White roof turning green

Vidar Lerum

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The thermal performance of a green roof on a single family residence in Norway has been monitored since 2003. A previous paper (1) reported on the dampening effect of the well insulated high mass roof on the heating load during winter conditions. It was also found that the surface temperature at the roof membrane was prevented from going below zero degrees C while the ambient air temperature dipped down to below minus ten degrees C. This effect, which was evident only when the freeze and thaw cycles were shorter than five days, was attributed to the thermal lag represented by the phase change of water into ice. A layer of snow with varying thickness and moisture content represents a dynamic, added R-value to the roof assembly. This second paper from the same research project reports on the analysis of the thermal performance of the green roof during summer conditions. Parallel to the winter performance, a dampening effect of the high mass roof on the roof membrane surface temperatures was detected. This means that the cooling system may be down-sized significantly or eliminated all together. It was also found that a grass roof may deliver additional cooling to the building interior on sunny days preceded by rain. At the actual location in Norway, this phenomenon was detected late in the fall when no cooling was required to condition the interior space. It was assumed that this evaporative cooling effect could represent a significant passive cooling strategy in arid climates, provided that the green roof was irrigated.

Original languageEnglish (US)
Title of host publicationProceedings of the Solar World Congress 2005
Subtitle of host publicationBringing Water to the World, Including Proceedings of 34th ASES Annual Conference and Proceedings of 30th National Passive Solar Conference
Pages424-429
Number of pages6
Volume1
StatePublished - 2005
Externally publishedYes
EventSolar World Congress 2005: Bringing Water to the World, Including 34th ASES Annual Conference and 30th National Passive Solar Conference - Orlando, FL, United States
Duration: Aug 6 2005Aug 12 2005

Other

OtherSolar World Congress 2005: Bringing Water to the World, Including 34th ASES Annual Conference and 30th National Passive Solar Conference
CountryUnited States
CityOrlando, FL
Period8/6/058/12/05

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ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment

Cite this

Lerum, V. (2005). White roof turning green. In Proceedings of the Solar World Congress 2005: Bringing Water to the World, Including Proceedings of 34th ASES Annual Conference and Proceedings of 30th National Passive Solar Conference (Vol. 1, pp. 424-429)