Envelope Thermal Performance Research Articles

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.

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.

The Influence of Window-Wall Ratio on Heating Energy Consumption of Rural House in Severe Cold Regions of China

Rural houses in severe cold areas of China are mostly single-storey independent buildings with large shape coefficient. Compared with urban residential, it has larger contact area between envelope and outdoor environment of each household. Meanwhile, the heat transfer coefficient of window is usually greater than that of external wall and roof. The window-wall ratio is one of the important indicators affecting the energy consumption of rural house. This paper takes window-wall ratio as the main variable, building orientation, thermal performance of envelope and window heat transfer coefficient as the auxiliary variables, and applies DesignBuilder software to quantitatively analyse the mechanism of window-wall ratio on rural house’s heating energy consumption under the interactive influence of multiple factors. Results show that the influence rule of window-wall ratio with different orientations on heating energy consumption will change when the thermal performance of envelope or window heat transfer coefficient changed. The synthetic effect of various factors should be considered in the design to reasonably determine the windowwall ratio of rural house.

High performance building façades for Zero Energy Buildings in Greece: State of the art and perspectives

Pursuing high energy performance with the least environmental impact of a building, along with ensuring the well-being of the occupants, is the ultimate goal of an institutional framework that addresses energy efficiency and environmental sustainability. The building sector is responsible for 38% of the total final energy consumption in Europe and is therefore in the epicentre of the effort to achieve improvements. This is being expressed by the targets of EU policies for 2030 and 2050, which set truly ambitious goals.Part of this effort is the improvement of the building’s envelope thermal performance, along with the respective one of the HVAC systems, but also integrating those two in the best possible way. The façade is the crucial factor, as it is the interface between the building and its environment, but also between the environment and the HVAC system; it is truly the building’s skin, which is therefore much more than a simple state boundary, if we want to have truly advanced buildings. Main scope of the paper is to present the results of an in depth investigation regarding the best available technologies and the upcoming trends of intelligent building façades, to be used in Zero and Positive Energy Buildings. This cannot be done without discussing the legislative and regulatory framework that applies for the building envelope, as solutions have to comply with regulations and standards, both national and international. In this line of approach an investigation of the practices and technical approaches best suited for Greece is being made, specifying their performance, possible drawbacks and approaches that are to be applied and the implementation of which is expected to contribute to the improvement of the buildings’ performance.Furthermore, the constructional approaches and the effectiveness of both naturally and mechanically ventilated façades are discussed, along with their adaptation to the Greek building practices. The integration of ventilated façades with the building’s HVAC systems may offer advantages, especially in spring and fall when preheating the air may lead to reduced energy requirements. In the opposite direction, heat rejection may be a problem in summer, where alternative cooling techniques can provide a solution. Finally, integration of innovative design elements such as the use of different final coating materials on the façades, the use of phase-changing materials (PCMs) and the integration of photovoltaic systems are evaluated.

Development of a Model for OTTV and RTTV based on BIMVPL to Optimize the Envelope Thermal Performance

The thermal performance of a building has a profound effect on sustaining the conditions of indoor environments, and it is critical in obtaining any energy-efficient design. Choosing an appropriate construction material is one of the most effective methods to prevent excessive energy consumption in the building, to minimize heat flows, and sustain a comfortable temperature for occupants. The majority of the existing buildings in Malaysia are mostly constructed using bricks for their outer walls; many studies nominated these materials as the producer of heat. This study is focusing on evaluating the thermal performance of construction materials in a tropical climate, with the involvement of manual calculation methods for Overall Thermal Transfer Value (OTTV) of walls and roof. Therefore, this study proposes integrating Building Information Model (BIM) and visual programming language (VPL) for supporting the calculation of OTTV based on MS1525:2014. The expected result of the proposed system will support designers on calculating OTTV coefficient comparable with the manual calculation, which is considered promising in minimizing time-consuming and human error when optimizing envelope performance during building design. This study proposed a model to access and extract construction materials properties from BIM library using VPL to estimate OTTV value using a real-time calculation tool.

Determination of the economical insulation thickness of building envelopes simultaneously in energy-saving renovation of existing residential buildings

ABSTRACTWhen the energy saving rate of existing residential buildings renovation is determined, the thermal performances of external walls, windows, and roof interact with each other. Therefore, it is necessary to study the determination of economical insulation thickness of building envelopes considering the interaction among building envelope performances. The objective function and its bound of envelope thermal performance optimization in the energy-saving renovation of existing residential buildings in severe cold and cold zones in China were established. It is the conditional extremum problem and can be solved through Lagrange’s method of multipliers to determine the economical insulation thickness of external walls and roofs simultaneously. The method is proved to be feasible by an existing residential building in Beijing. When the same window types are selected, the energy-saving renovation program of the building envelope determined by the Lagrangian optimization method can produce the minimum investment in insulation, minimum investment payback period, and the largest net present value (NPV) of the life cycle.

Monitoring System Analysis for Evaluating a Building's Envelope Energy Performance through Estimation of Its Heat Loss Coefficient.

The present article investigates the question of building energy monitoring systems used for data collection to estimate the Heat Loss Coefficient (HLC) with existing methods, in order to determine the Thermal Envelope Performance (TEP) of a building. The data requirements of HLC estimation methods are related to commonly used methods for fault detection, calibration, and supervision of energy monitoring systems in buildings. Based on an extended review of experimental tests to estimate the HLC undertaken since 1978, qualitative and quantitative analyses of the Monitoring and Controlling System (MCS) specifications have been carried out. The results show that no Fault Detection and Diagnosis (FDD) methods have been implemented in the reviewed literature. Furthermore, it was not possible to identify a trend of technology type used in sensors, hardware, software, and communication protocols, because a high percentage of the reviewed experimental tests do not specify the model, technical characteristics, or selection criteria of the implemented MCSs. Although most actual Building Automation Systems (BAS) may measure the required parameters, further research is still needed to ensure that these data are accurate enough to rigorously apply HLC estimation methods.

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.

Issues to be Improved on the Thermal Performance Standards for Sustainable Buildings Consolidation: An Overview of Brazil

Abstract The Residential buildings have a great importance on the increased demand for electrical energy that grows with population increase and urban development, especially in countries such as Brazil with a growing population. In this case, the requirements addressed in the building standards are relevant to ensure the suitability of the envelope thermal performance and, consequently,upgrade the building energy performance. The Brazilian standardsin thermal and building energy efficiency are relatively new and their application still points out to the necessity of improvements. Therefore, this paper analyzed those building thermal performance requirements according their prescriptive and simulation methods. The present study aims to explicit the differences between these two methods and also addresses the efficacy of the standard requirements to consolidate a better residential building thermal and energy performance in Brazil. As a result, some improvement considerations are proposed for those standards.

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).

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.

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.

External Insulation Design Impacts on the Energy Consumption and Greenhouse Gas Emission of Building

In order to determine the optimal parameters of the external insulation system and guide the energy saving and greenhouse gas emission reduction of building, a typical student dormitory building in Beijing was chosen as research object. The life cycle thinking and dynamic simulation method were used in the present investigation. The relationship between the expandable polystyrene (EPS) external insulation system design parameters and building energy consumption and greenhouse gas emission in each phase of materials production phase, operation phase and the whole life cycle was studied, systematically . The results show that the consumption of clay brick, concrete and cement mortar account for 98.1% of the total materials consumption, where concrete contributes most to both energy consumption (36.6%) and greenhouse gas emission (35.9%). Regarding the contribution to energy consumption and greenhouse gas emission for building life cycle, materials production phase accounts for 5.6%-18.8% and building operation phase takes up 80.6%-93.4%. With the increase of EPS insulation thickness, the energy consumption and greenhouse gas emission increase linearly in materials production phase, decrease in building operation phase, and have an optimization value in the building life cycle to reach the minimum when the heat transfer coefficient (K) is 0.3W / (m2 • K) equivalent to the EPS insulation thickness is 130mm. Building heating load reduces with the increases of insulation thickness, but the envelope thermal insulation performance has no significant influence on cooling load.

A thermo-activated wall for load reduction and supplementary cooling with free to low-cost thermal water

A building envelope serves as a thermal barrier and plays an important role in determining the amount of energy used to achieve a comfortable indoor environment. Conventionally, it is constructed and treated as a passive component in a building thermal energy system. In this article, a novel, mini-tube capillary-network embedded and thermal-water activated building envelope is proposed to turn the passive component into active, therefore broaden the direct utilization of low-grade thermal energy in buildings. With this proposed approach, low-grade thermal water at a medium temperature close to the ambient environment can be potentially utilized to either counterbalance the thermal load or indirectly heat and cool the space. With the revealing of the idea, effects of water temperature and flow rate on the envelope's thermal performance are investigated using a transient model. The results indicate that the thermo-activated wall can be effective in stabilizing the internal surface temperature, offsetting the heat gain, and supplying cooling energy to the space in summer. Utilization of the innovation should take the cost of total energy, energy benefit and efficiency into consideration. This article illustrates how low-grade energy can be actively used as a means for achieving net-zero energy buildings.