- Author
- Burch, D. M. | Luna, D. E.
- Title
- Mathematical Model for Predicting Attic Ventilation Rates Required for Preventing Condensation on Roof Sheathing.
- Coporate
- National Bureau of Standards, Washington, DC
- Journal
- ASHRAE Transactions, Vol. 86, No. Part 1, 201-220, 1980
- Book or Conf
- Proceedings of the ASHRAE Semiannual Meeting. February 1980, Los Angeles, CA, 1980
- Keywords
- residential buildings; ventilation; humidity control; air circulation; heat transfer; roofs; condensation; mathematical models; reprints | soffits
- Identifiers
- attic ventilation; moisture control
- Abstract
- A mathematical model for predicting the heat transfer and moisture-transfer processes in residential attic spaces is presented. This model is utilized to predict attic ventilation rates required for preventing condensation or frost accumulation on the underside of roof sheathing. Attic ventilation charts are developed covering a wide range of outdoor temperatures, ceiling thermal resistances, and ceiling air penetration rates. The effectiveness of a ceiling vapor barrier is investigated. The effect of indoor humidification on the required attic ventilation rate is examined. Using measured data of Hinrichs, attic ventilation rates predicted by the mathematical model are converted into net free ventilation areas for soffit venting. These values are subsequently compared with the attic ventilation requirements of ASHRAE and the HUD Minimum Property Standards.