What Does Fabric First Mean?
A fabric-first approach is a simple concept about making low-carbon, sustainable and affordable-to-heat houses by focusing primarily on reducing heat loss — best achieved through insulation, good windows, airtightness and optimised design to passively capture as much of the sun’s heat as possible.
Given that space heating constitutes about 60 percent of the energy consumed in the average home, getting this down means you’re a long way to making a truly low-energy home. It is one of those incredibly obvious-sounding ideas — if you reduce demand, it’s easier to meet it.
Looking Beyond Renewable Technology
I am amazed at how often I talk to people about their plans for a sustainable home and all they seem to be interested in is low-carbon technologies: heat pumps, photovoltaic panels, biomass, etc. They seem to be obsessed with how they are going to generate their energy, rather than how they might save it.
This is the equivalent of having a slow puncture and obsessing about how to blow up the tire, rather than simply fixing the hole. If you want to fix the hole (or stop your building losing heat) you need to be far less interested in generating heat, because a thoroughly insulated, super-airtight house with a good ventilation system requires, in many instances, no heating system at all. The kids, dog, computers, oven and electrical kit provide all the heat you need on all but the coldest of days.
Benefits of Limiting Reliance on Heating Systems
While no heating is the logical conclusion of a fabric-first approach, even if you do not want to go to this ‘extreme’, there is much to gain from following this logic. I have recently assisted on a barn conversion where it was not practical to do without heating, but we got the heat demand so low that there’s no boiler — instead, a couple of water tanks are heated by green tariff Economy 7 electricity which provides enough heat until the next evening’s Economy 7 top up.
We had explored all the low-carbon heating options, but the payback periods were simply uneconomical. For an air-source heat pump it worked out at 24 years, assuming nothing went wrong with it — for 24 years!
In many ways, this is why I’m such a big fan of the fabric-first approach. Technology can go wrong. It needs maintenance and servicing, monitoring and repair — insulation doesn’t. I appreciate insulation isn’t sexy. It doesn’t come in a box from Germany with a red light that flashes. It is hard to get excited by insulation, but it can last hundreds of years, has no running costs and it doesn’t break down on Christmas morning when 15 people are coming for lunch.
Matt and Sophie White’s home is super-insulated with Aerogel
Designing a Fabric First Home
Beyond this, what you can get excited about is the use of computer modelling to optimise the way your house uses insulation and passive solar design — all to create a super-efficient, self-heating living machine, scavenging just the right amount of the sun’s warmth while losing as little heat as possible.
There are several computer programmes that do this — the Passive House Planning Package (PHPP) being our office’s weapon of choice. It is a wonderful thing.
During our design process we:
- model what heat a building will need
- test what changes in the size, location and orientation of both the building and its windows will have so we can optimise the form
- we then explore the most cost-effective place for insulation and make a good guess at what the heating bills will be before the house is built — enabling us to thus drive down a home’s running costs and CO? emissions.
An Essential Part of Sustainable Design
This is what we should be focusing on with sustainable design: designing right and then building right. By embedding all the clever thinking in the house fabric, it should never go wrong.
I think many people have an aversion to paying for design, but the key to a ‘fabric-first’ approach is good design. If we really want to create sustainable homes, we have to start designing clever houses rather than throwing up stupid boxes and attaching clever technology to them.
There are reasons beyond being kinder to the planet (and your wallet) to embrace a fabric-first approach. Living in a house that is not losing heat, and has no draughts or cold-spots, is utter luxury. Once you’ve experienced it, you will never want to live in a ‘standard’ house again.