Energy Efficient Building Envelopes Research Articles

Structural insulation panel system (SIP) as an alternative for cooling energy saving, decarbonization, and energy cost reduction in hot and dry climates. A simulation-based approach

ABSTRACT During the last decades, the growing urban prospects represent a challenging condition to develop climate change adaptation solutions before the urban overheating effects and its challenges to the environment, human health, and building energy consumption, which is critical in hot arid climates with record-breaking heatwaves where society is turning to air conditioning instead of energy-efficient building envelopes. The primary aim of this study was to examine the influence of the Structural Insulation Panel (SIP) system heat transfer in energy-related aspects and contrast it with those of conventional construction systems. Therefore, a comparative study was carried out in low-income dwellings to measure the thermal transmittance of the building envelope and assess the thermal energy simulation allocated in Köppen-Geiger´s hot desert climate, characterized by typical maximum temperatures of 45°C in the summer season. The investigation ascertained the levels of energy consumption, the capacity of the air conditioning system, the associated energy costs, and the potential decrease in carbon footprint. The study shows SIP as a viable construction system alternative, the evidence shows a 20% heat gain reduction, the Heating, Ventilation, and Air Conditioning (HVAC) system capacity was reduced by 38%, and energy cost by 27%. The system also contributes to the decarbonization and carbon footprint by 20%. Likewise, to reduce the heat flow, a crucial element is evident, since transmittance in thermal bridges significantly affects the heat transfer in these low thermal conductivity systems with structural reinforcement elements.

Mitigating balcony thermal bridging: Experimental and numerical investigation of innovative solutions for energy-efficient building envelopes

Mitigating balcony thermal bridging: Experimental and numerical investigation of innovative solutions for energy-efficient building envelopes

Validation of 3D thermal simulations of the Double C Block, a novel composite masonry unit, using in-situ U-value measurements

Energy efficient building envelopes, particularly innovative prefabricated building components, can significantly contribute to lower the building industry energy-related emissions. In this research the composite masonry unit Double C Block (DCB) is quantitatively tested by means of three-dimensional thermal simulation validated by in-situ U-value measurements carried out in both summer and winter conditions.The simulations were enhanced by the experimental measurement of the dry thermo-physical material properties (specific heat capacity, thermal conductivity, and density) in laboratory conditions for both concrete and polyurethane. The samples were extracted from real-scale DCB prototypes. Furthermore, site-specific boundary conditions of Malta — representative a case study of a Mediterranean climate − were utilised in the simulations. Both laboratory and in-situ assessments of thermal transmittance, or U-value, had their uncertainty specified as part of the calculations.The validation exercise was performed by means of hourly recorded surface temperature and the selected indices were the root mean square error and mean absolute error. Results showed that these indices were within the recommended accuracy thresholds during both winter and summer assessments. For the hourly-based heat flux measurements, the mean bias error and coefficient of variation of the root mean square error were found lower than values reported in literature, thus supporting the robustness of the overall simulation outputs. Hence the 3D CVM simulation was experimentally validated by in-situ assessments.The convergence value of the experimental U-value provided respectively 1.51 ± 0.20 W/(m2K) (winter) and 1.44 ± 0.19 W/(m2K) (summer). Then, the validated 3D CVM model was adapted to calculate the theoretical U-value of DCB, using monthly values of recorded surface temperatures obtained by the test cells (in both seasons). The predicted thermal transmittance was of 1.47 W/(m2K), in both conditions, and this almost matches the above-mentioned experimental assessments and thresholds established in previous works.

Design of a positive energy district: A Nigerian case study

The potential of possible solutions for the design and implementation of a 50-house Positive Energy District (PED) in Southern Nigeria is presented in this study. Using a transient energy systems simulation software (TRNSYS 18), the energy demand of a typical building is estimated. Different passive design options considering building materials, window sizes, building orientation, roof ventilation are studied to determine the most energy efficient building envelope. TRNSYS and PVSyst (another energy simulation software), are also used to simulate the dynamics of a positive energy building and operation of solar energy systems used for electricity generation, domestic hot water heating and space cooling for Lagos weather conditions. In terms of electric energy balance, the total annual electricity demand is 598,000 kWh while the electricity generated by PV is 728,600 kWh in a year. As regards to site energy balance, annually, the district exports more electricity than it imports. The difference is 110,200 kWh. These results show that in such climatic conditions, despite economic poverty, it is possible to implement the modern PED principles. However, first, it is necessary to reduce energy consumption as much as possible, including solar passive solutions to the building architecture.

Controlling Thermal Bridging as a Value-Added Technique to Enhance Energy Efficient Building Envelopes

Controlling Thermal Bridging as a Value-Added Technique to Enhance Energy Efficient Building Envelopes

The Impact of Smart Materials Usage in Buildings Envelope: an Approach to Investigate Energy Consumption Versus The Aesthetics Forming The City Image in New Agglomerations

Abstract The notion of creating New Agglomerations often demonstrates the challenge between maintaining city’s identity and the necessity to adopt contemporary building materials. The main target in the current era is to monitor the degree of sustainable strategies adopted while defining the potential materials used whether in the construction process or for final building envelopes. This study aims to evaluate the implications of energy-saving potential of smart glazing materials in building envelopes through a comparative analysis creating the emergent city image created by building façade systems. A thorough review presents various types of smart glazing materials performance versus traditional glazing systems, in terms of heating and cooling results. The research presents a case study of actual buildings deploying smart glazing systems to provide real-world evidence of their energy-saving potential. The results showed that smart glazing materials can significantly reduce energy consumption compared to traditional glazing systems. The results also indicated that the performance of smart glazing materials varies with different types of materials, and the specific energy-saving potential depends on factors such as building orientation, glazing area, and climate conditions. This study provides insights related to emergent design decisions for new agglomerations in terms of energy-efficient building envelopes and energy consumption strategies.

A Building Information Modeling driven approach for improving building envelope energy efficiency in hot arid climates

As a response to growing energy demand and greenhouse gas emissions, enhancing the energy performance of buildings has become a global focus. Studies have shown that building openings are responsible for 40–50% of their energy loss, and these percentages are growing steadily. Silica aerogel represents a potential energy-saving technology for buildings. It has demonstrated its effectiveness as an insulating material in various climates; especially cold climates, however its success in hot arid climates has not been examined yet. Therefore, this paper aims to assess the thermal properties of silica aerogel to determine the dominant parameters that impact its thermal performance in a hot, arid climate. A numerical model of the silica aerogel is conducted using Autodesk Ecotect Analysis. The impact of different factors (thermal conductivity, density, specific heat, and thickness of silica aerogel) on the energy efficiency of the glass window was investigated. Results show that the thickness of silica aerogel has the highest impact on the thermal behavior of silica aerogel, followed by thermal conductivity. Meanwhile, density and specific heat showed a negligible effect on the energy performance of the material. Results showed that a 5 mm-thick aerogel layer and a thermal conductivity of 0.014 W/(mK) exploit the energy performance of the proposed material in hot, arid climates and could provide energy savings of around 63% and 15% in heating and cooling demands, respectively.

Experimental analysis of thermal energy efficient clay brick incorporated with phase change material and insulation

In this study, a combination of thermal capacitance (Phase Change Material) and thermal resistance (Polyurethane Foam and air) materials are incorporated into Energy Efficient Clay Brick (EECB) to assess its indoor thermal performance. Various configurations of EECBs were developed, featuring two rectangular slots to accommodate PCM, Polyurethane Foam (PUF), and air in varying orders. These EECBs were then tested in a real outdoor tropical climate over three consecutive days to evaluate the impact of integrating PCM, PUF, and air in indoor thermal performance. The results indicate that the combination of PCM and PUF in EECB-5, with PCM on the outer side and PUF on the inner side, demonstrates the best indoor thermal behavior compared to other configurations. EECB-5 exhibits a maximum reduction in indoor peak temperature of 11.2 % and a time lag ranging from 130 to 140 minutes. EECB-5 shows a decrement factor of 0.54, followed by 0.55 for EECB-2. Additionally, EECB-5 configuration achieves an average surface temperature reduction of 15.01 % compared to Conventional Brick (CB). In addition, the simulation analysis of various configurations of bricks further confirms that the EECB-5 configuration exhibits superior indoor temperature regulation compared to other configurations. It is concluded that PCM enhances the thermal capacitance of building elements by increasing their latent heat storage capacity. Hence, Phase Change Material (PCM) into building elements can help to provide viable solutions for creating energy-efficient building envelopes.

Contemporary roof pattern for energy efficient buildings: Air conditioning cost alleviation, CO2 emission mitigation potential and acceptable payback period

Buildings account for a significant portion of global energy use and consumption. Buildings have substantial energy consumption due to the use of heating, ventilation, and cooling systems. It is evident that the use of insulation materials and phase change materials (PCMs) in the design of buildings can effectively reduce the cost of air conditioning by reducing external heat gains and losses. Additionally, the use of environmentally friendly, cost-effective, and natural materials can be beneficial from an environmental standpoint. This paper aims to evaluate the potential for cost savings in the air conditioning of various PCMs and insulation-stuffed building roof configurations. In that respect, four types of phase change materials (HS29, HS36, FS42, and FS30) and four insulation materials (Therma cork, sawdust, aerogel, and sheep wool) were selected. The thermophysical properties of PCMs (solid and liquid state), insulation materials, and building elements were determined experimentally as per ASTM D 5334 standards. Ten various building roof models (contemporary roof pattern) are studied with four various PCMs and four various insulations. In addition, novel building roof design integrated with PCM/insulation were analysed numerically, related to environmental conditions that refer to two different scenarios in India (hot dry and composite climates). It further analyses the reduction in greenhouse gas emissions associated with different roof configurations. The aforementioned PCM/insulation materials were stuffed in the void spaces of the contemporary roof pattern. Thermo-economic analysis of novel roof design with PCM/insulation materials on air-conditioning costs, carbon dioxide emissions and payback time are compared with conventional roofs (CR) and contemporary roof patterns (CRP). The thermo-economic analysis was carried out based on the number of degree-hours of heating and cooling to determine the building's annual energy usage. HS29 PCM stuffed roof pattern (HS29RP) saved the highest total energy cost savings of 11.89/14.71 $/m2/year when compared with conventional roof and 11.35/13.89 $/m2/year compared with contemporary roof pattern for Jabalpur/Kota climatic conditions. HS29 PCM stuffed roof pattern (HS29RP) exhibits the maximum carbon emission mitigation of 215.32/275.37 kg/kWh when compared with conventional roof and 204.95/259.57 kg/kWh for climatic conditions of Jabalpur/Kota. While considering shortest payback span, sawdust stuffed roof pattern shows the minimum payback period of 0.69 and 2.15 years when compared with conventional roof and contemporary roof pattern. The findings of this research offer significant contributions to the development of energy-efficient building envelopes applicable to a wider range of buildings, including those with and without air conditioning systems.

Biomimetic approach for energy-efficient building envelope design in Doha

In this study, an approach is proposed for building envelope designs that directly affect the energy consumption of buildings in response to the ever-increasing energy demand of the built environment due to the increasing population around the world. Within the scope of the study, it is aimed to improve the energy efficiency of the building envelope system created with a nature-inspired approach, by considering both the design and simulation processes together. The entire architectural integration process of this envelope system, developed for the office unit located on the south facade of a fictitious office building in Doha, Qatar, with extreme weather conditions, is discussed. The effects of the developed biomimetic envelope design on cooling load and daylight parameters are analyzed along with the simulation outputs generated throughout the study. As a result of the study, it was observed that the building envelope system created with the biomimetic approach improved the building in terms of energy efficiency

Green building adaptation in hot-humid climates: assessment of coconut and corn husk fiber composite bricks as energy-efficient building envelopes

PurposeThis study has assessed the thermal performance of locally fabricated bio-based building envelopes made of coconut and corn husk composite bricks to reduce building wall heat transmission load and energy consumption towards green building adaptation.Design/methodology/approachSamples of coconut fiber (coir) and corn husk fiber bricks were fabricated and tested for their thermophysical properties using the Transient Plane Source (TPS) 2500s instrument. A simulation was conducted using Dynamic Energy Response of Building - Lunds Tekniska Hogskola (DEROB-LTH) to determine indoor temperature variation over 24 h. The time lag and decrement factor, two important parameters in evaluating building envelopes, were also determined.FindingsThe time lag of the bio-based composite building envelope was found to be in the range of 4.2–4.6 h for 100 mm thickness block and 10.64–11.5 h for 200 mm thickness block. The decrement factor was also determined to be in the range of 0.87–0.88. The bio-based composite building envelopes were able to maintain the indoor temperature of the model from 25.4 to 27.4 °C, providing a closely stable indoor thermal comfort despite varying outdoor temperatures. The temperature variation in 24 h, was very stable for about 8 h before a degree increment, providing a comfortable indoor temperature for occupants and the need not to rely on air conditions and other mechanical forms of cooling. Potential energy savings also peaked at 529.14 kWh per year.Practical implicationsThe findings of this study present opportunities to building developers and engineers in terms of selecting vernacular materials for building envelopes towards green building adaptation, energy savings, reduced construction costs and job creation.Originality/valueThis study presents for the first time, time lag and decrement factor for bio-based composite building envelopes for green building adaptation in hot climates, as found in Ghana.

Analysis of the building envelope materials, climate, and earthquake zones in energy-efficient building designs

Energy-saving has become one of the basic strategies for developing countries like Turkey that need energy imports. One of these strategies is energy-efficient building designs. The energy-efficient building envelope, which is one of the most important components of energy-efficient building designs, is of great importance in terms of insulation, indoor comfort, and environmental effects. In addition, the climatic and seismic characteristics of the regions where the buildings will be built are a matter of curiosity for building designers. It is an important problem to determine the effect of climate and earthquake zones on the building envelope. In this study, the effects of climate and earthquake zones on the costs of the building life cycle, together with the building envelope properties, are investigated. Life-cycle cost assessment (LCA) analysis is applied by considering the parameters of building envelope material cost, heating energy consumption cost, cooling energy consumption cost, CO2 emission cost, embodied carbon cost, and earthquake-based repair cost. A total of fourteen different decision variables are taken into account, including exterior plaster, wall, and roof insulation material, wall, interior plaster, the thickness of these materials, window type, and window/wall ratio. Significance levels of decision variables for heating energy consumption, cooling energy consumption, and CO2 emission are calculated. It is determined that five decision variables for heating energy consumption, four for cooling energy consumption, and seven for CO2 emission are more important. It is an interesting pattern that earthquake zones have 28, 46, and 13% importance for heating energy consumption, cooling energy consumption, and CO2 emission. It has been observed that the EnergyPlus based ANN approach proposed for LCA analysis provides over 95% accuracy on the sample data set.

A comprehensive review of the thermal performance in energy efficient building envelope incorporated with phase change materials

As the world's largest energy consumer, the building sector is under growing pressure to reduce energy consumption and CO2 emissions. To confront this challenge, the thermal performance of building elements, especially for cooling purposes, must be enhanced. One promising solution involves the incorporation of PCMs to augment a building's thermal mass. Unlike traditional building materials that store thermal energy sensibly, PCMs store it in a latent form by undergoing phase transitions at constant temperatures. This unique characteristic allows PCMs to store and release more heat efficiently than sensible heat thermal energy storage materials. As a result, PCMs have emerged as a prominent solution for passive cooling and heating applications in buildings. This paper proposes a systematic review of existing literature, classifying it based on building components and effective PCM integration methods while considering climatic influences. The primary objective is to comprehensively analyze the application of PCMs within building envelopes to enhance indoor thermal comfort. This study explores various methods for assessing the thermal properties of PCMs and PCM composites. Notably, integrating PCMs into building components like walls and roofs has shown remarkable potential in reducing energy consumption within the building envelope. This approach is precious in lightweight construction, where conventional passive design strategies may fall short. This study aims to bridge the existing research gap and provide valuable insights for designing energy-efficient buildings across diverse climates by systematically evaluating the impact of directly incorporating thermal energy storage systems into building components.

Heating electrification in cold climates: Invest in grid flexibility

One strategy to significantly reduce greenhouse gas emissions in end-use sectors such as building heat is to switch from fossil fuels to electricity. To date, electricity consumption follows a regular and predictable pattern; however, electrifying building heat, which is driven by ambient temperature, causes this pattern to change. Previous work has not fully addressed the implications of building heat electrification on the timing and magnitude of peak demands and on flexibility requirements of the electricity grid. In this work, a high-resolution heating demand model, featuring building stock turnover forecasts, is developed, and applied to British Columbia. The study determines energy, capacity, and flexibility requirements by computing regional energy load profiles for space and water heat. Six scenarios were developed to examine the decarbonization potential in the residential and commercial building sector, considering increased heat pump adoption, building envelope energy efficiency improvements, and the implementation of building energy codes. With an emphasis on building stock improvements, 90% heat pump penetration results in only 6% increase in electrical energy even with an annual population growth rate of 1.1%; however, this scenario leads to a 37% increase in peak electricity demand. Over the time-period considered, building energy codes and retrofit rates contribute relatively little to achieving net-zero emissions in the buildings sector, while building heat electrification has significant impacts on future flexibility requirements of the electricity grid.

MEVO: A Metamodel-Based Evolutionary Optimizer for Building Energy Optimization

A deep energy retrofit of building envelopes is a vital strategy to reduce final energy use in existing buildings towards their net-zero emissions performance. Building energy modeling is a reliable technique that provides a pathway to analyze and optimize various energy-efficient building envelope measures. However, conventional optimization analyses are time-consuming and computationally expensive, especially for complex buildings and many optimization parameters. Therefore, this paper proposed a novel optimization algorithm, MEVO (metamodel-based evolutionary optimizer), developed to efficiently identify optimal retrofit solutions for building envelopes while minimizing the need for extensive simulations. The key innovation of MEVO lies in its integration of evolutionary techniques with design-of-computer experiments, machine learning, and metaheuristic optimization. This approach continuously refined a machine learning model through metaheuristic optimization, crossover, and mutation operations. Comparative assessments were conducted against four alternative metaheuristic algorithms and Bayesian optimization, demonstrating MEVO’s effectiveness in reliably finding the best solution within a reduced computation time. A hypothesis test revealed that the proposed algorithm is significantly better than Bayesian optimization in finding the best cost values. Regarding computation time, the proposed algorithm is 4–7 times faster than the particle swarm optimization algorithm and has a similar computational speed as Bayesian Optimization.

An AI-driven model for predicting and optimizing energy-efficient building envelopes

Unlike many previous studies that often focus on optimizing energy efficiency for buildings when detailed design drawings are available, this paper introduces a newly integrated model for energy-efficient building envelope design in the early stages (when detailed design drawings are not yet available). The newly developed model includes three main components: a simulation model, a predictive model, and an optimization model. The simulation model simulates the building's energy performance, considering different values for various envelope parameters. The predictive model employs machine learning algorithms, including RF, ANN, DNN, SVM, GENLIN, and GB (in which GB has been identified as the most suitable algorithm), boasting a very high R2(0.994) to assess energy consumption. The optimization model which uses AI optimization algorithms (such as NSGA II, DSE, and MOPSO) integrates the machine learning predictive model into the evaluation function during the evolutionary process, efficiently searching for Pareto-optimal building envelope solutions. Results show simultaneous savings in cost and energy, with savings of 7.52 % in cost and 8.48 % in energy, or 21.17 % in cost and 0.4 % in energy, for a case study in Vietnam. This model establishes a foundation by providing design solutions for stakeholders to assess, and can incorporate additional objectives at later stages.

Evaluating the appropriateness of adopting a single Overall Thermal Transfer Value and its implication to building energy regulation

Control on Overall Thermal Transfer Value (OTTV) in buildings is one of the important building energy regulations that govern the design of energy-efficient building envelope. Currently, there are two distinct strategies for OTTV control: (i) a single OTTV limit applicable to all building types, regardless of their diverse operating hours; and (ii) different OTTV limits for different building types. Through building energy simulations of 40 real building cases in Hong Kong, it is revealed that applying a single OTTV limit to both commercial buildings (primarily operating during daylight hours) and hotel buildings (24-h operation) is problematic when considering both the cooling and heating demands. A 24-hr operating building can be designed to meet an OTTV limit but may have a comparatively poor thermal performance in the heating months when compared to another design option with the same OTTV limit. The literature review reveals that there has been no previous study on this problem. In order to tackle this research gap, a novel method including correlation factors, regression equations and additional OTTV requirement has been developed in this study for assessing the thermal performance of 24-hr operating buildings under the current OTTV regulation in Hong Kong. Based on the result from this study, 24-hr operating buildings can be properly designed under the OTTV regulation to achieve good energy efficiency in both the cooling and heating seasons. Policy makers are advised to incorporate this new OTTV evaluation method into the current OTTV regulation in the next round of OTTV review. The methodology developed in this study can be applied in other cities with OTTV regulation implemented.

Evaluation of energy efficient building envelope alternatives for sustainable cities

This study is aimed to create an exemplary project to present the contribution of the new buildings to energy savings when the residential buildings are transformed into green buildings. To create a sustainable built environment in residences, this study emphasizes that low-energy building strategies be combined with efficient and high-performance natural-sourced materials. Our findings show that using a natural-sourced material as the building envelope material has an impact on the use of primary energy and energy costs of the alternatives studied. In this study; In the case of replacing the building external wall components of an existing construction designed with internal insulation in the climatic conditions of Ankara, the change in energy performance has been investigated. The analysis was done with the help of BIM-based Revit Program and “Green buildings studio” where energy simulations were created. In the study, 54 different wall combinations were created by modeling combinations of different construction (porous, gas concrete, and pumice bricks), insulation (glass wool, rock wool, sheep wool, PUR, XPS, and EPS) and, roof (tile, asphalt shingle, and green roof) materials. When the outputs obtained from the analyzes were evaluated, the lowest energy consumption values were observed in the combination of pumice brick wall, green roof, and polyurethane insulation materials. In this scenario, the annual fuel consumption per square meter is determined as 30000.6 MJ/m2. On the other hand, the highest energy consumption values were observed in the combination of porous brick wall, tile roof and sheep wool insulation materials. In this scenario, the annual energy consumption per square meter is determined as 30026.6 MJ/m2. Although there are not high numerical differences between the findings, it has been observed that the results give consistent results with the thermal conductivity coefficients of the materials used in the combinations.

Scalable and flexible porous hybrid film as a thermal insulating subambient radiative cooler for energy-saving buildings

Passive daytime radiative cooling (PDRC) is one of the promising alternatives to electrical cooling and has a significant impact on worldwide energy consumption and carbon neutrality. Toward real-world applications, however, the parasitic heat input and heat leakage pose crucial challenge to commercial and residential buildings cooling. The integrating of radiative cooling and thermal insulation properties represents an attractive direction in renewable energy-efficient building envelope materials. Herein, we present a hierarchically porous hybrid film as a scalable and flexible thermal insulating subambient radiative cooler via a simple and inexpensive inverse high internal phase emulsion strategy. The as-prepared porous hybrid film exhibits an intrinsic combination of high solar reflectance (0.95), strong longwave infrared thermal emittance (0.97) and low thermal conductivity (31 mW/(m·K)), yielding a subambient cooling temperature of ~ 8.4 °C during the night and ~ 6.5 °C during the hot midday with an average cooling power of ~ 94 W/m2 under a solar intensity of ~ 900 W/m2. Promisingly, combining the superhydrophobicity, durability, superelasticity, robust mechanical strength, and industrial applicability, the film is favorable for large-scale, sustainable and energy-saving applications in a wide variety of climates and complicated surfaces, enabling a substantial reduction of energy costs, greenhouse gas emission and associated ozone-depleting from traditional cooling systems.

Evaluation of building energy load of a multipurpose hall and its optimization through spectrally selective fenestration and passive design concepts

Sports complexes and recreational centers are large and long-term investments that provide integrated facilities for training athletes and hosting social-cultural events. Due to their daily functioning, such buildings involve high energy consumption resulting in environmental impacts at both local and global scales. This article investigates the currently available methods for assessing the performance characteristics of a Multipurpose Hall using passive design techniques by modifying the building materials used for the wall envelope and fenestration design. Given that the proposed Multipurpose Hall is located near the composite climate of New Delhi, India, a study of climatic responses together with an energy evaluation of the building provides insight into the important envelope design for enhancing a building's energy efficiency. Several energy simulations were performed using DesignBuilder software to determine the annual lighting, heating, and cooling consumption for wall envelopes, window glazings, and dynamic shading techniques. Additionally, the solar gain of various fenestration designs was investigated, and the most energy-efficient building envelope was selected. The comparison of the baseline envelope with the modified envelope design revealed a notable improvement in energy performance.