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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. The purpose of this paper is to present the results of an indoor air quality (IAQ) and thermal comfort investigation in UK energy efficient homes, through a case study investigation.

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 airtightness of 2m3/m2/hr at 50 Pascal’s, and constructed without a central heating system. Physical IAQ 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.

The results suggest inadequate IAQ and perceived thermal comfort, insufficient use of purge ventilation, presence of fungal growth, significant variances in heating patterns, occurrence of sick building syndrome symptoms and issues with the MVHR system.

The findings will provide relevant data on the applicability of airtight, mechanically ventilated homes in a UK climate, with particular reference to IAQ.

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 localized climatic conditions and sensitive to the health of building occupants.

Energy efficient building design strategies are growing in popularity, promoted through increased awareness of climate change, rising energy prices, global consciousness and a demand for energy security. To aid this design process, assessment tools such as Code for Sustainable Homes (CSHs) and Passivhaus were introduced in the UK. However, it is suggested that these tools prioritise energy efficiency over occupant health through a fundamental lack of attention to indoor air quality (IAQ). The purpose of this paper is to investigate IAQ in selected dwellings built using CSHs level 6, level 3 and Passivhaus homes in the UK.

Using a case study approach, the investigation consisted of IAQ measurements during summer and winter months, occupant diaries and occupant interviews.

The results from the IAQ measurements show the recommended maximum level of 1,000 ppm was breached in all three Code 6 and two Code 3 homes, with levels slightly below this limit in the two Passivhaus homes. Measurements found high levels of formaldehyde, carbon dioxide and low levels of relative humidity.

There is a need for the adequate consideration of IAQ in sustainable assessment methods, including the use of mandatory credits to ensure occupant health is not disregarded in the drive towards zero carbon.

These results can be used to recognise areas of improvement in the CSHs and Passivhaus standard, and the design of energy efficient homes in general. Research of this nature is essential to ensure occupant health is not sacrificed through the drive towards zero carbon.