Warm homes without heating systems?
Back in the nineties sometime, I had occasion to visit a home in North Wales that was (the owner claimed) "imported" from, I believe, Switzerland. I don't recall anything externally that distinguished the property from others - it was dark - but inside there was a definite stereotypical swiss kind of look and feel to the place... think log cabin/sauna!
If you have such a house then you obviously provoke conversation. What I was told has always remained with me because, to my UK way of thinking, it was hard to get my head around... this was a home that had no heating system, whatsoever.
And yet, there I was, in the middle of winter, sitting quite comfortably in this spacious airy home... How does it work, was my next obvious question.
What I remember of the explanation given to me, can be summarised like this:
- Incoming fresh air enters the building at some specific point.
- Outgoing warm air "passes over" the incoming fresh air.
- Through heat exchange, the outgoing warm air heats up the incoming fresh air thus maintaining a fairly constant ambient temperature.
Wow! Over the years since that revelation - largely because of the suspension of belief I had in what I was being told - I have spoken to various people in the building trade - including heating engineers - and not one of them had heard of such a system... nor could they quite get their head around how it would work.
But it is indeed out there and known as Passive Housing.
What is Passive Housing?
The property is built to a very high specification of airtightness - This is key since we want internal air to maintain its temperature.
Consequently, incoming and outgoing air occurs at only one point in the property, which makes sense if we are to maximise the effectiveness of heat exchange.
From what I can gather, incoming air is ventilated to specific parts of the building first (typically the coolest parts), and "extracted" from the typical "wet" areas of the property last (such as the kitchen, bathroom, laundry room etc...). These areas are typically the warmest which means that by extracting this warm air last, we get maximum heat at the heat exchanger.
And so completes the cycle.
It seems there are various methods in which incoming air can be routed into the property - In Ireland, MosArt have built a passive house which uses underground ducting to funnel air into the property. They claim that through heat exchange with the soil, fresh air is preheated to above 5°C (41°F), even on cold winter days.
Add to all this, triple glazed windows and solar panels for hot water, and you begin to see the significant benefits of passive housing.
I have to say that I thought the owner of this "imported" swiss home was probably a tad eccentric and would likely discover later that he'd been sold an expensive duff.
Turns out he was well ahead of current thinking... as is so often the case with eccentrics.
More information
Webcast that explains the principles.
Promotion of European Passive Houses - Has an informative and more technical explanation of what's involved in the construction of passive housing and is supported by the European Commission.
Tags: environment, housing, heating-systems
