What is Airtightness?

Often we are asked what does the term airtightness mean.  Airtightness is an essential part of creating a healthy, comfortable, energy-efficient living environment.  In contrast, air leakage is where leaks occur due to gaps and cracks that should not be there in the first place.  This can account for up to 50% of all heat losses through the external envelope of a building.  There are many factors which can cause air leakage such as poor build design, poor workmanship, or indeed the inappropriate materials used.   It is important to remember that an airtight building does not mean it is hermetically sealed, rather it means that the air leakage has been reduced to a minimum.

What role does ventilation play in airtightness?

Ventilation is crucial in all buildings, not just airtight ones.  it is key to construct buildings which are both airtight and gap free and then introduce a designed and controlled ventilation system which ensures that adequate fresh air is supplied to meet the needs of the occupants.

Can I not just add more Insulation?

Insulation requires high levels of airtightness to perform.  This can be explained by the “woolly jumper” effect.  Imagine going hill walking and you only wear a single layer then the wind blows through the woolly jumper quite easily.  However, if you apply a light windshield over the single layer it has a dramatic impact as it reduces air movement through the jumper and consequently, the woolly jumper insulates much better