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Airtightness – What is it?

Airtightness – What is it?

Airtightness is a vital component in creating an energy efficient home.

With more and more emphasis being put on future proofing our homes, Airtightness is critical to consider. Creating a sustainable environment for ourselves and future generations is increasingly important. Airtightness is key when optimising the amount of energy used on heating, re-heating & maintaining the thermal comfort of a property. An airtight property requires less energy to heat, therefore reducing the overreliance on fossil fuels and creating a sustainable environment.

Why is Airtightness important?

The level of Air leakage from a home determines how airtight a property is. Air leakage is the flow or escape of air through cracks & gaps in walls, floors & roofs. The average UK property loses 15% of heat through drafts created by crack and gaps.

To comply with Building Regulations in the UK, properties are required to have an air leakage rate of 5m3/hr or less. This means that no more than 5m3 of air can escape per hour, per m2 of the properties surface area.

What do I need to consider increasing Airtightness?

The design of the property is important. A good design should consider all potential areas where air can leak from within the property. Key elements to consider prior to construction are;

Fabric Envelope – Walls, Floors & roofs are key components to make sure a property is airtight. The junction between these components is where most air is lost therefore it is essential that these components are considered at design stage and a plan is put in place to seal all joints and junctions. 

Windows & Doors – Airtightness is as important as U Values when considering which windows & doors to install. How windows & doors close is vital. It must be airtight upon install & the seal should last as long as the window or door. 

Pipes & Wiring – The installation of pipes and wiring can create holes or gaps which can result in air leakage. Pipes & wiring are usually found between walls & floors and can be hard to access. Therefore, it is important to consider these aspects during the construction phase of the property.  

What are the benefits of an Airtight property?

Improved Indoor Air Quality 
Airtightness improves air quality by limiting air containing allergens. Airtightness also limits draughts seeping into a property which can lead to a build-up of moisture and dampness. Both elements reduce the quality of air which can have a knock-on effect on the health of those living within the property. 

Cost Savings 
An Airtight property increases the energy efficiency of a property, resulting in reductions in heating & electricity bills.

Increased Durability 
An Airtight property blocks the infiltration of cold air with a high moisture content. In turn this eliminates the risk of the air entering the property, condensing & damaging the building fabric through damp, mould & corrosion. 

Better Sound Insulation 
Airtightness also aides in soundproofing a property. Due to the closure of cracks & gaps in creating an airtight barrier it in turn reduces the transmission of sound through walls.  

Is Ventilation important?

A ventilation system will be required in an airtight property. Many properties rely on Mechanical Ventilation with Heat Recovery (MVHR) or Positive Input Ventilation (PIVs) to create a healthy and comfortable atmosphere.

How do I know how Airtight my property is? 

Airtightness tests can be carried out on to determine how airtight a property is. This is usually carried out a by a reputable company at a reasonable price. (£200 - £250)