Assessing the importance of keeping the building envelope sealed

Improving airtightness is one of the best ways to reduce heat loss and make your home more energy efficient. By minimising uncontrolled air leakage, buildings become more efficient, comfortable and durable.

When installing any kind of heating system, it is important to keep as much of the heat inside the building without losing it to the outside. So before spending money upgrading your heating system, it would be sensible to investigate the most efficient way to prevent heat from being lost.

Start by checking your loft insulation, current standards recommend around 270mm of Rockwool or similar material. If possible, look under floors too. Insulation should be from the bottom of the joist to the floorboards with suitable net or breathable building paper to prevent sagging. Walls are more problematic as internal redecoration is required after retrofit work. It’s not always necessary to do all three as one or more may already be done. Using a thermal imaging camera is a good way to see the weak points or a blower test for air tightness will identify areas to be improved.

Reduction of heat loss

• Prevents warm indoor air escaping and cold outdoor air entering (infiltration losses)

• Reduces one of the largest contributors to total building heat loss

• Improves overall thermal performance of the building envelope

Check out the image below for a really simple explanation of a home’s heating system. The tap signifies the heat source, with the bucket being your house and the holes the heat being lost. It’s difficult to seal an entire house from losses without a deep retrofit but if you can insulate the loft, walls or floor then at least you’re reducing the rate at which water is being lost from your bucket.

By doing this you can reduce the flow of the tap or turn your thermostat down which prevents waste and increases efficiency.

Improved energy efficiency and lower running costs

• Reduces energy required for heating

• Lowers utility bills and operating costs

• Can reduce heating demand significantly when combined with insulation

Enhanced thermal comfort

• Eliminates draughts and cold spots

• Improves internal temperature stability

• Creates a more comfortable indoor environment year-round

  
  
  
  

  

Maximises insulation performance

• Prevents air movement through insulation (which reduces effectiveness)

• Ensures insulation performs to its designed thermal resistance (R-value)

• Avoids thermal bypass caused by uncontrolled airflow

Environmental benefits

• Reduces carbon emissions by lowering energy demand

• Supports compliance with energy regulations and net-zero targets

• Improves overall building sustainability

Additional benefits

• Reduces ingress of dust, pollen and pollutants

• Improves acoustic performance (less external noise)

• Enhances building durability and lifespan

In summary, airtightness is a critical component of modern building performance. When combined with good insulation and appropriate ventilation, it ensures maximum efficiency, comfort, and durability.

For retrofit and heat pump projects, achieving good airtightness is essential for accurate heat loss calculations and optimal system performance.

The cost of improving insulation will pay for itself very quickly. This will also result in a reduction in size of heat source and emitters. This will reduce the overall cost of installation and your ongoing running costs. More than all of the above though, you will feel more comfortable and there’s no substitute for comfort.