scholarly journals A Conceptual Review of the Potential of Cool Roofs as an Effective Passive Solar Technique: Elaboration of Benefits and Drawbacks

2021 ◽  
Vol 9 ◽  
Author(s):  
Babak Ashtari ◽  
Mansour Yeganeh ◽  
Mohammadreza Bemanian ◽  
Bahareh Vojdani Fakhr
Keyword(s):  
Clean Energy ◽  
Building Energy ◽  
Energy Performance ◽  
Cool Roof ◽  
Indoor Thermal Comfort ◽  
Pros And Cons ◽  
Passive Solar ◽  
Number Of Publications ◽  
Roof Design ◽  
Cool Roofs

Cool roofs, as feasible and efficient passive solar technique that reduces building energy requirements for cooling and improves indoor thermal comfort conditions, have received considerable attention in recent years and as a result, a number of concepts, methods, and experiences have been developed during the related research. Although some studies have been conducted on this subject in the form of review articles, taking into consideration the large number of publications, there is still a call for some review papers dealing with the potential of cool roofs and providing a thorough report on their energy performance and a detailed summary of their pros and cons on the basis of the relevant studies. On this account, this study contributes a systematic review of the issued paper in Scopus and Web of Science regarding the cool roof technologies to recognize the advantages and challenges of cool roofs in practice and its future trends. In addition, detailed summary of advantages and drawbacks of this passive solar measure has been developed, as itemized factors corresponded to the codified references. A total of 90 published reports were analyzed, declaring that a cool roof is an efficient approach for generating clean energy on the building scale. This article induces an overall view of the advantages and restrictions of the cool roof throughout the world. Conclusions give a valuable reference for improving the cool roof design for their more widespread use in the building industry.

Effect of roof and ceiling configuration on energy performance of a metamaterial-based cool roof for low-rise office building in China

2020 ◽  
pp. 1420326X2096155
Author(s):  
Saihong Tang ◽  
Nevzat Akkurt ◽  
Kai Zhang ◽  
Lufang Chen ◽  
Mingquan Ma
Keyword(s):  
Energy Consumption ◽  
Building Energy ◽  
Energy Performance ◽  
Office Building ◽  
Optimization Analysis ◽  
Cool Roof ◽  
The Past ◽  
Solar Reflectance ◽  
Electricity Saving ◽  
Cool Roofs

Cool roofs with higher solar reflectance and emittance can effectively reduce building energy consumption. However, it is still limited to use at night on account of the development of roof materials during the past decades. The newly proposed metamaterial-based cool roof (MCR) greatly improves the possibility of the radiative cooling in the daytime. To study the influence of MCR on the energy consumption for the office building, a small single-floor office was adopted to analyse the cooling performance of MCR by using EnergyPlus. In this study, the optimization analysis was conducted based on the proposed dimensionless thermal resistance ( θRTR) and roof pitch (Δ). Then the annual electricity saving potential of the office building with MCR was evaluated in details based on the selected cities from all five climate zones in China. The results show that more annual electricity saving can be achieved under the optimized values of θR7 = 1.53 and Δ = 20°. Furthermore, more than 15.7% of annual cooling electricity saving can be achieved while the optimized θRTR and Δ are applied.

scholarly journals Cool Roof Impact on Building Energy Need: The Role of Thermal Insulation with Varying Climate Conditions

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3354 ◽  
Author(s):  
Piselli ◽  
Pisello ◽  
Saffari ◽  
Gracia ◽  
Cotana ◽  
...  
Keyword(s):  
Thermal Insulation ◽  
Thermal Energy ◽  
Building Energy ◽  
Energy Performance ◽  
Cold Climate ◽  
Climate Conditions ◽  
Building Energy Performance ◽  
Cool Roof ◽  
Solar Reflectance

Cool roof effectiveness in improving building thermal-energy performance is affected by different variables. In particular, roof insulation level and climate conditions are key parameters influencing cool roofs benefits and whole building energy performance. This work aims at assessing the role of cool roof in the optimum roof configuration, i.e., combination of solar reflectance capability and thermal insulation level, in terms of building energy performance in different climate conditions worldwide. To this aim, coupled dynamic thermal-energy simulation and optimization analysis is carried out. In detail, multi-dimensional optimization of combined building roof thermal insulation and solar reflectance is developed to minimize building annual energy consumption for heating–cooling. Results highlight how a high reflectance roof minimizes annual energy need for a small standard office building in the majority of considered climates. Moreover, building energy performance is more sensitive to roof solar reflectance than thermal insulation level, except for the coldest conditions. Therefore, for the selected building, the optimum roof typology presents high solar reflectance capability (0.8) and no/low insulation level (0.00–0.03 m), except for extremely hot or cold climate zones. Accordingly, this research shows how the classic approach of super-insulated buildings should be reframed for the office case toward truly environmentally friendly buildings.

scholarly journals Framework for Developing a Low-Carbon Energy Demand in Residential Buildings Using Community-Government Partnership: An Application in Saudi Arabia

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4954
Author(s):  
Mohammad AlHashmi ◽  
Gyan Chhipi-Shrestha ◽  
Kh Md. Nahiduzzaman ◽  
Kasun Hewage ◽  
Rehan Sadiq
Keyword(s):  
Saudi Arabia ◽  
Energy Demand ◽  
Energy Use ◽  
Residential Buildings ◽  
Ghg Emissions ◽  
Clean Energy ◽  
Building Energy ◽  
Energy Performance ◽  
Low Carbon ◽  
Geographical Regions

Rapid population growth has led to significant demand for residential buildings around the world. Consequently, there is a growing energy demand associated with increased greenhouse gas (GHG) emissions. The residential building energy demand in arid countries such as Saudi Arabia is supplied with fossil fuel. The existing consumption pattern of fossil fuels in Saudi Arabia is less sustainable due to the depletion of fossil fuel resources and resulting environmental impacts. Buildings built in hot and arid climatic conditions demand high energy for creating habitable indoor environments. Enormous energy is required to maintain a cool temperature in hot regions. Moreover, climate change may have different impacts on hot climatic regions and affect building energy use differently. This means that different building interventions may be required to improve the performance of building energy performance in these geographical regions, thereby reducing the emissions of GHGs. In this study, this framework has been applied to Saudi Arabia, a hot and arid country. This research proposes a community–government partnership framework for developing low-carbon energy in residential buildings. This study focuses on both the operational energy demand and a cost-benefit analysis of energy use in the selected geographical regions for the next 30 years (i.e., 2050). The proposed framework primarily consists of four stages: (1) data collection on energy use (2020 to 2050); (2) setting a GHG emissions reduction target; (3) a building intervention approach by the community by considering cost, energy, and GHG emissions using the Technique for Order of Performance by Similarity to the Ideal Solution (TOPSIS) to select the best combinations in each geographical region conducting 180 simulations; and (4) a clean energy approach by the government using grey relational analysis (GRA) to select the best clean energy system on the grid. The clean energy approach selected six different renewable power generation systems (i.e., PV array, wind turbine, hybrid system) with two storage systems (i.e., battery bank and a combination of electrolyte, fuel cell, and hydrogen tank storage). This approach is designed to identify the best clean energy systems in five geographical regions with thirty scenario analyses to define renewable energy-economy benefits. This framework informs through many engineering tools such as residential building energy analysis, renewable energy analysis, multi-criteria decision analysis (MCDA) techniques, and cost-benefit analysis. Integration between these engineering tools with the set of energy policies and public initiatives is designed to achieve further directives in the effort to reach greater efficiency while downsizing residential energy demands. The results of this paper propose that a certain level of cooperation is required between the community and the government in terms of financial investments and the best combinations of retrofits and clean energy measures. Thus, retrofits and clean energy measures can help save carbon emissions (enhancing the energy performance of buildings) and decrease associated GHG emissions, which can help policy makers to achieve low-carbon emission communities.

scholarly journals The Effectiveness of Roofing Cool Coatings On The Building Energy Demand In A Cold Climate

2021 ◽  
Author(s):  
Tahmina Begum
Keyword(s):  
Energy Saving ◽  
Energy Demand ◽  
Building Energy ◽  
Cold Climate ◽  
Second Phase ◽  
Building Energy Efficiency ◽  
Cool Roof ◽  
Average Temperature ◽  
Energy Modelling ◽  
Cool Roofs

An average temperature increase of 2oC over the last 140 years in Toronto may not seem significant, but in reality heating demand for buildings will go down by impacting natural gas usage while cooling demand will go up by impacting electricity-usage. For preparedness against hot summer in cold climate, passive cooling needs to be adopted for building energy efficiency. In warm climate, cool roof technology proves effectiveness in reducing cooling energy demand of buildings but its use in cold climate is not much seen. Thus it is interesting to investigate the effectiveness of cool roofs in cold climate. This study investigates the properties of cool coatings available in North America, their performance on aging and energy saving benefits. The first phase of research includes selection of building, collection of information, field measurement of surface temperatures of the studied building and also lab testing of collected samples. The second phase includes energy modelling of the studied building with validation to understand their energy saving benefits. Finally the most effective cool coating for the studied building is recommended.

scholarly journals The Effectiveness of Roofing Cool Coatings On The Building Energy Demand In A Cold Climate

2021 ◽  
Author(s):  
Tahmina Begum
Keyword(s):  
Energy Saving ◽  
Energy Demand ◽  
Building Energy ◽  
Cold Climate ◽  
Second Phase ◽  
Building Energy Efficiency ◽  
Cool Roof ◽  
Average Temperature ◽  
Energy Modelling ◽  
Cool Roofs

An average temperature increase of 2oC over the last 140 years in Toronto may not seem significant, but in reality heating demand for buildings will go down by impacting natural gas usage while cooling demand will go up by impacting electricity-usage. For preparedness against hot summer in cold climate, passive cooling needs to be adopted for building energy efficiency. In warm climate, cool roof technology proves effectiveness in reducing cooling energy demand of buildings but its use in cold climate is not much seen. Thus it is interesting to investigate the effectiveness of cool roofs in cold climate. This study investigates the properties of cool coatings available in North America, their performance on aging and energy saving benefits. The first phase of research includes selection of building, collection of information, field measurement of surface temperatures of the studied building and also lab testing of collected samples. The second phase includes energy modelling of the studied building with validation to understand their energy saving benefits. Finally the most effective cool coating for the studied building is recommended.

Cool roof for improving building energy efficiency in moderate climates

2020 ◽  
pp. 80-87
Author(s):  
Salem Algarni
Keyword(s):  
Saudi Arabia ◽  
Energy Consumption ◽  
Thermal Comfort ◽  
Building Energy ◽  
Climatic Conditions ◽  
Building Energy Efficiency ◽  
Test Room ◽  
Cool Roof ◽  
Indoor Thermal Comfort ◽  
The Impact

At present, maintaining the thermal comfort in buildings is a significant challenge faced by majority of the developing countries. In this study, the impact of the cool roof on cooling and heating loads of buildings located in moderate climates is studied. The study presents a detailed simulation of a test room to estimate the impact of the cool roof on building performance in Abha, Saudi Arabia. Input parameters, such as building thermal properties, operation schedule, orientation, and climatic conditions were implemented. Furthermore, the experimental study of the test room was conducted at the main campus of King Khalid University, Abha. The results showed that the use of the cool roof reduced the energy consumption required for building cooling by approximately 52.5 kWh/m2/year; whereas the maximum increase in energy consumption owing to the winter heating is about 3.1 kWh/m2/year. The indoor thermal comfort was improved because the maximum indoor temperature decreased by 2.7 °C. The study concludes that the cool roof is an effective method to improve the indoor thermal comfort and reduce building energy consumption in Abha, Saudi Arabia and places with similar climatic conditions.

Hygrothermal performance of cool roofs with reflective coating material subjected to hot, humid and dusty climate

2021 ◽  
pp. 174425912110014
Author(s):  
Hamed H Saber
Keyword(s):  
Total Energy ◽  
Numerical Simulations ◽  
Energy Savings ◽  
Weather Conditions ◽  
Energy Performance ◽  
Coating Material ◽  
Eastern Province ◽  
Cool Roof ◽  
Reflective Coating ◽  
Cool Roofs

The measurements for the short-wave solar reflectivity of a Reflective Coating Material (RCM) with various cleaning operations that were obtained in a previous study were used in this study to conduct numerical simulations in order to assess the moisture and energy performance of cool and black roofs when they were subjected to the weather conditions of Saudi Eastern Province and Kuwait City. The results of the numerical simulations showed that black roofs always work with less moisture than cool roofs. Because the highest relative humidity in the different components of the black and cool roofs was well below 80%, there was no risk of condensation and mold growth in these roofs. For both weather conditions of Saudi Eastern Province and Kuwait City, the results showed that installing cool roofs have resulted in increasing the heating energy loads in relation to black roofs. Conversely, the results showed that the decrease in the cooling energy loads due to installing cool roofs were typically much greater than the increase in the heating energy loads. As such, cool roofs have resulted in net energy savings in relation to black roofs. Replacing black roof by cool roof in Saudi climate, the results showed that the annual energy savings in the total energy load was 25% and 34% as a result of installing cool roof with RCM at no cleaning and weekly homemade cleaning, respectively. Additionally, replacing black roof by cool roof in Kuwaiti climate, the results showed that the annual energy savings in the total energy load was 23% and 31% a result of installing cool roof with RCM at no cleaning and weekly homemade cleaning, respectively.

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