Modeling the effects of reflective roofing

TitleModeling the effects of reflective roofing
Publication TypeConference Proceedings
Year of Publication1996
AuthorsGartland, Lisa M., Steven J. Konopacki, and Hashem Akbari
Conference Name1996 ACEEE Summer Study on Energy Efficiency in Buildings
Volume4
Edition11
Pagination117-125
Date Published1996/08
Keywordscool roof, Heat Island
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 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.

Notes

Added to JabRef: 2010.04.21

URLhttp://www.osti.gov/bridge/product.biblio.jsp?osti_id=453493