One of the most misunderstood aspects of self build is what you do in terms of energy, sustainability and building performance. First up, the entire topic of self build is a minefield of so-called industry experts peddling expensive solutions for problems that often don’t exist.
Initially, you need to be straight with yourself. What’s driving your attitude towards sustainability? Are you really interested in ‘being sustainable’? Are you after low bills? Do you want to be self-sufficient or use less energy?
Without wanting to be too presumptuous, I am pretty sure that what is currently driving most self builders is a desire for an efficient building that uses as little energy as possible, is easy to build and is cost-effective to run. Let us not confuse this with ‘being sustainable’ or ‘environmentally friendly’.
Now that we’ve cleared the air, let’s talk about your build, and explode a few more myths.
The Magney House in New South Wales, designed by Glenn Murcutt, is a masterclass in how architecture can make a building perform naturally. The windows are cleverly positioned to maximise the amount of sunlight that enters the building
First, what’s the greatest and best use of solar energy? Nope, it’s not photovoltaic or solar thermal panels — it’s daylight.
You can maximise daylight in your house to the point where you don’t need the lights on during the day. We have enough natural light in this country to go without any artificial lighting for 90 per cent of the day.
You need to plan your house efficiently and accurately to gain the first chink of sunlight in the morning. This is also potentially the most interesting generator for architectural form, which should have nothing or little to do with the formal composition of elevations that match the buildings next door.
The architect Gianni Botsford designed a building on a tight backland plot that could still enjoy winter sun on a site that was heavily shadowed. This meant that the building had a beautiful, fascinating and unconventional form that reached up to ‘grab’ winter sunlight and, of course, consequently needed almost no artificial light.
My favourite architect Glenn Murcutt designs deceptively simple-looking buildings that are extraordinarily efficient in harnessing sunlight. He knows exactly how much sunlight to let in during winter and summer, and his buildings are millimetrically honed to the sun at any given time of the year. With nothing left to chance, his buildings are perfect models of passive efficiency in some of the world’s harshest climates. Does Murcutt randomly place windows because they look good? Of course he doesn’t. Each and every tiny aspect of his houses is exquisitely tuned to environmental factors, and they generate their form and areas of transparency from this.
Next up, heating. For some reason, this more than anything is the area many people obsess over. It is also the first thing that many people query if you’re designing an efficient building.
The simple response is that you should aim not to heat your house at all! Or, rather, you should want to make the fabric of the building so efficient that you rely as little as possible on any heating.
Taken to its point of conclusion, this is the PassivHaus model, which relies almost entirely on recovering the heat that is already in the building (i.e. given off by appliances and even the homeowners). This is achieved by exceptional levels of airtightness and super-insulation, to the point that if the house is left unoccupied and unheated in the middle of winter, it will only lose around 0.5°C of heat each day.
Insulation and Airtightness
The principle of PassivHaus – a fabric-first approach to building – is without question what you should aspire to achieve, even if going the whole hog is too expensive. It means, I’m afraid, that you won’t need to go shopping for any bolt-on, eco-bling baubles, but instead, you’ll need to focus on the decidedly unsexy stuff of insulation and airtightness.
There’s no excuse for not super-insulating your house to a standard far higher than Building Regulations, to achieve a U value of 0.1kW/m². The cost is hundreds of pounds, rather than thousands, and the difference in terms of energy saving is massive — assuming of course that your building has good levels of airtightness.
While achieving PassivHaus levels of airtightness can be difficult, excellent airtightness is fairly easy with good-quality construction and sensible detailing. By using the principles as a guide, you’ll be able to achieve 80 per cent of the standard for 20 per cent of the extra cost (as compared with the standards set out in the current Building Regulations).
If you do this then it doesn’t matter half as much how you heat your house, as you will have dramatically shortened your heating season and consequently your need to heat. A small and highly efficient condensing boiler will do just fine.
Remember, though, that you have an obligation to use your building efficiently and that often means a change of attitude. A study by Jones Lang LaSalle shows that the theoretically best-performing buildings often perform the worst as a result of the way they’re used, with occupants fostering a casual attitude to lights, heating and power.
Don’t Forget About Aesthetics
Finally, remember that creating a well-performing building isn’t enough — that alone is not architecture. You also have an obligation to aspire to the exceptional and the beautiful, and one of the best ways to achieve this can be an intelligent synthesis of environmental factors to determine the building’s form.
As architect Alison Smithson said of Murcutt: “He found an exquisite architectural poetry in sunlight and rainwater collection and harnessing the natural environment.” So can you!