The rise in construction of sustainable and high performing homes has seen a greater focus not only on insulation but also on the internal air quality of our homes.
In years passed, an open window or roof vent was all that was viewed as necessary for a 'little ventilation' or fresh air. This also meant lots of air leaks, making heating and cooling appliances work needlessly overtime and no ability to control or filter the airflow within a home. Some reports indicate that nearly 15% of the heat produced to warm a home can be lost through draughts. Add some moisture to the mix, either from the 11,000 litres of air we each breathe daily, our shower or the boiled kettle and even more warm moisture enters our internal living environment creating the perfect environment for mould and mildew.
Given that high-performance homes incorporate high levels of insulation and airtight membranes, the installation of a ventilation system is necessary which guarantees a continuous supply of fresh filtered air as well. However, it isn't just the internal living environment that is positively affected when buildings are constructed using an airtight membrane with a ventilation system.
For homes built without this membrane, moist air leaks into the building envelope and condenses, resulting in rotting timber, the corrosion of metal and the growth of mould. Even though it's all where we cant easily see it, it still has the ability to create a big impact on our own health and the health of our home.
However herein lies the first issue. If all we did was to increase the insulation and not include an airtight membrance this will only exacerbate the fact. As we insulate more, the colder the outer layers of the building become in comparison and the more they are likely to condense air leaking from the inside.
Therefore, homes that are designed to be high-performing and feature high levels of insulation, must also feature airtight membranes and ventilation.
Then a high performance home won't only perform well for heating and cooling, but the entire internal living environment and building envelope will also function better.