The current policies and regulatory frameworks in the construction sector aim to improve energy efficiency of new
buildings whilst maintaining acceptable level of indoor environmental quality (IEQ) including indoor air quality
(IAQ). In practice, however, there are often important trade-offs between these objectives. The aim of this paper
is to investigate the concentrations of volatile organic compounds (VOCs) in a recently built residential block in
the UK and the potential trade-offs between ventilation rates and VOCs. Concentration levels of VOCs that are
likely to have concentrations higher than their respective exposure limit values (ELVs) in low energy dwellings
were measured in five sample apartments in this block during typical weeks in winter and summer using diffusive
sampling methods. Whilst most target VOCs had concentrations lower than ELVs, benzene and formaldehyde
levels were regularly higher than the limits. Measurement of outdoor concentrations showed that benzene levels
were predominantly driven by outdoor sources whilst formaldehyde concentrations were driven by internal sources
including construction material and furniture. To investigate how formaldehyde levels can be reduced in a given
context determined by typical material used in the industry, two models were developed to calculate the effect of
enhanced ventilation on formaldehyde levels and energy efficiency of the apartment with highest formaldehyde.
Lack of clear definition of VOC characteristics of building material and ever-increasing use of material with high
formaldehyde emission factors such as medium-density fibreboard (MDF) in indoor furniture may contribute to
high formaldehyde concentrations in indoor air. The study found that to offset the effect of the existing internal
sources in the case study apartment and comply with the best practice ELV for formaldehyde, the ventilation rate
should be more than three times the existing rate required in the current Building Regulations, and this can
significantly increase energy use. Formaldehyde is currently not regulated in the UK Building Regulations. Given
the potential health impact of high formaldehyde concentrations and the empirical evidence, it is necessary to
cover formaldehyde in the next edition of the Building Regulations. This study points to the significance of
improving the existing regulations and standards to clearly define maximum permissible emission factors for
various VOCs in building material and indoor furniture. It is also important to improve source control measures
to reduce the concentration of formaldehyde. These measures may be complemented by enhanced ventilation. It
is, however, necessary to investigate the implications of enhanced ventilation for energy efficiency