Passivhaus Designer at Warm: Low Energy Building Practice Associate Lecturer University of Plymouth
One of the most useful (I’d say vital) things to do at the start of a retrofit project is an air test. Leak-finding while the building is depressurised gives so much useful information and should help to inform the strategy moving forwards. Although there have been studies which give typical results for different ages of house, that doesn’t actually tell you the magnitude or the location of leaks in your building. In a study of 6 homes, part of a large rural portfolio, we found that we simply couldn’t guess the airtest result from the age of house, its construction type, or the amount of work which had been done to it. In fact, the house which had received the most comprehensive renovation works previously was by far the leakiest. The leaks were always in similar places though, and this sketch shows where they were. Although it shows internal wall insulation on here, the leaks were in the same locations on pretty much every property, insulated or not, only varying in magnitude. These were all found by using the back of the hand, listening for air movement or noting a colder than average area and exploring that location further. I’m always very keen to attend air tests and really enjoy trying to work out the leak paths, maybe that means I should get out more!
Great piece Karl Parsons. We are finding the same issue with some previous extensive insulation works resulting in leakier fabric negating significantly the benefit. To get real value out of improvements we have to join the dots between insulation continuity/airtightness/windtightness to minimise thermal bypass/ thermal bridges.
And at key points in the build, before it all gets covered up! For a couple of hundred quid each time, it can save the end user thousands over time! A no brainer!
Realy interresting, thanks to share! When your'e talkin about an air test (negative and positive) do you have a thermal imaging analysis with it!? Because most of the time when "passive house" is abord by people, some effect of new materials or methods aren't applied well whwn older buiding are to be let say "upgraded"... Saying that, I don't thing I'll be retaired soon.... 🤣
Its usually where adhoc items are fitted either without architects/designers detailing to follow, or wasnt intended in original design, or as a cost cutting exercise by the QS or person responsible for PM at the long term cost to the user ....from over 30 years experience... before you then find with air testing and thermal scanning to form a strategy.
I couldn’t agree more! And there is nothing like a client seeing their carpet billowing to realise where the air leaks are or walking under the loft hatch to feel that cold air.
Worth doing on new builds before the plasterboards go on too.
Agree, the air test is useful and it's very popular in Norway. Not only when starting of retrofit project, it's also useful building the new one. Especially with timber building technology.
Depends on the building I think.
Very useful to hear empirical information on the subject of air leak tests at the beginning of refurbishments. Something I had suspected for some time that would be the proper way forward. Now I just have to convince the contractors and clients in my part of Spain.
Head of Built Environment, Coltraco Ultrasonics Limited
1yInterestingly should you wish to adopt a scientific approach consideration might be given to the use of our Portascanner AIRTIGHT which will enable the detection, location with microscopic accuracy, measurement to within a hair’s breadth (0.06mm), quantification of the air flow rate of each individual leak site as small as 0.5mm, and recording all this photo-acoustic data in an easily available format, without the need for any pressurisation of the space or building in question. Please view coltraco.com