Thermal Performance Of Buildings Research Articles

Simulation and Field-Based Study of Thermal Performance of a Building - A Case Study

Concerns about building thermal performance and energy consumption are fast growing as they account for roughly 40% of worldwide annual energy use. Building construction in Nepal is controlled by the National Building Codes (NBC), which focus solely on structural considerations and ignore thermal behaviour. As a result, housing tends to be too much warm and too cold during summer and winter respectively due to the lack of passive heating and cooling mechanisms considered during the construction phase. The Thakle Integrated Settle (TIS), built by the Department of Urban Development and Building Construction (DUDBC) under the National Reconstruction Authority and supported by Oxfam Nepal, was the subject of this research. The building’s performance in the chosen location was analysed using a field and TRNSY simulation-based technique. Using meteorological data from Meteonorm software, the TRNSYS model was created to examine the performance in terms of internal air temperature and heating/cooling load of two buildings with different orientations, e.g., North-East (NE) and South-West (SW). According to simulation results, there is a heating demand that covers roughly 37% of the year, while cooling and comfort conditions were 32% and 31%, respectively. For NE and SW-facing buildings, heating demand was 4.10 MWh and 4.07 MWh, while cooling demand was 1.302 MWh and 1.309 MWh respectively.

Evaluation of passive envelope systems with radiative sky cooling and thermally insulated glazing materials for cooling

Passive envelope systems for building cooling are of great significance to achieve sustainable and low-energy buildings. Although promising advances in radiative sky cooling and enhanced glazing materials have been achieved recently, there still lacks performance evaluation on integrating these novel materials as passive building envelope systems for the cooling purpose. To this end, the study newly proposes a passive envelope system by synthetically incorporating radiative cooling roofs, colored cooling walls and thermally insulated glazing windows into a standard-compliant commercial building archetype. Comprehensive building thermal, energy, economic and environmental performance across a variety of typical climates in the United States was evaluated. The results were compared to the baseline model, in which the envelope properties are location-dependent and in accordance with ASHRAE Standard 90.1 (β = 0.3, βvis = 0.3, ε = 0.9 for exterior walls, β = 0.23–0.55, ε = 0.75–0.9 for roofs, and U = 1.9–2.8, SHGC = 0.23–0.38, VT = 0.253–0.418 for windows). The highly solar reflective and thermally emissive radiative cooling coating (β = 0.98, ε = 0.97) applied on roofs is able to achieve the cooling electricity savings ranging from 8.2% to 29.7% in response to different climate regions. In comparison, the colored (yellow) cooling paint (β = 0.72, βvis = 0.59, ε = 0.95) applied on walls can achieve annual cooling energy savings regionally from 3.5% to 9.3%. Besides, the thermally insulated windows with the improved visual comfort can save cooling energy from −2.1% to 3.7%. From the maximized cost saving perspective, the optimal design schemes of passive cooling building envelopes for each region were accordingly determined, by which the net cost saving ranges from 0.03 to 2.13 $/(m2·year) in response to climate variability. Notably, the optimal building envelopes regionally correspond to the net avoided CO2 emissions ranging from 0.11 to 16.72 kg/(m2·year)), indicating the noticeable carbon neutral potential induced by the proposed passive envelope system. This research is an effort to provide effective passive cooling envelope systems by combining the existing advanced cooling materials towards sustainable and energy-efficient buildings.

OTTV'S Assessment on Thermal Performance of High-Rise Apartment Buildings in Penang

This study evaluates the envelope thermal performance of high-rise apartment buildings in Malaysia, which are being largely dominated due to the high economic development and increased population. The evaluation was conducted using the Overall Thermal Transfer Value (OTTV), which is the key tool used in the Green Building Index to assess the Energy Efficiency of buildings. Different high-rise apartment buildings were selected with different architecture styles, to account for several periods of building construction. The OTTV value was calculated for the west-oriented façade of the selected buildings, which is considered as a critical orientation that receives high solar radiation. The results showed that four out of the five investigated buildings achieved the minimum requirements for the OTTV, i.e., less than 50 W/m². The maximum and minimum OTTV values with the buildings’ original design were 82.60 W/m² and 41.54 W/m², respectively. However, one of the buildings achieved a lower OTTV value with the installation of shading devices by the owners, i.e., decreased from 48.39 W/m² to 37.60 W/m². The solar radiation penetration through the fenestration was found to be the major contributor to the total OTTV, while it can be controlled by the shading devices. Besides, using dark paints increased the heat conduction through the opaque walls by more than double compared to light paints. This study shows that some design considerations, such as paint colour, shading devices, and glazing material, can have a great influence on the heat gain in buildings.

The Impact of Windows Replacement on Airtightness and Energy Consumption of a Single Apartment in a Multi-Family Residential Building in Montenegro: A Case Study

One of the important factors influencing the thermal performance of buildings is the leakage of the envelope. When it comes to Montenegro, although there is a formal airtightness requirement, air permeability tests are not mandatory and therefore there is a lack of data in this regard. This paper reports the results of fan pressurization tests on a single apartment in a multi-family residential building before and after replacing the windows. The replacement of old wooden windows with new UPVC ones, provided that the installation is carefully supervised, proved to be an effective air tightening measure, as it resulted in a reduction of air change rate at the reference building pressure from 6.25 h−1 to 0.77 h−1, or by nearly 90%. The energy impact of air leakage was evaluated using the national software for calculating the energy performance of buildings based on the DIN V 18599 methodology. Calculations showed that by reducing infiltration, significant energy savings for heating can be achieved, while savings for cooling are practically negligible. Savings in relative terms were greater when the façade walls were thermally insulated and when the building was located in a colder climate zone. Savings in delivered energy ranged from 13 to 25 kWh/m2·year, depending on the climate zone.

Recycling Textile Waste to Enhance Building Thermal Insulation and Reduce Carbon Emissions: Experimentation and Model-Based Dynamic Assessment

By enhancing the thermal properties of cement-based building materials, energy consumption and carbon dioxide (CO2) emissions related to space conditioning in buildings can be alleviated. This study aims to present cement-based composites reinforced by textile fibers for application in building and construction. Several lightweight coating mortars were produced by partially replacing the sand in the mix with different percentages of textile waste. Mechanical and thermal characterizations of the reinforced cementitious composites were performed. The results showed that the thermal conductivity of cementitious compounds decreased as the proportion of reinforcing material in the mixture increased. In terms of mechanical properties, the textile slightly reduced the compressive strength of cementitious mortar, while it improved the flexural strength. A numerical study was then performed to derive the actual impact of these reinforced materials on the thermal behavior of a building element using COMSOL Multiphysics. Numerous configurations of walls coated with different mortar mixtures were studied. The results showed that coating both sides of a building wall with 20 mm of textile-reinforced mortar reduced the internal temperature by 1.5 °C. Thus, the application of these thermally improved mortars as coating mortars appears to be a relevant solution to enhance the thermal performance of buildings.

Thermal Performance and Energy Analysis of Phase Change Material-Integrated Building with the Auxiliary Heating System in Different Climate Regions

Phase change material (PCM) embedded in the building contributes to enhancing indoor thermal comfort and reducing the heating load in winter by absorbing/releasing solar energy. The application effects of PCM incorporated into a single-space passive solar building with the auxiliary heating system (AHS) were investigated numerically in the six representative regions of western China. In the calculation and analysis by the enthalpy model, it was found that the effectiveness of PCM greatly depended on local climate conditions, thickness, and location of PCM. The results indicated that it was necessary to adopt the AHS for winter heating of the passive solar building. On this basis of using AHS, it showed a favorable thermal energy storage effect after the application of PCM resulting in the minimum indoor air temperature being maintained above 15°C within the comfort range stably. The integrated discomfort degree in each region was decreased by more than 96% compared to the original building, and the average temperature in Lhasa was 2°C higher than that in Urumqi. Furthermore, the highest rate of energy saving and carbon dioxide emission saving in the six regions was 19.7% and 17.4% in Lhasa, and the lowest were 4.3% and 4.2% in Urumqi, while other regions were relatively close, respectively. As a result, it can be stated that for a passive solar building using the AHS during the heating period, PCM was the most suitable for application in Lhasa, unsuitable in Urumqi, and generally suitable in other regions.

Thermal bridges in buildings of consolidated contexts in high-altitude cities. Case study: Ambato, Ecuador

This research work has been centered on the study of thermal bridges in the urban area of the city of Ambato, this city is located at an altitude of 2570m with an average temperature of 15°C throughout the year, the construction systems used in the study area mostly consist of a layer of material either clay brick or concrete block and exterior and interior finishing’s. The objective is to diagnose the points where thermal leaks can be found in consolidated environments and to provide possible solutions in different construction elements. The methodology used is based on a mixed study, which analyzes the urban context, the buildings present, the construction materials used, their relationship with the current climate of the area and the quantification of latent temperatures for further simulation. The results were obtained through a calculation software where the diagnosis and the improvement plan were simulated to increase the ambient temperature of the houses from 15-17°C to the range of 20-24°C within the comfort temperature range for interior spaces. This study concluded that it is possible to significantly improve the thermal performance of buildings in consolidated contexts with specific interventions.

Predicting the response of heating and cooling demands of residential buildings with various thermal performances in China to climate change

Climate change will continuously impact building heating and cooling demands. Therefore, it is essential to characterise the varying future heating and cooling demands, which will help energy planning and avoid the lock-in effect of infrastructure. In this study, future meteorological data for building simulations were generated using global climate models under different shared socioeconomic pathways and were used in a large number of simulations by DeST to see the impacts on heating and cooling loads with different building performance and occupancy modes. Harbin, Beijing, Chongqing, Guangzhou, and Kunming were selected to exemplify the impacts on different climate zones. The future heating demand will decline evidently where the heating demand dominates, like Harbin, Beijing and Chongqing. For areas with a predominant cooling demand, like Guangzhou and Chongqing, the future cooling demand will increase significantly. As for enhanced building thermal performance, the annual heating and cooling demand are both effectively reduced, and the impacts of climate change are gradually diminishing. It is estimated that by 2060, the total energy consumption in urban residential buildings will be 5% higher considering the effect of climate change, and the percentage of cooling energy use will increase from 14% to 20%, resulting in higher importance of cooling energy sufficiency.

Techno-Environmental Assessment of Insulation Materials in Saudi Arabia: Integrating Thermal Performance and LCA

Arid and hot regions, like Saudi Arabia, utilize up to 60% of the country’s energy to regulate buildings’ indoor comfort. Energy efficiency is a long-term sustainability measure that is part of the government’s Vision 2030 strategy. A standard method of improving the thermal performance of buildings is through the use of insulation materials. Considering the cooling loads’ requirement and the Global Warming Potential (GWP), the present research evaluated the effectiveness of insulation materials, including extruded polystyrene, expanded polystyrene, rock wool, and glass wool in the hot, arid climate. For this case study, four similar villas facing the cardinal directions were selected from the residential project at Qassim University. HOBO data loggers were used to collect indoor temperature data. Thermal performance and Life Cycle Assessment (LCA) were conducted in accordance with Saudi Building Code-602 (SBC-602). Simulation outputs based on the four cardinal directions were used for assessing the thermal performance and LCA of the different thicknesses and densities of insulation materials. This was done using IESVE and SimaPro, IMPACR2002+, to assess their cooling load and GWP, respectively. The results suggest the potential for using lower insulation thickness for the northern and western façades without violating the SBC. The results obtained the actual thicknesses of the three insulation materials for achieving indoor temperatures in the four cardinal directions and the selection of materials and their densities along with associated GWP. The outputs of the study have been generalized in the form of a performance-based flowchart as a tool for selecting the type and thickness of thermal and environmental insulation in residential buildings in the Qassim region of Saudi Arabia.

Impact of green roof and green facade on building thermal performance and carbon sequestration in subtropical climate of China

This paper investigates the case building’s cooling effect, energy saving, and carbon sequestration with green facade and green roof. The west and east GF is covered with wisteria, and the GR is planted with different kinds of vegetables. The cooling effect of the GF and GR is analyzed by field test. The cooling energy saving of the GF and GR is deeply discussed with EnergyPlus software simulation. Carbon sequestrations of the GF and GR are calculated considering both plant photosynthetic and energy saving with the field test and simulation. The results show that the average external surface temperature reduction of the west GF, east GF, and GR is 4.5°C, 4.2°C, and 9.7°C on sunny days, 1.3°C, 1.3°C, and 1.4°C respectively on cloudy days. The total cooling energy saving of the GF and GR is 4.75 kWh/m2. The cooling energy saving of the GR with seven kinds of vegetables varies from 529.6 to 2936.3 kWh, which is related to the LAI and height of vegetables. The daily cooling energy saving in hot sunny weather scenario is almost three times that in cool sunny. The carbon sequestration ability per planted GF area is 1.4 kg C/m2, and per planted GR area with seven different vegetables varies from 0.88 to 2.21 kg C/m2, in which the strongest is peanut, and the weakest is lettuce. At last, the cooling energy savings of GF in different orientations on hot, warm, and cool sunny days are discussed, which is shown that the cooling energy saving effect of the different oriented GF mainly depends on the received solar radiation amount in this orientation. The results of this research can provide some assistance in improving the design of the building GR and GF.

Influence of the climate change on natural ventilation use in residential buildings in the tropical island of Mauritius

Thermal performance of buildings highly depends on the climate conditions, which have given rise to several traditional and modern climate-conscious strategies. However, these strategies might need to be modified to cater for global warming. This research considers the Representative Concentration Pathways (RCP) to predict the effectiveness of one such strategy, that is, natural ventilation for the year 2100 for the tropical island of Mauritius. A total of 3 regions (Port Louis, Vacoas and St Pierre), each with distinctive micro-climates, were selected to assess the thermal discomfort levels under future climate scenarios (RCP 4.5, RCP 6.0 and RCP 8.5). The results show that, in 2100, discomfort levels during occupancy periods will increase by a maximum of 15% in Port Louis, while the other 2 regions will have an increase of 11%, under the worst scenario, while using natural ventilation. Results, thus, establish that natural ventilation will not be efficient under the impact of climate change, although varying for different climate conditions. This research indicates that there is a need to shift from natural ventilation as traditional cooling method to other energy driven method such as Heating, Ventilation and Air conditioning (HVAC system) and hybrid mixed-mode systems for future climate change adaptation.

An approximate analytical solution for dynamic heat transfer of building walls

The present work deals with an approximate analytical solution for the dynamic temperature field due to the coupled effect of building walls to the adjacent environment. The solution is derived within the framework of weighted residuals and can be used as a handy tool to realize a reasonable estimation of the building thermal performance and to elucidate the dependence on the room descriptive parameters. Results from the present model are compared with predictions arising from both a commercial FEM code and the analytical solution from the standard EN 13786, showing satisfactory results. This conclusion is not surprising since it is demonstrable in view of the characteristic-time responses of the climatic forcing and the building walls. Finally, as an example of application of this approach, the model was focused on describing the thermal response of an open-loop regulated indoor environment.

Are Reliability, Resilience, Robustness, and Vulnerability Interrelated? A Survey Study on Thermal Performance of Buildings

Are Reliability, Resilience, Robustness, and Vulnerability Interrelated? A Survey Study on Thermal Performance of Buildings

Research on the Design and Application of Rural Houses in Northern China Based on Energy-saving Retrofit Technology

The poor thermal performance of rural buildings and the severe pollution caused by coal combustion in northern China are urgent problems that need to be addressed. To solve these two issues, the current status of building envelopes in rural houses in northern China and the commonly used heating methods by rural households were analyzed. The study found that most rural houses lack insulation measures in their building envelopes and require energy-saving renovations. To improve the thermal performance of rural houses, the thermal performance of a rural household’s building envelope was measured and energy-saving renovations were conducted. The measurement results showed that the heat transfer coefficients of the walls, windows, and roofs decreased by 72.7%, 61.59%, and 64.99%, respectively, after the energy-saving renovations, compared to the national limit values. The thermal performance of all building envelope components met the national requirements after the energy-saving renovations. The actual statistics showed a 66.74% reduction in biomass fuel consumption per unit temperature difference after the renovations, indicating a significant improvement in energy efficiency.

Review of future weather data for building simulations available in Japan and confirmation of its characteristics

Buildings use a large amount of energy, depending on the climate. To design buildings with high energy and thermal performance in the future, it is necessary to use weather data that reflect future climatic information. Some future weather files for building simulations have been developed. However, these datasets are based on different predictions, and each future weather file has a different creation process. Such methodological differences may lead to differences in predicting the energy and thermal performance of buildings. Understanding the characteristics of each data type is necessary for its appropriate use. However, limited information is available for properly utilizing future weather data for building simulations. This study aims to provide information on the characteristics of future weather data for better utilization. After thoroughly reviewing the existing data and creation methods, we propose a framework for understanding future weather data based on their creative process. We collected five types of future weather datasets available in Japan and compared their characteristics. One of these datasets is the future weather dataset based on climate information provided by the National Institute for Environmental Studies (NIES). We confirmed the degree of variation in each weather element and predicted cooling/heating demand using future weather data available in Japan.

Improving the Thermal Performance of Secondary School Buildings by Using Passive Techniques at Hyderabad

Improving the Thermal Performance of Secondary School Buildings by Using Passive Techniques at Hyderabad

Comparison Study and Assessment of Thermal Performance and Energy Self-sufficiency of Nearly Zero Energy Building (nZEB) in Two Different Climates

The paper presents a comparative study of a nearly zero-energy office building with respect to two different cities located in two different climate zones: a humid continental climate with dry winter, represented by the city of Seoul and a hot semi-arid climate, represented by the city of Benguerir. Obviously, climate is one of the most influential factors affecting indoor thermal comfort, energy demand and energy self-sufficiency of nZEBs. In this study, we first assess the impact of regional climate on the thermal performance, and we explore the influence of the local natural energy sources on the Solar BIPV and PV outputs in the two different cities: Benguerir and Seoul, respectively. And then, we explore the overall energy self-sufficiency of the nZEB for the respective climates. The differences in thermal need and energy self-sufficiency responses were statistically significant. With respect to Benguerir, the thermal energy needs for cooling amount to 71.5 kWh/m²/year, with almost no heating thermal needs and the Energy Balance (EB) reaches 0.88. On the other side, these metrics are around 52.56 kWh/m²/year for the total thermal needs with a share of 43% for heating thermal needs and a yearly EB equals to 0.6 for the nZEB in Seoul. Finally, it is important to mention that the BIPV output share out of the total solar energy output amounts to 57% and 61% for the cities of Seoul and Benguerir, respectively, which highlight the important role of BIPV in reaching advanced levels of energy self-sufficiency.

The HVAC model predictive control of building thermal dynamic characteristics

As the terminal energy user of urban power grid, it is significant to model and simulate the energy consumption characteristics of buildings. First, the author proposes a thermal dynamic model to predict the energy consumption of building refrigeration/heating, it is composed of several groups of heat transient energy balance equations, which can fully consider the impact of heat convection, heat conduction and heat storage on building energy consumption during the heat transfer process of building envelope. Then, the HVAC model predictive control (MPC) method considering the thermal dynamic characteristics of the building envelope is proposed for the heating, ventilation and air conditioning, the core energy unit of the building, the change of window wall ratio in building will affect the thermal insulation performance of the building, so the window wall ratio in building design should not exceed 0.7. From the perspective of building thermal insulation performance, the author analyzes the situation that the total 48 hours operating cost of buildings under two control methods changes due to the change of building thermal insulation performance with the change of window wall ratio in different environments, the simulation results show that when using MPC control method for HVAC, the daily operating cost of buildings increases with the window wall ratio at a lower rate than the traditional control method. It can be seen that the MPC control method has a better effect of energy saving and reducing the total operating cost of buildings in response to the environment where the window wall ratio of buildings increases or the thermal insulation performance of buildings becomes worse over time. It is proved that the HVAC control method based on MPC not only helps to reduce the building energy cost, but also deals with the reduction of HVAC energy efficiency level and the deterioration of building insulation performance, it is more conducive to saving energy and improving the operating economy of buildings.

The Potential of Using Passive Cooling Roof Techniques to Improve Thermal Performance and Energy Efficiency of Residential Buildings in Hot Arid Regions

In hot dry regions, the building envelope receives abundant solar radiation, which contributes to heat stress and indoor thermal discomfort. To mitigate overheating inside spaces, cooling is the main basic requirement during most of the year. However, due to the harsh climatic conditions, buildings fail to provide passively the required comfort conditions. Consequently, they are fully dependent on-air conditioning systems, which are huge energy consumers. As roofs are exposed to the sun throughout the daytime, they are estimated to be the main source of heat stress. In return, they can contribute significantly to achieve optimum comfort and energy savings when efficient design strategies are used in an early design stage. To examine the potential for cooling load reduction and thermal comfort enhancement by using cooling roof techniques in residential buildings, a study was performed in the city of Biskra (southern Algeria). Accordingly, an in-field measurement campaign was carried out on test-cells during five days in summer. Three different cooling roof techniques were addressed: (a) cool reflective white paint (CR), (b) white ceramic tiles (CT) and (c) a cool-ventilated roof (C-VR). These roofing alternatives were investigated by monitoring both roof surface temperatures and indoor temperatures. Comparative analysis showed that a cool-ventilated roof is the most efficient solution, reducing the average indoor temperature by 4.95 °C. A dynamic simulation study was also performed based on TRNSYS software to determine the best roofing system alternatives in terms of thermal comfort and energy consumption, considering the hottest month of the year. Simulation tests were run on a base-case model representing the common individual residential buildings in Biskra. Results showed that a double-skin roof combined with cool-reflective paint is the most efficient roofing solution. By comparison to a conventional flat roof, meaningful improvements have been achieved, including reducing thermal discomfort hours by 45.29% and lowering cooling loads from 1121.91 kWh to 741.09 kWh.

Computational Optimization of 3D-Printed Concrete Walls for Improved Building Thermal Performance

Three-dimensional printing technologies are transforming various sectors with promising technological abilities and economic outcomes. For instance, 3D-printed concrete (3DPC) is revolutionizing the construction sector with a promise to cut projects’ costs and time. Therefore, 3DPC has been subjected to extensive research and development to optimize the mechanical and thermal performance of concrete walls produced by 3D printing. In this paper, we conduct a comparative investigation of the thermal performance of various infill structures of 3DPC walls. The targeted outcome is to produce an infill structure with optimized thermal performance to reduce building energy consumption without incurring additional material costs. Accordingly, a computational model is developed to simulate the thermal behavior of various infill structures that can be used for 3DPC walls. The concrete composition and the concrete-to-void fraction are maintained constant to focus on the impact of the infill structure (geometric variations). The thermal performance and energy-saving potential of the 3DPC walls are compared with conventional construction materials, including clay and concrete bricks. The results show that changing the infill structure of the 3DPC walls influences the walls’ thermal conductivity and, thereby, the building’s thermal performance. The thermal conductivity of the examined infill structures is found to vary between 0.122 to 0.17 W/m.K, while if these structures are successful in replacing conventional building materials, the minimum annual saving in energy cost will be about $1/m2. Therefore, selecting an infill structure can be essential for reducing building energy consumption.