Ventilation, Infiltration and Air Permeability of Traditional UK Dwellings

Abstract

The focus of this paper is ventilation in traditional dwellings, specifically with reference to English Heritage's ‘rule of thumb’ for historic buildings, which is that it should be ‘twice the normal level of ventilation’. Examination of the subject has taken place through a literature review and the empirical case studies of two groups of unimproved dwellings.1The paper considers the ventilation of traditional buildings using the breakdown on the subject offered by the Building Regulations document for new build dwellings in England and Wales—Approved Document F. Where occupancy patterns are available, as with the case study on Fitz Steps, Cumbria, the validity of the rule of thumb is questioned. The paper will also show that, for the dwellings studied as a whole, lower air permeability results than orthodoxy would suggest were recorded, with common infiltration points between properties. There was also some evidence of modern extensions being less airtight than the original dwelling. A wide variation in measured air flow relating to chimneys was noted, raising questions over the air flow figures for this type of dwelling used in SAP (Standard Assessment Procedure) for the energy assessment of buildings.