Thermal Performance Of Building Envelope Research Articles

Thermo-energetic assessment of industrial buildings

The present paper is focused on the assessment of industrial buildings from their thermal and energy performance perspective, driven by the need to reduce energy consumption and CO2 emissions on a worldwide level. A state of the art will be elaborated regarding the environmental impact of buildings that led to an increased pressure on a more energy efficient design. The focus will afterwards turn on the constructive solutions of industrial buildings for a better understanding of their elements and materials used. Aspects regarding the national and international stock of industrial and logistics spaces, demand, price range and future evolution of this sector, are also presented. Description and comparison is conducted on the building envelope thermal performance and its impact on the energy performance of buildings. Several conclusions will be drawn based on the obtained energy indexes and future research paths will be suggested.

Parametric PGD model used with orthogonal polynomials to assess efficiently the building's envelope thermal performance

ABSTRACT Estimating the temperature field of a building envelope could be a time-consuming task. The use of a reduced-order method is then proposed: the Proper Generalized Decomposition method. The solution of the transient heat equation is then re-written as a function of its parameters: the boundary conditions, the initial condition, etc. To avoid a tremendous number of parameters, the initial condition is parameterized. This is usually done by using the Proper Orthogonal Decomposition method to provide an optimal basis. Building this basis requires data and a learning strategy. As an alternative, the use of orthogonal polynomials (Chebyshev, Legendre) is here proposed. Highlights Chebyshev and Legendre polynomials are used to approximate the initial condition Performance of Chebyshev and Legendre polynomials are compared to the POD basis Each basis combined with the PGD model is compared to laboratory measurements The influence of four different parameters on the accuracy of the basis is studied For each approximation basis, CPU calculation times are evaluated and compared

A study on heating of residential buildings in the Yangtze River Valley of China

Yangtze River is China's densely populated and the most economically prosperous region. It’s hot and humid in summer and cold in winter in this region. This area is considered as a non-heating region in winter, The residential building design usually does not consider the building heating requirements. The building envelope thermal performance is poor, and the indoor thermal environment quality is worse in the residential building in this region. In recent years, local experts and residents in the area have expressed strong willingness to building heating in winter. Consequently, on the basis of field investigation and field test, this paper has analyzed the choice of building heating mode from the aspects of local meteorological conditions, indoor environment status, local residents' living habits and residents' heating demand. Based on the results of the technological economic comparison of preliminary studies, suggestions on the suitable building heating mode were given in the Yangtze River Valley of China.

Analysing the Effect of Substrate Properties on Building Envelope Thermal Performance in Various Climates

Existing regulations on the thermal efficiency of building envelope assemblies are based on the steady state thermal properties of substrate materials. Heat transfer mechanisms of passive heat curbing methods such as phase change materials and cool materials, which are dynamic in nature, are currently not being accounted for. The effectiveness of thermo-physical and solar radiation properties of building materials (i.e., solid homogeneous layers without air gap) in reducing the heat gain into a building in a hot climate could be well understood with the equivalent thermal resistance (Req) concept. A simple and easy-to-use mathematical derivation (i.e., to estimate the instantaneous heat flux across an envelope assembly) is proposed in this paper to understand the mechanism of equivalent R-value (i.e., reciprocal of thermal transmittance, U-value) due to solar radiation properties of passive substrate materials. The model is validated against field experiments carried out at two apartment units of a residential building. The Req due to high outer surface solar radiation properties (i.e., by applying a cool coating) is dynamic as it varies with the weather conditions. The effect of a substrate material’s solar radiation and thermo-physical properties on the overall roof thermal performance is investigated using the Req model for four cooling dominated climates around the globe, having different diurnal conditions and sky temperatures. Increasing the outer surface’s solar reflectance (from 10% to 80%) reduces net heat gain through the flat roof during both daytime and nighttime. In contrast, adding only thermal resistance (from 5 mm to 75 mm thick polyurethane) or volumetric heat capacity (by adding 5 mm thick phase change material) to the building envelope brings down heat gain during the day, but not in the night. Thermal insulation is found to be the second effective property, followed by thermal mass irrespective of different diurnal conditions and sky temperatures across the climates.

Model order reduction for efficient deterministic and probabilistic assessment of building envelope thermal performance

To lessen the computational expense of building energy simulations, the potential of model order reduction methods for assessing building envelope thermal performance is assessed, through both deterministic and probabilistic case studies of modelling heat transfer through a massive masonry wall. More specifically, two model order reduction methods – proper orthogonal decomposition (POD) and proper generalized decomposition (PGD) – are investigated: therefore their calculation accuracies and computational costs are compared with a standard finite element method (FEM). The outcomes show that the POD model strongly outperforms the PGD and FEM models when deterministically simulating wall heat transfer. Additionally, the use of POD to simulate a problem differing from the training simulation can provide an accurate result, and hence the robustness and flexibility of POD is confirmed. This advantage thus expands the application scope of POD for simulating building envelope thermal performance with variable input parameters, rendering it excellent to replace a time-consuming original model in the probabilistic analysis. For the probabilistic case study, it is shown that the sampling errors are much more dominant in the accuracy, implying that the deterministic accuracy of the different models plays a much smaller role, and hence has a very limited effect on the overall convergence behavior of different models. Therefore, the use of POD with a smaller number of modes is strongly suggested in probabilistic analyses to reduce the overall computational expense as much as possible.

A High-Resolution Open Source Platform for Building Envelope Thermal Performance Assessment Using a Wireless Sensor Network.

This paper presents an in-situ wireless sensor network (WSN) for building envelope thermal transmission analysis. The WSN is able to track heat flows in various weather conditions in real-time. The developed system focuses on long-term in-situ building material variation analysis, which cannot be readily achieved using current approaches, especially when the number of measurement hotspots is large. This paper describes the implementation of the proposed system using the heat flow method enabled through an adaptable and low-cost wireless network, validated via a laboratory experiment.

Performance-rating-based approach to formulate a new envelope index for commercial buildings in perspective of energy efficiency and thermal comfort

Taiwan's building envelope thermal performance assessment method (ENVLOAD) was implemented in 1995. The lack of regard for thermal comfort in ENVLOAD has caused ENVLOAD certified buildings to have indoor areas that cause thermal discomfort, which leads to an increase in the energy end-use of the building during actual operation stage. This study aims to develop a new building envelop energy performance index by simultaneously analyzing the influence of energy consumption and thermal comfort. Latin hypercube sampling method is adopted to generate various building envelope samples for building energy simulation to construct the evaluation equations. By comparing to each sample’s annual sensible cooling energy against its own baseline case, indices of performance ratings (PR) based on the dry-bulb temperature and the operative temperature control are proposed. Another aim is to establish an algorithm to convert the proposed index to the previous ENVLOAD benchmark so that the new index can be directly applied to the existing building energy conservation regulations. The study found that the standard regression coefficient of the glazing's thermal insulation property rises from 0.11 to 0.20 when the control scheme switches from dry-bulb control to operative temperature control. Suggesting that the thermal performance requirements for the openings of building envelopes are more important for the new index based on thermal comfort, and that designers need to pay more attention to the control of indoor solar radiation heat gain.

Envelope Thermal Performance Analysis Based on Building Information Model (BIM) Cloud Platform—Proposed Green Mark Collaboration Environment

Building Information Modeling (BIM) and sustainable buildings are two future cornerstones of the Architectural, Engineering and Construction (AEC) industry. In Singapore’s context, the Green Mark (GM) scoring system is prevalently used to assess the sustainability index of green buildings. BIM provides the semantic and geometry information of buildings, which is proliferated as the technological and process backbone for the green building assessment. This research, through vast literature reviews, identified that the current procedure of achieving a Green Mark score is tedious and cumbersome, which hampers productivity, especially in the calculation of building envelope thermal performance. Furthermore, the project stakeholders work in silos, in a non-collaborative, manual and 2D-based environment for generating relevant documentation to achieve the requisite green mark score. To this end, a cloud-based BIM platform was developed, with the aim of encouraging project stakeholders to collaboratively generate the project’s green mark score digitally in accordance with the regulatory requirements. Through this research, the authors have validated the Envelope Thermal Transfer Value (ETTV) calculation, which is one of the prerequisite criteria to achieve a Green Mark score, through a case study using the developed cloud-based BIM platform. The results indicated that using the proposed platform enhances the productivity and accuracy as far as ETTV calculation is concerned. This study provides a basis for future research in implementing the proposed platform for other criteria under the Green Mark Scheme.

The analysis of thermal performance of vernacular building envelopes in tropical high lands using Ecotect

Climate change affects all areas, including those with low temperature. Wonosobo belongs to highland areas with low temperature. The thermal performance of buildings is influenced by micro-environment climate so that the climate change will affect the thermal performance of buildings. Vernacular buildings are believed to be able to make the occupants comfortable. The vernacular buildings in tropical highlands have either exposed stone walls or wooden walls. The present research seeks to analyze the thermal performance of building envelopes with wooden walls and exposed stone walls in highland areas. Simulation method using the Ecotect software was applied. There are 12 building models with a variety of roofing and flooring were selected. The results of the simulation indicate that the difference between indoor and outdoor temperatures of one model and other models is not significant. Warm temperature mostly occurs in houses with exposed stone walls. Highland areas need much warmth so that cold temperature will not disturb occupants.

Energy efficiency optimization strategies for university research buildings with hot summer and cold winter climate of China based on the adaptive thermal comfort

Hot summer and cold winter zone is a typical climate region in China with high temperatures and stuffiness in summer and low temperature and moisture in winter. The existing buildings bear of both poor thermal performance of building envelope and poor indoor thermal environment. With the development of social economy, increasing demand towards building indoor thermal environment is much more urgent than before, and hence energy consumption has rapidly risen. Energy efficiency retrofit with low cost has become a priority in this region.Universities and colleges are one of the typical energy consumers in this region, which are insufficient in research. Over all the campus buildings, research building occupies a large part in total campus energy use, and hence becomes the main retrofit objects. Research buildings have complicated functions of offices, scientific research and laboratories, and space heating and cooling behaviors have their own characteristics, which have the large effect on space heating and cooling use. However, there is little knowledge about adaptive thermal comfort and corresponding heating and conditioning energy-use behaviors.In view of this, in this paper, a typical research building located in Hangzhou was chosen and the measurements on indoor thermal environment heating and cooling behaviors, fenestration and energy consumption were carried out during July 2016 to October 2017. By the analysis on field investigation, delivered questionnaires and measured data, the typical space heating and cooling behaviors, fenestration and thermal environment are analyzed. On this base, energy efficiency optimization strategies in terms of building envelope thermal performance, sun shading, and adaptive space heating and cooling behavior are explored by the simulation. The study provides the technic support for energy saving retrofitting of campus buildings in this region.

Application of infrared thermography technique to the thermal assessment of multiple thermal bridges and windows

A major contribution to the global trend in reducing energy consumption can be made by improving the thermal performance of buildings. Minimization of heat loss via the building envelope is key to maximizing building energy efficiency. The building envelope contains different types of thermal bridging that must be accounted for while assessing the overall building envelope thermal performance. Multiple thermal bridges commonly occur and the distance between them determines the degree to which they interact thermally. To avoid overestimation of the linear thermal transmittance, it is important to account for interaction effects. Complex multiple thermal bridging occurs in window systems. The thermal performance of windows depends not only on the window performance itself but also on its installation into the wall. This study demonstrates an application of the quantitative infrared thermography technique to evaluate the heat lost via multiple thermal bridging. It is shown that using this methodology, the heat loss via multiple thermal bridges can be easily estimated in an existing building envelope, without any knowledge of its internal structure or material properties. For windows, it is demonstrated that jointly assessing the additional heat loss through the window and due to the installation of the window into the wall is a practical way to determine the actual heat loss caused by the presence of a window. A window thermal transmittance or M-value is introduced to quantify the total additional heat loss through the building element due to the presence of the window. The methodology was validated against experimental measurements taken on different specimens in a hot box device. Results from the thermographic analysis also co-related well with results from finite element heat transfer and computational fluid dynamics simulations.

Reduced-scale experiments to evaluate performance of composite building envelopes containing phase change materials

This study presents a convenient approach to rapidly assess the thermal performance of building envelopes containing phase change materials (PCMs) or other building materials. It establishes that the transient thermal behavior of full-scale building test structures featuring envelopes with PCMs can be represented by a reduced-scale test cell conveniently placed inside an environmental chamber. Indeed, PCM-composite envelopes have been considered for reducing and time-shifting the thermal load on buildings thanks to the latent heat associated with reversible transition between liquid and solid phases. First, a thermal model coupling outdoor, wall, and indoor temperatures and accounting for PCM latent heat was developed. It was validated against experimental temperature measurements within a reduced-scale test cell enclosure placed in an environmental chamber and subjected to a series of sinusoidal temperature cycles. Then, scaling analysis of the experimentally-validated thermal model was performed. It identified eight dimensionless numbers governing the transient thermal behavior of building structures with envelopes containing PCMs. The scaling analysis was validated using detailed numerical simulations for different enclosure geometries and outside diurnal climate conditions. Finally, the method was demonstrated on full-scale experiments reported in the literature. It can be used to assess building envelope thermal performance by designing representative reduced-scale experiments without requiring a significant amount of material, time, or space.

Building Envelope Thermal Performance Assessment Using Visual Programming and BIM, based on ETTV requirement of Green Mark and GreenRE

Accomplishment of green building design requirements and the achievement of the targeted credit points under a specific green rating system are known to be a task that is very challenging. Building Information Modeling (BIM) design process and tools have already made considerable advancements in green building design and performance analysis. However, Green building design process is still lack of tools and workflows that can provide real-time feedback of building sustainability and rating during the design stage. In this paper, a new workflow of green building design assessment and rating is proposed based on the integration of Visual Programing Language (VPL) and BIM. Thus, the aim of this study is to develop a BIM-VPL based tool for building envelope design and assessment support. The focus performance metric in this research is building Envelope Thermal Transfer Value (ETTV) which is an Energy Efficiency (EE) prerequisite requirement (up to 15 credits) in both Green Mark and GreenRE rating systems. The development of the tool begins first by creating a generic integration framework between BIM-VPL functionalities and ETTV requirements. Then, data is extracted from the BIM 3D model and managed using Revit, Excel and Dynamo for visual scripting. A sample project consisting of a hypothetical residential building is run and its envelope ETTV performance and rating score are obtained for the validation of the tool. This tool will support project team in building envelope design and assessment by allowing them to select the most appropriate façade configuration according to its performance efficiency and the green rating. Furthermore, this tool serves as proof of concept that building sustainability rating and compliance checking can be automatically processed through customized workflows developed based on BIM and VPL technologies.

Integrating 4D thermal information with BIM for building envelope thermal performance analysis and thermal comfort evaluation in naturally ventilated environments

Thermal performance of the building envelope exerts considerable influence on maintaining indoor environmental conditions. Acquisition of sensor data of a building is essential to ensure the improvement of the indoor thermal environment for the occupants. The environmental sensor technologies together with Building Information Modeling (BIM) are tools for assessing/analyzing the performance of a building. Although BIM has a potential to verify thermal performance by using a BIM database, integrating the surface-heat of building envelopes and sensing data has not been fully explored in the existing BIM. BIM requires tools to enable building professionals to effectively detect the location of thermal defects and analyze the thermal performance and indoor thermal comfort by accommodating environmental information to be used in the analysis process. Therefore, this research presents a novel method for integrating time-stamped 3D thermal data in the BIM. In the proposed method, the BIM model is integrated with spatio-temporal thermal and air temperature data. Visual scripting is used for extracting and then mapping spatio-temporal thermal data to a 3D BIM model. The proposed system converts the collected thermal images into numeric surface temperatures, integrates collected environmental data in the BIM, calculates thermal comfort variables, such as mean radiant temperature (MRT), and assesses the thermal comfort level for various locations inside the building. The applicability of the proposed method is validated in a real-world case study. The developed prototype system provides valuable visualization information and statistical data for analyzing thermal performance and assessing the thermal comfort level.

The impact of renovation measures on building environmental performance: An emergy approach

Approximately 30–40% of the total natural resources that are used in industrialized countries are exploited by the building sector, and almost 40% of the world’s consumption of materials converts into the built environment. Thus, improving the environmental performance of building sector could be crucial for reaching the sustainability of urban environment.The main scope of this paper is to highlight the interest of building renovation as an adequate measure for improving building environmental performance in term of emergy and identify processes that cause significant environmental stress on a local ecosystem. To enable the comparison of all phases and processes for the studied system, an emergy evaluation was performed. A multi-apartment building located in the city of Šabac, Serbia, was used as case study. Several building renovation scenarios were considered, which include different measures for building envelope thermal performance improvements, as well as installation of local renewable energy heat production system. Different renovation timelines were also compared.The overall results showed that 68% of the emergy flow is caused during the building operation phase, 24% during the construction phase and only 8% during the end-of-life phase. All renovation measures proved to be beneficial from the environmental point of view, and the use of additional materials and resources to conduct renovation measures considered did not have a negative impact on the building overall environmental performance. The effect of conducting renovation measures after the first decade of building lifetime improved the overall building environmental performance by almost 50% when compared to the same renovation measures conducted in the last decade of the lifetime (for all measures considered). Finally, based on the emergy indices analysis, it can be concluded that the application of building renovation measures improves the overall building environmental performance, enables higher efficiency in indigenous resource use, and lowers the pressure on a local ecosystem.

Study on the effect of building envelope on cooling load and life-cycle cost in low latitude and hot-humid climate

Cooling load characteristics play a key role to the building, especially in self-sustained building. It is determined mainly by the building envelope thermal performance. This research investigates the effect of the building envelope on cooling load in low latitude and hot-humid area. In this paper, based on cooling load simulations, the effect of reducing the cooling load of building envelope and the life cycle cost was analyzed. In addition, the energy-saving system was established. For the life cycle cost analysis, the cost of each strategy was obtained through a survey in local stores. This paper determining the effect of external walls, windows, roof, shading on the building cooling load, and pointed out the optimum insulation thickness of roof and all orientation exterior wall. And the optimum window structure and exterior shading length was give.

Optimization for energy efficiency of underground building envelope thermal performance in different climate zones of China

The object of this article is to investigate the influence of thermal performance of envelopes in shallow-buried buildings on energy consumption for different climate zones of China. For the purpose of this study, an effective building energy simulation tool (DeST) developed by Tsinghua University was chosen to model the heat transfer in underground buildings. Based on the simulative results, energy consumption for heating and cooling for the whole year was obtained. The results showed that the relationship between energy consumption and U-value of envelopes for underground buildings is different compared with above-ground buildings: improving thermal performance of exterior walls cannot reduce energy consumption, on the contrary, may result in more energy cost. Besides, it is can be derived that optimized U-values of underground building envelopes vary with climate zones of China in this study. For severe cold climate zone, the optimized U-value of underground building envelopes is 0.8W/(m 2 ·K); for cold climate zone, the optimized U-value is 1.5W/(m 2 ·K); for warm climate zone, the U-value is 2.0W/(m 2 ·K).

Application of Taguchi method in optimising thermal comfort and cognitive performance during direct load control events

Direct load control (DLC) is a demand response strategy that allows a utility or an aggregator to cycle specific appliances of their customers on and off or implement thermostat setback during peak demand periods. In the present research, a methodology is proposed to optimise DLC air-conditioning algorithms in order to achieve optimum and robust thermal comfort and cognitive performance outcome for commercial building occupants using Taguchi method. Human subject experiments were carried out simulating DLC events with four control factors in a university lecture theatre. Results reveal that off cycle fraction and adapting temperature are the two most important control factors that affect both the variability and mean response of building occupants' thermal sensation; off cycle fraction is the only significant control factor that affects the robustness of occupants' cognitive performance while none of the four control factors has any significant impact on the mean performance scores. DLC algorithms with off cycle fraction not higher than 50% and adapting temperature lower than occupants' neutral temperature are recommended to achieve optimum and robust thermal comfort and cognitive performance outcome. Cycling period and building envelope thermal performance do not have any significant impact. DLC air-conditioning strategies can be widely implemented in commercial buildings with various thermal performance conditions as long as the off cycle fraction and adapting temperature are optimised.

Concrete Walls Thermal Performance Analysis by Brazilian Standards

Concrete walls have been largely use for the construction of Brazilian social housing even if presenting bad results on thermal performance. Studies indicate the necessity of system changes to improve its performance. In this paper, the thermal performance of concrete walls was analyzed according to prescriptive and simulation methods presented in Brazilian standards for climate differences. A typical four story-housing model was tested in its original design and with building systems improvements. This study aims to explicitly the differences in results between the standard's prescriptive and simulation methods and also addresses the efficacy of system changes to improve the building envelope thermal performance for each Brazilian Bioclimatic Zone (BZ).

Evaluation of Thermal Performance of Residential Building Envelope

The paper describes an evaluation of thermal performance of residential building envelope. Basing on the visual-and-instrumental inspection the conclusion on the non-compliance of the stated object with the requirements of the design and normative documentation was drawn. The thermovision control allowed revealing latent defects of the buildings envelopes and outlining the ways of their elimination. The numerical modeling of heat transfer made it possible to reasonably develop suggestions aimed at enhancing the thermal performance of buildings envelope elements. The integrated application of these methods gave an opportunity to determine the thermotechnical state of the object in whole. The results of the study serve as a basis for the development of methodological foundations for design, construction, operation and reconstruction of energy-efficient buildings