The Importance of a Well-Sealed Home
Sustainable homes are fast becoming commonplace and are often on the bucket list of those looking to build. The thing that can often be overlooked though is how important it is that any home is well-sealed. Many people do not realise that this is essential in order to have a sustainable home. You could have incorporated a large number of sustainable design principles, materials, technologies, and construction techniques, but if your building leaks heat or cold then the benefits of these features are diminished. High air tightness can reduce your carbon emissions and energy bills by up to 25%. Some of the main sources of air leakage are:
- – Inefficiently sealed windows and doors
- – Wall & roof penetrations for piping, ductwork, or electrics, not sealed properly & reduced insulation
- – Air flow systems such as vents and exhausts that do not control excessive air flow
- – Gaps in floorboards and floor joints including skirting boards
- – General areas of poor construction, in particular at joints, where there are gaps in materials
There are means of testing how air tight your building is, which include a blower door test and a thermal imaging investigation. The blower door test uses a pressure monitoring fan to blow air at a consistent pressure into the house and measure the returning air pressure to determine how much air has leaked. The thermal imaging test uses an infrared camera to determine where the leaks in the house are.
However, with air tight buildings there also comes the issue of managing the quality of the indoor air and controlling the moisture levels. Moisture needs to be controlled otherwise mould can occur – this requires the appropriate use of vapour barriers and vapour permeable membranes. Additionally, toxins and pollutants can build up over time and need to be expelled from the building. There are different strategies and innovative technologies that allow controlled air exchange between the indoors and outdoors to prevent moisture and toxin build up, one example of these is heat recovery exchange units. We used this system in our most recently completed project, the Kensington House, and it works flawlessly. The exchange system draws in fresh air from outside while extracting heat from the outgoing air with heat exchangers and uses this to heat the incoming air before it is released inside the house. It can also dehumidify the incoming air to reduce air moisture levels internally.
There are many different design decisions that you can make throughout your project to minimise air leakage. It is important that you identify the need to manage air tightness in your home as you begin your design process. This will impact different decisions throughout your project, including material choices and construction techniques. With the air tightness of your home consciously considered you can make the most out of your sustainable design.