Martin Evans from The Malthouse Consultancy talks through how he built his own energy efficient home.
Interview with Martin Evans
Martin explains that he has been in construction all his life, starting as a civil engineer before moving into building. In the early nineties he experimented with renewable technologies and higher levels of insulation. This process developed through to the point where he built an example of a country house that is not compromised by any design constraints, but is built to be as energy efficient as possible.
Energy Efficiency Doesn't Have to Dictate The Design
Martin describes how he set about designing a house (6,500 sq ft) that best suited the site and took advantage of the lovely views. Having created the optimum design, he then worked out how it could use the least energy possible. The main considerations are very high levels of insulation that go a long way above building regulations; the house is carefully air-sealed so there's very little ingress of cold air from the outside during the winter; there is also a mechanical ventilation system (imported from Canada) to avoid stuffy conditions and fresh air passes through an efficient heat exchanger. Martin also generates his own energy from a ground source heat pump, which provides the main energy for the heating and hot water for the house. His total running costs are under £2000 a year.
Energy Efficiency is The Future
The UK has not been good with energy in the past and has not built houses that are deliberately low energy, other than rather odd looking houses. Martin says that he wanted to demonstrate with his house that you don't need to compromise on the look or the amount of glass, you just need to be careful in the way you specify and the way you build.
Advances are happening all the time and Martin describes how LED lighting has moved on since his build nearly five years ago. He highlighted the fact that when you dim a light it doesn't necessarily use less energy. So try to install a properly controlled lighting system, where the energy usage is proportional. Martin rarely needs to run his lighting in any room above 30% or 40%.
Renewable Technology Can Be Used in Old Houses
Martin talks about period homes that can be very efficiently heated by renewable technologies, such as ground source heat pumps. The key is to recognise the needs and to deliver a system that works properly. In the example of ground source, he said: “You can put in a very good ground source heat pump, which in theory can deliver the right energy for the house but if the heat emitters in the house aren't matched to give you the optimum performance of that heat pump, you very quickly get a big drop in performance of that heat pump. So you'll still get the house warm but it will cost you a lot more in energy. That's just about not understanding the full process of extraction of energy from the ground and delivery of energy into the houses.” Martin believes you can make any house efficient.
Sustainability in New Builds
Martin likes timber frames, mainly because there's very little embodied energy. He points to Canada as a good example of sustainability in wood – they grow the same amount of wood as they extract. That may not be true in Europe but things are moving in that direction. It's much harder with brick and concrete products because they've got a lot more embedded energy in them. However, when you actually look at the energy lifetime of the building, the energy we put into heating it, living in it and ventilating it, it makes the energy involved in the actual construction look relatively insignificant. Martins says it's probably right that we focus on what the building uses once it's completed as the priority, rather than worrying about how much is embedded in the building process.
An Energy Tax Might Provide The Right Incentives
With predictions that fuel costs will continue to rise, Martin hopes that the UK government will move away from trying to support certain technologies. If that approach is made much more general and it is just applied as an energy tax, which encourages us to do the right thing, then people will become more and more incentivised to reduce the energy that their buildings use. We may want to do it for altruistic reasons but also it needs to be the right thing to do financially.
The Passivhaus Standard
Martin explains that he didn't have his house certified but in terms of energy use, it exceeds the Passivhaus Standard. Whether you use a standard like Passivhaus absolutely or as a guide, there are lots of good learnings to be had from the methodology and approach.
Gauging Your Carbon Footprint
Martin talks about his consultancy work with England's largest hotel group where, from the outset, they designed and built hotels to the very lowest energy possible without changing the customer experience. The carbon footprint of a night's stay at one of these eco hotels compared to a top end, ‘energy is no object' approach, is about 50 times less. As people start to understand the choices, it could also influence their decision-making. With cars it is a lot more straightforward – you know what you are getting – but with houses and overnight stays etc. it's much more difficult. Of course, it's moving in the right direction. On the Carbon Trust website you can benchmark your energy usage.
Getting The Right Advice
There are lots of examples of things going wrong, where people have spent a lot of money and don't get the right results. It's usually about not getting the right advice. Quality of installation varies so dramatically that Martin stresses the importance of seeing how installed projects have worked. To do that you need proper data that shows the energy you've put into a scheme and the energy you got out so you can see how efficient the whole installation is. Martin wouldn't buy from companies that can't demonstrate seasonal figures showing how well their installations have performed.
There is Smarter Cooling Than Air Conditioning
Air conditioning is not energy efficient. In America they spend more money and more energy on cooling than they do on heating and Martin emphasises that we shouldn't be moving in that direction. There are ways of making very efficient comfort cooling in a house without using much energy. This means simultaneous heating and cooling of hot water. If at the same time as generating hot water we are generating cold water, then it's a free by-product of the process if we do it right. So you don't want a gas boiler heating your hot water cylinder and an air conditioning unit cooling your lounge, for example. We can be much smarter.
Martin's Tips For Energy Efficiency
- Make energy a consideration at the outset but it doesn't have to compromise your design.
- Technology should be a long way down your list of priorities. Design it right, specify it right, insulate it to very high levels, seal it well and mechanically ventilate it.
- Invest in the best products. They may not be a substantial premium but they will save more energy and should perform well in 40 or 50 years.
The Malthouse Consultancy
The Malthouse Consultancy is a highly acclaimed independent environmental consultancy providing unbiased advice and project management services to property professionals in the planning design and construction fields.
Listeners' Top 3 Tips
In episode 1 Ben Adam-Smith asked for your top 3 tips if you had been through the building process or commissioned a custom build. Carol from France got in touch with 7 tips, which we decided ought to feature as an article.
Listener Email About Poor Housing Development
Anastasia from Pevensey, UK, wrote an email about her previous house in Sovereign Harbour South. She tells us that, despite the building being 15 years old, it seemed to lack even basic insulation. Consequently her bills were sky high. She described the worst part as being the damp and mould, with fungus growing all over the house. However, the house design also left a lot to be desired with bedrooms that barely had room for the beds and a large part of the living space that was practically unusable as it was under the stairs.