External Roof Research Articles

Research on the Estimation of the Flexural Capacity of EPS Lightweight Concrete Panels

Expanded Polystyrene (EPS) lightweight concrete possesses numerous special characteristics, including exceptionally low weight, good sound insulation, effective heat insulation, great fire resistance, and low water absorption. Consequently, it has garnered significant attention for research and practical applications in the construction industry, particularly in the development of soundproofing and thermal insulation components, as well as lightweight elements to reduce the superstructure weight, such as external wall panels, floor slabs, roof panels, and base materials. The primary objective of this study is to analyze and estimate the flexural capacity of EPS lightweight concrete panels through both experimental and numerical methods. Furthermore, the influence of the longitudinal reinforcement ratio, strength, and thickness of EPS lightweight aggregate concrete panels on their flexural capacity is thoroughly investigated and evaluated. The findings demonstrate that the Abaqus software, with an appropriate material model for EPS lightweight aggregate concrete, can reliably predict the flexural capacity of EPS lightweight concrete panels reinforced with longitudinal rebars.

Simulation-based design: minimizing energy consumption in residential buildings through optimal thermal insulation

Purpose This study aims to optimize the energy consumption of residential buildings in mild and humid climates. It investigates the use of thermal insulation to reduce thermal load through energy simulation analysis. Design/methodology/approach A residential building located in Rasht city, Iran (a mild and humid climate zone), is simulated using DesignBuilder software. Subsequently, the minimum thermal resistance for external walls and roof is analyzed along with its impact on building energy consumption and carbon emissions. Findings The simulation results indicated a 26.5% reduction in heat loss through the walls and a 14.2% reduction through the roof due to optimal thermal insulation. Furthermore, optimal insulation led to a 19.2% reduction in cooling system energy use, a 12% reduction in heating system energy use and a combined 15.3% reduction in total energy consumption for cooling and heating. Originality/value This optimization process leads to several benefits: reduced costs associated with thermal and cooling energy losses in buildings, improved building performance against atmospheric factors and, ultimately, a reduction in energy consumption across the building industry. This research can be valuable to various stakeholders, including the construction industry and building sector, municipalities and engineering systems, building owners and contractors and environmental organizations. By implementing these findings, they can improve the state of modern building insulation and achieve greater energy efficiency.

Influence of the thermal insulation position in standard and cool roofs on their contribution to urban heating during heatwaves

The urban heat island, coupled with increasingly intense, frequent and long heat waves, leads to a significant risk of excess mortality and increased energy requirements in urban areas during the summer season. Various cooling techniques are therefore being studied to moderate the intensity of this phenomenon during the hot season. The aim of this study is to quantify the contribution of roofs to urban climate during heatwaves, depending on the position of the insulation in the structure and its radiative properties. This study is carried out in the laboratory, using an experimental set-up to submit roof samples to heatwave conditions. The experimental set up includes a temperature and humidity-controlled climate chamber with a solar simulator. Two roofing configurations are studied: roofs with external thermal insulation (ETI) and roofs with internal thermal insulation. Each configuration is studied for two types of roof: standard (low albedo), and reflective (high albedo). It appears that ETI roofs heat the outside air during the day, but not at night. While ITI roofs heat the ambient air less during the day, they release some of the stored daytime heat during the night. Whatever the structure, increasing solar reflectivity significantly reduces the contribution of roofs to urban heating, although the impact is stronger for internally-insulated roofs, since it reduces the amount of heat released. Finally, for the externally insulated structure, the increase in solar reflectivity reduces daytime convective exchange by 41% and heat entering the building by 75%. For the internally insulated structure, daytime convective heat exchange is reduced by 43%, and the heat stored in the concrete layer is reduced by over 50%.

Integrated optimization of the building envelope and the HVAC system in office building retrofitting

Increasing the energy efficiency of existing buildings is the major strategy to reach carbon neutral targets, given that the building sector is a major emitter. In particular, one major part of building energy usage is the building heating, ventilation and air-cooling system, which are highly depending on the thermal performance of building envelope and increase the challenge of selecting optimal packages of energy efficiency measures. This paper thereby presents a method for optimizing the building envelope and heating, ventilation and air-cooling system. The simulation-based NSGA-III approach developed in this paper is based on coupling the dynamic simulation models created in EnergyPlus software with the non-dominated sorting genetic algorithm, as the engine that performs an optimization process. A large domain of energy efficiency packages combined with heating, ventilation and air-cooling systems and building envelope are investigated to minimize energy consumption, retrofit cost and thermal discomfort in indoor environments, which including ideal loads air system, four pipe fan coil system and variable refrigerant flow system, insulation materials and insulation thickness for external walls and roof, different types of external windows, and window-wall ratio. An office building in Chongqing was chosen as a case study to demonstrate the practical implementation of the proposed method. The results show that the four pipe fan coil system was superior in the diversity and performance of the Pareto front. Then, the optimal packages were generated by a synthetic method, which have 58.57 kWh/m2 of energy consumption, 30.76 CNY/m2 of retrofit cost and 40.67 % of the percentage of thermal discomfort hours. The results also indicate that the yearly energy savings rates are 17.30 %, 23.05 % and 21.10 % separately for ideal loads air system, four pipe fan coil system and variable refrigerant flow system after performing optimization. These results highlight the importance and necessity of performing an optimization procedure for existing buildings to select the optimal retrofit measures.

Multi-objective optimization of rural residential envelopes in cold regions of China based on performance and economic efficiency

Building envelope renovation solutions are critical to building performance and post-renovation economics. Building renovation is easier to carry out if the impacts of building envelope renovation solutions on building performance and post-renovation economic efficiency can be foreseen and a more sustainable and efficient renovation design can be achieved. This paper explores the optimal design of building envelope renovation using genetic optimization algorithms and statistical analysis methods, taking the performance of the renovated building and the economic efficiency of the renovation solution as the starting points. In Qingdao, a cold region of China, a survey was carried out on typical rural areas in seven regions. The selected design variables include the external wall and roof insulation material type(TWall, TRoof), external wall and roof insulation thickness(δWall, δRoof), type of window construction(TWc), and area radio of the window to the wall(WWR). Minimization of total building energy consumption(E) and renovation cost(COSTRE) and after renovation maximization of the combined incremental cost-benefit ratio over a 20-year life cycle(CICBR20-year life-cycle), effective natural daylighting illuminance(UDI), and percentage of time spent in indoor comfort(PTC) were considered in the optimization of the envelope. The results show that in cold regions, different envelope renovation solutions affect the optimization objectives to different degrees; changing the south-facing window-to-wall ratio(S_WWR) has a bigger effect on E, PTC, and UDI; and choosing different TRoof has a bigger effect on COSTRE and CICBR20-year life-cycle. Renovation of the selected typical rural residence with the optimal solution results in an energy-saving rate(Re) of 53.08 %, an increase of 940.86 h/year in annual indoor comfort hours(HIC) and 377.00 h/year in annual effective natural lighting hours(HUDI).

The effect of lightweight geopolymer concrete containing air agent on building envelope performance and internal thermal comfort

Innovative building materials are the primary focus for researchers seeking to reduce energy consumption and advance global sustainability initiatives. This target could accomplished by addressing environmental issues and confronting the adverse impact of climate change. In this regard, this paper used a combined experimental and simulation approach to evaluate the effectiveness of lightweight geopolymer concrete (LWGC) incorporating industrial waste of aluminum powder (AP) and ferrosilicon waste powder (FWP) for reducing the energy consumption in the building envelop. Seven concrete mixes for LWGC were prepared using an air operator. Three mixtures contain 0.1 %, 0.2 %, and 0.3 % AP (FA), and three mixtures contain 0.1 %, 0.2 %, and 0.3 % FWP by weight of fly ash. The workability, unit volume weight, compressive strength, thermal conductivity, and microstructure analysis of the LWGC were examined. In addition, energy simulations were performed to evaluate their ability to reduce energy use in residential buildings. The inclusion of AP and FWP in LWGC resulted in a significant decrease in the density of the material, which amounts to 55 % for AP0.3 and 35 % for FWP0.3. The diameter of the LWGC pore structure increased as the Ca/Si ratio was reduced. The AP and FWP materials reduced energy consumption for building envelope elements such as external walls and roof insulation by 14.5 %, resulting in a 9.2 % overall reduction compared to the traditional concrete mix as a control sample.

Energy performance analysis of alternative building retrofit interventions for the four climatic zones of Greece

Climatic conditions determine which retrofit strategy can result in a satisfactory improvement of a building's thermal performance. This study systematically investigates alternative retrofit actions, as standalone and in combination, and assesses their energy performance. The retrofit actions include i) insulation on the external walls, ii) the incorporation of phase change material (PCM) on the roof and the increase of the building thermal inertia, iii) a mechanical ventilation system with a summer period operation, and iv) a cool roof coating. The energy analysis concerns a typical two-story family building and the four climatic categories of Greece and is conducted with the INTEMA.building tool, a dynamic energy analysis software developed in Modelica language. The importance of the present study is that it serves as a guideline for the selection of the energetically optimum single retrofit or multiple-retrofit strategy regarding a building's location climatic data, and provides calculations concerning the annual heating and cooling loads, and the corresponding heat pump electricity consumption. The retrofit actions of external wall insulation and PCM roof addition are characterized as more effective in reducing a building's heating energy loads, while the mechanical ventilation system and cool roof coating are more effective in reducing a building's cooling loads. The quadruple retrofit strategy results in the maximum electricity savings for Heraklion (28.01%), Athens (21.15%), and Thessaloniki (16.54%), while the triple retrofit strategy which does not include the cool roof coating, results in the maximum electricity savings for Kastoria (10.79%). Lastly, an economic analysis of the energetically optimum renovation strategies is conducted.

Technical State, Renovation Need and Performance of Renovation Solutions of Estonian Wooden Log Houses

The wooden log house serves as a prevalent architectural archetype in rural regions of several Nordic and Baltic countries. To ensure the long-lasting nature of these buildings, proper maintenance is imperative. However, in order to meet the evolving expectations of residents and minimize the environmental impact, a deep renovation is currently required. To successfully achieve the goals of this renovation wave and effectively address the personal needs of the homeowners, it is crucial to develop systemic renovation solutions that can be offered through a digital renovation passport. Consequently, the purpose of this study is to identify common damages, renovation requirements, and evaluate current renovation practices. The findings will serve as a crucial resource for the development of a digital renovation passport. In our study, we utilize rural wooden log houses (comprising 208 houses, 4 years of data) as our research subject. The building elements that are most in need of renovation are the external walls, roofs, and foundations, which require renovation in 77%, 63%, and 63% of the buildings, respectively. The primary cause of damage to the vulnerable structures is excessive moisture. Additionally, decay in the foundation can be attributed to factors such as erosion of mortar, frost, insufficient plinth height, inadequate foundation depth, and inadequate moisture protection. Recommendations provided by consultants primarily focus on restoring and preserving the dwellings' original architectural appearance. As a result, they are deemed insufficient in terms of improving energy performance and indoor climate. This lack of comprehensive consultation is concerning as it fails to consider the potential for cost efficiency, minimizing disruption to occupants, and achieving a comprehensive end result. The absence of recommendations for enhancing indoor climate, energy efficiency, general living quality, and reducing the building's carbon footprint performance the necessity for such renovation solutions and the importance of educating professionals and homeowners. The study's novelty lies in the establishment of statistical probabilities for damages and their causes, as well as the assessment of renovation and maintenance needs and the quality of existing recommendations. Results are scaled to the Estonian building stock, showing the renovation need on national scale. The findings can be incorporated into the digital renovation passport, along with specific renovation goals related to a given house.

Thermal Performance of Residential Roofs in Malaysia: Experimental Study Using an Indoor Solar Simulator

Previous researchers have detailed the problems in measuring the thermal resistance value of a whole roof assembly under hot conditions due to the uncertainty of the outdoor environment. Currently, no established method exists to experimentally investigate an entire thermal roof performance under a steady-state condition. This article details the properties of the indoor solar simulator and the research methods undertaken to measure the thermal resistance value of roof assembly. The indoor solar simulator utilizes 40 halogen bulbs to accurately replicate sun radiation. Thermocouples and heat flux sensors are installed at several locations on the roof assembly to quantify the heat transmission occurring through it. The thermal resistance value is determined by adding up the average difference in temperature across the external and internal roof surfaces and dividing the total amount by the total of all averaged heat fluxes. Subsequently, this study investigates the thermal efficiency of residential roof assemblies that comprise various insulation materials frequently employed in Malaysia, including stone wool, mineral glass wool, reflective bubble foil insulation, and radiant barriers. The analysis showed that the roof configurations with bubble foil reflective insulation produce superior thermal resistance values when coupled with enclosed air space or mass insulation, with thermal resistance values ranging between 2.55 m2K/W and 3.22 m2K/W. It can be concluded that roof configurations with bubble foil reflective insulation resulted in high total thermal resistance and passed the minimum thermal resistance value of 2.5 m2K/W under the Malaysian Uniform Building By-Law 38 (A) requirements. Furthermore, the radiant barrier produced a high thermal resistance value of 2.50 m2K/W when installed parallel to a 50 mm enclosed air space, emphasising the crucial function of an enclosed air space next to a reflective foil to resist the incoming heat radiation. The findings from this research can help building professionals determine the optimum insulation for residential building roofs in Malaysia.

Energy efficiency optimization of architectural projects using an Evolutionary Algorithm combined with Energy Plus

This study formulates an optimization problem that adjusts social housing physical parameters to minimize energy consumption and thermal discomfort. Candidate solutions were generated using Genetic Algorithm via the Python computational platform and evaluated on the EnergyPlus program. The analyzed social housing unit meets minimum conditions according to Brazilian standards NBR 15575 and 15220 and the Federal Government’s Casa Verde Amarela Program. Optimization variables included cardinal tweaking; thickness of materials that make up external walls, roofing, and flooring; external wall and roof absorptance; floor-to-ceiling height and window size. Unlike other studies, instead of optimizing the thermal transmittance of walls, roof, and floor, we decided to directly target their thickness and to optimize window size and the floor-to-ceiling height. Evaluated according to different physical project configurations, the results proved to be coherent, presenting adequate variable exploration in order to obtain a project that universalizes the use of simple and systemic techniques to improve energy efficiency and that can be applied to any type of housing. We also obtained solution automation, providing an optimal feasible solution that increases energy efficiency and reduces energy consumption, thus contributing to a more sustainable project.

Predicting Passivhaus certification of dwellings using machine learning: A comparative analysis of logistic regression and gradient boosting decision trees

Passivhaus has gained recognition as a reliable solution for low-energy residential housing. However, existing studies lack comprehensive quantitative analysis of real-life cases, restricting the availability of evidence and experience from certified buildings. This study addresses this gap by examining the relationship between characteristics of certified passive houses and their energy performance. The objective is to establish dependable statistical models and best practices for early design stages of passive houses. The study analyzes a significant number of certified cases (n = 785) in residential settings situated in two climate zones: Temperate, no dry season, warm summer (n = 328, 41.78%) and Cold, no dry season, warm summer (n = 457, 58.22%). To assess whether residential buildings meet passive house energy standards, models using logistic regression and gradient boosting decision trees were developed employing three boosting methods: XGBoost, LightGBM, and CatBoost. Results reveal that CatBoost (F1 = 0.73, Logloss = 0.63, AUC = 0.78, Brier = 0.22) outperforms logistic regression (F1 = 0.72, Logloss = 0.62, AUC = 0.72, Brier = 0.22) in terms of accuracy. Additionally, LightGBM (F1 = 0.79, Logloss = 0.58, AUC = 0.75, Brier = 0.20) exhibits superior predictive calibration. This study indicates that external wall, floor slab, and roof thermal performance are crucial factors for meeting passive house standards (P-value = 0.0046). The research also discusses innovative practices and technologies derived from the certified cases. Overall, this study provides valuable insights for certification systems and early design strategies.

Experimental and numerical study on thermal performance of phase-change-material cool roofs in summer

Cool roofs can reduce building energy consumption and improve indoor and outdoor thermal environments. A phase change material cool roof (PCMC roof) was proposed in order to reduce roof heat gain in the indoor thermal environment in summer. Indoor thermal and energy environmental parameters in three full-size rooms (ordinary room, PCM room, and PCMC room) were tested from July to September 2022. The heat transfer characteristics and energy saving effect of roofs were investigated by combining experimental analysis with numerical analysis. Compared with the ordinary roof, the PCMC roof decreased external and internal roof surface real-time temperatures up to 30.0 °C and 6.4 °C respectively, and reduced the roof inner surface heat flux of 33.3%-66.7%. Compared with the relevant roof studies, the energy saving and cooling effects are more significant. Then, based on the mathematical model of roof heat transfer, the correlation analysis between seven different elements was carried out to evaluate the energy-saving effect of PCMC roof. This study investigates the PCMC roof from the aspects of roof heat transfer characteristics, influence on indoor thermal environment, energy saving evaluation, etc., which provides a more complete and valuable reference for advancing building roofs.

Parametric BIM-based life cycle assessment framework for optimal sustainable design

The construction sector is liable for a sizable amount of CO2 emissions and waste. Life Cycle Assessment (LCA) is considered one of the crucial tools that aids in evaluating the impacts of construction emissions. This research aims to quantify the life cycle impacts of the initial and recurrent embodied emissions, operating and reuse/disposal emissions, and utilizing Building Information Modeling (BIM) for a more holistic life cycle approach. The research proposes a parametric BIM-based LCA framework for quantifying the environmental impacts and evaluating the effects of material selection for both embodied and operating emissions. In addition, it considers the different reuse scenarios and percentages and their effect on both the embodied and operating impacts. The proposed framework consists of five main modules: data acquisition module, operating and embodied emissions module, life cycle assessment module, optimization module, and decision-making module. This parametric assessment can be applied for both the conventional and circular approach impacts. For the decision-making process, the resulting emissions are optimized utilizing the Non-dominated Sorting Genetic Algorithm II (NSGA-II) and evaluated through an LCA and Data Envelopment Analysis (DEA) methodology for the material selection. A case study of a residential villa in Cairo is worked out to illustrate the key features of the proposed framework. This assessment analyzes the building materials’ characteristics and efficiency investigating the external walls, internal walls, floors, roofs, and windows design possibilities, and uses visual programming to control the resulting emissions for a more flexible approach. By comparing the integrated LCA and DEA models three optimum design solutions, the conventional approach develops design solutions of higher embodied Global Warming Potential (GWP) than the circular approach. However, it develops lower operating GWP with better applied U-values. The circularity approach employment has reduced the efficiency of the operating GWP due to utilizing materials with high heat transmittance ability.

Evaluating carbon payback time by optimizing insulation materials for different orientations: A cradle-to-gate life cycle assessment

The European Union aims to reduce greenhouse gases emissions by 80–95% compared to 1990 levels by 2050. Therefore the life cycle concept has gained widespread acceptance as a model for evaluating the environmental impact of goods and services. In this study, the optimal thickness of various insulation materials for external walls, roofs, and floors using a Mediterranean climate zone's hot summers and mild winters for a hypothetical residential building for four cardinal orientations was determined. The criteria for determining the optimum thickness represent a turning point in terms of cooling energy consumption (electricity). The optimum thickness of nine different types of insulation materials was defined using the aforementioned approach. These materials included aerogel, polyisocyanurate, polyurethane, extruded polystyrene, expanded polystyrene, phenolic foam, cellulose fiber (cellulose), mineral wool, and glass wool (GW). The purpose of this paper is to calculate the carbon payback time (CPBT) using the cradle-to-gate life cycle assessment method by considering the global warming potential (GWP) of insulation materials at their optimum thickness. The CPBT is calculated as the ratio of the total building's GWP to the GWP of savings from cooling and heating (electricity and natural gas). The results indicated that when evaluating the average CPBT for four cardinal orientations (FCO), aerogel has the longest CPBT of 2.34 years, and GW has the shortest CPBT of just 0.09 years. Aside from cost payback time, the findings of this study provide a new perspective on selecting appropriate thermal insulation.

Simulation-based sensitivity analysis of energy performance applied to an old Beijing residential neighbourhood for retrofit strategy optimisation with climate change prediction

Due to the high energy consumption in the building sector and the ever-increasing urbanisation rate, the demand for retrofitting old buildings in urban areas is increasing in China, especially in metropolitan cities like Beijing. However, despite national and local policies calling for extensive building retrofitting, it is a challenge to determine a cost-effective retrofit strategy. Considering this, the study establishes a novel approach that analyses the sensitivity of building energy consumption on parameters defining the materials used on the building envelope, as well as the solar shading and airtightness of the building. This research builds EnergyPlus models using geometric data captured from the map, building fabric data from local design standards, and a set of varying activity schedules, and carries out simulations to calculate the building energy consumption of a residential neighbourhood in Beijing, China. The energy consumption data is then used for a sensitivity analysis using the Morris Method on 14 building envelope parameters in total. For different building shapes, the sensitivity analysis results highlight that the energy is most sensitive to infiltration, followed by window U-value and window SHGC. The solar absorptances and U-values of external walls and roofs are also found to have a moderate influence on total energy consumption. By using predicted weather files, this research further discusses the changing influences of these parameters considering climate change over the next few decades. The approach of this research is instructive for the analysis of buildings in other cities in cold climate regions due to the generalisability of the studied neighbourhood, and the result has the potential to inform the building management teams and policymakers to determine suitable retrofit strategies.

Chagas prevention and control in an endemic area from the Argentinian Gran Chaco Region: Data from 14 years of uninterrupted intervention.

Chagas Disease (ChD) is a Neglected Tropical Disease (NTD) affecting 6 to 7 million people worldwide, mostly from Latin America. In Argentina, a national control program has been implemented since 1962, yet there are still an estimated 1.6 million infected individuals. Control programs were based almost exclusively on entomological surveillance and chemical control of households and were not continuous given a lack of coordination and resources. Argentina´s ChD program was originally vertical and centralized; later, it was partially and, in general, unsuccessfully transferred to the provinces. Herein, we describe the implementation of a control program for ChD with an ecohealth approach in rural settlements around the city of Añatuya, Santiago del Estero. The program included yearly household visits for entomological surveillance and control, health promotion workshops, and structural house improvements. Improved structures included internal and external walls and roofs, as well as the construction of water wells and latrines, and the organization and improvement of peri-domestic structures. Activities were carried out by specifically trained personnel except for house improvements, which were performed by the community, under technical guidance and provision of materials. Data was collected using standardized questionnaires for household characterization, entomological infestation status and chemical control activities. This program was continuously implemented since 2005 with high community participation and adherence, incorporating 13 settlements and 502 households. During the surveillance phase, 4,193 domiciliary inspections were performed, and both the intra- and peri-domestic infestation rate were reduced from 17.9% to 0.2% (P < 0.01) and from 20.4% to 3%, respectively. Additionally, 399 households were structurally improved. The program is still ongoing and, after 14 years of implementation, has built social networks and collaboration between implementers and beneficiaries with a reduction of T. infestans infestation in the intra- and peri-domicile. This reduction, especially inside the household, has enabled access to diagnosis and treatment of the population, with minimal risk of re-infection.

Research on Multiple Energy-Saving Strategies for Existing Coach Stations: A Case of the Xi’an Area, China

In the context of China’s dual-carbon goals, energy efficiency in public buildings has become a focal point of public concern. As large-scale public transportation buildings, the indoor thermal comfort and the current state of energy consumption of coach stations are increasingly being emphasized. This research used existing coach stations in the Xi’an region as the object; through on-site investigations and field tests of indoor thermal environments in winter and summer seasons, it was found that the coach stations had energy waste and high energy consumption; the enclosure structures had poor thermal performance; and the stations lacked effective energy-saving measures. Energy-saving transformation strategies were proposed from two aspects: enclosure structures and renewable energy utilization. Using DeST-C for energy consumption, the external walls, roofs, insulation materials, and glass materials were simulated, and nine different combinations of energy-saving schemes were simulated using orthogonal experiments. The optimal scheme was selected based on the comprehensive energy-saving rate and economic analysis results, which included using 80 mm XPS external insulation for the external walls, low-e hollow glass for the windows (low transmittance type), and an 80 mm PUR board for the roof insulation. The energy-saving rate of this scheme was 26.84%. The use of rooftop solar photovoltaic power generation and fresh air heat recovery devices can effectively reduce building energy consumption, and the investment payback period is less than 5 years. The research applications have practical significance for improving the indoor environment of existing coach stations and saving energy consumption.

Multi-objective evaluation of different retrofitting scenarios for a typical Greek building

In this study, multiple retrofitting scenarios of a typical Greek house were investigated. These scenarios encompass the addition of insulation to the building’s external walls and roof, a green roof construction, the use of high-quality windows and the installation of an efficient heat pump. The aforementioned techniques were simulated separately and in combination with the use of the DesignBuilder software, on an annual basis, for the city of Athens, Greece. The pivotal innovation of this work lays in the energy simulation and the comprehensive comparison of the 34 retrofitting scenarios according to a multi-objective evaluation procedure. An additional novelty was the investigation of the energy impact of each renovation action when applied separately. The goal of the multi-objective evaluation procedure was to determine the optimum renovation case, for maximizing the energy savings and minimizing the life cycle cost. According to the results, the optimum retrofitting case included the installation of insulation to the building’s external surface and the heat pump retrofitting. The optimum scenario resulted in a 41.7% reduction in the building’s heating loads and a 14.9% reduction in its cooling loads. Finally, the primary energy savings were 66.1% and the life cycle cost analysis showed 6,645 € lifespan savings.

Optimizing PCM Integrated Wall and Roof for Energy Saving in Building under Various Climatic Conditions of Mediterranean Region

Energy conservation in buildings has been the focus of many studies since nearly one-third of global energy consumption is due to buildings. Phase change material (PCM) technology promises to be an attractive solution for energy saving in buildings since it is a passive and effective technology, as demonstrated in the literature. Therefore, this study focuses on the energy-saving performance of PCM-integrated buildings located in a Mediterranean climate to reveal their energy-saving potential. PCM is integrated both in external or internal south walls and roofs of buildings under four different climatic conditions. EnergyPlus, which is a well-known building simulation software, is adopted for building thermal analyses. The effects of melting temperature, location of PCM layer in the wall, thickness of PCM layer, type of envelope (wall or roof), and PCM double-layer system in the wall are investigated. The corresponding energy savings and CO2 emission reductions are obtained for the considered cases. The results showed that up to 41.6% reduction in energy demand can be obtained depending on the PCM application. Besides, PCM with a low melting temperature (21 °C) favored heating energy savings, while PCM with a high melting temperature (29 °C) favored cooling energy savings. Moreover, the double-layer PCM system provided higher energy savings than the single-layer PCM system, especially in warm and arid regions (Sousse and Tozeur).

Passive solar sunspace in a Tibetan buddhist house in Gannan cold areas: Sensitivity analysis

Attached sunspace is an effective energy system of passive solar energy utilization, which has been extensively employed in many nations. This study investigated, tested, and analyzed a representative Tibetan Buddhist house with attached sunspace in Gannan. The thermal comfort of the building was evaluated. The influence of building orientation, depth of sunspace, glazing type, insulation type and thickness of external wall and roof, thickness of wall and roof on thermal comfort and energy consumption were ranked by sensitivity analysis and numerical simulation. Local sensitivity analysis was also performed on the components with high sensitivity, and suggestions were provided for the design of attached solar houses in this area. The results show that the most relevant parameters of thermal comfort and energy consumption are roof insulation thickness and roof thickness. The optimum thickness of rammed earth is 1.1–1.2 m, and the design range of thermal insulation thickness is 10–90 mm, of which 10–40 mm is the best. At the same time, the best orientation of the attached sunspace is south, and the glazing type has a little effect on thermal comfort and limited impact on energy consumption.