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IT in Building Science |
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International Institute of Information Technology, Hyderabad |
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Measured Cooling Energy and Peak Demand Savings from the Installation of Cool Roofs on Two High-tech Educational Buildings in Hyderabad, India | ||||||
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Sponsored by :
U.S.A.I.D
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“A reflective roof is typically light in color and absorbs less sunlight than does a conventional dark-colored roof. Less absorption of sunlight lowers the roof’s surface temperature, reducing the heat transfer through the roof. Thus, reflective roofs reduce air-conditioning (a/c) energy use. The magnitudes of energy savings depend upon building type, level of roof insulation, ventilation rate between roof and ceiling, a/c size and efficiency, and of course, roof solar reflectance. In this study, We measured and analyzed air-conditioning energy savings and power-demand reduction of two identical office buildings in Hyderabad, India that were retrofitted with a reflective roof coating." |
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Monitoring Details :: |
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The monitoring project started in January 2006. From January 15, 2006 to March 22, 2006, we monitored the base-case air conditioning energy use for both building. On March 23-26, we installed a cool roof (initial reflectivity of 0.80 and aged reflectivity of about 0.7) on one building (West) and a hot roof (initial and aged reflectivity of 0.12) on the second building (East) and continued monitoring the buildings through July 2006. On the beginning of August 2006, we installed a cool roof on the East building and continued monitoring to date. At 30-second intervals, we measured the a/c energy use, total building energy use, temperatures at a variety of locations (including the roof surface, the bottom of the roof, the plenum between the roof and the ceiling, and the conditioned space), and climate parameters (ambient temperatures, wind speed and direction, and solar intensity). |
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Savings :: |
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The average daily maximum roof-surface temperature of the initial concrete roof was about 52°C, for the black roof was 60°C, and for the white roof was 32°C. The average daily a/c savings (applying cool coatings on concrete roof) were 30 kilowatt-hours (5% of total a/c use, annual saving of 9000 kWh). At Rs 5 per kWh, the total discounted savings over the expected life of the roof are estimated to be Rs. 430,000. |
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| Related People :: | ||||||
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Dr.Hashem Akbari | Dr. Vishal Garg | Murari Hari Babu | |||
