Eco homes need a bit of breathing space

oliver General, Healthy spaces, Technology/ Energy Saving

Build tight, ventilate right.

With the weather turning just a little my mind is sadly turning towards getting the home ready for winter. With the cooler weather, comes the closing of doors and windows, so the house is getting noticeably less natural ventilation, it’s not just that the smell of my cooking is sticking.

But it seems to me that achieving the right levels of ventilation in our homes is probably the most misunderstood areas of the way our homes work. The basic issue is that we need to ventilate our homes in order to prevent the build up of stale air, damp and mould which can all be harmful to our health.

As many leaky old windows have now been changed for sealed up UPVC  windows our homes have become more airtight so reducing the number of air changes that our houses were traditionally built with. Ok so many are now fitted with simple trickle vents to allow rooms to be ventilated, but this is rather reliant on external wind speed and don’t take external temperature into account, meaning that valuable heat from our homes is just being wasted.

When I refurbished my home a year ago I fitted a Vaillant heat recovery unit. This is basically a mechanical box, about the size of a dishwasher, located in the attic which has a system of pipes running to each room in the house. These pipes take warm moist air from the spaces that contain water or moisture (kitchen, bathrooms, utility room and toilets), it then extracts the warmth and mixes it with fresh air taken from outside, and sends this warm fresh air back to the living spaces of the house, such as bedrooms, hallways, lounge and living room. The result is that even when the house is closed down for winter we get warmed fresh air circulating around the house; it recycles warmth and also supplies healthy clean fresh air, preventing a build up of damp and mould.


Now this system works great but it was tricky and expensive to fit due to the complex series of 6 inch supply and extract pipes. I also had to totally seal the house preventing all draughts round windows, under floors etc, plus we had to get the pipes to every room which is something that is more likely to happen in a new build rather than a retro fit.

So whilst its works really well, it really isn’t a great catch all answer for ventilating every home.

Luckily there is now an alternative, one that I used in a recent episode of the BBC1’s DIY SOS, with great success. Its called the Vent Axia Tempra low carbon fan, and is a continuous running fan which has a self contained heat extractor which recycles around 80% of the warmth from extracted air, so great for kitchens, bathrooms and toilets. Running costs are around £4 a year and once fitted its surprisingly quiet. Plus it means that we aren’t simply ventilating rooms via the ambient external wind speed or temperature.

It seems to be a great solution for the retrofit market, and means that even the worst cooks don’t have to worry about lingering smells sticking round for long!