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Title: Modeling the effects of reflective roofing

Abstract

Roofing materials which are highly reflective to sunlight are currently being developed. Reflective roofing is an effective summertime energy saver in warm and sunny climates. It has been demonstrated to save up to 40% of the energy needed to cool a building during the summer months. Buildings without air conditioning can reduce their indoor temperatures and improve occupant comfort during the summer if highly reflective roofing materials are used. But there are questions about the tradeoff between summer energy savings and extra wintertime energy use due to reduced heat collection by the roof. These questions are being answered by simulating buildings in various climates using the DOE-2 program (version 2.1E). Unfortunately, DOE-2 does not accurately model radiative, convective and conductive processes in the roof-attic. Radiative heat transfer from the underside of a reflective roof is much smaller than that of a roof which absorbs heat from sunlight, and must be accounted for in the building energy model. Convection correlations for the attic and the roof surface must be fine tuned. An equation to model the insulation`s conductivity dependence on temperature must also be added. A function was written to incorporate the attic heat transfer processes into the DOE-2 building energymore » simulation. This function adds radiative, convective and conductive equations to the energy balance of the roof. Results of the enhanced DOE-2 model were compared to measured data collected from a school bungalow in a Sacramento Municipal Utility District monitoring project, with particular attention paid to the year-round energy effects.« less

Authors:
; ;  [1]
  1. Lawrence Berkeley National Lab., CA (United States). Energy and Environment Div.
Publication Date:
Research Org.:
Lawrence Berkeley National Lab., CA (United States)
Sponsoring Org.:
USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
OSTI Identifier:
453493
Report Number(s):
LBL-38580; CONF-9608106-14
ON: DE97003749; TRN: AHC29707%%63
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Conference
Resource Relation:
Conference: 1996 American Council for an Energy-Efficieny Economy (ACEEE) summer study on energy efficiency in buildings, Pacific Grove, CA (United States), 25-31 Aug 1996; Other Information: PBD: Aug 1996
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; ROOFS; REFLECTIVE COATINGS; ENERGY CONSERVATION; D CODES; COMPUTERIZED SIMULATION; R CODES; THERMAL RADIATION; ATTICS

Citation Formats

Gartland, L.M., Konopacki, S.J., and Akbari, H. Modeling the effects of reflective roofing. United States: N. p., 1996. Web.
Gartland, L.M., Konopacki, S.J., & Akbari, H. Modeling the effects of reflective roofing. United States.
Gartland, L.M., Konopacki, S.J., and Akbari, H. Thu . "Modeling the effects of reflective roofing". United States. https://www.osti.gov/servlets/purl/453493.
@article{osti_453493,
title = {Modeling the effects of reflective roofing},
author = {Gartland, L.M. and Konopacki, S.J. and Akbari, H.},
abstractNote = {Roofing materials which are highly reflective to sunlight are currently being developed. Reflective roofing is an effective summertime energy saver in warm and sunny climates. It has been demonstrated to save up to 40% of the energy needed to cool a building during the summer months. Buildings without air conditioning can reduce their indoor temperatures and improve occupant comfort during the summer if highly reflective roofing materials are used. But there are questions about the tradeoff between summer energy savings and extra wintertime energy use due to reduced heat collection by the roof. These questions are being answered by simulating buildings in various climates using the DOE-2 program (version 2.1E). Unfortunately, DOE-2 does not accurately model radiative, convective and conductive processes in the roof-attic. Radiative heat transfer from the underside of a reflective roof is much smaller than that of a roof which absorbs heat from sunlight, and must be accounted for in the building energy model. Convection correlations for the attic and the roof surface must be fine tuned. An equation to model the insulation`s conductivity dependence on temperature must also be added. A function was written to incorporate the attic heat transfer processes into the DOE-2 building energy simulation. This function adds radiative, convective and conductive equations to the energy balance of the roof. Results of the enhanced DOE-2 model were compared to measured data collected from a school bungalow in a Sacramento Municipal Utility District monitoring project, with particular attention paid to the year-round energy effects.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1996},
month = {8}
}

Conference:
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