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Zero Carbon Hub and NHBC Foundation call for action to ensure healthy indoor air quality in tomorrow’s new homes

The Zero Carbon Hub Ventilation & Indoor Air Quality (VIAQ) Task Group has concluded the first phase of its work with the publication of Mechanical ventilation with heat recovery in new homes – interim report.

The VIAQ Task Group, chaired by Lynne Sullivan OBE, comprises of a broad cross-section of industry practitioners and academics and was set up to review the existing evidence around indoor air quality and consider the associated issues in detail.

As improvements to Part L require new homes to be built to increasing standards of airtightness, minor gaps in the building fabric no longer contribute significantly to ventilation. As a result, occupiers are becoming wholly dependent on the effectiveness of the installed ventilation system to maintain good indoor air quality.

It is commonly accepted across the industry that mechanical ventilation with heat recovery (MVHR) will grow to become the dominant installed ventilation system because of its ability to recover heat from the exhaust air and contribute to carbon savings. However, evidence from the UK, Europe and various other countries reviewed by the Task Group has identified a number of issues with these systems that need to be addressed as a priority.

Recommendations from the report

The Task Group’s interim report recommends that MVHR practice must change substantially to ensure that systems are designed, installed and commissioned correctly. It also points to the importance of fully taking into account the needs of the consumer in good system design, providing appropriate controls and making sure that there are proper arrangements for ongoing maintenance.

Neil Smith, NHBC’s Group Research & Innovation Manager and secretary to the VIAQ group, commented that “the interim report brings together useful evidence from a number of studies and highlights some key concerns that must be addressed as a matter of priority. Clearly it is imperative that in our pursuit of higher energy efficiency standards, new homes continue to provide healthy indoor environments and there is no risk to occupant health from changes in building practice.”

The work of the Task Group is expected to conclude later in 2012 and will take into account monitoring of a number of occupied homes with MVHR that are currently being monitored.

The interim report, this is now available to download from and