Effect of radiant barriers and attic ventilation on residential attics and attic duct systems: New tools for measuring and modeling
A simple duct system was installed in an attic test module for a large scale climate simulator at a US national laboratory. The goal of the tests and subsequent modeling was to develop an accurate method of assessing duct system performance in the laboratory, enabling limiting conditions to be imposed at will and results to be applied to residential attics with attic duct systems. Steady-state tests were done at a severe summer and a mild winter condition. In all tests the roof surface was heated above ambient air temperatures by infrared lights. The attic test module first included then did not include the duct system. Attic ventilation from eave vents to a ridge vent was varied from none to values achievable by a high level of power ventilation. A radiant barrier was attached to the underside of the roof deck, both with and without the duct system in place. Tests were also done without the radiant barrier, both with and without the duct system. When installed, the insulated ducts ran along the floor of the attic, just above the attic insulation and along the edge of the attic near the eaves and one gable. These tests in a climate simulator achieved careful control and reproducibility of conditions. This elucidated dependencies that would otherwise be hidden by variations in uncontrolled variables. Based on the comparisons with the results of the tests at the mild winter condition and the severe summer condition, model predictions for attic air and insulation temperatures should be accurate within {+-} 10 F ({+-} 6 C). This is judged adequate for design purposes and could be better when exploring the effect of changes in attic and duct parameters at fixed climatic conditions.
- Research Organization:
- Oak Ridge National Labs., TN (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 656856
- Report Number(s):
- ORNL/CP-98782; CONF-980650-; ON: DE98006063; BR: EC1206000; TRN: AHC29817%%416
- Resource Relation:
- Conference: 1998 ASHRAE summer annual meeting, Toronto (Canada), 20 Jun 1998; Other Information: PBD: [1998]
- Country of Publication:
- United States
- Language:
- English
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