Energy Measurements May Be Flawed

Researchers from Leeds Beckett University have found that a test used to measure the energy efficiency of UK homes may be flawed.

Airtightness ‘blower door’ tests, known as fan pressurisation tests, tell how leaky a home is and therefore how much heat is lost through cracks and gaps around windows, doors and floors and where services penetrate through walls, ceilings and floors.

These tests help determine how energy efficient our homes are and what EPC grade a home gets, as well as checking that it has sufficient ventilation to avoid damp and mould.

The research identified that the test could overestimate air leakage by around 20% in semi-detached and terraced homes, because air is being forced into neighbouring homes, which the test doesn’t account for.

Professor David Glew, Director of the Leeds Sustainability Institute at Leeds Beckett University said: “The blower door test is a fantastic tool to check how buildings perform, and we hope our research can help improve the test. The inter-dwelling air exchange we have observed could be quite a serious issue for semi-detached and terraced homes, which may be being penalised as being too draughty, when in reality they are not, and so could be erroneously given a worse rated EPC.

“Also, because the test says these homes are getting more fresh air than they are in reality, there is a risk that they are being assessed as not needing any additional mechanical ventilation, and so they could end up being under ventilated, which might be causing damp and mould issues.

“Our findings raise question marks around current airtightness testing protocols, which is especially problematic as there is so much emphasis on ventilation, energy efficiency and mould now. The standards might need to be revised or adapted to account for this new finding, but we need to understand more about it by doing further tests in more homes. It may be that this affects some house construction types more than others, and we haven’t even started looking at how this affects flats.”

Hundreds of thousands of fan pressurisation tests take place each year, most are undertaken to make sure new homes comply with building regulations, but more and more are used to measure air leakage in older homes before and after retrofits take place, and this new research has implications for millions of tests that have taken place over the last few decades in the UK, as well as those that have been undertaken in other countries.

To learn more, the research article can be found here.