy consumptions. The daily thermal energy consumptions, as well as the indoor air temperatures of the single dwellings, were monitored daily for over four heating seasons and their variations were analysed before and after the implementation of the personalized feedback. A saving in normalized natural gas consumption of the buildings was found on average equal to −14,8% after the feedback campaign, with no significant variations in the indoor air temperatures. However, some critical issues have been highlighted in the response of individual end-users to the feedback provided. A greater propensity of the occupants to regulate the indoor air temperature through the thermostatic radiator valves in the unoccupied rooms of the house was also observed after the occurrence of the feedback campaign. [ABSTRACT FROM AUTHOR]

Increasing the building renovation rate is a key initiative to drive energy efficiency in the sector and contribute to the European Green Deal. Within this paper, the BIM-based building renovation decision support system RenoDSS is described. RenoDSS (i) automatically generates renovation scenarios based on user preferences and the IFC representation (including second level space boundaries data) of the current building configuration (baseline), (ii) calculates baseline and renovation scenario KPIs, and (iii) identifies the most suitable scenarios by comparing the scenarios' energy, finance, and sustainability KPIs. Validation conducted at two pilot sites shows that RenoDSS reduces the time for (i) identifying potential renovation scenarios, (ii) calculating their energy and LCA/LCC KPIs, and (iii) producing an IFC file for each renovation scenario by around 80% compared to tool-supported manual means. RenoDSS is used by (i) renovation designers that want to optimize the thermal building hull in combination with PV, solar thermal, and HVAC, as well as (ii) decision makers who want to collaboratively identify the most promising renovation option out of the ones generated by RenoDSS. [ABSTRACT FROM AUTHOR]

[Display omitted] • Development of two benchmark models for post-world war II residential buildings. • Average energy use intensity per household (archetypes A and B) were 166 and 155 kWh/m2/year. • Models validated with four-year monitoring data on energy consumption. • Households are dominated by senior adults and their occupancy profiles are presented. • Findings on energy needs and use intensity are useful in temperate and continental climates. In the context of the European carbon neutrality targets, building benchmarks are a key issue for the renovation of existing buildings. Although there are various benchmark methods for energy efficiency characterization, their application to the residential sector is still limited. This paper developed two building simulation models for post-world war II houses in Belgium based on data from post-occupancy measurements and field survey campaigns. The study reports the energy characteristics and occupancy profiled of detached single-family houses. An analysis of energy consumption (electricity and natural gas) and a walkthrough survey were conducted between 2016 and 2019. The benchmark model's validity has been further checked against public statistics and verified through model calibration and monthly energy bill comparison. Two reference models representing 633.702 post-WWII single-family houses in Belgium were created and validated. The first archetype has an average energy use intensity of 166 kWh/m2/year and represents detached single-family houses built between 1945 and 1969. The second archetype has an average energy use intensity of 155 kWh/m2/year and represents detached single-family houses built between 1970 and 1990. The paper provides a timely opportunity to evaluate the real performance of post-world war II most common archetypes concerning design assumptions and how building professionals can turn the energy performance gap challenge to their advantage. The findings on energy needs and intensity are useful for creating future renovation scenarios for similar archetypes in Western European countries. [ABSTRACT FROM AUTHOR]

This paper studies the problem of indoor zone temperature control in shared workspaces equipped with heterogeneous heating and cooling sources with the goal of increased energy savings and environment personalization. Shared workspaces typically witness distinct, pre-scheduled intervals when they are occupied or are unoccupied. In this work, we develop indoor climate control strategies for each of these intervals. For the interval when the workspace is unoccupied, we propose multiple time-bound control strategies for pre-conditioning the workspace in preparation for a scheduled activity (Phase I). For the interval when the workspace is occupied, we propose a separate control strategy which enhances the thermal comfort of the occupants by harnessing the spatial differentiation of the thermal environment to satisfy the different temperature preferences of the individuals (Phase II). Utilizing a physical test-bed and data-driven model learning, we show that our proposed pre-conditioning strategies in Phase I are less computationally expensive than conventional model predictive control (MPC). For Phase II, we use a low complexity quadratic program to minimize the thermal discomfort experienced by individuals based on their temperature preferences. The experimental results show that for Phase I, the proposed control policies can save a significant amount of energy and achieve the desired mean temperature in the space fairly accurately. We further note that for Phase II, the control scheme can achieve a significant spatial differentiation in temperature towards satisfying the occupants' thermal preferences. [ABSTRACT FROM AUTHOR]

• Thermal insulation panels fabricated using recycled cardboard aggregates and bio degradable binders. • Physical, thermal and mechanical properties of the panels are characterized. • The panels report good thermal conductivity values, microstructure analysis shows good adhesion between cardboard aggregates and cornstarch binder. • Optimum panel selection made using selection methods by considering complex relationships between characteristic properties. • Results of the study prove that fabricated panels can be used for thermal insulation in buildings and further investigated for commercial use. Buildings contribute a major part to the energy use in the world. Thermal insulation of buildings is a passive strategy to achieve energy efficiency by reducing heating and cooling loads. Using recycled materials ensures efficient use of available resources by reducing material consumption. This study reports fabrication of thermal insulation panels using recycled cardboard aggregates and different biodegradable binders (corn starch, lime, clay) in varying percentage weight fractions and experimental characterization of their physical, thermal, mechanical and microstructural properties. Cardboard aggregates have been homogenized with binders and additives to fabricate nine panels. All the panels have reported good thermal conductivity values due to their porous nature, and sufficient compressive and flexural strength for use as thermal insulation in buildings. Strong adhesion between cardboard aggregates and cornstarch binder has been observed in SEM (Scanning Electron Microscope) analysis. This study also addresses selection of the optimum insulation material from various fabricated panels by considering the complex constraints that exist between physical, thermal and mechanical properties. Results of the study prove that the fabricated panels can be used for thermal insulation in buildings and can be further investigated for commercial use. [ABSTRACT FROM AUTHOR]

• An integrated energy-economic analysis of Net ZEB office buildings was proposed. • A thorough discussion on the energy balance was provided for Italian climate zones. • Energy grid integrations, self-consumption, storage and losses were analyzed. • The cost assessment of office buildings was performed and compared to state-of-art. • The energy-economic benefit of a new Net ZEB office in Italy was demonstrated. Recently, the built environment has become one of the leading sectors in the challenge of decarbonization and energy consumption reduction. Because of the specific use and the complexity of the typological, architectural, and technical characteristics, non-residential buildings represent a challenge to overcome the nearly Zero Energy Building standard and to achieve the objective of Zero or Net Zero Energy Buildings. It is desirable that the energy produced in situ from renewable sources totally covers the energy demand (ZEB); alternatively, the amount of energy self-produced and dispatched into the grid must be greater than (or equal to) the energy withdrawn from the grid (Net ZEB). At the same time, it is necessary not to neglect the economic aspects. The aim of this work is to propose an integrated energy-economic analysis to demonstrate the actual feasibility of new Net ZEB offices in different Italian climate zones. Thus, the energy analysis of a reference building, based on consolidated and cost-effective envelope and HVAC systems, has been carried out through dynamic simulations. The photovoltaic field located on the roof provides the energy needed for lighting, appliances, and HVAC. The obtained results are the energy demand and the energy production from renewable sources for the case study in each Italian climate zone. Moreover, the paper discusses the complexity of the annual energy balance, considering contributions such as grid integrations, self-consumption, energy stored and losses. Finally, the cost assessment of the proposed building has been carried out and compared to the state-of-art, pointing out the economic feasibility of the Net ZEB. [ABSTRACT FROM AUTHOR]

This paper presents a numerical investigation of dew formation on the roofs of buildings, and its influence on building thermal and energy performance. A new semi-analytical model was developed to evaluate the effects of rooftop dew, including the release/absorption of latent heat due to condensation/evaporation, the variation of apparent thermal emittance of the roof upper surface, and the dew runoff characterised based on laboratory experiments. A set of case study simulations was carried out by implementing the rooftop dew model in the building performance simulation (BPS) software EnergyPlus. Through its impact on roof top surface temperature, dew was found to significantly influence predictions of benefits and penalties of a 'cool roof' versus a bare metal roof. When dew effects were neglected in the simulations, the electricity savings attributed to the cool roof were over-predicted by between 39 % and 204 %, however, the gas heating 'penalty' of using a cool roof was over-predicted by 266 % to 362 %. Results from this study demonstrate that the thermal effects of dew on roofs can be important in BPS studies, and the model that is presented provides a relatively simple means by which to include such effects in simulations. [ABSTRACT FROM AUTHOR]

[Display omitted] • 72 interviews were performed with operators in 7 countries and 5 climate zones. • Climate influences complaint but does not explain setpoint temperatures differences among countries. • Most operation aspects and drivers are influenced by country-related aspects. • There is a great untapped potential for control systems (BMS/BAS) worldwide. • Guidelines and standards are needed worldwide for adaptive, and occupant centered operation. Occupant-centric building design and operation has attracted recent research efforts in many countries, as building occupants are being more recognized as the main drivers in planning and operating safe, comfortable, energy-efficient indoor environments. In this matter, the role of building managers and operators is crucial to capture the needs of occupants and to adapt the response of the building accordingly. IEA EBC Annex 79 participants conducted 72 interviews with operators and facility managers across 7 countries (Brazil, Canada, Germany, Italy, Poland, Singapore, and USA) covering a wide range of ASHRAE 169 climate zones (from 0 to 5 in the climate classification). This paper presents a qualitative cross-case analysis of operators' perspectives and experiences to identify regional differences. Therefore, the analyses are based on the hypotheses that climate or other country-related aspects would be the main drivers of building operation procedures differences. Results show climatic differences have little influence on building management, while occupants' complaints are very influenced by them. Moreover, operators are lacking clear tools, like guidelines and standards, on how to optimize building management in a climatic-adaptive and occupant-centric manner. Therefore, the development of operation protocols for building sustainable operation respecting climatic context and occupants' control is recommended. [ABSTRACT FROM AUTHOR]

• A study on housing stock improvement potential in Mediterranean areas is presented. • Three typical case studies were chosen from the stock of a southern Spanish city. • Monitoring on environmental and electricity data and tests logged real performance. • Energy models were built and adjusted based on real occupancy conditions. • The considered building retrofits raise indoor temperature and reduce discomfort. Renovating buildings is one of the major targets within the current European goals toward decarbonized cities in 2050. The residential stock offers extensive opportunities to achieve current energy horizons, since more than 75% of the existing buildings in the European Union are energy deficient, with poorly insulated thermal envelopes which drive indoor conditions far from current comfort standards. This paper aims to provide a protocol for forecasting the upgrading potential of this housing stock in southern Europe, particularly in Mediterranean areas, identifying the level of obsolescence and possibilities for improvement, especially in winter indoor thermal conditions, offered by standard passive strategies. Following an architectural, constructive, and energy analysis of common patterns throughout the urban stock of the southern Spanish city of Córdoba, three case studies built-in 1951–1980 – pre-dating the first Spanish regulations on thermal conditioning in buildings – were selected for the assessment. Long-term monitoring and in situ tests (i.e., infrared thermography, airtightness) recorded the performance of these buildings under real occupancy conditions, subsequently incorporating them into the calibration of simulation energy models, aiming to predict the potential improvements after implementing standard passive strategies in these buildings. Results show that building retrofits not only improve the quality of indoor thermal conditions by increasing indoor temperatures by 3–4 °C but also almost eliminate occupied hours outside the comfort range. [ABSTRACT FROM AUTHOR]

The capability to dynamically plan, predict, and control indoor conditioning allows to adapt to individual preferences of inhabitants and enables demand side management. While former mainly improves thermal comfort of inhabitants so does latter unlock ecological and financial opportunities mostly for energy utilities. Commonly, dynamic indoor conditioning is based on piece-wise constant indoor temperature constraints. This paper's contribution is the presentation of additional constraints: in particular ones expressed relative to the nominal behavior of a hydronic heating system. This allows to simultaneously harness the relevant process variables in particular during the pre-loading and post-loading phases of a load reduction. The findings are based on data sets acquired on 10 inhabited, residential buildings in Stockholm over a whole year. One of the findings is that building models need to be adaptable if predictive control is applied in practice. This adaptability is assured by a novel concept, i.e. a so called model manager on which the control is relying for the selection of the most accurate model. Centralized optimal control of buildings connected to a district heating network is challenging in practice due to a high computational load. In order to reduce it, the herein presented method elaborates plans only every hour instead of at every control step for optimal control. Since these plans cannot be optimal due to the lack of regular update a hitherto unknown cascaded control logic has been developed that corrects planning errors and other disturbances. Capabilities are demonstrated and compared to conventional controllers in dynamic simulations of a multi-zoned building. The herein presented method is to our knowledge the first to provide all flexibility desired by energy utilities and inhabitants alike through harnessing the consequences of transitions. [ABSTRACT FROM AUTHOR]

• We innovated a new PM removal approach based on the augmented particle sink effect. • The purification device achieved best performance when its porosity was 30%–40%. • This approach can save at least 50% of the device running time. • This approach has advantages with limited economic costs and energy consumption. Traditional indoor air cleaning technologies are mostly equipped with fans and auxiliary components in addition to the core purification unit, and consequently use more energy in the building environment. To energy-efficiently improve indoor air quality, this paper presents a new approach to remove indoor airborne particulate matter. The approach couples the negative pressure effect over the point sink zone by considering the electrohydrodynamic flow generated in a high-voltage gas discharge process to augment the particle sink effect. This facilitates indoor airborne particulate matter to be collected and removed more quickly. We evaluated the influencing factors on the particulate matter removal proportion by laboratory scale experiments: the applied voltage, interelectrode distance, and porosity and shape of the collecting electrode, and compared the particulate matter control performance and energy efficiency of this approach with those of the existing studies. Results showed that the 30 %–40 % porosity of the collecting electrode and stronger electric field intensity had a clearer removal proportion of particulate matter. Moreover, the energy efficiency for 1–2.5 μm particulate matter of this approach (12.7 (m3/h)/W) was 2.3–7.9 times higher than that of the commercially available conventional air cleaners (1.6–5.6 (m3/h)/W). Compared to conventional particle sink purification technique, this approach could save at least 50 % of the sink running time to achieve a better particulate matter removal effect, and shorten approximately 50 % of the 1–2.5 μm particulate matter reverse mass transfer time. This study provides an important reference basis for improving indoor air quality and the creation of a more sustainable society. [ABSTRACT FROM AUTHOR]

A rapidly warming planet provides a significant challenge to the design, delivery, and maintenance of habitable housing across Australia. Information on the adequacy of current measures for cooling Indigenous houses in regional and remote communities in relation to climate change and rising energy consumption costs is lacking. Such information is needed to better protect low socio-economic status householders, people with pre-existing health conditions, and people living in climatically exposed regions. This article models the thermal performance of both existing and 'improved' (built to current national construction code standards) housing stock in relation to various occupancy density, cooling system, and ventilation practice scenarios. This modelling was undertaken for housing in Australia's tropical, arid, and hot/mild climate zones, matching the sites where most discrete Indigenous communities are located. Results show that retrofitting existing housing stock and even building new stock to meet recommended standards are not adequate measures for current or future climate changes. This paper challenges current knowledge, policy, and practices regarding Indigenous housing, demonstrating that significant reform is necessary to maintain habitable conditions and improve energy resilience. [ABSTRACT FROM AUTHOR]

• A DCE is conducted to assess households' willingness to insulate their homes. • Determinants for the adoption of façade thermal insulation are identified. • The investment cost required in the existing building stock is below the obtained WTP. • The required subsidy level is lower than the grants set by existing aid programs. • Increased tax rebate has greater incentive effect than soft financing. This paper assesses Spanish households' willingness to thermally insulate their homes and the drivers that influence such a decision-making process. Stated preference data were collected through a discrete choice experiment (DCE). The final sample of 191 respondents and 1,145 observations was analysed by the use of a mixed logit model, weighing the factors that encourage homeowners to carry out façade energy renovations or not. The model enables the quantitative estimation of renovation adoption rates depending on the households' characteristics and public support instruments in place. The results show that homeowners are extremely interested in increasing the thermal insulation of their homes. The actual investment cost required in the existing building stock is lower than the obtained willingness-to-pay. Furthermore, it was found a relevant effect of a variety of household features on renovation choice (income, age, heating system, etc.), which should be contemplated in the energy efficiency policy design. Additionally, a case analysis is performed which comprises 3 household categories. The results reveal that the required subsidy level is different in each case, sometimes even unnecessary, although all of them lower than the grants set by existing aid programs. Thus, to reduce the free-riding effect, a closer perspective would enable targeted support mechanisms towards each household category. Moreover, the policy performance can be improved by combining subsidies with other measures such as low-interest loans or increased tax rebates, which could contribute to improving the cost effectiveness of the public expense associated with direct grants. Overall, an increased tax rebate is preferred to soft financing, although the influence of the latter increases in low-income households. [ABSTRACT FROM AUTHOR]

Heating and cooling of residential buildings is accountable for a significant share of the EU's final energy consumption. In order to determine the current condition of the building stock and to implement appropriate measures and requirements to improve energy efficiency of buildings, a detailed analysis of existing buildings is essential. This paper aims at describing characteristics of the building stock of Salzburg by analysing energy performance certificates. Therefore, the building stock is grouped into archetypes based on the construction period, building condition (not-retrofitted and retrofitted) and building type (single-family house and multi-family house) and then analysed regarding energy need for space heating, energy carrier, heat emission system, share and U-values of building elements and window to wall ratio. The analysis of the data demonstrates that the structure and naming conventions within the EPC-database pose hurdles for a correct investigation of the data. A comprehensible and distinct notation as well as versioning is inevitable for the sake of avoiding a loss of information and enabling international comparability. An analysis of energy carriers of the archetypes reveals, that a significant share of buildings still uses fossil fuels like oil and gas for energy supply, although electricity (heat pumps) and district heating are on the rise for buildings constructed in recent periods as well as for retrofitted buildings, with heat pumps being the most important energy carrier for new single-family houses amounting to a share of 65 % and district heating for new multi-family houses amounting to a share of 46 %. A detailed observation of the thermal performance of buildings and building elements reveals high potential and practicability not only for energy efficient new buildings, but also retrofitted buildings throughout all construction periods and for both, single-family houses and multi-family houses (e.g. median U-values for retrofitted ceilings/roofs range from 0.17 to 0.26 W/(m2K) compared to a median of 0.14 W/(m2K) for not-retrofitted ceilings/roofs from the most recent construction period). The conducted analysis provides detailed statistical information on the Salzburg building stock and hence a robust basis for further studies regarding the thermal performance of the building stock and future scenarios by means of urban building energy modelling approaches. Furthermore, based on this information, policies for energy efficient buildings can be improved and adapted according to current circumstances. [ABSTRACT FROM AUTHOR]

• Optimized designs for controlled environment agriculture (CEA) facilities are described. • The designs utilize life cycle cost analysis to achieve optimal energy performance. • Energy efficiency and renewable energy measures are part of optimized CEA designs. • Optimal savings of over 65% can be achieved compared to baseline CEA designs. The paper describes a systematic analysis approach to optimize the design of indoor farming facilities considering both energy efficiency and renewable energy systems. The design optimization is based on a life cycle cost (LCC) analysis to account for both capital and energy costs over the lifetime of the facilities. The analysis indicates that LCC-based optimal designs consistently reduce annual energy consumption of the indoor farming facilities compared to the baseline case reaching up to 65%. The most effective energy efficiency measures for indoor farming facilities include high performance heating and cooling systems as well as optimized operational controls. While the heating and cooling system depends on the climate, daylighting controls and temperature settings are found to be consistently suitable for optimized designs in all US locations. The optimization analysis indicates that net-zero energy (NZE) designs for indoor farming facilities, while technically feasible, are typically not cost-effective in most US climates. Only NZE facilities located in Sacramento, CA, can be achieved cost-effectively. [ABSTRACT FROM AUTHOR]

• A heat pump simultaneously driven by a gas engine and an electrical motor proposed. • A prototype was developed and tested to approve the feasibility. • Compressor rotation speed and engine power ratio can both change the heating capacity. • Engine power ratio can be adjusted for better efficiency and economic performance. • The heat pump has higher efficiency and less operating costs than traditional systems. The gas engine-driven heat pump (GEHP) has a higher primary energy ratio (PER) than the electric heat pump (EHP) for heating, but has a lower PER than the EHP for cooling. To exploit the advantages of GEHP and EHP, a heat pump system where the compressor could be driven simultaneously by a gas engine and motor was proposed in the paper. An experimental platform was established to investigate the feasibility and performance of the HPHP system. In addition, numerical models were built for further performance analyses. The results indicate that: (1) Increases in the rotation speed of the compressor and engine power ratio lead to an increase in the total heating capacity. The rotation speed should be adjusted first to meet the required heating load, and then the engine power ratio can be adjusted to achieve better performance; (2) Engine power ratio changes the loads of the engine and motor, thus their efficiencies change, leading to different PERs of the HPHP system. Under different local gas and electricity prices, the engine power ratio can also be adjusted to reach a minimum operating cost; (3) For the case-studied commercial building in Beijing, the annual primary energy consumptions for HPHP, GEHP, and EHP are 94.2, 95.7, and 100.0 kWh/m2, respectively. In addition, HPHP saves operating costs by 17.5 % and 35.1 % compared to GEHP and EHP, respectively, with static payback periods of 2.45 and 1.47 years, even if it is only used for heating in winter. [ABSTRACT FROM AUTHOR]

• A new methodology to investigate the impact of thermal mass is defined. • The use of unrepresentative boundary conditions could lead to inaccurate conclusions. • High thermal mass helps to decrease and regulate the internal temperature. • High thermal mass could increase energy use in the summer and winter seasons. • Isolating thermal mass through internal insulation results in better energy performance than external insulation. Contradictory conclusions have been reported on whether thermal mass reduces or increases energy demand in hot and cold climates. A novel approach to measuring the impact of thermal mass on the building's energy consumption is presented. The method aims to better represent reality and applies two different control conditions simultaneously in a numerical model: the first condition, which has been used in past studies, adjusts the internal boundary condition based on the time duration of heating/cooling activation (simulating an occupancy pattern) and the second, which has not been used in past studies, adjusts the internal boundary condition based on both the time duration and the internal temperature (simulating an occupancy pattern and the thermostatic control system). When investigating the impact of thermal mass on the internal temperature in a scenario where no heat is transferred into the building, the high thermal mass outperforms the low thermal mass, showing a time-shifting effect, long time lag, and small decrement factor. However, when modelled using the method presented in this paper, high thermal mass results in greater energy consumption during summer and winter periods in Saudi Arabia. During transition seasons where temperature swings occur on either side of the indoor set-point temperatures, thermal mass reduces thermal transmission. The impact of thermal mass is also investigated for several climatic conditions in Saudi Arabia. Simulation results show that an internally exposed thermal massive wall section results in greater energy consumption when compared to a similar building with isolated thermal mass (i.e. insulated internally). This is due to the fact that even though the internal temperature inside the building is being cooled/warmed up to the set-point, the thermal mass continues to transfer heat that is absorbed by the building's fabric from/to the interior, placing a greater demand on the cooling/heating system. Over the course of a year, however, the impact of thermal mass is negligible when compared to other factors, such as the insulative properties of the building's fabric. [ABSTRACT FROM AUTHOR]

Utility incentive programs are an important channel to support the deployment of energy efficiency in buildings. To date, these programs have largely been limited to single-component strategies. However, many utilities are now motivated to identify and develop multi-component system retrofits to achieve deeper energy savings, which are essential to achieving broader energy and greenhouse gas reduction goals in the buildings sector. In this paper we present the energy savings, demand reductions, and cost-effectiveness of 16 systems retrofit packages in six utility regions in the United States. These results are being used by these utilities to inform and develop incentive programs for systems retrofits. Our analysis shows that packages with proven lighting and HVAC measures can provide 5–22% whole building annual energy savings, and 13–22% annual energy costs savings, using utility incentive program baselines (code and existing building). The packages are reasonably cost effective for replace-on-burnout but generally not for a retrofit scenario prior to end of equipment life. Demand response can increase both the energy savings and energy cost savings, further improving the cost effectiveness of these packages. We analyzed the impact of using existing building vs. code baselines for calculating savings, showing that the choice of baseline in developing utility incentive programs has a substantial impact on the attributable energy savings to a program, with significant implications for the overall viability of a program (generally savings against existing building condition are higher and improve project and program cost-effectiveness). [ABSTRACT FROM AUTHOR]

• Ownership structure of small commercial buildings makes energy retrofits challenging. • Retrofit package for Zero Net Energy small offices in Mediterranean climate. • Energy use and occupant comfort evaluated experimentally, side-by-side, in real time. • 65%-68% energy savings for cooling season; 22%-25% for heating season. • Energy savings are achieved while maintaining visual and thermal comfort. Making buildings zero-net energy (ZNE) is one of the major strategies for achieving carbon emission reduction goals. For this strategy to be successful, it entails a very significant reduction in energy use – 50% or more. In small commercial buildings, however, owners and building management teams usually have limited resources for identifying, analyzing, and procuring appropriate retrofit measures for reducing such use. An approach to overcome this limitation is the development of bundles of energy efficiency measures that can be presented to building owners/operators as a comprehensive package. The research presented in this paper focuses on an experimental evaluation of the impacts of a retrofit package developed for small office buildings in California. Performing this evaluation in a full-scale whole-building integrated systems test facility allowed a side-by-side evaluation in real time, against a reference case, of the impact of the retrofit package not only on energy use but also on visual and thermal comfort. The retrofit package evaluated is comprised of a combination of HVAC, lighting (including daylighting), and plug load measures. The evaluation occurred at different times of the year in order to account for seasonal variations in environmental conditions, including solar angles and weather. The experimental facility allowed testing for two different façade orientations: south and west. Results show that the proposed ZNE retrofit package can save significant amounts of energy for small commercial buildings. During cooling-prevalent periods, total energy savings were 65% for south orientation and 68% for west orientation; during heating-prevalent periods total energy savings were 22% for south orientation and 25% for west orientation. Measurements indicate that the ZNE retrofit package resulted in small but not very significant changes in comfort levels for building occupants. [ABSTRACT FROM AUTHOR]

Occupancy-Centric Controls (OCC) are specialized control sequences which modulate building operation as a function of the sensed occupancy status, thereby leading to increased energy savings, while maintaining thermal comfort. However, occupancy sensor nonidealities, such as bias, latency, random noise, or misdetection, can degrade the performance of OCCs. In this paper, we perform a systematic simulation-based investigation to understand the impacts of nonidealities from both occupancy counting and presence sensors on OCCs. We use a prototype medium office EnergyPlus-based building model, with a detailed zoning layout, as our evaluation testbed. Subsequently, we evaluate the effectiveness of rule-based, occupancy-centric HVAC, lighting and equipment control strategies on an annualized basis. Furthermore, we systematically characterize occupancy sensor nonidealities. Our results indicate that for counting sensors, although the effects of random noise on energy consumption and thermal comfort are minimal, sensor bias and latency can increase HVAC and whole building energy consumption by up to 3.3 % and 4.9 %, respectively. Additionally, noting that an enumeration approach to understand the sensor impact evaluation map for all considered nonidealities may be resource- and time-intensive, we propose a Bayesian Optimization (BO)-based smart sampling approach to efficiently identify the most impactful sensor nonideality sets. Our results indicate that the proposed BO-based approach is able to increase the computational efficiency by 60-fold, when compared to an exhaustive grid-search (enumeration) method. For presence sensors, we observed that higher false positive rates could have a direct impact on HVAC and whole building energy consumption. A low-grade presence sensor could lead to the increase of HVAC and whole building energy consumption by 12.5 % and 8.1 % on average. [ABSTRACT FROM AUTHOR]

• Miscellaneous loads are a major opportunity to save electricity in vacant buildings. • A method for inferring vacancy was developed. • The model generates a continuously updated likelihood of vacancy. • The vacancy inference model requires less ground truth data. • The sensor fusion approach is robust and enables flexibility. Recent events have forced building managers to examine energy use during vacant periods and revealed miscellaneous electrical loads (MELs) as an opportunity for savings. This paper addresses a key step in unlocking these savings, specifically the reliable identification of when a building is vacant. A Vacancy Inference Engine (VIE), using sensor fusion, was developed to identify vacant periods based on outputs from common sensors, historical building vacancy patterns, and expert knowledge. The VIE calculates the confidence that a building is vacant, allowing building managers to balance the capture of energy savings with the possibility of complaints due to powering down MELs. The VIE has the advantage over logistic regression and other models in that it does not require a full set of ground truth for the training process. The VIE successfully predicted vacancy in an office building using input data streams of instantaneous electricity demand, indoor carbon dioxide concentrations, and the number of active Wi-Fi connections. The VIE's ability to predict vacancy was compared to that of logistic regression using a metric based on the Complaint Opportunity Rate and found to be nearly identical (0.94 versus 0.95, respectively). [ABSTRACT FROM AUTHOR]

[Display omitted] • A research topic relatively new but with an increase interest in the last five years. • The largest scientific contribution from China, Australia and Italy. • The main journals in the field Building and Environment and Energy and Buildings. • Three main direction of research: thermal energy performance of buildings, ecological benefits and reducing the urban heat. • The main limitation of using green walls is the high cost of installing and maintenance. The continuous state of development of the human society imply a big effort and demand to generate and use more and more energy to power our lifestyle. The impact of human activity has negative effects on the environment and thus solutions to maintain or increase our development rate but in the same time to decrease the pressure on the environment must be developed. In this context, the purpose of this paper is to investigate if the use of green walls systems can be a solution to decrease the energy demands in buildings. The investigation include a bibliometric literature research, a scientometric analysis and an in-depth discussion. The data used for the research were obtained by interrogating the ISI Web of Science and Scopus databases, were selected using the guidelines of the PRISMA method and processed with the help of VOSviewer and Bibliometrix software. The research results indicate an increase interest in this topic in the last five years and that the use of vegetation in the constructed grey areas can bring a lot of benefits especially from environmental point of view. Green walls can be a solution to decrease the temperature on the wall surface in hot summer days and to prevent heat loses in the winter time, and thus have beneficial effects on the amount of energy required to maintain a proper interior temperature. The main limitation of using green walls is given by higher costs of installing and maintain the vegetation on walls, thus, finding new more economical, systems of green walls must be developed in the future. Considering all of this it can be state that green wall systems have the potential to become good solutions not just to improve the energy efficiency of buildings but also to create more sustainable urban areas. [ABSTRACT FROM AUTHOR]

• The thermo-injection masonry wall drying method was studied. • The behavior of wall samples during drying in a semi-laboratory scale was investigated. • Energy consumption during drying with different parameters was investigated. • The lowest amount of energy was consumed for drying without heating. • Drying with heating showed high moisture removing efficiency and energy consumption. • Two-phase drying showed a good perspective for the optimization of the process. Excessive wall dampness causes damage to buildings, increases energy consumption for heating and cooling, and favors breeding microorganisms dangerous for people's health. In that case, moist walls must be dried and renovated, including making them waterproof. However, present methods for drying are highly time- and energy-consuming and its optimal implementation should be searched. This paper investigates the behavior of wet masonry wall specimens during the drying process in the semi-laboratory scale. The study aimed to examine the influence of different operating parameters of the considered masonry wall drying method on samples' drying rates and propose an optimal drying strategy. Small-scale masonry wall samples made of red ceramic bricks, cement-lime binder, and plaster were considered. Specimens had similar dimensions of approximately 1000×1000×600 mm and a dry mass of roughly 1050–1150 kg. Two types of constructions were studied, i.e., plastered and unplastered. The drying process was conducted by applying the thermo-injection method and using a dedicated device that ventilated and heated the wet sample. Different drying device operating conditions and drying process implementations were tested, i.e., single-phase drying without and with heating for two constant mass flow rates of drying air and two-phase drying initially without and then with heating and with two different mass flow rates of drying air. Moisture mass change in the wet specimen, temperatures in several locations in the sample, relative humidity and temperature of the surrounding air in the room, as well as the drying device electrical parameters, were monitored to have insight into the drying phenomenon and assess the energy efficiency of the process. In both tested constructions, the lowest amount of energy was consumed during drying with ventilation mode on and without heating. However, much less moisture was removed from samples in these implementations than for drying implementations with heating. The drying with heating mode activated showed the highest moisture removal efficiency, but energy consumption increased significantly. The drying strategy with a two-phase drying process, i.e., initially without and later with heating of the specimen, showed promising efficiency and a good perspective for the future optimization of the process. [ABSTRACT FROM AUTHOR]

In this paper, a value-engineering based integrated design approach is presented to improve energy efficiency of residential buildings. The design approach is based on reducing construction costs from oversizing structural systems of the building to allow investing in energy efficiency measures. The integrated design utilizes optimized selection procedure to identify set of measures that can minimize life-cycle costs while maximizing energy consumption for the buildings without exceeding budget thresholds defined by the value engineering analysis. The integrated design approach is demonstrated and applied to design a prototypical villa in Kuwait considering both homeowner and government perspectives to optimize the selection of energy efficiency measures. The results indicate that significant reductions in construction costs can be achieved due to commonly practiced oversizing of the villa's structural systems. These cost reductions are more than sufficient to cover the incremental costs of implementing optimally identified energy efficiency measures with the benefits of lowering annual energy demand by 70% compared to the current design practices in Kuwait. [ABSTRACT FROM AUTHOR]

• The research method has three main steps. 1. Experimental study, 2.Survey study and 3. Modelling and simulation for long-term energy and daylight analysis. • In the modelling process 5 blind strategies are investigated as BSDF materials by Five-Phase matrix method considering energy and daylight analyses. • The subdivided window blind strategies showed energy efficiency up to 40% considering occupants satisfaction. • The evaluation of daylight and glare metrics showed that the DGP(low light)<0.45, DGPs 0.2-0.28, UDI300-3000 and DAv300,50% indices support the occupants' visual comfort in the spaces with shaded window. • Occupants' working-place, their field of view and daytime are the important parameters for evaluating daylight performance in the room and selecting the most appropriate blind strategy. Thermal and lighting performance in buildings depend on their facade characteristics, and are important factors to achieve environmental sustainability. Application of an integrated model that balances these two performance indices would help optimise window and shading configurations by considering the comfort of occupants. As occupants infrequently operate shadings in shared spaces, the energy efficiency and visual comfort could be improved by planning appropriate shading strategies in initial design process. Thus, this paper presents a multi-stage study on the control strategies of venetian blinds by considering visual comfort and daylight metrics, and through energy analyses. First, the case study was performed in a south-oriented daylit office room. 30 people were interviewed via a survey about working on a laptop considering three different times of a day, five blind types, and three positions. The impact of daylight on their visual comfort was surveyed at different illuminance levels which were measured by daylight loggers. The useful daylight illuminance (UDI), Daylight Availability (DAv), spatial daylight autonomy (sDA), annual sunlight exposure (ASE), and simplified daylight glare probability (DGPs) were used to evaluate the results. Finally, the window and blinds were modelled for different window to wall ratios (WWRs) for long-term energy and daylight analysis, by considering bi-directional scattering distribution function (BSDF) materials and using the five-phase matrix method. Therefore, the positions of the occupants and their activities were determined to be important parameters in deciding the most suitable blind strategy. According to occupants' working place and daytime, subdivided shadings are recommended, particularly in 90% WWR considering both energy efficiency (40% savings) and satisfaction of occupants. [ABSTRACT FROM AUTHOR]

• A systematic review on personal comfort systems (PCS) has been conducted. • Local thermal discomfort determines the effectiveness of PCS. • PCSs may balance thermal comfort, energy efficiency and health in offices. • This review provides guidelines for PCS design. Personal comfort systems (PCS) promise individualized thermal comfort, energy-savings and may even contribute to health by locally heating/cooling specific body segments. To date, however, insights into PCSs' specific design guidelines or their effectiveness on whole-body thermal comfort are scarce. The fundamental question on which body segments should be targeted has not yet been answered. This paper attempts to answer this question by systematically reviewing studies on PCSs' effects on local body segments and the whole body restricted to office scenarios. The results imply that the local thermal discomfort distribution over the body determines the PCSs' effectiveness and that PCSs should eliminate local thermal discomfort by targeting it directly or indirectly. In a typical office scenario, local cooling may affect thermal perception in non-targeted body segments, however local heating may not. Therefore, PCSs could heat uncomfortable body segments directly in cold environments while indirect cooling may also effectively relieve discomfort in warm environments. Moreover, moderate local conditioning does not affect skin temperatures in most non-targeted body segments. The findings suggest that human thermoregulation may be stimulated, and hence, benefit our health, without compromising thermal comfort. Directions for future PCS design are proposed to bridge thermal comfort, energy-efficiency and health in offices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Distributed real-time optimal control was developed for typical HVAC systems. • Physical meaning in decomposition was enhanced in the proposed scheme. • Computation load was significantly distributed from BEMS to local computation unit. • Global convergence of the distributed optimal control was investigated. • Distributed and centralized optimal control led to similar energy performance. Real-time optimal control (RtOpt) is an efficient tool to improve the energy efficiency of heating, ventilating and air-conditioning (HVAC) systems. RtOpt is always centralized and solved entirely in building energy management systems (BEMSs). However, centralized optimization is not be an efficient solution because real-time operation data in local loops need to be sent to the central computation unit in BEMS for optimization. This paper, therefore, proposes a distributed RtOpt scheme for typical centralized HVAC systems, which uses a dual decomposition mechanism to break the centralized problem into one mater problem and several sub-problems that can be solved in parallel and independently. The mater problem is converted to a simple mean value calculation using a projected sub-gradient method, thus distributing the computation load from the central computation unit into local computation units. Unlike available decomposition schemes in literature, the proposed method considered the functionality and spatial distribution of the major components of HVAC systems, which could enhance the physical meaning and facilitate the application of the decomposition scheme. The proposed distributed RtOpt scheme was tested in case studies, with numerical analysis being used to demonstrate its potential benefits. [ABSTRACT FROM AUTHOR]

For decarbonization of the building sector to happen at scale, net-zero energy levels of operational efficiency must be achieved. A global consensus is emerging around the Passive House energy performance level (15 kWh/m2/a thermal energy demand) as "net-zero energy ready". Given the imperative to rapidly transform buildings and shortcomings of the traditional prescriptive approach, a growing number of building energy regulations are adopting the performance-based or outcome-based approach, seeking to mandate net-zero energy performance with ambitious timelines. Some such regulations are based on the Reference Building Approach (RBA) where the energy performance of a building is assessed based on a hypothetical building of the same design but meeting a set of minimum prescriptive requirements. More commonly, performance targets are defined in absolute terms, based on energy intensity metrics. Although the European version of the RBA reconciles the absolute and relative performance targets through mandatory statistical performance baselines, the RBA in North America is used as an independent alternative to absolute energy use/demand intensity metrics (kWh/m2/a). This paper examines the North American Reference Building Approach, focussing on its implementation in the British Columbia Energy Step Code as an instructive example. It is shown that the RBA has serious flaws. Most importantly, by creating a sliding scale, the RBA does not deliver net-zero energy performance, while incentivizing inefficient designs and poor energy modeling practices. Despite the regional focus of the data, the conclusions are applicable to the RBA in general. Based on the results, it is recommended that the use of the RBA in building energy codes and standards be discontinued. [ABSTRACT FROM AUTHOR]

• End-use of electricity consumption in residential buildings in Gulf Cooperation Council countries was presented. • Discrepancies in certain indicators have been observed by the end-use of electricity consumption. • Improving the efficiency of air conditioners and thermal insulation of the walls are the best measures to conserve electricity in residential buildings. • The results can be used in areas with a similar climate, living standard, buildings types, and the inhabitants' behavior. Energy conservation and improvement in energy efficiency yield multiple technical, economic, environmental, and social benefits and realize comfort and sustainability of residential buildings (RBs). This review paper presents the end-use of electricity consumption in RBs and the results of economic analysis. In addition, a description and discussion of studies on energy conservation measures, Net Zero Energy Building, and renewable energy in RBs are discussed. The percentage of end-used energy consumption for different purposes obtained in many studies are often not consistent. Moreover, discrepancies in certain indicators have been observed, necessitating the need to clarify the factors in the consumption of electricity in RBs. Further, a few studies used the term energy consumption in buildings (total or electrical); however, specifying the type of buildings to identify and use the necessary indicators of energy consumption in each type of building are desirable. Furthermore, most studies emphasized improving the efficiency of air conditioners and thermal insulation of the walls as these are the best measures to conserve electricity. [ABSTRACT FROM AUTHOR]

In view of advancing global warming, climate change adaptation and mitigation measures for buildings are becoming increasingly important. The following article discusses the question of whether current urban planning principles still provide a suitable framework for this purpose. Therefore, the aim of this paper is to identify and quantify the main parameters of the urban planning framework regarding energy demand and energy generation of buildings. In a novel, holistic approach, passive design measures were evaluated in a joint analysis based on a case study in the city of Vienna (Austria) with respect to their impact on heating and cooling energy demand, overheating potential, daylight availability, and solar potential of new buildings. The results show that by improving the thermal insulation of the building envelope, the importance of a high compactness of the buildings to lower the heating energy demand is decreased. In addition, moderate compactness can help reduce the energy demand for space cooling and artificial lighting and increase the solar potential of the buildings. Accordingly, the results question the dogma of a high degree of compactness that still exists to some extent and indicate that changing climatic conditions also require new approaches in the urban planning process. [ABSTRACT FROM AUTHOR]

• A systematic literature-approach to classify retrofitting is proposed. • An overview of Spain's previous guidelines on residential retrofits is presented. • A review of financial and subsidies mechanisms in Spain to renovate buildings is introduced. • A literature-based matrix on retrofitting actions is presented. • A classification of energy efficiency strategies for retrofitting is proposed. The building sector is responsible for more than 40% of final energy consumption in Europe; consequently, retrofitting existing buildings can significantly contribute to mitigate greenhouse emissions. Nevertheless, although the European Union has introduced relevant policy instruments, up to now the annual retrofit rates are considerably low with an average of 0.2% at European level. Understanding the past would support the success of the new strategies, such as the recent ones launched through the New Green Deal, which reinforces the importance of renovating existing buildings stock, as the main aim of the renovation wave. As a starting point for assessing the main challenges to allocate the Recovery funds, this paper provides a review of Spain's relevant literature to clearly define the characterization of the existing building stock, which actions have been typically considered under the scope of retrofits, and which strategies have been implemented until now, considering both, private and public initiatives and public financial schemes. The present work has a strong focus on energy-related strategies, although other interrelated actions are mentioned, such as accessibility measures and interior refurbishment of dwellings. Differences and similarities within these approaches are presented through the analysis of 27 relevant references of retrofitting actions and 52 references of financial mechanisms. As in Spain 93% of multifamily buildings were constructed prior to the national transposition of the first Energy Performance Building Directive (EPBD), and therefore are in need of deep energy renovations, the retrofitting of multifamily buildings topic has been widely addressed, even though often in a disjointed manner. The study suggests that although historically there have been several recommended strategies, few are conceived as integral actions, only 15% of the intervention packages refer passive and active energy-related measures and renewable energy incorporation. Furthermore, considering the antiquity of the building stock and the advantage of addressing the topic through clusters, only 63% of the resources directly refer these actions to specific clusters among the six distinctive periods, although in most cases focusing their recommendations on buildings constructed before 1980 where the worst energy performance buildings are concentrated. Concerning public financial and funding instruments, the research illustrates that there has been a substantial increment of programs over the last years promoting energy-related measures, renewable energy and other complementary aspects such as accessibility and interior renovations, mainly for older clusters. Nevertheless, the funds constitute only 8% of the necessary declared investments, which along with the dispersion between the different procedures and the complexity of the processes, have significantly reduced the global impact of these actions without generating robust and oriented market dynamics. Despite the several resources found, both financial instruments and guidelines tend to describe in more detail strategies related to heating demand and consumption and not delve into other relevant actions for warmer climates, fact associated both to the dynamics coming from other countries, and to a vision of the past in which people do not consume refrigeration. This clear focus on heating loads rather than cooling could present limitations for warmer regions in the near climate-change future. [ABSTRACT FROM AUTHOR]

Through tests conducted at the Toronto and Region Conservation Authority's (TRCA) Archetype Sustainable Houses, a hybrid residential space heating system with a supervisory controller was monitored and studied to evaluate its performance and effectiveness for the heating season. A high efficiency natural gas furnace (NGF) and an electric air source heat pump (ASHP) were coupled together to meet the space heating demand of the house. This integrated system is called the cloud based Smart Dual Fuel Switching System (SDFSS) that considers time-of-use (TOU) pricing, fuel cost, short-term weather forecast, and equipment efficiencies and capacities. This multi-variable decision-making process defines an optimal schedule for the hybrid system to run more cost effectively. This paper analyses two separate SDFSSs. According to these analyses, the SDFSS systems showed lower operating cost with respect to the furnace or the ASHP system alone with various carbon tax (CT) levels from $0 to $250/tonne of CT with an increment of $10/tonne of CT that were simulated, along with a significant GHG emission reduction relative to the conventional heating systems. Furthermore, with these technologies, Canada's residential sector could potentially meet Canada's Paris Agreement goals. The SDFSS technology is a is flexible, user friendly, ubiquitous technology for the smooth transition from today's natural gas dominated space heating system to the future's low carbon infrastructure powered by a heat pump and renewable energy. [ABSTRACT FROM AUTHOR]

In the current economic situation in Ukraine, the operation of heat supply systems occurs at a reduced temperature of circuit water. The increased temperature graph of 95/70 °C due to the high cost of fuel is impractical. The experience of such countries as Denmark, Germany, Finland, Sweden and Holland with developed centralized heat supply indicates the need for the first-class equipment of an individual heating point (IHP) of a building with an automatic control system, and then the transition to technology with a reduced temperature graph is carried out. Therefore, the modernization of heat supply systems in Ukraine aimed at the use of a reduced temperature graph will require a transition to closed independent heating systems, to qualitative and quantitative regulation and to automation of consumer IHP systems. A lot of district heating systems in Poland also require modernization to meet the requirements of the European Directive EED 2018/2002. This paper presents the results of numerical study of the influence of design and operating parameters of the heat supply network on the choice of the optimal temperature and flow- rate of circuit water of a distric heating system (DHS). [ABSTRACT FROM AUTHOR]