Preliminary experimental assessment of the comparative thermal performance of attics and cathedral ceilings in a cold climate

This paper describes a residential research facility built for the experimental measurement of the relative energy and moisture performance of various residential building envelope components and systems. The building comprises 12 test bays on an east/west axis bounded on each end by a guard bay. The eastern six test bays are framed in steel, and the western six bays are framed in wood. Each half of the building contains a symmetrical mix of vented and unvented cathedral and attic roofing systems and is built above a heated basement. During the heating season, the entire building is maintained at a uniform temperature within ±0.9°F (±0.5 K) by a computer control system, and data are stored with an aggregation period of approximately 20 minutes. The thermal performance phenomenology of a vented attic and cathedral ceiling are analyzed via heat transfer and mass flux parameter correlations. Attic and cathedral ceiling roofing system relative thermal integrities are compared as a function of framing material and ventilation status. Within the preliminary context of the data reported, it appears that metal framing yields a lower thermal integrity than wood framing with particularly poor performance when applied to a vented cathedral ceiling. The ridge vent mass flux in ventilated attics and cathedral ceilings is shown by the data reported to be largely independent of roof configuration.