Purpose - Concern of the deterioration of indoor environmental quality as a result of energy efficient building design strategies is growing. Apprehensions of the effect of airtight, super insulated envelopes, the reduction of infiltration, and the reliance on mechanical systems to provide adequate ventilation (air supply) is promoting emerging new research in this field. This paper presents the results of an indoor air quality and thermal comfort investigation in UK energy efficient homes, through a case study investigation.

Design/Methodology/Approach – The case study dwellings consisted of a row of six new build homes which utilize mechanical ventilation with heat recovery (MVHR) systems, are built to an average air tightness of 2m3/m2/hr @ 50 Pascal’s, and constructed without a central heating system. Physical indoor air quality measurements and occupant interviews were conducted during the summer and winter months over a 24 hour period, to gain information on occupant activities, perception of the interior environment, building related health and building use.

Findings – The results suggest inadequate indoor air quality and perceived thermal comfort, insufficient use of purge ventilation, presence of fungal growth, significant variances in heating patterns, occurrence of Sick Building Syndrome (SBS) symptoms and issues with the MVHR system.

Practical Implications – The findings will provide relevant data on the applicability of air-tight, mechanically ventilated homes in a UK climate, with particular reference to indoor air quality.

Originality/Value – Indoor air quality (IAQ) data of this nature is essentially lacking, particularly in the UK context. The findings will aid the development of effective sustainable design strategies that are appropriate to localised climatic conditions and sensitive to the health of building occupants.