Airtightness is basically a measure used to work out how much air gets in and out of your house when everything is closed (doors, windows, trickle vents, loft hatches etc). Air does need to circulate to ensure we have fresh air, and importantly that mold does not form inside our homes - but air coming in and out also means heat and cold coming in and out, which can significantly impact how much energy you use to heat or cool your home.
In the UK, older houses have notoriously poor airtightness - and even in newer builds, this can often be overlooked by homebuilders unfortunately. Each new build should have an airtightness test completed on it - however more often than not, it is completed on a completed house of the same "type" and then they will just check that the other houses of the same type are built to spec. If you want to see some examples of the quality of this checking - just find the social media channels of some new build snaggers. They go round new builds which have been signed off and check them against spec....I'll let you see the results for yourself.
Common areas where airtightness issues are found:
Joins not sealed properly (around skirting boards, doors and windows)
Windows and doors themselves (gaps, mis-alignmnents or incorrect fitting)
Behind sinks and toilets where pipes enter a wall (and where they come out of the external wall) are not sealed
Poorly fitted loft hatches
Corners (gaps/cracks)
Trickle vents incorrectly fitted or covers broken
Fire places (although you should get this checked by a professional as the airflow requirements depend on what fire it is)
Incorrect door type (into garage or eaves storage areas)
Ideal world, if you have issues and want to fix them - you can get a professional around to complete an airtightness test. They will seal everything up and put a big fan in your door to reduce the pressure and then go around with a thermal imaging camera and show you exactly where you have issues. Doing this will also highlight areas with missing insulation too so win win all round.
Ok - I can't afford that so what can I do about it?
Clearly this option isn't accessible to most - and isn't perhaps the best idea if you aren't sure whether you've even get a problem. Thankfully, there are some ways you can do this for (almost) free yourself:
On a cold day, heat your home a bit warmer than usual (appreciate this will cost a little bit - but identifying and fixing any issues will more than offset this cost)
After it has been that temperature for a few hours, go around checking the places mentioned above to see if you can feel a cold air breeze. A bit of tissue paper can also really help with this (just hold a corner and run it along the areas and see if it moves).
You shouldn't have a breeze coming in any of the areas above so mark down any that do or take pictures so you know what needs to be resolved.
Go around and fill the gaps - it doesn't need to be anything special, caulk will usually do the trick! Although clearly if there are bigger gaps (like around pipe entries or behind toilets) you may need something more substantial.
Finally, if you have any broken trickle vents - these are very cheap to replace and you can usually pick them up from any hardware stores.
But how much energy/money will it save?
This is really hard to say unfortunately and not a simple question. It depends massively on how much it costs to heat your home, the extent of the issues you've fixed and also how you use your home (if you always have your windows open anyway, then clearly fixing these types of issues won't make much difference).
That said, studies have shown that a detached house with poor airtightness score (via the test mentioned earlier) can cost over 40% more to heat than a house with a "good" airtightness score. So if you find some fairly obvious issues (draughty doors, missing trickle vents, unsealed loft hatch, holes behind your sinks/toilets), you could make some significant savings! One thing I will say though is that if your home is poorly insulated (e.g. missing loft insulation) then fixing the airtightness issues won't make as big of a difference - so ideally you need to fix both.
If you have any thoughts, feedback or ideas you wish to contribute on this or any other topic covered by The Climate Coach - please get in touch, we'd love to hear from you.
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