Secondary Author(s)

Parker, Danny; Sherwin, John

Report Number

FSEC-CR-1336-02

URL

http://publications.energyresearch.ucf.edu/wp-content/uploads/2018/06/FSEC-CR-1336-02.pdf

Keywords

Roofs; Buildings

Abstract

The Flexible Roof Facility (FRF) is a test facility in Cocoa, Florida designed to evaluate five roofing systems at a time against a control roof with dark shingles. The intent of the testing is to evaluate how roofing systems impact summer residential cooling energy use and peak demand. In the summer of 2001, the following roofing systems were tested.

Cell # Description

  1. Weathered white barrel tile with sealed attic
  2. Double roof with radiant barrier, sealed attic and insulated roof deck
  3. High reflectance brown metal shingle with vented attic
  4. Terra cotta barrel tile with vented attic
  5. Dark shingles with standard attic ventilation (Control Test Cell)
  6. Weathered white metal with sealed attic

All had R-19 insulation installed on the attic floor except in the configuration with the double roof (Cell #2) which had R-19 of open cell foam sprayed onto the bottom of the roof decking. The measured thermal impacts include ceiling heat flux, unintended attic air leakage and duct heat gain. We also developed a new analysis method to estimate total cooling energy use impacts of different roofing systems considering the various influences.

The sealed attic double roof system (Cell #2) provided the coolest attic space of all systems tested (average maximum mid-attic temperature was 81.9°F), and therefore also the lowest estimated impact due to return air leakage and duct conduction heat gains. However, it also had the highest ceiling heat flux of all strategies tested, reducing its improvement over the standard dark shingle roof.

Sealing the white tile (Cell #1) and white metal (Cell #6) roofs' soffit vents this summer decreased their performance from the last two years in which they were vented, although some of the decrease was likely due to weathering. Both mid-attic temperatures and estimated total heat gain for the weathered white tile and white metal roof systems were comparable (20.6°F and 17.5°F lower than the control dark shingle for the white tile and white metal roofs respectively).

The highly reflective brown metal shingle roof (Cell #3) provided the coolest peak attic temperature of all cells without roof deck insulation. Its average maximum mid-attic temperature was 98.4oF (21.3oF lower than the control dark shingle cell). While the brown metal shingle roof's reflectance was somewhat lower than the weathered white tile and white metal roofs we observed evidence that the air space under the metal shingles provides additional effective insulation.

We also estimated the combined impact of ceiling heat flux, duct heat gain and unintended attic air leakage from the various roof constructions. All of the alternative constructions produced lower estimated cooling energy loads than the standard vented attic with dark shingles.

Date Published

11-1-2002

Notes

Reference Publication: Sonne, J K, D S Parker and J R Sherwin (2002). Flexible Roofing Facility: 2001 Summer Test Results. FSEC­CR­1336­ 02. Florida Solar Energy Center, Cocoa, FL.

Subjects

Buildings - Roofs

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