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With the recent heatwave now out of the way we can now see how well the UK’s Passive Houses have been doing. I had a long discussion on LinkedIn about how other’s building’s were doing and it seems a bit of a mix.
Some contributors were finding their homes heating up to around 25 degrees internally, the official threshold for overheating, others (including us) were able to ‘purge ventilate’ in the evenings and early mornings to keep the internal temperatures down. However, even in the houses that kept cool during most of the day activities such as cooking were causing temperatures to rise quickly. This spurred two topics of conversation, one being how we cool Passive Houses effectively and in a low impact way and the second, cooking outside to keep our houses cool.
In the UK we aren’t really used to needing air conditioning in our homes but if climate change causes more extreme summer temperatures as we have just experienced then we will need to consider this. Of course the same principles apply for Passive Houses in that they also require less cooling in the summer but they do still need cooling. We found the simple course of daily life, going in and out of the house with children leaving all the doors open, caused the house to warm up as the day went on.
The discussion went over ‘Ground Exchange’ as a method of cooling the incoming air and although this can work well it does required a lot of earth moving and if installed incorrectly it can grow mould. I suspect that small air con units will need to be coupled with the ventilation systems as time goes on. This can at least use PV to provide the energy to run the unit and so does not have to have any net emissions at all.
With regards to outdoor cooking, it makes very obvious sense to include an outdoor cooking area for summer use, even if it is a small barbecue that is just used to cook on with the food prep being done indoors. I feel that although we can make a house cope with whatever the occupants throw at it, it would make more sense to construct houses more simply, with less reliance on systems, and encourage more thought in the occupants.