Thermal Performance Of Buildings Research Articles

Evolution of climate zones for building in Spain in the face of climate change

It is essential to design buildings that take on the dynamics of the climate throughout their entire life cycle, guaranteeing the development of a building stock that is certainly sustainable and resilient. This study's main objective is to demonstrate that the official Spanish climate zones for building do not represent the current climatic conditions and to show how these climate zones will evolve due to the impact of climate change. Given the significant impact that climate change will have on this country, as well as its climatic variety, the proposed methodology can be used as a reference in other regions. Updating of the climate zones of peninsular Spain for 49 cities has been carried out, through the adaptation of these zones to the RCP 4.5 and RCP 8.5 scenarios. The results show that two-thirds of these cities are currently designing and constructing buildings with obsolescent climate data that do not take into account the current or future climate reality, which is significantly affecting previous calculations on the thermal performance of buildings. This work represents a significant scientific contribution in terms of reflecting on the current capacities and the possibilities of improving the building stock.

Passive Cooling Strategies for Improving Thermal Performance of Residential Buildings in Naya Raipur, Chhattisgarh

Passive Cooling Strategies for Improving Thermal Performance of Residential Buildings in Naya Raipur, Chhattisgarh

Exterior insulation finishing system using cementitious plaster/microencapsulated phase change material for improving the building thermal storage performance

Among the construction methods used for the construction of buildings, exterior insulation finishing can effectively utilize the thermal energy of a building as it prevents the occurrence of thermal bridges, unlike internal insulation. Recently, along with the global energy saving efforts, building energy saving methods, which effectively use the heat energy in buildings, have emerged. However, the development of superior insulation materials, such as aerogels and vacuum insulation materials, have attracted significant attention. In this study, we optimized the external insulation plastering method using a phase change material (PCM) to improve the efficiency of thermal-energy use and prepared a mortar/microencapsulated PCM (MPCM) composite specimen for use in the external insulation plastering method. Herein, various analyses were conducted to evaluate the prepared specimen, including scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The results showed that even if only 10 wt% of MPCM was used, the time-lag effect was improved by 59.4%, indicating excellent thermal storage performance. Therefore, we believe that the use of proposed MPCM can achieve significant thermal performance improvement when applied to various mortar areas in buildings.

Current Status of Aged Public Buildings and Effect Analysis Prediction of Green Remodeling in South Korea

The purpose of this study is to analyze the scope of the expected improvement effect of office buildings and educational research facilities according to green remodeling. Thus, in order to quantitatively grasp the architectural performance of the existing buildings, the building thermal performance, the airtightness, the indoor environment, and the air quality were measured using equipment. The analysis indicated that the envelope performance and the indoor environment were unsatisfactory compared to the current legal standards, and for indoor air quality, CO2 and formaldehyde were measured to be dissatisfactory in some buildings. The energy analysis results indicated that the improvement range differed according to the renovation history for each building, resulting in differences in the energy-saving rate for each alternative. The reduction rates of primary energy consumption using energy simulation were 38.5–67.4% for office buildings and 23.7–66.3% for educational research facilities, and the payback periods were 14 to 27 years for office buildings and 12 to 30 years for educational research facilities. These results are expected to contribute to the activation of green remodeling because they can be used as indicators to predict the expected construction cost, the payback period, and the expected effect required for green remodeling.

Effect of Phase Change Materials on the Thermal Performance of Residential Building Located in Different Cities of a Tropical Rainforest Climate Zone

This study aims to investigate the thermal performance of PCM and PCM combined with nighttime natural (NV) and mechanical ventilation (MV) applied to a residential building located in eight cities of tropical rainforest climate zone (Af). The analysis was accomplished using numerical simulations and developing a unique methodology for selecting the PCM melting temperature based on the thermal comfort limits. The thermal performance of the PCM integrated building was quantitatively evaluated using the concept of peak temperature drop. Additionally, a novel indicator of Total Temperature Drop (TTD) was introduced to determine the overall impact of the PCM and PCM combined with NV/MV on the thermal comfort conditions inside the building. The results showed that PCM 28 was the most efficient in improving the thermal performance of the building located in the Af climate zone, achieving a TTD of up to 356 °C per year. The usage of PCM 28 combined with nighttime natural ventilation improved the TTD values by up to 15%, whereas the integration of PCM 28 combined with mechanical ventilation resulted in a TTD values increase of up to 45%. Conclusively, mechanical ventilation showed its superiority over natural ventilation in the tropical rainforest climate, and PCM 28 applied together with mechanical ventilation could be used as the optimum combination for the whole climate zone.

Effect of Aging on Solar Reflectance of White Cool Roof Coatings: Natural Weathering and the Influence on Building Energy Needs for Different Climate Conditions in Brazil

The use of cool materials on the building envelope is one of the most cost-effective ways to increase indoor thermal comfort conditions in hot climates and decrease the cooling energy needs. Despite the benefit of reducing cooling loads, researches have demonstrated that aging of roof coatings changes the initial solar reflectance (SR), which influences the long term building thermal and energy performance. Thus, this work presents preliminary natural weathering tests performed on samples of nine white coatings exposed to natural weathering for one year in the city of Sao Carlos, Brazil. Solar reflectances were measured with a spectrophotometer before and after exposure, every 3 months, for identifying the effect of aging along the time. The findings showed changes of 13% to 23% on SR after one year of natural weathering, with higher decrease on SR for rougher surfaces. The cleaning process restored from 90% to 100% of the original SR, which means maintenance can be an effective solution to restore the initial SR. Simulations indicated that roofs with higher solar reflectance increase indoor thermal comfort conditions and decrease the cooling energy need for buildings in hot climates, but the aging of white coatings increased the cooling energy needs along the time

Development of a new spectral selectivity-based passive radiative roof cooling model and its application in hot and humid region

Radiative sky cooling has attracted worldwide attention due to its passive cooling potential with zero energy input. Daytime cooling materials with outstanding spectral properties are developing rapidly. Using these new cooling materials as roof coatings can become one of the most prominent radiative cooling methods integrated with buildings. Current existing models and numerical tools are not able to incorporate the spectral selectivity of radiative cooling materials and local precipitable water vapor, thus failing to accurately predict roof thermal performance. To this end, the paper newly develops a spectral selectivity-based passive radiative roof cooling model to integrate full spectral properties of emerging cooling materials and consider precipitable water vapor-induced atmospheric radiation for precise evaluation of roof cooling performance. A field experiment was carried out to validate the developed model. The mean bias errors (MBEs) of the model in the prediction of rooftop temperatures were found less than 4.6%, verifying the sufficient accuracy of the new model in characterizing roof temperature variations. After validation, the developed model was used to investigate the potential benefits of radiative cooling as a rooftop strategy in the hot and humid region of Hong Kong. The whole year on-site weather data were collected as the model input. Compared to the baseline coating, the reductions in monthly cumulative roof thermal transfer values by applying a porous polymer cooling coating are 18.5–22.3, 33.7–40.5 and 2.9–3.5 kWh/m2 for residential concrete-based, industrial galvanized steel-based, and standard-compliant commercial multilayered roofs, respectively. For the above three roofs, the radiative cooling coating is able to save the annual roof-induced cooling electricity of 54.7–76.6, 97.4–136.4, and 8.8–12.2 kWh/m2, corresponding to the cooling cost saving of 71.8–100.5, 127.8–179.0, 11.5–16.0 HK$/(m2·yr), respectively. The new spectral selectivity-based radiative roof cooling model can be widely employed to accurately evaluate the utilization of daytime radiative coolers as a rooftop strategy in improving building thermal and energy performance.

Thermal performance of residential building with mixed-mode and passive cooling strategies: The Brazilian context

The definition of user behavior in computer simulations for building thermal performance analysis is a challenging and complex task. People behave differently depending on their routine and culture, among many other factors. Thus, in this study, mixed-mode climatization for cooling and heating (air conditioning and natural ventilation) was analyzed considering different thermal performance indicators, construction systems and climates in Brazil. The typology analyzed was a single-family dwelling. The results showed not only how different cooling strategies can change the dwelling thermal performance, but also how this performance may be perceived differently based on the indicator. Depending on the indicator, distinct envelopes would be recommended. Also, the study demonstrated that for public policies, the stakeholders need to understand the behavior and occupancy patterns of residents who are representative of a country in order to identify, with more accuracy, the most appropriate envelope for each case. In the case of the indicators, metrics that are most easily adapted to considerer resilient according to climate changing are recommended for inclusion in standards and regulations.

Computer simulation of moisture transfer in walls: impacts on the thermal performance of buildings

ABSTRACT In order to reduce electricity consumption in buildings, it is imperative to improve their thermal performance. Due to the many variables involved in thermal processes computer simulation is a consolidated method for thermal analysis. However, in many energy efficiency analyses calculus of heat conduction through the dwelling envelope does not consider moisture transportation and storage. The objective of this work was to evaluate the impacts of moisture transfer in walls on the thermal performance of naturally ventilated and artificially conditioned buildings using EnergyPlus computer simulation. This research contributed to the literature by showing the difference in thermal zone air humidity, temperature and annual energy demand (i.e. electricity consumption) when moisture effects are considered in walls. Buildings were composed of masonry and solid concrete envelopes and three numerical models were simulated: Conduction Transfer Function Model (CTF), Effective Moisture Penetration Depth Model (EMPD) and Combined Heat and Moisture Transfer Model (HAMT). The CTF model does not consider moisture effects. Results found a higher relative air humidity for the studied thermal zone by applying the HAMT model in the numerical simulation, and the envelope porosity was proven to affect HAMT humidity results. Comparing the HAMT and EMPD models with the CTF model, the annual energy demanded for cooling presented a 21% reduction for the EMPD model in the masonry and 9% increase for the HAMT model in the solid concrete. This article shows the importance of an accurate EnergyPlus heat transfer model for simulating a whole building to check edification attendance of minimum comfort parameters and select envelope materials aiming the reduction of electricity consumption.

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

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

Evolutionary artificial intelligence approach for performance prediction of bio-composites

Giving the high amount of carbon and energy emission from the use of traditional building materials, the use of bio-composites made from industrial crops especially hemp has caught attention from researchers in recent years. These bio-composites not only enhance the thermal performance of buildings but also promote sustainable development due to their eco-friendly nature. Due to their highly heterogeneous nature, however, most of the existing studies on the bio-composites have only focused on experimental investigations, while mathematical modeling of physical, thermal and mechanical properties of bio-composite remains a challenge for the researchers. In this paper, an artificial intelligence (AI) based gene expression programming (GEP) technique is used to develop the mathematical models for predicting the dry density, compressive strength and thermal conductivity of hemp-based bio-composites. A large amount of database was established based on past studies and the most influential parameters were identified by several trial analyses. The proposed mathematical models showed a high correlation with the experimental results. All the models passed the statistical and performance index checks showing strong predictability, generalization capability and high accuracy of GEP-AI models. Comparison of results with the regression analysis techniques further proved the superiority of GEP-AI models over the traditional methods.

The impact of wall and roof material on the summer thermal performance of building in a temperate climate

The main objective of this study was to compare the effect of phase change material (PCM) and reinforced concrete on the summer thermal performance of existing building in a temperate climate. Research has shown that the use of reinforce concrete walls and roof has greatly improved thermal performance of the rooms during periods of consistently rising internal temperatures due to increasing outdoor temperatures and high solar radiation. Lining the wall and roof surfaces with PCM with an optimum melting point of 21.7 °C did not reduce the indoor temperature below 23 °C even in the coldest month of June, with an average outdoor temperature of 15.7 °C, completely preventing its solidification. This suggests that during heat waves, problems with PCM solidification can be expected even with materials with much higher optimum melting temperatures. The results indicate that in a building without air conditioning, it may not be possible to plan an optimum range of PCM melting temperature that would allow it to be effective during all summer months. Replacing the lightweight structure with a very heavy one allowed to reduce the maximum daily indoor temperatures by 2.0–2.5 K during a 15-day intensive heat wave with an average outdoor maximum temperature of 32.4 °C. An analysis of air-conditioning market development trends in residential buildings allows us to conclude that a reduction of maximum daily indoor temperatures in such a range in the temperate climate of Zielona Góra in Poland should significantly reduce the need to install new air-conditioning systems in residential buildings at least until 2050, even under the IPPC RCP8.5 scenario.

Characterizing leaf area index of rooftop farm to assess thermal-energy performance by simulation

This paper presents an exploratory research about the possibilities to simulate the thermal performance of buildings with green roofs, or in this case rooftop farming. Different from the green roofs, a rooftop farming has a leaf area index (LAI) variable during all the year because the vegetable crops growing cycle repeats sometimes along the year. The contribution of this paper is to bring this discussion to the art state. The method uses computer simulation as a research strategy using the software Energy Plus. The research method was developed in 3 steps. In the first one, a literature review was performed in order to search data from 18 vegetable crops and 3 substrates. One of these data was the LAI, which in the second research step was simulated considering 5 different possibilities (LAI constant all the year; LAI observing monthly the growing cycle; Average LAI considering the growing cycle; crop rotation with average monthly LAI; and LAI defined each ten days considering the crop growing cycle). The results demonstrated that: a) the simplified LAI found in the literature considering the rooftop farming simulations are defined as constant; b) using LAI constant all the year can overestimate until 7% the energy use intensity (EUI) in buildings for the climate in the South of Brazil. c) Thus, in order to simulate the performance of buildings with rooftop farming it is important to develop a data base of the vegetable crop considering the LAI variation along the cycles, and also the number of cycles during the year.

Effect of using PCMs and shading devices on the thermal performance of buildings in different Algerian climates. A simulation-based optimization

The use of phase change materials (PCMs) in the building envelope has emerged as an attractive passive design strategy that can be used to improve the energy performance of buildings. This paper discusses the effect of using PCMs on the thermal performance of shaded and unshaded lightweight structures in different Algerian climatic zones. A simulation-based optimization was carried out by coupling EnergyPlus and GenOpt tool, to determine the optimum melting temperature of PCM when integrated into the building envelope. Results show that the shaded building with PCM is a preferred design model in majority of Algerian climates when it is free floating. The annual percentage of thermal comfort ranges between 44.13% and 59.11% in cities where the PCMs showed positive potential. Furthermore, the optimization results show that the PCMs achieved a modest cooling energy saving for mechanically-ventilated buildings in summer, especially in hot-dry climate with optimal melting points equal to or close to 28 °C. The control of solar heat gain by using shading devices is critical to enhance the thermal performance in summer. In winter, the PCMs achieved a noticeable reduction in the heating energy requirements where it reached a maximum of 63.23% in the city of Tamanrasset. The shading device is not recommended during the winter because it hinders the use of solar radiation for passive heating. During this season, the optimal melting points of PCMs are generally bounded between 18.50 °C and 21.25 °C. When considering both periods, the most advantageous design varies from climatic zone to another.

Examining the attitude-behavior gap in residential energy use: Empirical evidence from a large-scale survey in Beijing, China

Occupant behavior in residential buildings has great energy-saving potential and offers an important opportunity for realizing the targets of energy conservation and carbon emission reduction. Traditionally, it is believed that occupant behavior aligns with people’s energy-related attitude. However, an attitude-behavior gap has been observed in many recent studies, which rarely focused on specific attitudes and behaviors in urban residential buildings. Therefore, based on a large-scale empirical survey (N = 1003) in Beijing, China, we explore the relationship between energy-related attitudes and behaviors. Specifically, purchase and habitual behaviors are investigated along with relevant attitudes, including the willingness to pay (WTP) more for energy efficient products, whether paying attention (WPA) to energy efficiency parameters/indicators of products when making a purchase, and the willingness to change behavior (WTC) for further residential energy reduction. The results show a mixed picture. There is a consistency between the occupants’ WPA and purchase behavior. In contrast, the occupants generally don’t behave consistently with their reported WTP and WTC, suggesting the existence of attitude-behavior gaps. Different reasons may lead to these gaps, demonstrating the necessity of a more comprehensive and flexible strategy for energy policymaking. Furthermore, a closer look at the factors underlying different attitudes shows the significant effects that perceived building thermal insulation performance and past experiences of changing behavior may have, suggesting the effectiveness and importance of building thermal retrofits and more targeted awareness campaigns. A self-reinforcing feedback loop may exist between attitude and behavior, demonstrating the great potential of social interactions and peer influence for behavioral change.

Replacement of Natural Sand with Expanded Vermiculite in Fly Ash-Based Geopolymer Mortars

Increasing the thermal insulation of building components to reduce the thermal energy loss of buildings has received significant attention. Owing to its porous structure, using expanded vermiculite as an alternative to natural river sand in the development of building materials would result in improvement of the thermal performance of buildings. This study investigates the properties of fly ash (FA)-based geopolymer mortars prepared with expanded vermiculite. The main aim of this study was to produce geopolymer mortar with lower thermal conductivity than conventional mortar for thermal insulation applications in buildings. A total of twelve batches of geopolymers were prepared for evaluating their different properties. The obtained results show that, at a given FA and expanded vermiculite content, the geopolymers prepared with a 10 molar NaOH solution exhibited a higher flowability, water absorption and porosity, as well as a lower dry unit weight, compressive strength, ultrasound pulse velocity and thermal conductivity compared with those prepared with a 15 molar NaOH solution. As is also shown, the geopolymers containing expanded vermiculite (15%) developed a lower flowability (~6%), dry unit weight (~6%), compressive strength (~7%), ultrasound pulse velocity (~6%) and thermal conductivity (~18%), as well as a higher apparent porosity (~6%) and water absorption (~9%) compared with those without expanded vermiculite at a given FA content and NaOH concentration. The findings of this study suggest that incorporating expanded vermiculite in FA-based geopolymer mortar can provide eco-friendly and lightweight building composites with improved sound and thermal insulation properties, contributing toward the reduction of the environmental effects of waste materials and conservation of natural sand.

Impact of climate change on future bioclimatic potential and residential building thermal and energy performance in India

This paper aims to investigate the implication of present and future bioclimatic potential of passive heating and cooling design strategies for climate change scenarios of five locations covering all climate zones of India. Weather data for future climate change were developed for A2 (medium-high) scenario of the Intergovernmental Panel on Climate Change (IPCC) for four time slices, namely TMY (Typical Meteorological Year), 2020, 2050 and 2080. A case study residential building was used for calibration and validation of the bioclimatic potential using EnergyPlus simulation. Results show a strong correlation between the annual bioclimatic summer and winter discomfort hours and the corresponding annual cooling and heating energy load for the changing climate scenarios. Results also show an overall increase in annual cooling energy load, over and above the base case, ranging from 18% to 89% among the five cities in 2020; 32% to 132% in 2050 and 58% to 184% in 2080 if residential buildings continue to be operated in the same manner as it is done today without passive strategies. The use of passive strategies may reduce the annual cooling load by about 50%– 60% in residential buildings in future.

The recent residential apartment buildings’ thermal performance under the combined effect of the global and the local warming

Both global and local heating phenomena can potentially influence the building thermal performance and comfort. The residential construction sector had a real estate “boom” in the beginning of the 2000’s in Sao Paulo and there is no available information on how this recent built stock performs under the current climate and how it will do, considering the warming climate. Therefore, this study addresses the real estate residential apartment buildings developed in the 2000’s, aiming to investigate their thermal performance and expected comfort conditions, considering the urban present and future climate. The average air temperature difference (ΔT) between the high-rise dense urban area and the suburban stations was registered and then coupled to the future weather file. Comparing the apartment’s thermal performance under the base weather file (SWERA) and the Future (2045–2074) + UHI, in yearly values, an important decrease in comfort hours (from 81% to 65%) was found, while in a hot period (February) the results are much more critical (64% heat discomfort hours). It is important to address how central is the adaptability for improving the domestic comfort conditions, especially in the pandemic and post pandemic scenarios, when people are expected to spend more time inside their homes.

On the Energy Performance of Micro-Encapsulated Phase Change Material Enhanced Spackling with Night Ventilation

Phase change material (PCM) is an attractive solution for improvement of thermal performance in buildings, and have excited a vast amount of research in recent years. There are however practical challenges with ensuring adequate phase transitions of the PCM to exploit the passive heat storage benefits. Night ventilation (NV) with free cooling have surfaced as one of the most promising methods to properly utilize PCMs and maximize energy savings. This work deals with a novel spackling compound enhanced with microencapsulated PCM. The product is intended for use at inner walls and ceiling surfaces of buildings and is suited for new and retrofitting building applications. Ensuing former experimental studies, a validated simulation model is developed and used to study the PCM with natural and hybrid NV strategies in an office building during summer conditions in Oslo, Norway. Cooling load reduction and energy savings are analyzed with varying air flow rates of 0.5–5 air changes per hour (ACH) and 2–4 mm PCM layer thickness. It is shown how increasing air flow rates and PCM thickness greatly enhances energy performance, but at a diminishing rate. Although the NV alone can reduce the cooling load by 11.5% at 1 ACH, 40.2% at 3 ACH and 59.8% at 5 ACH, one can achieve further reduction up to 19.5%, 78.2% and 95.5% for the respective ACHs with 4 mm PCM. The natural NV provides more energy savings compared to the hybrid strategy. As energy requirement by fans increases with the increase of air flow rates in the hybrid strategy, the energy savings eventually start to reduce. The hybrid strategy can save 38% energy at most with 3 ACH, and the savings is increased to 50% with the inclusion of 4 mm PCM. On the other hand, the natural strategy saves 56% of energy at the same air flow rate, and 69% with 4 mm of PCM.

Effect of melting point on thermodynamics of thin PCM reinforced residential frame walls in different climate zones

Energy consumption in building sector has increased dramatically over the past two decades. The incorporation of phase change materials (PCMs) into building envelopes is considered as an effective thermal energy storage strategy to improve building thermal performance and reduce space heating/cooling load. Despite significant efforts in PCMs technologies and their applications to buildings, how to effectively improve energy efficiency of latent heat generated from PCMs for building energy and how to select proper PCMs for buildings under different climate zones still post great challenges. Lack of systematic and comprehensive studies in these gaps hinder their broad applications in the building sector. To meet the need, this study aims to numerically explore the impacts of critical design parameters including PCM layer location, thickness, and the loading conditions associated with different climate zones and months on the selection of the PCM melting point. COMSOL Multiphysics® software is used to simulate multilayer walls containing PCM to unveil the thermal performance under various climate loading conditions. The results reveal that selecting proper PCM melting point according to those design parameters reduces the indoor peak temperature and temperature oscillation, and thus diminishes the energy consumption by the heating, ventilation, and air conditioning (HVAC) system to regulate the indoor temperature. The optimal PCM melting point is in direct proportion to the input loading conditions, suggesting that a higher PCM melting point is needed for a building envelope subjected to higher input temperature associated with climate zones. Results also show that PCM with a melting point within the occupant thermal comfort zone can increase indoor thermal comfort duration more effectively for the “moderate” climate loading conditions. The findings are expected to assist engineers with better utilization of the PCM-based building envelope in different climate regions.