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Role of Solar-Reflective Coating in Improving Building Envelope Thermal Performance in the Urban Context of Phoenix, Arizona
Rastegar, Roja
Rastegar, Roja
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Abstract
Energy consumption is increasing around the world and the building sector shows an even faster increase because of rising family income, changing lifestyles and more interest in urbanization, and easy access to electricity. These factors lead to rising demand for energy. U.S. Energy Information Administration (EIA) monthly review for the year 2020 showed that the building sector accounted for about 76% of electricity use and 40% of total primary associated greenhouse gas (GHG) emissions in the United States. This growing interest in energy use in buildings raised some awareness and renewed interest in reducing the energy demand of buildings over the past twenty years. At the level of building codes, groups such as the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) have been working on correcting and developing the performance criteria for building envelopes and systems. Building designers also need to find and implement types of building technologies and solutions that can both practically and economically improve the building's energy performance and reduce the energy demand. The building envelope as a separator between inside and outside spaces has a major role in controlling heat transfer and building energy demand. An efficient building envelope can reduce the operating costs of a building and heating, ventilation, and air-conditioning (HVAC) system while maintaining occupant thermal comfort, adequate building pressurization, and good indoor air quality. Although building insulation plays a key role in making buildings energy-efficient, the amount of material that can be added to the building walls or roof assemblies is limited. This matter is even more important for existing and older buildings. Some studies show that the application of surface coatings offers an option in terms of increasing the ability of the building envelope to control the effect of the environmental situation and increase building energy efficiency, especially in existing buildings.This thesis evaluates the role of solar-reflective coating on horizontal and vertical surfaces of multi-family residential buildings in the urban context of Phoenix, Arizona. Review of literature indicates a lack of data on the application of these coatings at a neighborhood scale taking into consideration the shadow effect and the effectiveness of solar-reflective walls in comparison to the solar-reflective roof. The thesis also studies the application of solar-reflective coating as a thermal retrofit solution for existing older buildings. This study is an experimental and simulation study that aims to evaluate the impact of solar-reflective coatings on multi-family residential buildings in the city context of Phoenix, Arizona as a case study. The study considers the important role of urban block arrangements and compactness that may cast shadows in the neighborhood and how this can determine the effectiveness of solar-reflective coatings. For this purpose, this research investigates 76 cases which include one, two, three, and four-story older multi-family buildings in four urban block typologies. 64 cases are oriented in the East-to-West direction and 12 cases are in the North-to-South direction. For existing envelope conditions, building walls and roofs do not have solar-reflective coating, while in optimized conditions, walls and roofs are optimized with solar-reflective coating. Results indicated that solar-reflective coating can reduce the annual HVAC load in all study cases. The percentages of reduction after the application of solar-reflective coating for one and two-story buildings in low compact blocks were about 5% to 12.4%. Three and four-story buildings in medium and high compact blocks showed less than 5% reduction in overall annual cooling and heating energy consumption.
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2022-05-31
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University of Kansas
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This item contains archived web content.
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Keywords
Architecture, Energy Saving, Envelope Thermal Performance, Overshadowing, Retrofitting, Solar Radiation, Solar-Reflective "cool" Coatings