It feels like it has been a very long journey to get to this point. We moved into a rental in Exminster in March 2008 and found the plot we are now trying to build upon about 8 months later.
Building a house seems to involve overcoming a series of obstacles, each one of which has the potential to scupper the project entirely. Our latest obstacle was one of finance. We now have a plan to overcome this, which involves me moving from self-employment to salaried employment. As a result we expect to be able to obtain finance to start the build in March 2011.
In the meantime, the quotes we have had for building the house have varied from 170% of our original budget to 210%. Clearly we have some work to do to overcome this new obstacle. Our architect, Darrell Willcocks, came up with a great design and between now and March 2011 we need to refine this design and secure suppliers and builders who can build the house we want to the budget we can afford. Thanks to an Exminster.net reader (thank you Paul!) we now have an extremely experienced project manager, Nigel Skudder, to fight our corner and ensure we have a plan that will work.
We knew from the outset that building this house was likely to be challenging. We want a house with similar energy performance to a PassivHaus, and these typically cost 50% more than the equivalent conventional build. Our budget, however, is very conventional and not at all in the PassivHaus league.
In addition, I naively thought when we first specified the house that building an energy efficient house was pretty much run-of-the-mill. We'd read lots of magazine articles about PassivHouse and low energy projects and all the associated technology. The government has told the building industry that all new builds will be 'energy efficient' in 2016 (according to the Code For Sustainable Homes), surely everyone involved knows how to build a house like ours that will work?
The reality is much more complex. For example, to date in the UK only two houses have been built and certified as PassivHaus standard. Just to model the heat flows for a house like ours (with no fossil fuel derived space heating) would typically cost more than £5000.
The modern approach to energy efficiency (and the design of our house) relies on very good insulation and, most importantly, airtightness. This vogue for airtightness originates in countries where leaving a door or window open in winter temperatures of 25C below zero would be lunacy.
Here in the UK it's different. Our weather is milder. Our builders are not used to building airtight buildings and we are not used to living in them. Our trades are not used to maintaining airtight buildings.
New cable TV? Just drill a hole through the wall . . . oops, there goes the airtight membrane. Open window in the bedroom? The mechanical ventilation system will rapidly spread the cold bedroom air to the rest of the house.
If the airtightness of the house deteriorates over time, it will become colder and harder to keep warm. Unless we take steps to directly monitor the airtightness not only will its performance degrade, we probably won't know it's happening and we certainly won't know why. Building regulations only stipulate that airtightness is measured when the house is built. There's nothing to say it should be measured during the life of the house. The very few long term studies of the real performance of UK energy efficient house designs do not make happy reading.
So what are we doing about this?
In our house, we will embed temperature sensors in most rooms of the house, linked to a real time monitoring service (built by me). This service will not only show the current temperature in each room, it will also send email/SMS alerts when temperatures exceed limits. The idea is to rapidly spot problems and locate the source of the problems. This service will help protect the energy performance of the house during its life.
The models used to simulate the thermal properties of our house originate from the German PassivHaus standard. How well do these models apply to the UK? To help answer this, Tom Blight and David Coley at Exeter University's Centre for Energy and the Environment will monitor the long term thermal performance of our house, using our temperature sensors. In return for this data, they have modelled the thermal performance of the house and assisted in the design of the heating system.
For us, it's pretty exciting. We now have a realistic timetable for the build and a fighting chance of getting what we want built to our budget. The resulting house might even be warm in winter and cool in summer!
But my experience really makes me question the ability of the UK housing industry to deliver real improvements in the energy performance of new houses in the near future. My experience of the building process so far is that the expertise required to design a working energy efficient or zero carbon house is too expensive and not sufficiently widespread amongst the design and build professions. Instead, the industry will spend lots of money on new technology that will simply end up being no better or may even be worse than current buildings.
The attempts to measure the real world performance of the new approaches to building are also too few and far between. Where performance has been measured and found wanting, those best placed to learn the lessons (architects, builders) seem uninterested.
I'm hoping that not only will we get a great house, but that through Exeter University we will play a (very) small part in helping the UK build houses that really are energy efficient.
