How I made my house zero carbon, and how you can too

A series by BEG volunteer Matt Wood. Matt works as an energy consultant for housing retrofit initiative Energiesprong and is also a member of the Bristol Advisory Committee on Climate Change.

2: Green energy and doing the basics

In this series, I’m going to explain how I’ve made my house zero carbon and how you can too.

My house is a fairly unexciting pebbledash mid-terrace built in the 1930s. When I bought it, it had double glazing and cavity wall insulation, plus a 5-year old gas boiler. It had an Energy Performance Certificate (EPC) rating of E-44 on the A-G scale, with a potential of achieving a low C . This is pretty typical of houses of this age. The EPC doesn’t cover most of your electricity consumption, it just covers lighting and any usage by the heating system (immersion heater, storage heaters etc.), so the rating should give you an idea of how energy efficient your home is. It's based on modelled energy usage to make it comparable between different houses and to ignore different people's heating patterns.

The main low-cost recommendations on my EPC were to increase the loft insulation (+5 points), install low-energy lighting (+1 point) and upgrade the heating controls (+6 points). A new gas boiler (+5 points) and 2.5 kW of solar panels (+6 points) were the higher-cost recommendations.

One day I promise I will paint the house a less horrible colour

My EPC rating in 2010

A is the best rating, G is worst. There is also a number scale from 1-92+. Annoyingly the numbers run the other way to the letters, so G-1 is the lowest and A-100 is the highest.

My zero carbon journey

Step 1(a): First of all, I signed up to 100% green electricity with Ecotricity, who later added a small proportion of green gas to their gas supply too. This meant all my electricity usage was zero carbon. Job done, right? Well, buying green electricity is great, but since there’s a big empty space on my roof that could be generating renewable electricity it’s a bit of a cop-out. Plus I’m still using fossil fuel for heating. We should definitely all be buying green energy, but we also need to be making our homes more efficient.

We currently get most of our renewable electricity from big offshore wind farms in the North Sea, solar farms in Cornwall and hydroelectric dams in Scotland and Wales. In the future, most of our cars and heating systems will also use electricity rather than petrol and gas, so we have to make our homes really efficient and generate renewable electricity wherever we can, because we’re going to need a lot of it going forward.

Unfortunately not all “green” electricity is actually green, so be careful which supplier you sign up to. Here’s a good blog about greenwashing.

Some rolls of insulation

Step 1(b): I topped up the loft insulation from 100 mm to 300 mm. This was a DIY job that cost a few hundred pounds and saves £10-20 a year (10x as much if you start from zero loft insulation).

I also installed low-energy lightbulbs in every room. Later I upgraded these to LEDs.

You can buy loft insulation and LED lightbulbs at DIY stores. Installing loft insulation is a relatively easy job, although not particularly pleasant.

So what did this do to my carbon footprint? You can see that buying green electricity saved around 1 tonne a year. The loft insulation probably saved around 50 kg (0.05 tonnes) and bumped the EPC rating up from an E to a D. It should be noted that I’m pretty stingy with my energy use, so most houses in my area use about twice as much energy.

Next time: solar panels!

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