Reference: BRE IP 4/06 Airtightness of ceilings - Energy loss and condensation risk (2006) Sanders C, Haig J, Rideout N
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Abstract or summary
Typically about 20% of the air entering a house leaves via its loft, adding to the risk of condensation in the loft and reducing the energy efficiency of the roof. This airflow, together with the ventilation of the loft space, is not accounted for in standard diffusion-based methods of condensation risk analysis, which therefore do not apply to cold pitched roofs. This paper describes the airflow routes between a house and its loft and the steps that can be taken to reduce the flow. The methods that can be used to measure the airtightness of ceilings are discussed and a method for assessing the condensation risk, taking account of the airflows, proposed.