Performance Of Building Envelope Research Articles

Evaluating the thermal performance index for future architectures in China’s hot summer and cool winter regions

In the face of resource shortages and energy crises, green environmental protection has become a vital and central focus for human sustainable development, leading a booming area of architectural development of energy efficiency and comfort. As a result, a new method named Envelope Thermal Performance Index (ETPI) was proposed to evaluate overall thermal performance of residential building envelope. The energy consumption of building envelope by unit volume was taken into account in this method, including cooling, heating and annual period. The influences of heat transfer through external building envelope, heat gain from solar radiation and heat loss by infiltration were considered comprehensively in the ETPI. The energy consumption simulation software eQUEST was used to calculate the ETPI parameters. An ETPI calculation formula for four cities (Shanghai, Nanjing, Shaoguan, and Zunyi) was obtained by simulation results and influence factors. The correlations between ETPI and energy consumption were gained considering geographical factors. The influence of airtightness of building envelope was considered and the problem of different orientations in the parameter calculation were solved in the ETPI method to make ETPI better reflect the thermal insulation of building envelopes. Thus, the ETPI method can calculate the energy consumption of each part of building envelope and estimate energy consumption of air conditioning.

Investigating the performance of the PCM-integrated building envelope on a seasonal basis

BackgroundThe PCM-integrated building envelope has shown significant potential in energy management and heating/cooling loads reduction. However, PCM layer performance highly depends on environmental conditions, configuration and its thermo-physical properties. The right choice of these characteristic features is great of importance since it may cause inverse effects. MethodsSo, in this comprehensive study, the performance of PCM wallboard under realistic sessional weather and solar radiation by considering different values of melting points (22, 24 and 26 °C) is investigated. To capture the solid/liquid interface and liquid fraction, the precise enthalpy-porous model, as well as the actual heat transfer chain consisting of radiation, convection and conduction from the environment to the room ambient, are implemented. Significant findingsThe results showed that the PCM layer is not always advantageous and more than 5% negative impact on energy loss is observed. So, the performance is highly dependent on other key factors including the environmental conditions and its volumetric amount. Also, the existence of optimum values for PCM layer thickness regarding the costs and wall density is observed for different types of PCM. The effect of the melting point on energy-saving is another significant parameter that has shown a considerable impact on appropriate PCM selection for specific regional conditions.

Evaluating thermal performance of vertical building envelopes: Case studies in a Canadian university campus

Campus buildings at the University of Victoria (UVic) were largely constructed before the advent of building energy codes. The University is in the process of commissioning vertical building envelope upgrades/retrofits with added intention of addressing potential energy and greenhouse gas (GHG) savings in their building stock. The aim of this paper is to present the methodology adopted to evaluate potential energy savings from vertical envelope retrofits of 49 non-residential buildings across the campus portfolio, and to further validate those savings through more detailed energy models for a subset of buildings. To this end, the thermal performance of a building envelope was quantified based on its heat loss coefficient (UA), obtained from multiplying its surface area (A) by its thermal transmittance (U-value). Heat loss (UA) calculations were used as an energy loss metric to inform envelope rehabilitation prioritization, in addition to data gathered from building envelope condition assessments (BECAs). UA data were also analyzed against other building data such as floor area, vertical envelope area, vertical area to floor area ratio (VFAR), window-wall ratio (WWR), age, and type of construction for potential correlations. Finally, archetype energy models were used to evaluate the impacts of envelope retrofits on energy and GHG savings on three selected buildings. The outcomes of this study allow the University to weigh the benefits of improved energy performance from envelope retrofits against associated capital cost expenditures.

Sequence-to-sequence deep learning model for building energy consumption prediction with dynamic simulation modeling

This study used a more detailed dataset approach to address the limitations of existing building energy prediction methods and to predict building energy demand more accurately. The EnergyPlus dynamic simulation program closely modeled building envelope performance, zone division, and heating, ventilation, and air conditioning systems. Building energy simulation used actual weather data and generated occupancy data. The occupancy, lighting, and equipment schedules for each zone were generated in 5-min intervals using the Lawrence Berkeley National Laboratory occupancy simulator. Summer electric power consumption based on Internet of Things information from the testbed building validated the model. When applying generated occupancy, lighting, and equipment schedules, the mean bias error of simulation similarly improved to 4.73%, and the coefficient of variation of the root-mean-squared error (Cv(RMSE]) improved to 12.26%. Subsequently, a demand prediction model was constructed as a sequence-to-sequence (seq2seq) model using long short-term memory (LSTM) cells in recurrent neural network (RNN) algorithms, then its accuracy was evaluated. In the seq2seq model, the learning performance based on the EnergyPlus data exhibited an RMSE of 4.48% and a weighted average percentage error of 3.07%. As a result of applying prediction methods while changing climate scenarios, prediction performance also satisfied statistically significant levels. The occupancy information and solar radiation were determined to exert the greatest influence on the building energy demand prediction. • The occupant schedule for each zone was generated in 5-min intervals using the LBNL occupancy simulator. • When applying the generated internal schedules, the MBE improved to 4.73%, and the Cv(RMSE) improved to 12.26%. • In the seq2seq model, the learning performance based on the EnergyPlus data exhibited an RMSE of 4.48% and a WAPE of 3.07%. • The occupant information and solar radiation were determined to exert the greatest influence on energy demand prediction.

Adaptive building envelope simulation in current design practice: findings from interviews with practitioners about their understanding of methods, tools and workarounds and implications for future tool developments

ABSTRACT Adaptive building envelopes can dynamically adapt to environmental changes to improve thermal building performance. To predict the performance of design proposals with adaptive building envelopes, Building Performance Simulation (BPS) tools can be employed. However, one shortcoming of existing tools is their limited extensibility, which implies that accurately predicting adaptive building envelope performance remains a challenge and requires ad hoc approaches. This challenge has made practitioners reticent in considering adaptive building envelopes, which in turn has led to a slow uptake of them in the built environment. This study seeks to advance the understanding of the limitations of adaptive building envelope simulation in current design practice and to suggest implications for future tool developments. To this aim, the study adopts a user-centred perspective through interviews with experts in the field. Findings suggest that current BPS tools hinder the reliable prediction of adaptive building envelope performance, as accurately representing the level of detail of the building envelope is challenging. The subsequent workarounds applied are either time- and cost-intensive or do not consider the dynamic building envelope components. More flexible modelling approaches that allow for rapid prototyping and easy integration are required to enable designers to take full advantage of adaptive building envelopes.

Optimizing Multi-Family Building Massing for Affordability and Envelope Performance: An Investigation of the Trade-Offs Implicit in Low Rise Residential Buildings

The United States faces twin crises of housing affordability and environmental degradation. Under these clouds, the nation is experiencing an explosive growth in new construction multi-family housing. This paper seeks to evaluate how designers might optimize the organization of such projects to minimize cost and maximize environmental performance. A method is developed for evaluating the construction costs and environmental performance of multifamily developments across four variables: building height, number of buildings, building width, and building floor area. Our analysis suggests that buildings with deeper floor plates are preferable for both economic and environmental reasons. We also suggest that taller buildings have more performative envelopes while shorter buildings are more economical to construct. Finally, we offer a method of finding a compromise between economic and environmental objectives for projects of a given square footage. Most commonly, this “compromise” takes the form of a moderate number of mid-rise buildings with deep floor plates. This investigation adds nuance to the existing literature on the effects of building shape on building cost and envelope performance. It also provides designers with a method of potentially constructing multifamily buildings in a less expensive and more environmentally conscious way.

An Intuitionistic Fuzzy-based MCDM Approach For Location Selection Of Pilot Area For Green Roof Systems In Igdir Province, Turkey

Green roof systems have been placed as the key to facilitating to mitigate the effects of climate change and weather effects on urban environmental conditions. Green roof systems are defined as sustainable systems due to fact that these systems improve building envelope performance along with many advantages such as improvement on air quality, reduction on carbon emission and mitigation of urban heat island. In addition, Igdir is one of the provinces with the highest carbon emission-environmental pollution in Turkey. Hence, green roof system infrastructure is critical to mitigating effects of anthropogenic emissions of carbon dioxide and other “greenhouse” gases in Igdir. In this study, an intuitionistic fuzzy-based multi-criteria decision making approach is proposed to evaluate 5 neighborhoods that have been selected according to population density to find out a pilot area for installation. Three main; economical, environmental and social, and 12 their corresponding sub-criteria are used and the results indicate that the approach indeed found out that Baglar neighbourhood is the best area as a pilot to build up a green roof system.

Multiobjective optimization of building energy consumption based on BIM-DB and LSSVM-NSGA-II

The building envelope performance significantly influences the building energy consumption, and the major influencing factors of the building envelope include the external wall U-value, external wall solar absorptance, roof U-value, roof solar absorptance, external window U-value, and window-to-wall ratio. This paper proposed a framework that integrates Building Information Modeling (BIM) with LSSVM (least square support vector machine (LSSVM) and non-dominated sorting genetic algorithm-II (NSGA-II) to study the influence of building envelope parameters on building energy consumption and discover the best design. The DesignBuilder (DB) is used to perform energy consumption simulation and orthogonal experiment to obtain the sample data set. The LSSVM is utilized to learn the data set to establish a prediction model between the building envelope and energy consumption, which is used as the fitness function of the building energy consumption in NSGA-II. With the objective of minimizing building energy consumption and maximizing the indoor thermal comfort (measured by predicted mean vote or PMV), an NSGA-II multi-objective optimization model is established. The Pareto front is obtained through calculation, and the optimal combination of building envelope parameters is discovered using the ideal point method. A case of a proposed school building in China is used to demonstrate the feasibility and effectiveness of the developed framework, the results show that: (1) The LSSVM has great ability to predict building energy consumption, achieving an accurate prediction with a goodness-of-fit of 0.9549 and an RMSE of 0.0273; (2) The optimized envelope design parameters of the proposed building are presented, including the External wall U-value is 0.2, the External wall solar absorptance is 0.55, the Roof U-value is 0.2, the External window U-value is 0.4166, the External window U-value is 1, the Window-wall ratio is 0.215. (3) The developed LSSVM-NSGA II hybrid approach can effectively improve the building’s energy consumption and thermal comfort with the building energy consumption reduced by 10.6% and the thermal comfort increased by 32.2% than the initial values, respectively. The proposed LSSVM-NSGA II framework is able to optimize building envelope design parameters than its precedent, which can provide effective thinking for similar problems.

Integrated Building Envelope Performance Evaluation Method Towards Nearly Zero Energy Buildings Based on Operation Data

Integrated Building Envelope Performance Evaluation Method Towards Nearly Zero Energy Buildings Based on Operation Data

Envelope performance of residential building in cool, warm and hot climatic zones: Results from self-designed in-situ monitoring campaigns

Climatic conditions can exert significant impacts on energy demand of residential buildings. Therefore, case-based evidence is necessary for aiding local policy making on building energy performance. By designing and carrying out in-situ monitoring campaigns respectively in Cambridge, Hong Kong and Shanghai, we present in this paper a cross-regional analysis of actual building envelope performance in these three climatic regions that operate under different energy efficiency policies. Compared with conventional tabulated data, information gleaned from the method of in-situ monitoring shows lower uncertainty and higher precision, especially when the wall has good thermal properties. By comparing practices in different regions and with accurate post-occupancy thermal data, the analytical results further show that the effectiveness of building-related policies on energy performance varies across regions. This is one of the pioneering studies that make interactive policy recommendations based on the evidence obtained from cross-regional, in-situ monitoring campaigns.

A conceptual model for how to design for building envelope characteristics. Impact of thermal comfort intervals and thermal mass on commercial buildings in U.S. climates

The paper presents a simplified conceptual model for energy demand calculations based on building envelope characteristics, thermal mass and local climate. It is based on a network model and lumped analysis of the dynamic process. Characteristic parameters for the buildings are suggested; Driving temperature (DT), Driving temperature difference, (DTD), External Load Temperature (ELT), and Thermal Load Resistance (TLR). The Building Envelope Performance (BEP0), based on a controlled constant indoor temperature is introduced. Solution techniques using stable explicit forward differences based on analytical solutions are derived. The conceptual model has been used for mapping the Driving temperature difference and introduced two performance factors α and β. The first factor represents the effect of thermal comfort interval and thermal mass on the energy demand. The latter represents the ratio between cooling and heating energy demand. These three parameters and factors have been visualized on U.S. maps and enable a possibility to communicate the demand of energy, and cooling and the coupling to building characteristics, in a concise way.

Multi-objective optimization design of green building envelopes and air conditioning systems for energy conservation and CO2 emission reduction

Configurations of the building envelope and the air conditioning system have a considerable effect on annual building energy efficiency. Taiwan government proposed two green building indices, namely the Envelope Energy Load (ENVLOAD) and the Performance of Air Conditioning System (PACS), as energy performance models of building envelopes and air conditioning systems. Relatively few studies, however, have been mainly conducted, using multiobjective optimization design for building envelope and air condition systems, with a goal to treat both the building energy systems and the envelope. Consequently, this study is to make contribution to this related filed by proposing a multi-objective optimal building envelope and air conditioning system energy performance decision model (MOBELM).This model was used to design the optimal configurations of building envelopes and air conditioning systems based on the ENVLOAD and PACS constrictions and the two conflicting objectives. The first refers to the minimal construction cost when the building envelope and air condition system are built. The second is concerned with the minimal CO2 emission when the envelope materials are manufactured and used to form the building envelope. In the case study, the optimized configurations that dominated the original unoptimized design could validate the MOBELM.

Comparison of ground coupled heat transfer models for predicting underground building energy consumption

Underground buildings have gained attentions to alleviate urban land-scarcity. Evaluation of energy performance remains complex and uncertain for underground buildings, where the heat transfer through building envelopes is a typical three-dimensional unsteady heat transfer process. A few models have been proposed to calculate the ground coupled heat transfer (GCHT) through underground building envelopes. This paper evaluates and analyzes the influence of different GCHT models on energy consumption prediction of underground buildings. The models tested include: Ground Domain Xing (EnergyPlus), Basement Preprocessor (EnergyPlus), Foundation Kiva (EnergyPlus), and Frequency Response Analysis (DeST), which are compared under the criteria of consistency of model outputs and computational time. The study reveals that the Ground Domain Xing model can be considered as the relatively accurate GCHT model with low computational cost. One critical factor that differentiates these GCHT models is the ground surface boundary condition used. The study further explores the influence of thermal characteristics of underground building envelopes on annual energy consumption for five climate zones of China using the Ground Domain Xing model. The results show that the better thermal performance of underground building envelopes may increase the annual energy consumption in different climate regions.

Building moisture diagnosis: Processing, assessing and representation of environmental data for root cause analysis of mould growth

The occurrence of surface condensation and mould can lead to concerns of poor indoor air quality and adverse health implications of occupants. Remedial actions require identification of the root causes, but this can be challenging even for experts. The focus of the research is the development of a diagnostic tool that helps to streamline root cause analysis. The diagnostic method comprises a protocol with guidelines for installation of sensors, easy data collection, and a set of calculations to process environmental information. Environmental parameters collected and calculated from an environmental monitoring exercise of dwellings with and without mould, include physical properties associated with the indoor surface of external walls and surrounding air conditions. The methodology relies on linking specific surface and air environmental parameters together with critical thresholds proposed for the control and avoidance of surface condensation and mould growth in dwellings. These parameters were assessed and used to determine the likely causal factors of a moisture imbalanced environment leading to surface condensation and mould growth; poor thermal building envelope performance, an imbalanced heat-moisture regime, and/or insufficient ventilation. Examples from different scenarios are presented to show the process towards environmental data collection, post-processing to compute and assess pertinent parameters, and the display of environmental conditions in a clear and easy-to-interpret manner. The novel developed system is a time-saving method for processing and represents environmental data. It provides a straightforward building moisture index (BMI) and a systematic diagnostic procedure for environmental assessment and possible causes of mould growth. This helps to support neutral decision making, to identify rectification strategies and direct to more cost-efficient solutions to existing damp and mould problems in buildings.

Factors shaping buildings of low energy consumption

The Directive 2010/31/EU introduces a new building standard (NZEB) in all member states of the European Union from 1.01.2021. In Poland, a low-energy building has been defined. The design, construction and use of such building is a complex process and requires knowledge of many aspects concerning building materials, general construction, building physics, installations, renewable energy systems and architectural design. Implementation of the current technical requirements in this area encompasses examining many parameters of an entire building but also of its external walls and joints. Defining them according to the applicable legal regulations and relevant standards evokes many questions and uncertainties regarding calculation procedures and interpretation of physical aspects. On the basis of conducted calculations and analyses, the authors have started a discussion on calculation methods in this field, proposing changes in legal regulations and calculation procedures.
 The paper describes selected factors influencing low-energy buildings: physical parameters of building envelope elements, support of modern ventilation systems, energy performance parameters. The calculation part of the work concerns the analysis of physical parameters of the elements of low-energy building envelope and energy performance parameters of a buildings with consideration of energy saving and thermal insulation criteria. Formation of material systems of external walls and building joints requires taking into account innovative insulation materials and specific parameters of the air inside and outside of a building. The use of professional software for calculations and analyses provides reliable results.
 Many coherent factors such as: architecture of a building, structural and material solutions of the external walls and their joints (elements of the building envelope), type and efficiency of the ventilation, central heating and hot water systems, use of renewable energy sources, integral management of the building in the field of energy production help to obtain optimal parameters of energy performance of the building and reduce emissions of CO2 to the atmosphere.

Identification of the Building Envelope Performance of a Residential Building: A Case Study

Since households are one of the most energy-intensive sectors in Europe, retrofit of dwellings is promoted to increase energy efficiency. Recent research, however, shows that the energy performance after retrofit does not always meet the target values, which can be caused by amongst other things, a deviating building envelope performance. This paper compares the theoretical and measured building envelope performance for a real-life case study in post-retrofit state, in order to illustrate the limitations of calculation methods and characterization models. First, the performance is evaluated on building scale by verifying the correspondence between the default theoretical heat loss coefficient (HLC) and the measured HLC, which was determined by following the guidelines formulated within IEA EBC Annex 58 and Annex 71. In order to illustrate the limitations of the standard calculation method in real-life conditions, the theoretical variability of the HLC is evaluated, generated by variating infiltration heat losses and heat exchange with neighboring dwellings. Second, the performance is investigated on a component scale by assessing the theoretical and measured thermal resistances, identified from heat flux tests. Additionally, nonhomogeneous assembled components and air leaks are simulated to verify probable causes for the locally varying measured values and to illustrate the limitations of calculations and characterization methods. The results illustrate the limitations of the calculation methods by the assessment of the strong variability of the theoretical HLC, depending on assumptions regarding infiltration and heat exchange with neighboring dwellings. In addition, component simulations indicated that deficiencies on a component scale could be caused by a nonhomogeneous assembly and air cavity flows of the component. Moreover, a detailed assessment of an unreliable thermal resistance illustrates the limitations of the used characterization method. Finally, a contrast was found between the quite good performance on building scale (15% deviation between the theoretical and measured HLC) and poor performance on a component scale (only one out of nine monitored components met their theoretical target values), which illustrates the complexity of the building envelope performance.

A Comparison of Energy and Thermal Performance of Rooftop Greenhouses and Green Roofs in Mediterranean Climate: A Hygrothermal Assessment in WUFI

In urban areas, a considerable proportion of energy demand is allocated to buildings. Since rooftops constitute one-fourth of all urban surfaces, an increasing amount of attention is paid to achieving the most efficient shapes and component designs compatible with every climate and urban context, for rooftops of varying sizes. In this study, three types of rooftop technologies, namely insulated, green roof, and rooftop greenhouse, are evaluated for energy and thermal performance using computer simulations. Water surface exposure, absorption, and intrusion are the three important factors in the calculation of hygrothermal models that impact energy consumption and building envelope performance; however, a few studies are specifically focused on providing realistic results in multi-dimensional hygrothermal models and the assessment of the impact of moisture in roofing solutions. This paper aims at evaluating the performance of three different roofing technologies through a two-dimensional hygrothermal simulation in software WUFI. To accomplish this, a precise localized microclimate model of a complex urban context on the scale of a neighborhood was employed to evaluate the cooling and heating loads of the buildings, the impact of the water content in the green roof on the thermal behavior of the roof surface, and the feasibility of designing a building with nearly zero cooling needs. A two-story building in the city center of Bologna, Italy is modelled. Simulation results have shown that during the cooling period, the performance of the designed rooftop greenhouse is the most effective by 50% reduction in cooling loads. Besides, the impact of moisture in green roofs has been detected as a negative factor for thermal and energy performance of the building in the Mediterranean climate. The results ultimately highlighted the capability of passively-designed rooftop greenhouses to create a building with nearly zero cooling needs.

Energy Efficiency of Novel Interior Surface Layer with Improved Thermal Characteristics and Its Effect on Hygrothermal Performance of Contemporary Building Envelopes

Facing the consequences of climate change and fuel price rises, the achievement of the requirements for low-energy consumption of buildings has become a challenging issue. On top of that, increased demands on indoor hygrothermal conditions usually require the utilization of additional heating, ventilation, and air-conditioning (HVAC) systems to maintain a comfortable environment. On this account, several advanced and modern materials are widely investigated as a promising way for reduction of the buildings’ energy consumption including utilization of passive heating/cooling energy. However, the efficiency and suitability of passive strategies depending on several aspects including the influence of location, exterior climatic conditions, load-bearing materials used, and insulation materials applied. The main objective of this study consists of the investigation of the energy performance benefits gained by the utilization of advanced materials in plasters by computational modeling. Results obtained from a computational simulation reveal the capability of the studied passive cooling/heating methods on the moderation of indoor air quality together with the reduction of the diurnal temperature fluctuation. Achieved results disclose differences in terms of energy savings for even small variation in outdoor climate conditions. Additionally, the effectivity of passive cooling/heating alters considerably during the summer and winter periods. Based on the analysis of simulated heat fluxes, the potential energy savings related to improved thermal properties of the applied plaster layer reached up to 12.08% and thus represent an interesting passive solution towards energy sustainability to meet the criteria on modern buildings.

Parametric behavior maps: A method for evaluating the energy performance of climate-adaptive building envelopes

This research presents a new method for evaluating the energy performance of climate-adaptive building envelopes (CABEs) called parametric behavior maps (PBMs). There are three main challenges when evaluating a CABE for energy performance that are not overcome by the currently accepted process: (1) representing complex three-dimensional dynamic geometry; (2) generating various candidate CABE control scenarios by integrating environmental factors and their thresholds; and (3) representing a CABE's time-varying behavior within a single building energy model (BEM). To overcome these challenges, the PBM method was developed. This method makes two key contributions to the field of performance-driven building design. First, it is capable of generating hourly CABE operation scenarios to evaluate CABE performance using a single BEM, regardless of dynamic operation and any geometric complexity. Second, the PBM method is superior at handling the effects of thermal energy storage with dynamic operations than is the currently accepted process. The reliability of the PBM method was validated by comparing indoor temperature profiles obtained from a PBM and the existing method. The new method enables designers to integrate the energy performance of a CABE system with multiple control scenarios, ultimately improving the building design process.

Quantitative Analysis and Multi-Index Evaluation of the Green Building Envelope Performance in the Cold Area of China

In China, relevant standards about building energy efficiency and green buildings have resulted in corresponding requirements for the envelope thermal performance. However, improvement of the thermal performance of the envelope is accompanied by an increase of the environmental impact and cost. This study quantitatively analyzed the thermal performance, environmental impact, and cost of the green building envelope in cold areas and established a common practice database, as well as a multi-index evaluation model. The results show that the best thermal performance improvements are 40% in residential buildings and 30% in public buildings, respectively, based on the relevant standards. The exterior walls and windows have the greatest impact on building heat consumption. There is no significant correlation between the heat consumption and the comprehensive heat transfer coefficient of 10 green buildings. Therefore, the comprehensive heat loss coefficient is corrected. The verification results show that all errors except project 10 are within 15%. Additionally, the projects with balanced thermal performance improvement of exterior walls and windows showed a better performance. Finally, the best combination of residential building envelopes in the cold area was selected, using the evaluation model and quantitative database to calculate the comprehensive score.