Modeling impacts of roof reflectivity, integrated photovoltaic panels and green roof systems on sensible heat flux into the urban environment

Adam Scherba, David Sailor, Todd N. Rosenstiel, Carl C. Wamser

Research output: Contribution to journalArticle

91 Citations (Scopus)

Abstract

This study presents results of a modeling effort to explore the role that sustainable roofing technologies play in impacting the rooftop energy balance, and the resultant net sensible heat flux into the urban atmosphere with a focus on the summertime urban heat island. The model has been validated using data from a field experiment conducted in Portland Oregon. Roofing technologies explored include control dark membrane roof, a highly reflective (cool) roof, a vegetated green roof, and photovoltaic (PV) panels elevated above various base roofs. Energy balance models were developed, validated with experimental measurements, and then used to estimate sensible fluxes in cities located in six climate zones across the US. On average the black roof and black roof with PV have the highest peak daily sensible flux to the environment, ranging from 331 to 405 W/m2. The addition of PV panels to a black roof had a negligible effect on the peak flux, but decreased the total flux by an average of 11%. Replacing a black roof with a white or green roof resulted in a substantial decrease in the total sensible flux. Results indicate that if a black membrane roof is replaced by a PV-covered white or a PV-covered green roof the corresponding reduction in total sensible flux is on the order of 50%. The methodology developed for this analysis provides a foundation for evaluating the relative impacts of roof design choices on the urban climate and should prove useful in guiding urban heat island mitigation efforts.

Original languageEnglish (US)
Pages (from-to)2542-2551
Number of pages10
JournalBuilding and Environment
Volume46
Issue number12
DOIs
StatePublished - Dec 2011
Externally publishedYes

Fingerprint

sensible heat flux
Roofs
reflectivity
heat
roof
Heat flux
climate
modeling
energy
Fluxes
heat island
experiment
methodology
Energy balance
energy balance
membrane
Membranes
urban climate
urban atmosphere
mitigation

Keywords

  • Architectural design
  • Building
  • Environmental impact
  • Green roofs
  • Sustainable development
  • Urban heat island

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Environmental Engineering
  • Geography, Planning and Development
  • Building and Construction

Cite this

Modeling impacts of roof reflectivity, integrated photovoltaic panels and green roof systems on sensible heat flux into the urban environment. / Scherba, Adam; Sailor, David; Rosenstiel, Todd N.; Wamser, Carl C.

In: Building and Environment, Vol. 46, No. 12, 12.2011, p. 2542-2551.

Research output: Contribution to journalArticle

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