A research facility with several test cells was constructed in the Midwest. The facility contains roof assemblies with several variables:
• flat-ceiling truss-framed attics and cathedral ceilings,
• dark and white shingles,
• vented and unvented construction,
• one- and two-layer shingle placement,
• measurement location toward the ridge and toward the eaves, and
• roof deck installed directly over foam insulation.
Thermocouples are used to measure temperature hourly at various shingle layers--north and south side. Three summers of temperature data are used in this analysis and presented. The temperature profiles for each condition are compared to a base case. By using regression of the test case against the base case, adjusted for a crossing point, the resulting regression slopes can legitimately describe a percent by which the test case is hotter or colder than the base case. Those data are presented and they permit a ranking of the various factors that affect shingle and roof sheathing temperature. An error analysis accompanies the comparison presentation. The findings are used to sponsor a discussion of the role of ventilation as a temperature regulator for roof assemblies visa- vis the other factors that affect temperature. The implications of that ranking on the continued use of ventilation regulations in building codes and product warranties are discussed.

Authors: William B. Rose

Citation: Thermal Performance of the Exterior Envelopes of Buildings VIII

Keywords: December, Florida, 2001