Articles published in 2007

There is a variety of technologies to choose from at all stages of selfbuild. There is more to consider than just the hoary old chestnut of whether to go for masonry or timber frame construction. I am fairly clear in my mind on most of the issues, but I am undecided about one – and that is the question of ventilation. The exhortation, 'Build tight, ventilate right', is pithy, but just what does ‘ventilate right’ mean in practice?

In last month’s article we looked at the energy cost of ventilation. The cost of the heat lost when stale air is extracted is much greater than any energy used by fans. But by using a heat exchanger, most of the heat that would otherwise be lost can be saved.

We’ve now reached the fifth article in my mini-series about ventilation – I said at the outset that it was a complex subject. In the first article, we looked at the four main systems of ventilation given in the Building Regulations’ Approved Document F, ‘Means of Ventilation’. In passing, the document says that Positive Input Ventilation (PIV) may also be acceptable.

In the quest for zero carbon housing, the received wisdom is that the best ventilation method is Heat Recovery Ventilation (HRV) in an extremely airtight house. Whether or not that will still be the received wisdom in ten years’ time remains to be seen. What is not in doubt, though, is the increasing importance that will be attached to ventilation.

If this article were confined to describing the selfbuild policies of the UK’s political parties, it would be a very short article indeed. The Greens and the Libdems do have policies encouraging selfbuild schemes (ie, group selfbuild), but the websites of the other parties make no mention of selfbuild at all. What all the parties do have policies about is housing – and in particular making homes affordable for first time buyers.

The government has called for a revolution in house building, and in July they published their policy statement, ‘Building a Greener Future’. This outlines how they intend to use the building regulations to bring about the revolution. 

As we build more airtight homes, consideration of their ventilation becomes more necessary. Last month we had a look at the various technologies available for ventilating a home. Let’s now delve a little deeper into a topic which is not as simple as it first appears.

Last month we looked at Heat Recovery Ventilation, one of the benefits of which is said to be lower humidity levels in the home. But as we shall see later, all ventilation systems result in lower humidity levels, not just those based on a heat recovery unit – albeit heat recovery may be desirable in itself.

We are coming towards the end of my mini-series on ventilation, and I think it may be useful to summarise the rather rambling series in this article. Some of the finer details of the building regulations’ requirements are also included.

Last month, we were speculating about future developments in ventilation. We continue in this vein by looking at the role that air cleaning can play in reducing the amount of ventilation required.

When I was a boy I wondered about all the exhaust fumes from vehicles. Weren’t all these gases being pumped into the air harmful? It would seem not, as the grown-ups weren’t bothered – then. But many of them are now, and some say that man-made climate change is the biggest threat that humankind faces. 

So what are we doing about it? ‘Not a lot’ is the answer for most of us. Chelsea tractors still rule the roads, and we take cheap flights to everywhere. If the radical changes that are required aren’t coming from the grass-roots, they will have to be coerced from the top.

As I’ve explained in my last couple of articles, the government’s intent is that in nine years’ time all newly built housing will have to be zero carbon. Probably the most practical way for a selfbuilder to achieve this will be to include, amongst other things, PV and thermal panels on the roof, masses of insulation, and the use of wood for heating. Although the requirement for zero carbon emissions (taken over a year) will usher in something of a revolution in house building, that is only one aspect of the drive to reduce the UK’s greenhouse gas emissions. This month, I’d like to consider the bigger picture within which the zero carbon requirement for new housing will be but a fragment.