In this project, we are measuring the airtightness in 60 homes across New Zealand and the ventilation levels in a subset of 40 of these homes. This work is being performed in conjunction with Auckland, Otago and Massey Universities.
So are our newer buildings more airtight than our older ones? Based on our preliminary results, the answer appears to be yes. While there are benefits to this - including lower energy bills - it is not without risk. What we are seeing is that the natural ventilation associated with these structures is often at the lower limit of health guidelines. In many cases, the homeowners in our survey are operating their homes to adequately supplement this ventilation by opening windows and the like. Without these measures, there is a risk of stale air and moisture accumulation.
Although relatively airtight, the homes measured are not really tight enough to take full advantage of heat recovery systems, but this aspect will be more thoroughly investigated in another project investigating different ventilation configurations.