The excessive uncontrolled air infiltration rates meant the air quality in the existing house was generally good. Certainly sufficient to remove CO2, pollutants from VOC releasing materials and odours. But the poor insulation levels also also meant we were not immune from condensation and black mould! Ironically air quality was better than the 1994 house we lived in during the build - this always felt stuffy. (I know I could open the windows but I object to warming the atmosphere during the heating season)

The plan with the refurbishment is to try and obtain good air quality by minimising uncontrolled air infiltration through careful design and execution. In addition we will avoid carpets and other volatile emitting products. The MVHR system has to meet the minimum standards required by Building Regulations but in practice will be run at much lower rates. (This will depend upon monitoring air quality post occupation).

The builders are experts in airtightness so and they do not forsee any reason why 0.3 ac/h can’t be achieved on the final air test - we will see. Their optimism is based on their experience and the proposed design which tries to avoid penetrations of the air tight layer. The penetrations that remain are
  1. MVHR intake
  2. MVHR extract
  3. Soil pipe
  4. Electricity supply
  5. Water supply
  6. BT line
  7. Satellite cable
  8. Solar pv cable
Items left out to prevent excessive uncontrolled air infiltration are
  1. Loft access - no storage will be possible in the loft space
  2. Cat flap - this one created some discussion but cats are clever!
So the final air test result will depend mainly on the fitting of the windows and doors! Parge coats and wet plaster on the masonry should hopefully deal with the external envelope.