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Highlights • Definition of passive envelope indexes and caracterization of libraries in La Plata. • Environmental monitoring: achievement of preventive conservation indexes. • Correlation between passive envelope indexes and preventive conservation indexes. • Determination of the most influential passive envelope indexes for the achievement of preventive conservation indexes. Abstract The common approach for libraries to preserve their paper-based collections from irreversible deterioration is by controlling quantitative parameters, such as temperature and relative humidity. Variations of these parameters for preventive conservation can be expressed by the "performance index" (PI) and the "amplitude index" (AI). Building envelope is the first filter of the external climate, buffering the external weather fluctuations and maintaining the building's indoor climate stable. Its shape, window areas and envelope materials are the most influential parameters. As they capture the relationship of a few geometric and physical variables with the building's performance, the envelope characteristics can be expressed as certain passive envelope indexes. This paper studies the relationship of certain passive envelope indexes and the preventive conservation indexes for books for several libraries and archives located in La Plata, Argentina. The results show the impact of every passive envelope index upon the preventive conservation indexes. The compactness, heaviness, adjacency to spaces and adjacency to ground have a positive linear correlation meanwhile transparency and global transmittance are parameters with a negative correlation. In general, the most influential parameter is the relative area adjacent to other spaces, followed by global transmittance, transparency, heaviness, relative area adjacent to ground and compactness. [ABSTRACT FROM AUTHOR]

Paper-based materials, due to their availability, environmental benefits and high thermal properties, have already been implemented in several building envelope designs. However, most of them either did not optimise the use of the material or did not provide sufficient thermal insulation for use in permanent buildings. The presented research analyses six original paper-based building envelope core proposals, suitable for use in permanent buildings in temperate climate of Europe, in terms of thermal and environmental efficiency. Proposals include cores with embedded paper tubes structural elements, timber-cardboard studs and sandwich designs. The heat transfer coefficient of the envelopes was obtained for repeatable modules via 2D computer simulations (ThermCAD software), and the environmental impact was assessed for a representative square metre of the envelope via LCA analysis, based in ecoinvent 3.8 database. All analysed designs showed high thermal insulation properties and met the requirements for U max = 0.20 W/m2K, did not cause the risk of surface condensation, nor have excessive thermal bridges. The analysed building envelope designs based on embedded frame wall structure showed environmental superiority over conventional envelopes (timber frame and SIP panels). The research may serve as a proof of concept, for using paper-based building envelopes in sustainable architecture. [ABSTRACT FROM AUTHOR]

• Switchable insulation is an effective means of regulating heat through envelopes. • Current research on switchable insulation is fragmented across multiple domains. • We review existing technologies systematically and propose a classification system. • We assess their performance and improvement opportunities for building applications. Switchable thermal insulation, in the form of an opaque panel that alternates between thermally conductive and insulated states, can be an effective means of regulating the thermal environment by selectively transferring heat between the indoor and outdoor environments. Pioneering work has been undertaken by researchers to develop switchable insulation technologies intended for applications in the built environment, automotive, and aerospace, where conventional space heating and cooling technologies are either too bulky or too energy consuming to meet design requirements. Switchable insulation technologies are in their infancy and the emerging research on this topic is unstructured and fragmented across disparate application sectors and very few of the adaptive insulation concepts and technologies are actively being pursued by the buildings research community. The aim of this paper is therefore to advance the understanding of switchable insulation for possible applications in the building envelope, by reviewing and classifying the existing technologies systematically, with a particular focus on their working principles, theoretical performance and improvement opportunities. The paper provides a qualitative and quantitative assessment of the most promising switchable insulation technologies for building envelopes and identifies the opportunities for further research in each of the technologies. [ABSTRACT FROM AUTHOR]

Several studies have demonstrated the capability of data-driven modelling based on on-site measurements to characterise the thermal performance of building envelopes. Currently, such methods include steady-state and dynamic heating experiments and have mainly been applied to scale models and unoccupied test buildings. Nonetheless, it is proposed to upscale these concepts to characterise the thermal performance of in-use buildings based on on-board monitoring (OBM) devices which gather long-term operational data (e.g., room temperatures, gas and electricity consumption...). It remains, however, to be proven whether in-use data could be a cost-effective, practical and reliable alternative for the dedicated tests whose more intrusive measurements require on-site inspections. Furthermore, it is presently unclear what the optimal experimental design of the OBM would be and which data analysis methods would be adequate. This paper presents a first step in bridging this knowledge gap, by using on-board monitoring data to characterise the overall heat loss coefficient (HLC) [W/K] of an occupied, well-insulated single-family house in the UK. With the aid of a detailed building physical framework and specifically selected data subsets a sensitivity analysis is carried out to analyse the impact of the measurement set-up, the duration of the measurement campaign and the applied data analysis method. Although the exact HLC of the building is unknown and no absolute errors could hence be calculated, this paper provides a new understanding of the decisions that have to be made during the process from design of experiment to data analysis. It is demonstrated that such judgements can lead to differences in the mean HLC estimate of up to 89.5%. [ABSTRACT FROM AUTHOR]

This paper deals with the minimization of a building's external wall thermal transmittance, with the aim of improving the energy efficiency of the building. The wall's thermal transmittance must abide by the current legislation, but also suit the limitations of other construction parameters, mainly budget and thickness, but also time limit, workforce, number and thickness of the layers and availability of materials depending on the approach. The optimization is achieved formulating an Integer Linear Programming (ILP) problem involving the parameters mentioned above. Therefore, any available ILP solver can be run to obtain the best combination of the different materials and thicknesses for the layers, in order to minimize the thermal transmittance. This paper presents a case study of a common but representative external wall consisting of 6 layers, with more than 670,000 possible combinations of materials and their thicknesses. The study concludes with a comparison of the lowest thermal transmittance obtained for a selection of budget and thickness combinations for the mentioned wall. [ABSTRACT FROM AUTHOR]

Reducing energy consumption in buildings and increasing renewable production are key goals of European policies to achieve a sustainable and competitive low-carbon economy by 2020 and beyond. Non-residential buildings constitute a heterogeneity sector characterized by high energy consumption and various building types, sizes and energy characteristics over Europe. This paper presents the overall results of the data collected by the GreenBuilding Programme (GBP), launched in 2006 to promote and improve energy efficiency in new and existing European non-residential buildings. The GPB involved building owners willing to adopt energy efficiency measures to decrease energy consumption of their buildings by of at least 25%. Based on voluntary participation, hundreds of partners joined the project, which collected data from more than a thousand buildings of different age, size, use and type (such as offices, hotels, and industry). This paper provides an overview of the Programme and its main results up to its completion in 2014. The paper focuses on building characteristics, energy performance, efficiency measures and energy savings, which are globally estimated to be around 985 GWh/year. A more detailed focus is then given to office buildings, which represent the most frequent building category in the Programme. Case studies are presented to show best practices in various countries with consolidated energy efficiency policy strategies. The paper categorises the main technological measures related to envelope, appliances and systems. It shows how a wide range of technologies are becoming an integral part of buildings and how technology plays a major role in exploiting the massive potential benefits of reducing building energy consumptions. The analysis of the results generates a reliable snapshot of European non-residential building stock. [ABSTRACT FROM AUTHOR]

Modern cities and their architectural structures undergo significant functional and physical changes. In recent years, the interventions on building envelopes have increased. Therefore, it is necessary to analyse potential remodeling of glass facades, along with applying the concept of smart technologies, in order to increase energy efficiency of the existing buildings. This paper analyses the modernization process of devastated glass façade of the tall Slavija hotel, built in 1960s in Belgrade, Serbia, taking into consideration some positive examples of transformation and reskinning of buildings, where the aspect of medialization is an active part of urban renewal. The subject of this paper is the analysis of research findings about the improved thermal comfort of this building, after performing the replacement of its glass façade and converting the hotel building into an office building. Special attention was paid to the implementation of media technologies and final effects on energy balance of the newly designed facade. The proposed solution is supposed to evaluate the improved thermal comfort that was achieved by a radical renovation of the facade and by replacing the existing facade with a new single façade (double and triple glazed units), with media elements as well as without them. The research results are presented as proposals for improving EE public buildings by implementing the latest system of curtain walls in order to increase the value of the buildings. One of the most important criteria included in the process of energy refurbishment is technological improvement of the existing buildings, along with the presentation of media facades. The case study is based on EnergyPlus simulations. [ABSTRACT FROM AUTHOR]

Application of building integrated photovoltaic (BIPV) technology in the building envelope gives an aesthetical and modern appearance. BIPV is a practical, innovative and promising technology for net zero emission buildings. This paper introduces the best in class of the BIPV products and their properties along with international guidelines and testing standards. BIPV products for rooftops, façades and windows have been highlighted in this paper. The properties of BIPV products incorporate solar PV efficiency, V oc , I sc , P max and fill factor (FF). The life cycle sustainable assessment of BIPV module has been reviewed by examining energy payback time and GHG emission. [ABSTRACT FROM AUTHOR]

The carried scientific research regarding evaluation the hygrothermal effects of integration the vegetation into the building envelope was influenced with the differences in necessity to use air-conditioning in the houses, which are not surrounded with vegetation in horizontal structure and which have such vegetation during the summer time. The experimental testing is based on the precise measurements of the relative humidity and temperature, which were carried close to the building plaster in the place without influence of vegetation and between the wall and vegetation. Vegetation on the house, which was used for experimental purposes, is made up of the vine species with a thickness of 40 cm in the place where measurement was carried. Although the investigation takes longer, the paper aims to one month to show the summer time. The mathematical modelling of the obtained data was realized using the numerical as well as the statistical methods The paper aims especially on modelling the differences in relative humidity and temperature of the air and between the wall and vegetation. The dependence of temperature differences was expressed as a piecewise function using the method of Least squares of multiple regression as statistical method. Also the proportional energy to that which might be saved daily instead of its use for air-conditioning in the house was determined. The measurements as well as the used methods: showed sufficient accuracy. [ABSTRACT FROM AUTHOR]

To meet the goals established by the 2015 Paris Accord, scientists say that we will need to achieve zero emissions between 2030 and 2050, which will require a drastic departure from current practices in the building industry, as buildings are a primary contributor of carbon emissions and a major consumer of natural resources. However, building technology research is often driven by disciplinary 'experts' and end-users have little opportunity for involvement in the design process. As buildings become more technologically complex, users must rely on industry professionals with specialized knowledge to design, manufacture and manage these increasingly complex environments Instead, this paper provides an alternative attitude to approachable research methods that open up building technology innovation opportunities to untraditional innovators. When the user has control of the design/innovation process, it opens up a new realm of possibilities rich with lived experience. Understanding the movement of heat, or thermal transmittance , through materials and assemblies is critical in controlling energy consumption in buildings. Despite recent advances in computational technologies, physical testing is still the industry standard to determine a material's thermal properties. However, this process can require expensive equipment, a controlled environment for testing and deep technical knowledge to create a degree of accuracy that is not necessary for all phases of the innovation process and can even act as a barrier to the early stages of design. In this paper we propose the Approachable Hot Box (AHB), a low-cost, low-tech and accessible testing apparatus that can quickly and easily evaluate the impact of simple building materials and assemblies on ambient environmental conditions. By reducing unnecessary complexity for early-level design decisions, the AHB is consistent and reliable at an affordable price. Not only does the AHB rapidly and affordably test small material samples, it helps to articulate potentially complex concepts in a tangible and understandable way, which helps to lower the barrier to innovation. By creating a non-disciplinary, iterative design approach that uses conventional materials and accessible concepts, this work demonstrates that rapid experimentation can be used as a tool to study building assemblies or systems by non-traditional innovators. [ABSTRACT FROM AUTHOR]

[Display omitted] • Systematic review of hybrid system controls for mixed-mode buildings. • Meta-analysis of controls, case studies, platforms and building performance. • Optimal control most often use model predictive control or reinforcement learning. • Studies across 15 climate zones showed a medium energy saving of 28%. • 80% of case studies were simulation-based signaling need for actual implementation. Mixed-mode buildings utilise a combination of natural ventilation from operable building envelopes and mechanical systems to realise climate-friendly ventilation and cooling. The control of such hybrid systems is a promising solution to improve energy efficiency for buildings and comfort for occupants. Meanwhile, it is also a challenging task due to the complexity of the systems and coupled indoor and outdoor air flows and disturbances. This paper presents a systematic review of mixed-mode building controls. From the topical aspects of case studies, the paper analyses locations, climates, building and space types, and sensors. From a control point of view, the paper presents control algorithms based on a well-structured taxonomy, where various algorithms are classified into four categories (On-Off and PID control, rule-based control, optimal control including model predictive control and reinforcement learning, and computational intelligence including fuzzy logic and data-driven control). From an evaluation point of view, the paper illustrates evaluation platforms (simulation and real-world implementation) and results. Modelling and control tools for (co-) simulation are summarised. The evaluation results are compared based on metrics of natural ventilation and night cooling potentials, thermal comfort, indoor air quality, and energy savings. Finally, findings from the review and future research concerns are discussed. [ABSTRACT FROM AUTHOR]

Building hygrothermal performance, indoor air quality and energy consumption depend heavily on envelope airtightness. Over the last three decades, single-family dwellings have been amply studied in this respect by researchers in North Europe, the United States and Canada. However, very few studies have been conducted on airtightness in multi-family housing in warm climates such as Mediterranean Europe. This paper aims to enhance the understanding of building airtightness in early twenty-first-century multi-family buildings in southern Spain. Blower Door tests were conducted in 45 units in seven such buildings. The main airtightness parameter values found are reported and compared to the data for other buildings in southern Europe. The paper includes a statistical analysis of the findings, characterises building types and describes the protocol used to identify and quantify air leakage pathways. The conclusion drawn is that although a rough predictive model can be developed, the results are widely scattered due to the impact of the random component of manual construction, even in buildings with identical construction characteristics and types. The values recorded are nonetheless consistent with the findings for other European surveys. [ABSTRACT FROM AUTHOR]

• This paper quantifies model errors in fan pressurization tests in windy anisothermal conditions. • Maximum error is characterized with fan-induced, weather-induced, and reference pressures. • Both the power-law and the quadratic law can yield significant errors at low pressures. • Possibilities for testing in windy anisothermal conditions are extended compared to ISO 9972. Building pressurization test methods assume that the flow through building envelopes follows a power law or a quadratic law with a specific correction to account for wind and stack effects. This paper investigates the model error stemming from these assumptions using a numerical approach. The model developed calculates the air flow rate through a building envelope assuming it can be viewed as an array of parallel cracks following a quadratic law. On the one hand, the model gives the ideal leakage air flow rate at a given reference pressure across all leaks; on the other hand, it calculates the leakage air flow rate at the same reference pressure that would be obtained with a pressurization test. In calm isothermal conditions, sensitivity analyses show the error in the leakage air flow rate is in the range of –32% to 0% and −15% to 25% at 4 Pa for the quadratic and the power laws, respectively; it is in the range of 0% to 1.5% and −1% to 0.7% at 50 Pa. In windy anisothermal conditions, the range of the relative error strongly depends on the constraints put on the induced pressures. In our analyses, ISO 9972 constraints disqualify a significant number of tests without reducing the maximum error. The results obtained on a very large number of tests enabled us to derive a simple relationship between the maximum error on the leakage air flow rate, the fan-induced pressure, the weather-induced pressure, and the reference pressure. This relationship could be used for estimating uncertainties in pressurization tests for a given building in given weather conditions without invalidating tests a priori based on criteria such as the zero-flow pressure or the wind speed. The discussion details the model limitations. Note in particular that it applies only to steady weather conditions. Further research is necessary to consider unsteady conditions which are common in the field. [ABSTRACT FROM AUTHOR]

• Novel 24-h perturbation method for the estimation of the Heat Transfer Coefficient. • Binary signals with 5 + -hour heating and free-floating periods show highest accuracy. • BIC model selection among RC models most accurate for physical interpretation. • Proposed method very accurate in winter conditions. • Mid-season conditions might need slighlty longer measurement durations. On-site measurement of the actual thermal performance of a building envelope could considerably benefit to the building sector by securing an effective performance of newly built or retrofitted buildings. Current methods to estimate the Heat Transfer Coefficient, for example, suffer however from either excessive equipment downtime and therefore large costs, or fail to achieve a reasonable accuracy. This paper aims therefore at developing and assessing an original 24-h perturbation method for estimating a whole-building Heat Transfer Coefficient. Based on a binary heating signal, the proposed method exploits the data collected with stochastic RC models. The paper first presents a numerical comparison of 398 binary signals along with variable initial indoor temperatures to bring out common characteristics of signals that achieve highly accurate HTC estimations. An experimental campaign in a highly insulated wooden-framed house then implemented one particular signal and assessed its reproducibility under variable weather conditions. The paper shows that the proposed 24-h method indeed achieves a highly accurate estimation when performed in cold weather. In mid-season conditions, the method shows a better robustness from 30- to 36-h measurements. The results invite to further investigate other building types in variable weather conditions to validate the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, potential energy savings by implementing different energy saving methods to enhance the building envelope are presented and calculated through transient simulations using TRNSYS software. To do that, a reference building was selected. In order to develop an accurate model, a dwelling of that building was monitored during 3 months, and data obtained in that monitoring study was used to calibrate and adjust the simulation model. The monitoring study as well as the definition of the building model and the different assumed hypothesis are presented in this paper. Then, different energy saving measures (ESM) are defined for roof, façade and windows, and 64 combinations are simulated. Those results, which are evaluated under economic and energy criteria, are assessed using as reference thermal requirements fixed by Spanish regulation (both for new buildings and for building renovations). These results show how energy renovations in buildings involve important benefits not only under an energy or environmental approach, but also considering economic issues. Moreover, they evidence how the Spanish thermal regulation can be still toughened in order to meet European goals led to the mitigation of CO 2 emissions. [ABSTRACT FROM AUTHOR]

Energy consumption presents increasing trends during last decades, presenting a great challenge. The building sector contributes to a high proportion of the energy consumed and therefore efforts should be focused to improve energy efficiency of buildings. For such purpose, the use of phase change materials in building envelopes has been extensively studied and its benefits were demonstrated. However, there is a lack of simple evaluation tools to assess these benefits. In this paper a previously proposed methodology based on four indicators, which were tested through simulation only are experimentally validated using brick, concrete and timber constructions, incorporating PCM. Results show that the methodology is successful for buildings with heat gains and having low thermal inertia or insulation. However, for highly insulated buildings with significant inertia and low heat gains the method fails to assess the potential benefit of the PCM. Moreover, the ITD indicator is found to be the most accurate in assessing PCM benefits compared to other parameters studied. In this paper the ITD indicator will be modified to take into account an upper and lower comfort temperature levels rather than single set temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • This study presents a state-of-the-art on thermal bridges focusing on slab on grade TB, including calculation methods, norms and software summary. • A numerical study of possible technical solutions to decrease slab on grade TB's effect is presented. • Different external insulation solutions to renovate existing building were compared. • The study highlights the effect of soil thermal properties on slab on grade TB calculation. • Improving insulation thickness and depth does not necessarily reduce the thermal bridges effect. The building industry is responsible for considerable energy consumption and the production of large amounts of greenhouse gas emissions worldwide. Hence, reducing the building heat losses that occur through the building envelope, especially through the floor foundations, is important. This paper provides an up-to-date review on thermal bridges (TBs), mainly with respect to slab-on-grade TBs. First, different thermal bridges types are defined; then the standards used to evaluate TBs are presented. Common approaches to evaluate TBs are discussed, such as the U-value method, the equivalent method approach, and the three-dimensional dynamic method. This latter focuses on heat loss through the foundation and soil in existing buildings. Soil's effect on thermal bridges is described and our case studies showed that thermal bridges heat losses are inversely proportional to soil thermal conductivity. This analysis is involved in the present paper. Finally, exterior insulation solutions at ground level are presented among those the trapezoidal double insulation type can reduce TBs up to 65% compared to no insulation case. As conclusions, directions for further works are suggested to fill current literature gaps. [ABSTRACT FROM AUTHOR]

Abstract: Accurate understanding of the thermal behaviour of building components is essential for predicting heating or cooling needs and facilitates the implementation of more successful energy saving strategies and retrofits. This paper focuses on a specific measure commonly introduced through the residential energy efficiency retrofit programmes in Ireland–insulation. Traditionally, assessments of the performance of building envelopes have been based on assumed thermal resistances of the materials involved, laboratory tests and computer modelling. The aim of the present work is to investigate the in situ thermal behaviour of a case study building and its components under transient and quasi-steady environmental conditions, comparing data before and after the fixing of cavity wall and ceiling insulation. The paper concludes by proposing that predicted values of heat loss using standardised assumed material properties of the existing structure do not reflect the actual values achieved in situ for this test case. These values greatly overestimated the impact of the retrofitted insulation on heat loss through the ceiling and wall. [Copyright &y& Elsevier]

Abstract: This paper aims to present the more recent advances regarding the climatic zoning based on the Climate Severity Index and its relation with the building energy requirements. Three are the major contributions in this paper, the first one is the comparison of the energy performance requirements in different European Union Member States; secondly the definition of the global Climate Severity Index, and finally the definition of the Climate Severity Index for tertiary buildings. Regulators and building designers are the most interested in these results. The comparison of the energy requirements, gives to the regulators, valuable information in order to establish a consistent requirement in their own country. Thanks to the definition of the Global Climate Severity Index, the previous can be done in terms of global-heating plus cooling-energy needs, allowing a homogeneous comparison along Europe or Worldwide. Also, these results allow comparing the energy requirements in one country to those with similar climate. From the designer point of view, the results of this paper could be used to estimate the thermal properties –U values – of the building envelope, and the solar shading factor of the windows of a tertiary building assimilating it to a residential building in an equivalent climatic zone. [Copyright &y& Elsevier]

• This study evaluates cost-optimal energy renovation strategies for various historic building types in a Northern European climate using LCC optimization software OPERA-MILP. • Twelve building types, which are typical of the historic building stock in Visby, Sweden, are selected as the study object. • Decreases of 12–38% in LCC can be obtained by selecting various cost-effective energy efficiency measures and a cost-optimal heating system. • The environmental performance of the energy renovations is closely connected to the assumptions made about the energy system boundary. The life cycle cost (LCC) optimization is a vital method when performing building energy renovation. The present paper provides an evaluation of cost-optimal energy renovation strategies for historic buildings using LCC optimization software OPERA-MILP. The evaluation is performed based on preset targets depending on LCC (LCC optimum) and energy use (decrease by 50%), where the environmental performance is also addressed. Twelve building types, which are typical of the historic building stock in Visby, Sweden, are used as the study object. The results show possible decreases of 12–38% in LCC when targeting LCC optimum. When targeting a 50% decrease in energy use, the LCC is decreased in 21 of 26 cases compared to before energy renovation. Cost-efficient EEMs on the building envelope are characterized by low renovation costs and additional insulation of building components with poor thermal properties. Furthermore, the environmental performance from the energy renovations is highly dependent on the chosen energy system boundary. [ABSTRACT FROM AUTHOR]

Highlights • Element based bottom-up energy model for Swiss residential building stock. • Distribution of specific and aggregated space heating demand for 54 archetypes. • Correlation of energy demand with urban-rural typology, building type and age. • Buildings constructed before 1970 contribute 70% of total final space heating demand. • Possibility to use the results for analysis of element based energy saving potential. Abstract Reducing space heating demand from the residential building stock has been established as a crucial element of the energy transition across Europe. Focusing on Switzerland, this paper presents a bottom-up model (SwissRes) which allows to analyse the demand for space heating by building element and by building archetype (54 archetypes in total). The model is based on detailed data on the building envelope and heating systems of over 25,000 Cantonal Building Energy Performance Certificates (CECB PLUS). We identify three building characteristics which result in above-average final energy demand: rural typology (18% higher than urban), single-family houses (41% higher than multi-family) and in particular age of buildings (525% higher from newest to oldest). In combination, these three factors can lead to up to seven times higher demand per m2 and year in extreme cases compared to the most efficient archetype. Among buildings constructed before 1970, single-family houses (SFH) show very high specific final energy demand for space heating ranging between 170 and 200 kWh/m². On the national level, SFHs and multi-family houses (MFH) are featuring almost identical shares of total final energy demand. Buildings in suburban areas account for almost 50% of the total final energy demand. In total, the buildings constructed before 1980 account for 70% of the national final energy demand for space heating, with buildings constructed before 1920 contributing 22%. Most heat is lost through walls (40%) followed by windows (25%), roofs (17%) and the floor (18%). Losses from walls are particular high (73 kWh/m²) for buildings constructed between 1920 and 1945. Given the scalability of the model, it is readily applicable not only for the country as a whole but also for a province (canton), a city or a larger neighbourhood. The energy demand by archetype and building element identified with the SwissRes model can be used to assess the techno-economic potential of large-scale energy retrofit scenarios. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Highlights • Our equivalent wall method uses the structure factors and harmonic heat fluxes. • The method is tested on three 2-D thermal bridges. • The comparison is based on numerical simulations results. • For a realistic, severe or step evolution of outside temperature, results are precise. • Equivalent walls results are much better than those for a classic 1-D evaluation. Abstract This paper presents a mixed method to determine a 1-D three-layer wall having the same static and dynamic behaviours as a multidimensional thermal bridge. It is based on the calculations of thermal resistance, heat capacity, structure factors and an objective function using harmonic heat fluxes features. This mixed method is applied to three 2-D details. The heat flux through inner surface is analysed over time for a step solicitation and for given boundary conditions: a sinus evolution of the inside temperature and a severe or a more realistic evolution of the outside temperature. Results are really satisfactory, evolution of heat flux through the thermal bridge is close to that of the corresponding equivalent wall. For an outside temperature profile (T e) close to real data, the error on integral value of heat flux is less than 1% in each case. The results for equivalent walls are significantly better than for a classic 1-D evaluation: for a severe evolution of T e the average error is 6 to 28 times lower in the tested cases. [ABSTRACT FROM AUTHOR]

Highlights • Analysis of the average temperature dependency of thermal conductivity in VIPs. • Analysis of the heat transfer contributions that affect thermal conductivity in VIPs. • Evaluation of the combined effect of ageing and temperature on thermal conductivity. • Impact of thermal conductivity variation on thermal behaviour of a VIP-based roof. • Measures to mitigate severe conditions for VIP-based components were introduced. Abstract Over the last few years, the adoption of Vacuum Insulation Panels (VIPs) in building envelopes has increased. However, in order to obtain a correct implementation of VIPs in buildings, it is crucial to conduct a proper analysis of the thermal bridging, the service life and the ageing effects at both the design stage and during building operation. A further factor that should be considered is the dependency of thermal conductivity on temperature. In this paper, an experimental campaign has been carried out to evaluate the variation in the thermal conductivity of VIPs with the average temperature and to qualitatively assess the heat transfer contributions that affect this variation. The study has also been devoted to evaluating the effect of a variation in the thermal conductivity considering various VIP ageing stages. Moreover, dynamic heat transfer simulations have been performed, using a validated model, to investigate the impact of considering a temperature dependent thermal conductivity on the overall thermal behaviour of a building roof with VIP-based insulation. [ABSTRACT FROM AUTHOR]

Highlights • Effect of nonlinear dynamics of a hydronic heat emitter on the DR potential. • The nonlinear thermal effects had insignificant effects on the DR performance. • Shifting potential depends on the energy efficiency of the building envelope. • A reliable radiator model suitable for any simulation-based research is proposed. Abstract Existing simulation-based studies on applying model predictive control (MPC) schemes for space heating operation to enable demand response (DR) make use of linear models for the heating system, usually by assuming convective electrical baseboard heaters. However, buildings connected to district heating networks are typically equipped with hydronic heat emitters, such as radiators, that behave nonlinear. This paper therefore investigates the effect of including the nonlinear dynamics of a hydronic heat emitter on the DR potential of MPC for space heating. Furthermore, the performance of a practical two-level control approach suitable for real application, in which a heating setpoint was determined by a linear MPC and communicated to a conventional proportional integral controller, was investigated. The simulation framework for the investigation was based on the application of an experimentally obtained hydronic radiator model applied in different co-simulation setups, featuring a model of a poorly and a highly insulated apartment, respectively. The results indicated that inclusion of the nonlinear thermal effects of hydronic radiators did not significantly affect the DR performance when compared to the results of an MPC scheme controlling convective electrical baseboard heaters. In general, both setup achieved operational cost savings of approx. 5% and 18% in an existing and retrofitted building, respectively, while restricting the amount of thermal comfort violations to a limited extent. This suggests that results obtained in previous studies featuring electrical baseboard heaters also apply to buildings equipped with hydronic heating systems, and that future simulation-based studies and practical implementation of MPC for space heating can continue to rely on the use of far less computationally demanding linear control-models. Furthermore, the results suggest that the two-level control scheme seems like an appropriate control setup suitable for real applications. [ABSTRACT FROM AUTHOR]

Highlights • A methodology is presented for ranking green building design factors. • Criteria and sub-criteria are identified through a review of leading rating systems. • A pair-wise evaluation process is performed to define distinct research areas. • Building envelope has the greatest influence on the environmental impact of buildings. Abstract Green building rating systems define a set of standards that seek to mitigate the negative environmental impact of buildings by promoting sustainability in the construction industry. Although these systems successfully answer the "Why" and "What" in regard to green building design (i.e., the environmental effects and the proposed sustainable design principles), the "How" has yet to be addressed. This paper aims to advance existing green building practices by introducing a systematic criteria-based ranking of green building design factors (GBDFs) that help construction practitioners reach sustainability goals (i.e., answer the "How") by identifying the most influential factors to consider during the design process. The proposed research process begins with identifying a set of criteria and sub-criteria through an extensive review of leading green building rating systems. GBDFs are then cross-referenced with the governing sub-criteria in order to define distinct research areas for a pair-wise (sub-criterion, GBDF) evaluation process performed in accordance with the frequency of relevant publications. As a result, a criteria-based ranking of GBDFs is established, which, in addition to presenting an important step toward achieving a systematic framework for the implementation of green building principles, further improves existing rating systems by capturing the full impact of GBDFs in reference to their respective ranking scores. [ABSTRACT FROM AUTHOR]

Abstract In the construction sector, strong efforts are being made to reduce energy consumption in buildings, particularly regarding thermal insulation in northern countries. However, the objectives set for the thermal insulation performance of the building envelopes are rarely achieved in practice. For this reason, there is increasing interest in taking onsite measurements. This paper presents the new achievements obtained by the ISABELE (In Situ Assessment of the Building EnveLope pErformances) method for data treatment to evaluate the global transmission heat transfer coefficient of a building with a consolidated uncertainty and within a short unoccupied period. Most of the work relates to the quantification and propagation of systematic errors and to the adaptation of the thermal model used for the inverse method. Practical applications on a test cell and a demonstration on a low-energy house in real outdoor conditions are presented, as are comparisons with other measurement methods (coheating, Quick U-Value of Buildings (QUB)) and the resulting calculated parameters, which show coherent outcomes. The test cell results reveal that a stabilized, repeatable measure with an acceptable uncertainty range (± 10 % in average) can be obtained within 2 days. The house results are slightly less precise (± 15-20 %) but can be obtained just as quickly, assuming that both configurations are insulated from the inside. [ABSTRACT FROM AUTHOR]

Highlights • This study presents a detailed review on IRT for the investigation of building envelope defects. • The literature survey is conducted regarding existing IRT methodologies for building envelopes. • The previous studies with measurement methods, analysis schemes and analysis types are categorized in the literature matrix. • Recent advances and future trends on IRT methods are presented. Abstract Thermal radiation generated by limited resources is emitted from the surfaces and interpreted as temperature. On the other hand, the limited resources necessitate prevention of energy leakages causing noticeable temperature differences on surfaces. Providing sensitive information on temperature contrast, infrared thermography (IRT) is a prominent tool for detecting infrared energy on the surfaces of the objects. IRT is also very promising method for detecting thermal irregularities, air leakages and even moisture abnormalities on building envelopes. Since the concept of nearly zero energy buildings is to be the main target of energy policies in European Union published by European Commission, improving thermal performance of buildings becomes crucial in the last decade. Therefore, implementation of IRT for visualizing and analyzing concealed defects on building envelopes is very promising for improving the energy efficiency of buildings. Given recent regulations and benefits of emerging thermogram technologies mentioned above, a detailed review of the previous studies investigating the abnormalities of building envelopes by IRT is presented in this paper. Furthermore, the applications with measurement methods, analysis schemes and analysis types are classified to highlight the potential of IRT in inspection of building envelopes for providing energy efficient solutions. Finally, recent advances and practical future opportunities are presented for additional contribution of the IRT methods previously employed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The hysteresis is due to the difference of primary nucleation mechanism during heating and cooling. • The PCH is related to the properties of the material itself and the experimental measurement conditions. • The hysteresis temperature is positively correlated with the heating/cooling rate. • The hysteresis effect is more obvious in an incomplete phase transition. • Numerical models of the hysteresis effect of complete and incomplete phase transition are summarized. As an efficient energy storage material, phase change material can be combined with lightweight buildings to reduce the energy consumption of the building envelopes effectively, while it is often accompanied by phase change hysteresis(PCH) and supercoiling (SC) phenomena during the phase transition. SC means that the nucleation does not solidify at the theoretical solidification temperature and needs to be nucleated at a lower temperature. PCH indicates the difference between the melting temperature and the solidification temperature of the phase change materials (PCMs). So far, a lot of research on SC has been done and there is still a lack of research on PCH. On the one hand, the PCH is proportional to the energy loss of the system, the latent heat of PCMs cannot be exploited if PCH is beyond the operating temperature range of the system. On the other hand, when PCMs are combined with building envelopes, the greater the hysteresis temperature, the better the thermal performance of the wall. It's vital to use the hysteresis temperature to improve the performance of the system. Especially, PCMs are equipped in building envelopes, the hysteresis phenomenon of incomplete phase transition will be more obvious because of large temperature fluctuation outside. The hysteresis effect of PCMs in building envelopes is discussed in this paper, the numerical simulation methods and experimental research of PCH are reviewed and analyzed from two aspects of complete and incomplete phase transition. It showed that the PCH should be considered when simulating the thermal behavior of PCMs in building envelopes. The results would be more accurate if two enthalpy-temperature curves (H(T) curve) are used to represent the melting and solidification process, respectively. In addition, the nucleation mechanism of PCH has not been discussed in previous articles and there is no explanation about whether the hysteresis phenomenon is caused by the properties of the material itself or is affected by experimental measurement conditions. Therefore, the related issues are discussed in this paper, it is considered that the PCH is not only related to the properties of the materials but also affected by the experimental measurement conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] The hot box test method has been applied to evaluate both the steady-state (U-value) and dynamic thermal properties of building envelopes. However, the high construction cost of full-scale hot box apparatus and the testing time required (usually several days) may prevent its wider adoption. To overcome the limitations of full-scale hot box tests, this paper proposes a novel method to evaluate the dynamic thermal performance of building envelope components using a small-scale calibrated hot box and scaled-down specimen. In this paper, the scaling relationships of thermal properties evaluated using a full-size specimen and a scaled-down specimen are established based on the Laplace transform of the heat transfer equations. In addition, dynamic thermal properties obtained from scaled-down experimental tests are compared to the values calculated by the EN ISO13768 (ISO) method. A small-scale hot box with a 355 mm × 355 mm metering area was constructed and calibrated to validate the correlations. Three scaled-down concrete sandwich wall panels were then tested and the scaling relationship was cross-validated using the experimental results, finite difference (FD) simulations, and the ISO method. The results indicate that the dynamic thermal properties obtained from a scaled-down hot box test can be correlated to its full-size counterpart when certain conditions are met. The scaled-down hot box test is demonstrated to be an effective yet economical alternative to a full-scale test with significantly reduced experimentation cost and turn-around time. [ABSTRACT FROM AUTHOR]

• An inverse heat conduction problem of the building green facades is proposed. • Levenberg Marquardt algorithm is used as inverse method with Maple as direct solver. • The method can estimate the unknown thermo-physical properties of the GFs. • Thermo-physical properties of the GFs have no functional relationship with I glob,90 and T a. Green facades are becoming increasingly popular in building design, and accurate thermophysical properties of the plant canopy are important to quantitatively evaluate the performance of green facades. The purpose of this paper is to propose an inverse heat conduction problem for estimating the unknown thermophysical properties of building green facades using Maple as the direct solver and the Levenberg Marquardt (LM) algorithm as the inverse method. The proposed method is applied to calculate the thermophysical properties of a green facade with greenery layer thickness of 0.4 m and 0.1 m air gap, and the measured leaf area index is 3.4. The results show that the thermophysical properties of the experimental green facade have no obvious functional dependence on solar radiation (I glob,90) or ambient air temperature (T a). The mean values of the thermal conductivity (λ), the density (ρ) and the specific heat (c p) were determined to be 4.4 W/m·K, 6.1 kg/m3 and 7171.2 J/kg·K, respectively. The thermophysical properties calculated in the computational experiment were verified by measured data. The results indicate that the overall trends are similar and show relatively good agreement, but there are still deviations between them, especially during daytime, in the presence of solar radiation. The main influencing factor for errors is the volumetric heat generation (q en). In this study, heat generation is assumed to be the transmitted solar energy totally absorbed by the homogenous layer. This assumption needs be refined in future studies, especially in the presence of higher global solar radiation. The proposed inverse method can be used not only in the analysis of the thermal response of green facades or vertical greenery systems, but also to analyze other building envelopes of unknown thermophysical properties. [ABSTRACT FROM AUTHOR]

• A well-functioning space heating system can operate below 70 °C for 98% of the year and below 55 °C for 71% of the year. • The performance gap between measured and calculated energy use is widening across building age groups, with a clear increase for post-1980 buildings. • Pre-1980 buildings can operate with supply temperatures below 70 °C for 96–99% of the year and below 55 °C for 67–71% of the year. • Building envelope improvement, whilst recommended, is not a pre-requisite for using low-temperature supply in pre-1980 buildings. • Post-1980 buildings could have limitations in respect of using low-temperature heat under windy conditions. Decarbonising heat in the UK by 2050 will require the wider adoption of low-temperature heat. Current systems, largely relying on gas boilers, have design operating temperatures of 82/71 °C (supply/return) while new standards for 4th Generation District Heating are 55/25 °C. Local authorities must set-up strategies to get their buildings "Heat network ready" but this raises the question of the ability for existing buildings to use low-temperature heat. The aim and the novelty of this paper is to establish a relationship between an energy 'performance gap' in Scottish public buildings and their ability to use low-temperature heat. This performance gap has been evaluated for 121 non-domestic buildings, primarily schools, operated by The City of Edinburgh Council. Space heating system are assumed oversized by 10%. The results show that renovation of the building envelope, while highly desirable, is not a pre-requisite for using low-temperature heat in pre-1980 constructed buildings, which represent 64% of the stock. It also highlights that post-1980 buildings, predominantly utilising mechanical ventilation systems, demonstrate an increasing performance gap which could limit their ability to use reduced operating temperature, especially in windy conditions. [ABSTRACT FROM AUTHOR]

Considerable energy is used for cooling buildings in hot climates like those found in Gulf Cooperation Council (GCC) countries. Designing building envelopes for the purpose of saving energy can necessarily help reduce the building's operating expenses and therefore energy demand over time. For roofing systems, a research project was recently conducted to assess experimentally and numerically the performance of the roofing systems. This paper presents the experimental results of this project. Cool/reflective/white roofs use reflective materials or coatings to reflect a portion of the incident solar radiation. This results in lowering the surface temperature of the cool roofs compared to black roofing systems. As such, cool roofs help reduce the cooling loads during the summer season. This paper presents the test results of characterizing the short-wave solar reflectivity of a reflective roofing material that can be used in cool roofs of Saudi buildings. A Reflective Coating Material (RCM) that is commercially available in the GCC markets was used in this study. Also, the reduction in the solar reflectivity due to dust and dirt accumulations on the surface of the RCM was investigated in this study when this coating was exposed to a dusty and polluted climate of Jubail Industrial City (JIC). As well, the effect of applying different cleaning operations on the solar reflectivity of the RCM was investigated. The test results showed that dust/dirt can significantly contribute in reducing the short-wave solar reflectivity of the RCM. For the RCM subjected to the natural weathering conditions at different exposures times, the results showed that a maximum enhancement of 5% in the short-wave solar reflectivity was achieved, as a result of conducting air plowing process that simulates the wind action. Additionally, a maximum enhancement of 45% in the short-wave solar reflectivity was achieved as results of conducting water cleaning/rinsing process that simulates the rain action and as well conducting washing with dishwashing detergent that simulates homemade cleaning. Furthermore, conducting professional cleaning has resulted in insignificant enhancement in the short-wave solar reflectivity compared to conducting homemade cleaning. Finally, this paper provides a test procedure for characterizing the dust concentration/intensity on the surface of the RCM at different exposure times to the natural and polluted climate. This test procedure can easily be applied on different types of reflective roofing materials and membranes that can be used in cool roofs. [ABSTRACT FROM AUTHOR]

Bio-based insulation materials (such as wood or hemp) are emerging as a promising alternative in building envelope applications, aiming at improving in-use energy efficiency. When compared to common insulation materials (rock and glass wool or petrol-based foams) bio-based materials present the advantage of being renewable, with a low embodied energy and CO 2 neutral or negative. Moreover, these materials have a distinct hygrothermal performance, as the sorption/desorption of water vapour in their porous structure, in dynamic equilibrium with their surrounding environment, constantly modifies their hygric and thermal properties while causing energy transfers itself. In this paper, the hygrothermal performance of two different bio-based materials in outdoor conditions is evaluated. The first is an innovative light-weight composite made from corn pith and alginate. The second a commercially available wood insulator. The materials are tested alone and as components of external thermal insulation systems (ETICS) and compared to a conventional polystyrene foam. The results show how the sorption process influence the hygrothermal performance of the materials when the surrounding conditions are modified. When subjected to cyclic changes in temperature and relative humidity, the bio-based materials tested show a lower temperature variation than polystyrene. This is in part due to their lower thermal diffusivity, but also to the water absorption and desorption mechanisms occurring within the materials, which were measured by the change in mass of the materials during the tests. The differences in the thermal performance were more noticeable when the insulation materials were tested alone than when these were tested as a part of an ETIC System. [ABSTRACT FROM AUTHOR]

This study investigates an energy-inefficient council housing tower block in London, due for retrofit, by exploring the correlations between occupancy and energy consumption patterns, thermal comfort and building energy performance in the winter. The aim of this study is to evaluate the building performance and develop a reliable building simulation model to be employed in the second phase of the study for developing an energy-efficient and cost-effective retrofit strategy to support the council's plans. The research seeks to demonstrate the significance of using dominant occupancy and energy use profiles as opposed to relying on standardised profiles when calculating building energy consumption using building simulation software. The paper reports on the results from the first phase of the study where a quantitative methodology; including a questionnaire, structured interviews, indoor monitoring, and building simulation modelling was adopted. The results provide evidence that occupants’ socio-demographic characteristics have a considerable impact on household energy consumption and fuel bills. The results also show that indoor environmental issues experienced in many flats are partly attributed to the thermally inefficient building envelope and partly due to occupants’ patterns of operating their homes with evidence of excessive heating energy use in attempts to alleviate the indoor issues experienced. [ABSTRACT FROM AUTHOR]

Demand-controlled-ventilation (DCV) refers to a ventilation system with controlled air flow rate based on indoor air quality. DCV operates at reduced air flow rates during most of the operation time. Therefore, less energy is required for fan operation, compared to a constant-air-volume (CAV) ventilation system. Typically, DCV has a two-layer control with variable-air-volume (VAV) valves, and a fan speed control to maintain a constant-static-pressure in the duct system based on a pressure set point. However, this nominal design based fan pressure setpoint is higher than required when all VAV-valves are closed to a certain extent. Therefore, advanced pressure-reset (PR) control - resetting the pressure set point - potentially reduces fan energy use even further. This paper assesses the impact of fan control on both fan energy use and ventilation performance in DCV system of a densely occupied office. Results of a simulation model and realistic measurement setup are compared. The PR control, using air flow rate and VAV-valve position measurements as feedback, causes significantly reduction on fan energy use. These reductions compared to conventional DCV and CAV respectively, are approximately 10% and 72% in case of high occupancy and 50% and 93% in case of low occupancy. Largely, DCV with PR control is strongly considered, especially when occupancy is often expected to deviate significantly from the nominal conditions. Moreover, both simulations and measurements show that there is a clear trade-off between air flow rate deficit and fan energy use, when the fan energy use is lower, the air flow rate deficit is higher and vice versa. Furthermore, the results show that VAV-valve accuracy, characteristics and its lower operational limit hamper the ventilation system in achieving the predicted performance as in the simulation. [ABSTRACT FROM AUTHOR]

A concept of exhaust air insulation (EAI) is proposed for application in cooling dominated buildings. The EAI wall in basic form is composed mainly of an air-permeable porous material layer, a ventilated cavity, and an external protection structure. The excessive indoor air pressure or mechanical ventilation forces the exhaust air from the conditioned space to flow through the porous layer firstly, and eventually to ambient through the ventilated cavity. The outflowing exhaust air makes the temperature of the inner surface of the porous layer very close to that of the indoor air. And consequently, the heat gain through the building envelope wall can be dramatically reduced in the cooling season. In this paper, an unsteady-state heat transfer model is developed to predict the temperature distribution of the EAI wall. Experimental measurements are carried out for validating the heat transfer model. Numerical simulations are performed to simulate the transient heat transfer of the EAI wall in cooling season. The exfiltration heat recovery efficiency of the EAI wall is quantitatively investigated. Effects of the airflow velocity, the thickness of porous layer, and the thermal conductivity of porous material on the thermal performance of EAI wall are analyzed. Performances of a conventional brick wall and an external insulation wall are also calculated and compared with that of the EAI wall. Results show that the EAI wall can reduce 84.7% and 67% of the daily total heat gains in cooling season compared with the brick wall and the external insulation wall, respectively. Excellent thermal performance can be achieved by employing thicker porous layer or higher airflow velocity. At a velocity of 0.003 m/s with porous layer thickness of 50 mm, the heat flux entering indoor spare can be decreased to practically zero. [ABSTRACT FROM AUTHOR]

The paper contributes to the fulfilment of the environmental targets of the EU by introducing an innovative solution for envelopes of nearly zero-energy buildings (nZEB). It presents the development of an environmentally friendly alternative to aluminium curtain wall systems for new constructions or renovations. The research and development were from the early stages led by design strategies for low embodied energy and embodied carbon structures. The first technical concept was analysed using comparative life cycle assessment (LCA). Prototypes were tested to verify their technical performance (air- and water tightness, fire resistance, acoustic properties, short- and long-term hygrothermal monitoring). The final pre-production design was subjected to a detailed LCA, and various possibilities for its improvement were suggested and assessed. The early-stage LCA showed a high potential for reduction of the embodied environmental impact by utilization of natural materials. The results of the experimental testing proved that thus developed curtain wall system fulfilled the standard technical requirements. The detailed pre-production LCA study proved that the fabrication of one panel of the curtain wall system being developed causes significantly lower environmental impact compared with a panel of a common aluminium curtain wall system. [ABSTRACT FROM AUTHOR]

This paper presents test methods and results of assessment data necessary for determination of building energy consumption, based on measurements in an occupied typical single-family house in Poland. Comprehensive on-site measurements included the building envelope, heating system, domestic hot water system, ventilation system with heat recovery and indoor environment quality. A new wireless measurement system was used. The results obtained from the thermal diagnostics were used to analyze the energy consumption of the house in four different successive building modernization stages. The steps undertaken included improvement of wall and window insulation, installation of mechanical ventilation with heat recovery, improvement of house airtightness and replacement of the boiler and the hot water storage vessel with more efficient ones. Such steps are typical activities undertaken without a prior energy analysis by owners of single-family houses. Before thermal renovation the indicator of non-renewable primary energy was 243 kWh/(m 2 y) and after renovation this decreased to 147 kWh/(m 2 y). Proper selection of thermo-modernization measures would allow to reach the lower value of this indicator. However, it still would be higher than the required for newly built single-family houses in Poland. The execution of thermal diagnostics both before and after thermal renovation of the house enable the correct performance of that process and the achievement of greater energy savings. [ABSTRACT FROM AUTHOR]

Building integrated Photovoltaics (BIPV) receives growing attentions from both architectural and energy saving perspectives. Large commercial building envelopes can be utilized due to their great potential of reducing building energy consumption and increasing PV integration impact, especially in climate zones with rich solar resources. Most current studies have been focused on predicting electricity generation of BIPV systems with existing envelope geometries, while few studies have discussed the generation of proper envelope shapes for PV integration due to the challenge of integrating architecture and engineering. This paper introduces a novel optimization method for BIPV shape development based on the shape grammar theory. The method reforms given building shapes/envelopes to produce a set of better BIPV shape alternatives, as well as determines the best placement and matching BIPV systems for the optimized envelopes. The main set of criteria considered during the generation and optimization process include PV power generation, PV economic impact and building energy consumption. Architectural preferences are included in generating preferred design alternatives, such as view consideration and shape direction. Commercial buildings in Egypt are used to demonstrate and validate the applications of the developed method and tool. The method and tool can help designers in achieving an optimal design of building envelope that is most suitable for maximizing PV integration. [ABSTRACT FROM AUTHOR]

To ensure good thermal performance is delivered consistently and at scale, there is a need to measure and understand the as-built heat loss of dwellings. Co-heating is a steady state, linear regression method, used to measure whole building heat transfer coefficients. This paper assesses the uncertainties in such outdoor, in situ, measurements due to the presence and treatment of solar gains. Uncertainties relating to solar gains are explored through both a number of field test results and simulated co-heating tests. Results demonstrate the potential for fractions of solar gains received on one day to be re-emitted on subsequent days. This dynamic behaviour can lead the steady state analysis to underestimate heat loss. Furthermore, inappropriate measurements of on-site solar radiation are shown to lead to bias in heat loss measurements. In particular, horizontal on-site solar radiation measurements are shown to significantly overestimate heat loss in buildings experiencing high proportions of direct gains through vertical openings. Both forms of uncertainty are dependent upon both the environmental test conditions and the characteristics of a test dwelling. Highly glazed, low heat loss and heavyweight buildings prove to be the most susceptible to such uncertainties, which ultimately limit both when tests can be successfully performed and which buildings can be tested. [ABSTRACT FROM AUTHOR]

[Display omitted] • A state-of-the art review and discussion is presented for the ADBEIPCM. • Experiment studies were needed to show the long-term performance of the ADBEIPCM. • Organic PCMs and the macro-encapsulated methods were most used. • Intelligent control methods determine the performances of the ADBEIPCM. • Outlooks and recommendations for ADBEIPCM can facilitate its further development. the research of PCMs in the field of building energy efficiency has developed rapidly over the past decade. The static PCM-built envelopes cannot flexibly adjust their heat storage and release according to the changes in weather conditions and occupants' demands, resulting in low heat storage and release efficiency. The application of the adaptive dynamic building envelope integrated with PCM (ADBEIPCM) addresses this problem. This paper systematically reviewed the ADBEIPCMs for the first time, including their system configuration, working principles, control strategies, and system performance. The research methods and the PCM properties were also well summarized. The results show that the ADBEIPCM can store solar energy and release heat in time to reduce building load and improve comfort mainly by rotating, moving, flipping, and controlling the state of vents. This review divided the ADBEIPCMs into two categories: opaque envelopes and transparent envelopes. The experiment studies and simulation studies accounted for 15.28% and 84.62% of the research on opaque envelopes, and each accounted for 50% of the research on transparent envelopes. But onsite monitoring studies on transparent envelopes only accounted for 25%. In the design of ADBEIPCM, the main encapsulation method of PCM was macro-encapsulation, and the type of PCM was mainly organic. This review analyzed the shortcomings of existing studies and gave recommendations for engineers, architects, and scholars. Future research should focus on the development of novel PCMs with high strength and stability, the development of artificial intelligence-based short-term control strategies, and the development of ADBEIPCM based on bionic technology and powered by renewable energies. [ABSTRACT FROM AUTHOR]

[Display omitted] • An innovative framework is proposed for robust multi-objective optimization for NZEBs. • Open-source technique combining coding language and dynamic energy simulation is set. • The workflow is tested on a representative office building in Mediterranean climate. • The most robust configurations of building-HVAC system are found for NZEB target. • Analysis of occurrence frequency of design variables in Pareto front is provided. Net Zero Energy Buildings (NZEBs) play a key role to save energy. However, unpredictable scenarios and uncertainties about stability of energy production from renewables frequently cause measured performance of the building-plants system that differs from predictions. So, it is crucial to individuate the best alternatives in the early-stage design of the building and related energy systems, also considering uncertain circumstances. Hence, the aim of this paper is to enhance reliability of the building design process by providing an innovative workflow based on multi-objective optimization that encompasses robustness assessment of different design alternatives against uncertain scenarios. The standard genetic algorithm optimization routine has been deeply improved to set as a key performance indicator the robustness of energy performance of several building-HVAC system configurations, also considering the financial aspects optimization. Compliance with NZEB target of the obtained optimal solutions is then automatically verified by the algorithm. The new methodology combines open-source coding language Python and the dynamic energy simulation engine EnergyPlus. The robustness of each solution is evaluated through Taguchi method. First obtained results are related to energy-efficient solutions for the building envelope. Regarding the HVAC system, ground source (instead of air source) heat pumps and variable refrigerating flow systems are preferable. Finally, medium–high size of photovoltaic panels is preferred, although with high investment costs. [ABSTRACT FROM AUTHOR]

• Traditional envelope leakage tests are labor-intensive and disturb building operation. • An innovative approach to measuring leakage using MEMS-based sensors is proposed. • A lab test compares MEMS-based sensors with traditional differential pressure sensors. • A field test uses the new pressure sensors to measure envelope leakage. • The new approach can estimate envelope leakage within 3–16% of a standard test. Micro-electromechanical systems (MEMS)-based sensors have seen significant improvements in accuracy and cost over the past several years, and due to the need for altitude sensing in unmanned aerial vehicles and wearable technologies, absolute pressure sensors have shown the most dramatic improvements. This paper investigates applications of MEMS sensors in commercial buildings, including pairing two absolute pressure sensors to determine differential pressures between different locations in and around buildings. Differential pressure measurements are commonly made in commercial buildings for a number of applications, including static pressure measurements for variable-speed supply fan control, air balancing in hospitals, and for envelope and duct air leakage testing. This paper focuses specifically on envelope air-leakage testing applications of these sensors. The use of continuous pressure measurements in addition to one-time non-intrusive outdoor airflow measurements of rooftop packaged units is investigated. A comparison with standardized leakage testing indicated that continuous measurements with MEMS pressure-sensors were able to estimate envelope leakage to within 3–16% of the standardized test result. In addition, the magnitude and stability of differential pressure differences that can be resolved with absolute pressure sensors are also investigated in the laboratory and the field. Results show that the sensors can be effectively used for pressures seen in low rise buildings with rooftop units. [ABSTRACT FROM AUTHOR]

Built environments contribute significantly to mitigating climate change. However, existing buildings, which form most urban infrastructures, do not typically meet contemporary stringent energy efficiency standards. They are naturally continuously deteriorating, making them a continuous negative contributor to their surrounding environments, which keeps getting worse. Therefore, there is a need to develop performance diagnosis frameworks and approaches for accurate Building Energy Model (BEM) simulations to develop impactful retrofitting design solutions that could make existing buildings perform closer to current efficiency measures. This paper reports on research that focuses explicitly on calibrating envelopes of existing BEMs using drones equipped with thermography sensors. The study specifically focuses on the automation of on-the-fly envelope U-value estimations and verification of calibrated envelope BEMs. The paper examines a renovated campus building in Boston, MA., representing material degradation, thermal bridging, and insulation failures using thermal imaging. A BEM is then calibrated, and post-renovation metered and modeled wintertime heating energy are compared. Goodness of fit measures showcase BEM performance improvement from 21.8%to 0.9%, which demonstrates the utility of the proposed framework. Further research is recommended to expand the focus on anomalies in the envelope and increase the scope from the building scale to the neighborhood scale. [ABSTRACT FROM AUTHOR]

Thermal properties have significant impact on ecological footprint and life-cycle assessment of buildings. This is even more crucial aspect for glass buildings, which have been criticised as major factors in climate change around the world. Recent debates on glass facades, which culminated in plans for a "glass building ban" in New York City highlighted the importance of innovation in glass construction. The current solutions for mitigating energy consumption for glass facades are improving insulation (U-value) and solar heat gain coefficient (SHGC) with advanced glazing or using shading devices. A fourth approach is the recent technology of water-filled glass (WFG), which utilizes water layer to improve thermal comfort and energy performance of the façade. This paper introduces Smart Water-filled Glass (SWFG) control method, which enables the change of the opacity of the façade element by colouring the fluid over a year regarding seasonal changes. The impact of changing transparency of water layer on cooling and heating energy demand is evaluated by simulating and analysing the energy performance of a reference office room with large glazing facade in different climates. The significance of this energy evaluation is that a water-filled glass with switchable transparency is simulated and assessed here for the first time. The paper analyses the performance in seven cities from all relevant major climatic regions using LBNL WINDOW and TRNSYS (v.18) As a novel approach, the simulation study makes it possible to evaluate the overall performance of two proposed operational methods (insolation-based & storage-based) for adjusting water layer settings depending on climate conditions and reusability of the captured heat in water layer. Moreover, seven different base cases are presented in this study to compare the performance of proposed system, including conventional solutions (e.g. double or triple glazing with/without shading) and a state-of-the-art switchable technology (e.g. electrochromic glazing or EC). The results verify the hypothesis that the impact of SWFG compared to WFG varies depending on the climate with 0%-5.28% for hot climates and 0.25–3.39% for climates with heating demand. The discussion includes comparison with standard glass facades, where SWFG shows 47.41%-78.01% energy savings depending on climate. The climate-based approach of SWFG and WFG offers a significant shift in façade design that sees glass buildings as an opportunity for sustainability rather than liability for climate change. [ABSTRACT FROM AUTHOR]

As of 2007 more than half of the world’s population is living in urban areas (a figure expected to rise to 60% by 2030). Thus, the liveability of the high-density city is gradually becoming a central point of focus and concern. A successful skyscraper model of urban planning could provide the possibility to increase city-space vertically as opposed to the current continuous expansion outward, which has obvious environmental consequences. However, skyscraper development, as well as all other new construction and gradually the older building stock, has to comply with current strict regulations on building energy efficiency. Contemporary high-rise examples do not present a sustainable solution to an increasing population or as models of prosperity, as they are linked to high-energy demand, environmental and social imbalances. This paper looks at design strategies towards promoting skyscraper energy efficiency by considering a climatically responsive design, where orientation, the thermal properties of the building envelope and the effect of altitude, become the main design tools. Initial simulations were performed for a residential and an office reference structure 100 m high. Different scenarios were implemented for gradually upgrading the building envelope and studying its relationship with the changing microclimate with altitude (wind speed increase and dry bulb temperature drop) between ground and top level. The advanced envelope was then simulated to up to 400 m high (120 stories high), and heating and cooling loads were compared in relation to different building heights and uses. EnergyPlus is used as the main simulation tool as it accounts for wind speed increase and dry bulb temperature drop with height. The location chosen is Tel Aviv, Israel, a city already growing upwards and expected to have a significant increase in skyscraper construction in the coming years. The results of the simulations performed present the base upon which further design strategies can be implemented towards reducing the environmental impact of this challenging building type. [ABSTRACT FROM AUTHOR]

Occupant behaviour determines how energy is spent in buildings. In addition to properties of building thermal envelops and technical features of HVAC systems, it can drastically influence the consumption of energy. Applied ICT solutions have been recognised as an essential factor for reducing consumptions and emissions in the operational stage of buildings. However, keeping users engaged is still a challenge to overcome. This paper aims to critically review approaches for user engagement from conceptual and technical points of view and to propose an enhanced engaging procedure. Common user engaging practices provide advices on how to save energy or present feedbacks through a number of solutions. Generally, these solutions detect direct measures through sensors, but barely make information valuable to users. The proposed engaging procedure intends ensuring user commitment through a bottom-up approach based on gaming strategies, conceived upon user-made rules. Basically, by means of a dedicated platform, users are able to define specific rules tackling everyday life actions, experiencing in an active way the use of sensors and actuators. Additionally, a set of rules, generated beforehand by experts for promoting energy saving behavioural changes, is gradually proposed through the platform accordingly to user commitment level. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of occupant lifestyle patterns on the energy performance of the residential buildings with various building envelopes in different climate zones. For this purpose, an existing multi-family apartment building in Iran was selected as the experimental residential building and the validity of energy simulation was examined based on the real data of the building energy consumption. The energy demand of the building before and after renovation was simulated via EnergyPlus for different climate zones. The sensitivity analyses confirmed that the occupants’ behavior has a significant impact on the building's thermal energy usage especially in hot climate areas and can change the heating and cooling loads up to about 90%. Using the validated model, a parametric study was performed to investigate the influences of the occupant's behavior on the efficiency of the building envelope including window and cladding materials in different climate zones. The results show that the interaction between the occupants’ behaviors and envelope materials is significant in that the occupant behaviors can change the strategy of choosing the envelop material types. Fluctuation of thermal energy consumption caused by changing of window types can rise to 20% for this case study. Also, it is shown that underestimating the level of occupancy loads can exaggerate the effects of the envelope on the thermal energy consumption rate. Overall, this study emphasizes the importance of applying near actual user behavior data on energy simulation analyses performed for the studies of building sustainability and lifecycle assessment. [ABSTRACT FROM AUTHOR]

As a building component with long history, green envelope has received much attention for its thermal and energy benefits in the past decades. However, few studies have taken into account the two-way effect of green envelope on indoor and outdoor environment during thermal performance evaluation. In this paper, a coupled hygrothermal transfer model of green envelope is developed and validated against field measurements, and the results demonstrate that the model could reasonably reproduce temporal variations of temperature and moisture in green envelope. Then the green envelope model is implemented into an urban canopy model to predict its thermal performance under urban canopy context in Shanghai area. The simulations for a district of office buildings indicate that green envelope decreases sensible heat getting into the indoor and outdoor space significantly, and the maximum indoor temperature difference between buildings with and without green envelope is up to 0.34 °C under free-floating condition. Meanwhile, for outdoor environment, the maximum differences for air temperature, mean radiant temperature and SET* are up to 0.1,0.9 and 0.2 °C respectively under air conditioning condition. What’s more, sensitivity analysis shows that building density has a significant effect on the relative cooling benefit of green envelope against common envelope. [ABSTRACT FROM AUTHOR]

This paper extends the admittance method to predict the diurnal energy flux reduction E r associated with adding microencapsulated phase change materials (PCMs) to single and multilayer building envelopes. The effects of phase change on the thermal load through composite building walls were accounted for by modifying the decrement factor f AM and time lag ϕ AM . The procedure was demonstrated for single and multilayer PCM-composite walls subjected to a constant indoor temperature and to (i) a sinusoidal sol-air outdoor temperature, (ii) a non-sinusoidal idealized sol-air temperature, or (iii) a sol-air temperature based on weather data for three different days in California climate zone 9 (Los Angeles, CA). In all cases, the analytical results for the daily thermal load passing through PCM-composite walls agreed very well with those predicted using detailed finite element simulations. The computational speed and simplicity of this procedure can enable straightforward evaluation of the energy benefits of PCM-composite walls via user-friendly design tools and platforms. [ABSTRACT FROM AUTHOR]