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Title: Demonstration of energy savings of cool roofs. Executive summary

Abstract

The use of dark roofs affects cooling and heating energy use in buildings and the urban climate. At the building scale, dark roofs are heated by the summer sun and thus raise the summertime air-conditioning (a/c) demand. For highly-absorptive (low-albedo) roofs the difference between the surface and ambient air temperatures may be as high as 90 F on a summer afternoon. While for less absorptive (high-albedo) surfaces with similar insulative properties, such as roofs covered with a white coating, the difference is only about 20 F. For this reason, cool roofs (which absorb little insolation) can be effective in reducing cooling energy use. Earlier studies have suggested that cool roofs incur no additional cost if color changes are incorporated into routine re-roofing and re-surfacing schedules. There is a sizable body of measured data (primarily collected for residential sector) documenting energy-saving effects of cool roofs as shown. Both measured data and simulations clearly demonstrate that increasing the albedo of roofs is an attractive (and cost-effective) way of reducing the net radiative heat gains through the roof and hence, reducing building cooling loads. To change the albedo, the rooftops of buildings may be painted with reflective coatings or covered with a newmore » light-colored material. Since most roofs have regular maintenance schedules or need to be re-roofed or re-coated periodically, the change of the albedo should be done then. In that case, the cost would be limited to the incremental cost associated with the high-albedo material. In buildings and climates with significant air-conditioning use, increasing the albedo of roofs will reduce energy use and produce a stream of savings immediately.« less

Authors:
; ;  [1];  [2]
  1. Lawrence Berkeley National Lab., CA (United States). Environmental Energy Technologies Div.
  2. Davis Energy Group, Davis, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab., Environmental Energy Technologies Div., CA (United States)
Sponsoring Org.:
Environmental Protection Agency, Washington, DC (United States); USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
OSTI Identifier:
296884
Report Number(s):
LBNL-40673-Exec.Summ.
ON: DE98058297; TRN: AHC29903%%282
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Jun 1998
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; ROOFS; REFLECTIVE COATINGS; ENERGY CONSERVATION; INSOLATION; TEMPERATURE CONTROL

Citation Formats

Konopacki, S., Gartland, L., Akbari, H., and Rainer, L. Demonstration of energy savings of cool roofs. Executive summary. United States: N. p., 1998. Web. doi:10.2172/296884.
Konopacki, S., Gartland, L., Akbari, H., & Rainer, L. Demonstration of energy savings of cool roofs. Executive summary. United States. doi:10.2172/296884.
Konopacki, S., Gartland, L., Akbari, H., and Rainer, L. Mon . "Demonstration of energy savings of cool roofs. Executive summary". United States. doi:10.2172/296884. https://www.osti.gov/servlets/purl/296884.
@article{osti_296884,
title = {Demonstration of energy savings of cool roofs. Executive summary},
author = {Konopacki, S. and Gartland, L. and Akbari, H. and Rainer, L.},
abstractNote = {The use of dark roofs affects cooling and heating energy use in buildings and the urban climate. At the building scale, dark roofs are heated by the summer sun and thus raise the summertime air-conditioning (a/c) demand. For highly-absorptive (low-albedo) roofs the difference between the surface and ambient air temperatures may be as high as 90 F on a summer afternoon. While for less absorptive (high-albedo) surfaces with similar insulative properties, such as roofs covered with a white coating, the difference is only about 20 F. For this reason, cool roofs (which absorb little insolation) can be effective in reducing cooling energy use. Earlier studies have suggested that cool roofs incur no additional cost if color changes are incorporated into routine re-roofing and re-surfacing schedules. There is a sizable body of measured data (primarily collected for residential sector) documenting energy-saving effects of cool roofs as shown. Both measured data and simulations clearly demonstrate that increasing the albedo of roofs is an attractive (and cost-effective) way of reducing the net radiative heat gains through the roof and hence, reducing building cooling loads. To change the albedo, the rooftops of buildings may be painted with reflective coatings or covered with a new light-colored material. Since most roofs have regular maintenance schedules or need to be re-roofed or re-coated periodically, the change of the albedo should be done then. In that case, the cost would be limited to the incremental cost associated with the high-albedo material. In buildings and climates with significant air-conditioning use, increasing the albedo of roofs will reduce energy use and produce a stream of savings immediately.},
doi = {10.2172/296884},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1998},
month = {6}
}