Roof Insulation Research Articles

Research on Passive Design Strategies for Low-Carbon Substations in Different Climate Zones

In the energy-saving design of substations, the building envelope thermal parameters, window-to-wall ratio, and shape factor are three crucial influencing factors. They not only affect the building’s appearance but also have an important impact on the total building energy consumption. In this paper, we applied the energy consumption simulation software DeST-c to study the influence of the above three elements on the total energy consumption of the building in a representative city with different thermal zones. The optimal envelope thermal parameters, optimal window-to-wall ratio, and optimal shape factor were derived through combination with economic analysis. Finally, the sensitivity analysis of different elements was carried out to determine the suitable passive design solutions for substations in different climate zones. It was found that the thickness of roof insulation has the greatest influence on the energy consumption of substation buildings among all envelopes. The optimal window-to-wall ratios were 0.4, 0.4~0.5, 0.3, 0.3~0.4, and 0.5 for severe cold, cold, hot summer and cold winter, hot summer and warm winter, and mild regions, respectively; and the optimal shape factors were 0.29, 0.30, 0.23, 0.31, and 0.33, respectively. The conclusions of this study can provide architects with energy-saving design strategies and suggestions for substations in different climate zones, and provide references for building energy-saving designs and air conditioning and heating equipment selection.

Optimization Bundle Paths of the Building Envelope for Zero-Carbon Strategies

Improving building energy performance with minimum emission and cost is important for zero-carbon strategies. In this regard, this study mainly focuses on the envelope of an apartment block. The aim is to investigate the tripartite relationship between energy performance, CO2 emission, and cost by using different wall and roof insulation materials, and various glazing types in a typical reinforced concrete five-floor apartment block in Istanbul, Turkey. In a building performance simulation tool - Cove. Tool, material alternatives’ impacts on energy use, cost, and CO2 emission are calculated. Consequently, 32 different design bundles are generated. Finally, the most advantageous material combination is explored from the design combinations to make cost-conscious, performance-driven, and environmentally-friendly decisions.

Modular and Prefabricated System for Waterproofing and Insulation of Flat Roofs

Recently, there has been an attempt to implement increasingly significant prefabrication in building construction, since this method is considered to represent an opportunity to reduce impacts in the construction sector. For pitched roofs, there have been relevant developments, such as sandwich panels, asphalt shingles, lightweight roof panels, among others. However, in relation to flat roofs, the advances have been of little relevance and are mainly limited to the improvement of technical characteristics and prefabrication of the construction materials used. The main goal of this article is to demonstrate the possibility of developing new solutions for more sustainable flat roofs in the carbon footprint, and for this purpose a system was developed called ADAPTIVE—Advanced Production System for Sustainable and Productive Roofing Retrofit, which consists of developing a composite solution for the rehabilitation of flat roofs, completely prefabricated and with zero waste, with the aim of increasing energy behaviour, collecting and storing rainwater, and using the roof as a garden leisure space. To obtain the validation results, computerised theoretical modelling was conducted with theoretical assessment of the components and the set of components developed, which allowed us to conclude that the system meets the high hygrothermal, acoustic, and structural requirements.

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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.

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.

Analyse the Effect of Glasswool Roof Insulation Based on the Orientation of the Room to the Sun

In the countries with tropical climates such as Malaysia, humidity and hot weather are well-regarded; this weather can affect the heat conditions and indoor room. The effects of the poor thermal condition are non-conducive human activities and a comfortable environment in the room. They improved the tilt angle for roof building or house design with insulation to achieve comfort and reduce the indoor temperature. Thermal insulation is one of the methods to reduce heat transmission through the room by applying proper material and installation. The main objective of this study is to test Glasswool insulation in different orientations of the roof for Malaysian houses. The insulation material has been tested by airflow simulation using SolidWorks software which applies to the rooftop on the east and west orientations, where the indoor temperature of the house has been reduced from (29°C - 27°C East and 30°C - 28°C West) without considering any air movement. The simulation result shows the temperature reduction before and after applying the insulation corresponds, while the reduction is 2°C temperature (7.4% reduction) at both orientations. The significant reduction helped the occupants to reach their comfort zone and save the cost of the electrical bill.

Optimization of top-floor rooms coupling cool roofs, natural ventilation and solar shading for residential buildings in hot-summer and warm-winter zones

The high building energy-saving potential of integrated passive technologies has drawn significant public attention. This paper combined field measurements and multi-objective optimization to reduce lighting and air conditioning (AC) energy by coupling cool roofs, natural ventilation (NV), and solar shading. Experimental measurements verified the cooling effects of cool roofs and NV based on thermal performance. The influences of cool roofs on heating and cooling energy were obtained. A building simulation model was validated by measurement data of thermal performance and AC energy use collected from a Guangzhou residential building. Energy-saving potentials under NV and daylight implemented strategies were then quantified. Compared to the black room without energy-saving strategies, daylight could reduce lighting energy by 3.3 kW h/(m2·yr), and AC energy use could be reduced by 4.7, 22.7 and 26.9 kW h/(m2·yr) in the black, blue and white rooms adopting NV, respectively. The roof albedo, roof insulation thickness and window-to-wall ratio notably impacted AC and lighting energy based on global sensitivity analysis. Optimal design schemes based on multi-objective optimization could reduce the top-floor room energy consumption by up to 52.3 kW h/(m2·yr).

Simulation of roof retrofitting strategies to mitigate attic overheating issues of the terrace house under hot and humid climate

The purpose of this study is to investigate the potential mitigation strategies to overcome the overheating issue at the attic of the landed residential house located in a hot and humid climate area. An existing terrace house with 178 m2 was selected for this research. A building simulation model was created and calibrated by using the previous site measurement data collected by Ng et.al. in the year 2018. The calibrated model was subsequently used to evaluate various retrofitting methods and strategies, including roof insulation, and passive radiative cooling methods. The study shows that high albedo cool roof paint is the most effective roof retrofitting strategy compared to other approaches.

Heat Transfer Rate Analysis of Different Roof Insulation Materials

The building sector is crucial in Middle East countries because it is one of the primary energy consumers. Currently, reinforced cement concrete (RCC) is preferred for roof construction due to its durability and possesses higher strength. Heat is conducted rapidly through rooftops composed of RCC because it has more thermal conductivity compared to other roofing materials. In the Middle East, RCC roofs are usually lined with marble and polyurethane to increase thermal insulation and reduce heat transfer from the roofs. In this research, the thermal conductivities and temperature reduction capabilities of distinct material combinations for roof insulation have been investigated. The rates of heat conduction were estimated, and a suitable roof combination was found based on the maximum heat resistance and temperature reduction ability. The hot plate guarded method determines the thermal conductivity of marble and polyurethane sheets. Fourier law of heat conduction was employed to calculate the rate of heat flow through roof samples. According to the experimental findings, compared to concrete without insulation, the rate of heat conduction was reduced by 11.8% with combination B (RCC lined with marble) and by 84.3% with combination C (RCC lined with marble and polyurethane).

Thermal Comfort Improvement with Passive Design Strategies in Child Development Centers in Thailand

Child Development Centers (CDCs) in Thailand are developed from the same national standard building plan across the country. Due to hot weather conditions, low-cost building materials, and a failure to consider the specific surrounding conditions of each case, thermal discomfort results. This study focuses on an improvement in the thermal comfort of a pilot CDC building in Maha Sarakham province, Thailand. Three CIBSE TM52 model criteria were applied to assess the level of overheating in the CDC building. The IESVE simulation tool was employed to assess the improvement from using passive design strategies (such as orientation, solar protection, thermal insulation, and ventilation). The results showed that passive design strategies could improve the overall thermal comfort of the CDC building. Thermal insulation, especially roof insulation, was the key element in reducing overheating in the building. A fully insulated building with shading devices and a night-time only window-opening pattern could meet the three targeted overheating criteria. Although the limitations of using the CIBSE TM52 model in hot and humid regions have been identified, these findings can be used as an exemplar of passive design strategy integration for other CDC buildings across the country.

A low-carbon optimization design method for building roof insulation using comprehensive economic analysis model and evaluation index

The building industry plays an important role in economic and social development, but it is also a major source of carbon emissions. However, to date, there is no mature design theory for low-carbon buildings. In this paper, a low-carbon optimization design method is presented for roof insulation using carbon emissions assessment method, comprehensive economic analysis model, and evaluation index. The traditional economic analysis model is extended to cope with carbon emissions of insulation, and a new comprehensiveeconomic analysis model is developed to evaluate economic performances of insulation. Moreover, a balanced index consisting of a carbon reduction factorand an additional economic inputs factor is proposed to assess carbon reduction of insulation. The validation results show that carbon emission cost can apparently improve economic performances of insulation. The economic benefits of insulation increase gradually with an increase in the service life. The ranking of balanced indexes of insulation in the low-temperature granary roof concerned is recycled EPS > recycled XPS > non-recycled EPS > non-recycled XPS > recycled RW > recycled PU > non-recycled RW > non-recycled PU. The low-carbon optimization design method presented can provide a useful tool in the low-carbon design of roof insulation in real buildings conveniently.

Multi-Objective Optimization of Ultra-Low Energy Consumption Buildings in Severely Cold Regions Considering Life Cycle Performance

Net-zero energy buildings (NZEB) have received widespread attention for their excellent energy and carbon reduction potential in various countries. However, relatively little research has been conducted on the life performance of its primary form: the ultra-low energy building (ULEB). This paper proposes an optimization method combining meta-models to investigate the carbon reduction potential of ultra-low energy buildings in severely cold regions of China. The XGBoost algorithm is used to construct a meta-model of building performance, and the grid search method is used to obtain a high-precision meta-model with an R2 of 0.967. Secondly, NSGA-II is used to find passive technical solutions based on the meta-model that minimize the global warming potential (GWP), global cost (GC), and operation energy consumption (OE). Finally, the variables affecting the life-cycle performance of buildings were ranked by sensitivity analysis. The results show that GWP, GC, and OE are reduced by 12.7%, 6.7%, and 7.4% compared with the original building through the optimization process proposed. Sensitivity analysis showed that for GWP, the top four sensitivities are window type (TW) > WWR of south wall (WWRS) > roof insulation thickness (IR) > WWR of north wall (WWRN). For GC, the top four sensitivities are: TW > WWRS > IR > WWR of west wall (WWRW); for OE, the top four sensitivities are: TW > IR > WWRS > WWRN. This paper’s optimization framework and research results can effectively guide the design of the ULEB in severely cold regions.

Porous Ceramic Roof Insulation in Malaysia’s Construction Industry: A Review

Nowadays, Malaysia's construction industry has risen to become one of the country's fastest-growing industries. The application of green building is becoming more popular towards increasing the use of sustainable products in the construction industry. Nevertheless, due to rapid construction and low sustainable products for buildings, problems related to thermal comfort could indeed arise which may cause people stress and irritation. As a result, the objectives of this paper are to identify the issues, problems, concepts, and needs of Porous Ceramic Roof Insulation. In order to do so, extensive literature reviews conducted via various databases (i.e., Scopus, Web of Science, and Scopus) were explored. The findings have revealed that Porous Ceramic Roof Insulation has the potential to be marketed due to its great benefits (i.e., roof cooling, water absorption, solar absorption, and heat absorption within the building). Thus, it is anticipated that the study of Porous Ceramic Roof Insulation would improve the building's well-being while increasing thermal comfort.

ENERGY-EFFICIENT INSULATION SYSTEMS FOR LOW-RISE BUILDINGS

Statement of the problem. Low-rise construction is characterized by a relatively low cost and a possibility of forming effective insulating structure shells. Frames and massive walls are used as load-bearing structures, it is also possible to use concrete. Taking into account the current realities, the most relevant is the orientation of systems to the use of domestic materials including those capable of functioning effectively in harsh climatic conditions. Results. It was established that the properties of polyethylene foam and products based on it make it possible to recommend this material both in facade and roof insulation systems as well as in those in contact with the ground. It was found out that polyethylene foam causes almost no changes in the properties under freezing conditions down to minus 70 °C and in the range of sign-variable temperatures from -60 to +70 °C. With prolonged contact with water or water-saturated soil, the properties of the material are also stable. Conclusion. The use of rolled polyethylene foam is promising both in terms of the properties of the material itself and in view of the possibility of forming seamless insulating shells. The formation of seamless insulating shells creates practically impenetrable heat-vapor- and water-insulating barriers along the perimeter of the insulated object. The study of the properties of polyethylene foam in various operating conditions and insulation systems was the goal of the research described in the article. Methods approved by domestic standards were adopted as the basis for the research.

On the energy impact of cool roofs in Australia

Urban overheating is a serious environmental issue with a significant impact on cooling loads, peak electricity demand, indoor air temperature, health, pollution, sustainability, and the economy. Cool roofs – which are characterised by high solar reflectance (ρ) or albedo and high thermal emissivity (ε) – are one of the most effective technologies to mitigate the urban overheating effect and its undesirable impacts. The existing literature on the energy impacts of cool roofs in various building types and climate zones is vast but fragmented and predominantly assessed the building-scale and urban-scale benefits separately. Here, we computed the energy conservation potential of cool roofs in 17 building archetypes with different occupation hours, internal heat gains, thermal insulation levels, and building heights under various Australian climates. This study presents a holistic approach to assessing the magnitude and spatial variation of the cooling load savings, the peak electricity demand reductions, and indoor air temperature reductions generated by the building-scale and combined building-scale and urban-scale implementation of cool roofs in all representative building types under various climate conditions in Australia. In Sydney, a city with a warm/mild temperate climate, cool roofs can reduce the cooling loads of a typical low-rise office building without roof insulation by 10.2–13.8 kWh/m2 (37.6–42.0 %) during the summer months of January and February. When cool roofs are implemented in both individual buildings and the whole urban area, the cooling load conservation potential for the same building increases to 14.9–17.4 kWh/m2 (50.3–63.7 %). The corresponding peak electricity demand and indoor air temperature reductions by the combined building-scale and urban-scale application of cool roofs are 53–70 % and 11.2–12.0 °C, respectively. The energy conservation potential of cool roofs can be noticeable even for high-rise buildings with a high level of thermal insulation. We estimated that the cooling conservation potential by combined building-scale and urban-scale application of cool roofs can range between 4.0 and 7.1 kWh/m2 (29.3–48.3 %) in a new high-rise residential building with high levels of thermal insulation to 18.5–24.5 kWh/m2 (23–29.6 %) in an existing low-rise shopping mall centre with low levels of thermal insulation in Sydney. Cool roofs lead to additional savings as the reduced temperature increases the energy efficiency of air conditioning systems, with cooling load savings between 0.6 and 3.7 kWh/m2 (3–11 %) for a typical low-rise office building without roof insulation in Sydney. Also, the heating load penalties induced by cool roofs are negligible compared to the cooling load savings in all building types and Australian cities/climate zones except for non-commercial buildings in the cold climate of Hobart. Policymakers can use the results of this study to obtain a deep knowledge of the expected performance of cool roofs when applied city-wide to mitigate urban overheating and counterbalance its adverse impacts on energy uses and indoor thermal comfort.

Production of Roof Board Insulation Using Agricultural Wastes Towards Sustainable Building Material

Malaysia, like most other developing countries, is facing an increase in the generation of waste and accompanying problems with the disposal of this waste. A large number of biomass wastes were generated due to increased activity in the agricultural and agro-industrial sectors, which led to producing environmental hazards and waste management issues. On the other situation, the energy consumption to cool the indoor building environment is high due to the building being exposed directly to solar radiation throughout the daytime, which increases the temperature outside and inside the building. Most of the low-medium cost housing schemes were constructed using metal roof covering without providing a roof insulation layer which causes a rising in indoor temperature and creates uncomfortable surroundings. Moreover, existing materials for roof insulation in the market use inorganic synthetic materials that could harm human health. The study aims to investigate the potential use of agricultural wastes for the production of roof board insulation material that can provide economic value added to agricultural waste, reduce the environmental issue and provide eco-friendly, sustainable building material. In this study, these agricultural wastes are combined in different proportions of 50% individual fibres, such as sugarcane bagasse with coconut husk, empty fruit bunch with mesocarp fibre, coconut husk with empty fruit bunch, and sugarcane bagasse with mesocarp fibre. The sample was fabricated using the hot-press machine and went through various physical and mechanical testing, which involved thickness of swelling, modulus of rupture, and thermal conductivity. The finding showed that the mixed fibre of empty fruit bunch and mesocarp fibre achieved all the criteria such as density (427 <500kg/m3); thickness of swelling (19< 20%); modulus of rupture (514<800psi), thermal conductivity (0.0856<0.25 W/m.K) met with the standard requirement in every laboratory test conducted. The outcome of this study suggests that empty fruit bunch and mesocarp fibre are the potential materials for the production of roof board thermal insulation. However, modification of physical and mechanical properties of waste fibre is required to achieve superior performance and is ready to be provided in the market. This study is aligned with the government initiative for the growth of green building materials for sustainable development in the construction industry.

The Impact of Traditional Raw Earth Dwellings’ Envelope Retrofitting on Energy Saving: A Case Study from Zhushan Village, in West of Hunan, China

This study presents the CO2 emissions and energy performance of traditional raw earth dwellings’ envelope retrofitting located in the Zhushan Village, western Hunan Province, China. The numerical simulations of heating energy consumption on the building models were performed using DesignBuilder, an energy simulation program. The energy performance was evaluated using the indexes (including energy consumption, CO2 emissions, heat balance analysis, and air temperature profiles). The detailed evaluation process of the energy performance is presented as follows. First, the current situation was analyzed through the field research, and two typical building models were built. Second, all schemes were simulated using the DesignBuilder software. Subsequently, the four main retrofit measures (replacing the external insulation windows, setting the external wall insulation layer, setting the roof insulation layer, and setting the ceiling insulation layer) were analyzed, respectively. The optimal parameters of the respective retrofit measure were calculated. Lastly, a multi-objective optimization analysis was conducted on all retrofit plans using the coupling method. In the winter, the results indicated that the “I-shape” dwelling heat consumption of the enclosure structure was reduced by 12.8 kW·h/m2, and the CO2 emissions were reduced by 882.8 kg. While in the benchmark building, the results showed that the “L-shape” dwelling heat consumption of the enclosure structure was decreased by 13.27 kW·h/m2, and the CO2 emissions were reduced by 894.4 kg. As the renewal scheme has been progressively implemented, the whole Zhushan Village will save energy by 11.2 × 104 kW·h after the insulation renewal of the envelope structure is completed.

Optimized radiative parameters of building roof surfaces for energy efficiency: Case studies in China

To improve the thermal performance of the roof and building energy efficiency, this study investigates the optimized combination of the shortwave absorptivity and longwave emissivity for exterior roof surfaces. A simplified 3-day field measurement was first performed for model validation. Next, simulations were performed in 12 representative Chinese cities with both radiative parameters varying between 0.1 and 0.9 for the exterior surface of un-insulated and insulated roofs, focusing on the thermal load of the building. Experiment confirmed that WUFI Plus could reliably process the radiative boundary condition, with the daily surface temperature difference between the measurement and simulation being approximately 1 °C. Furthermore, simulation showed distinct requirements for the radiative parameters of the building roof surface, with regional and seasonal differences being significant. In general, for cold areas and seasons, a combination of high shortwave absorptivity and low longwave emissivity is preferred. Conversely, for hot conditions, a low shortwave absorptivity combined with a high longwave emissivity is optimal. For scenarios with balanced heating and cooling loads, optimization can only be achieved through case-by-case analysis. Finally, a map of optimized radiative parameter combinations for building roofs is provided, accounting for annual building energy efficiency.

Resilient cooling pathway for extremely hot climates in southern Asia

Global warming is increasing extreme heat conditions, with existing energy efficiency policies showing trade-offs between mitigation objectives and adaptation to climate change. This research aims to identify the best resilient cooling solutions that should be promoted in the built environment of extremely hot countries to increase their heat resilience capacity. The impact of climate change on climate zones, cooling thermal demand (kWh/m2), and indoor heat discomfort hours (DHh, hours) in buildings is evaluated in different extremely hot dry climates of southern Asia through a parametric analysis for 2020, 2050 and 2080 under the A2 (medium–high) emission scenario. Then, cooling alternatives with higher synergies and trade-offs between energy efficiency (energy consumption) and resiliency to extreme heat (passive survivability) are highlighted. TRNSYS simulation software and ASHRAE criteria were used to characterise climate zones and calculate buildings' cooling needs and discomfort hours. Pakistan, in southern Asia, was selected as a hot reference region characterised by various climatic regions. The simulated scenario shows how Pakistan's extremely hot dry climate surface may increase from 36.9 % to 78.1 % by 2080, increasing annual cooling needs ranging from 20.56 to 66.96 kWh/m2 and indoor discomfort hours ranging from 423 to 1267 h. The results demonstrate how the passive solutions with higher synergies between energy savings and indoor comfort hours are, in decreasing order, ventilative cooling, reflective and ventilated roofs, shading in windows, and roof insulation. They can provide energy savings ranging from 13.1 to 7.1 kWh/m2 while reducing indoor discomfort by 320 to 131 h for extremely hot climates. Moreover, the sufficiency action related to higher thermostat settings, from 24 to 25 °C to 25–26.5 °C, was the most effective strategy to decrease energy demand. Additionally, there are trade-offs between energy-saving and heat resilience with highly insulated alternatives when ventilation is not adequately addressed. Despite increasing energy savings by 14.4 kWh/m2, discomfort hours are increased by 256 hours when air conditioning is unavailable, increasing building overheating by 5.1 %.