An air-tight case: why air is a vital element in efficient homes

In countries with colder climates a lot of attention is given to the role of insulation as a means for improving heat retention in homes. While it makes sense to make sure homes are well insulated, putting too much emphasis on insulation alone potentially disregards the role of air and moisture in the ecology of a building.

The way air enters and moves through a building can make a real difference to its physical condition and internal environment. A building that leaks air - even a well insulated one - will lose heat and create an unstable internal climate. Research has found that a building can lose up to 30% of heat through air leaks, which adds up to a lot of wasted energy.

Air infiltration can also bring unwelcome elements into homes. A build-up of moisture and pollutants over time will cause material damage and poor air quality. Their effects will be more serious in buildings with poor ventilation and insulation creating potentially harmful conditions.

At the same time, a lack of air flow in a building can also reduce air quality and cause problems. A continuous supply of fresh, clean air helps reduce moisture build-up and regulate the internal climate. But there is a difference between controlled air flow and uncontrolled air leakage.

The air flow within a building should be regulated by a ventilation system that supports the circulating of fresh air and the removal of damp, unclean air using natural and mechanical methods. Natural methods include windows, doors and vents operate without power and are low maintenance. On the other hand, mechanical ventilation methods need power to physically move air but can be more reliable in more demanding conditions.

Another dimension that can be added into the air-related mix is the concept of breathability, which refers to the ability of a building and its materials to respond and adapt to changing conditions. Breathable design materials can help manage the effects of moisture and control humidity by absorbing and wicking away moisture on contact. The use of these materials combined with an air-tight construction and well-designed ventilation system results in a highly effective air controlled building.

Managing air, moisture and heat can be part of a whole building design approach to energy efficiency and sustainability where all parts of a building and its environment are considered as an interdependent whole. This approach will provide reliable, long-lasting improvements based on an assessment of the building's existing condition and its internal and external environment.

In a backdrop of climate change and environmental degradation, it's understandable that governments are prioritising simple ways to improve energy efficiency. But any plan to make homes healthy and efficient should always be based on an awareness of the effects of the simplest element: air.

Air-related takeaways

• Controlling air flow in buildings offers a variety of benefits including heat conservation, moisture control, protection from air and noise pollution
• A whole building approach to heat conservation considers how insulation can work alongside measures to improve air-tightness, flow and moisture protection across the entire building.
• The movement of air in a building should be controlled by the ventilation system.
• Natural ventilation methods are lower maintenance and can be utilised in combination with mechanical methods to greatest effect
• Mechanical methods require maintenance and are best reserved for spaces with need for stronger air extraction