A Green and Pleasant Home

Dora Varszegi transformed her west London ex-council house into a bastion of efficient eco-living. Using the German-developed Passivhaus standard, which calls for exceptionally airtight buildings with an extremely low heating demand, she slashed her energy bills and even got rid of her mould problem. We asked her how she went clean and green.

What inspired you to retrofit your home into an eco-house?

If my son or daughter asks me one day, “Mummy, if people knew species died and weather changed why did they do nothing about it? And why did you do nothing about it?” I want to be able to tell them at least I tried.

Having a Passivhaus for us looked the boldest change we could make to our energy footprint with no compromise on comfort. We live the same way, but the house uses 36 MWh less energy every year. As a bonus we have a very even 22°C throughout the property winter and summer, and humidity is also ideal: 50 to 55 percent, whereas before we were struggling with high humidity and mould.

We’ve had the know-how to build houses like this since 1991, but it has just started to be adopted in the UK in the last two to three years. Three years ago we were in the first few successful retrofits—this year there are a few dozen.

Did you have to find a specialty builder to carry out the work?

Very hard to find them yet. We found some good, listening builders, who are proud of their work and real team players, and had to train them.

Passivhaus projects start with a computer simulation about current and future energy use and a Passivhaus architect or consultant helps to work out every tiny detail. You get a drawing of every little junction detail which the builders have to understand and follow very strictly. With all the successful projects I know, there was real teamwork between the architect, client, builder and site coaches. The main differences compared with the good-old construction habits are insulation, airtightness and design free of thermal bridges (junctions where heat loss is greatest).

I hope that by training tradesmen, working with the community and having finished a number of low-energy makeovers in west London it will be just as easy to find a Passivhaus or low-energy builder as any other tradesman. On my blog I started to collect such builders. That is one of my objectives. This should be the default way to renovate if the house requires a serious makeup and finding people to do it should be simple, too. We will have to find ways for people who want to do smaller steps for a more comfortable and less wasteful home. The Association for Environment Conscious Building, the Energy Saving Trust and the Passivhaus Trust are all amazing and clear sources of information.

What was the total cost of the renovation?

We added a two-storey extension as well as subdivided the house into two flats, so our project was more than making it into a Passivhaus. I summed up the all expenditure that related solely to the energy upgrade (or downgrade). Expenses like loft insulation, external insulation, solid insulated floor, extra we paid on windows, mechanical heat-recovery ventilation system, new boiler, solar thermal all fell into this category. I excluded other alterations. The sum came to around £45,000 in 2012, all of which is detailed in my article.

How much money have you saved by converting to a green house? What are your monthly bills like now versus before?

Before the renovation we paid £2,320 on gas; it is now £179 for two households per year. This is equal to a monthly payment of £7 per household on gas including heating, hot water and cooking (see here for more details). Electricity is also down 40 percent compared with an average household, but that can be achieved without a Passivhaus makeover.

Altogether the return on investment is around 20 years if you freeze energy prices, but in the last two years they increased way over inflation. So realistically it is around 15 years or maybe even less. However your comfort, a warm home, clean air and no mould are also a return on your investment, which is hard to express in numbers. Some people spend similar amounts on a car, travelling or on a cheaper loft extension; we paid this extra on a future-proof and healthy home instead. It took less than 10 percent of our property value. I just heard last week that some mortgage providers have started to give better rates for homes like this, too.

If you could suggest one thing that people should do to make their home more energy efficient, what would it be?

For years I have been trying to come up with top ten suggestions of small steps, but now I believe it is more useful to assess someone’s home a little more holistically and maybe simulate the building using the Passivhaus planning design tool, then come up with a reasonable plan for the house: this could be a boiler upgrade or just reconfiguration, draught-proofing or new windows, but it is hard to give one-fits-all advice.

Are there any grants available to convert your house to an eco-house in the borough?

Not too many. Solar thermal and other renewables are supported and if the new Renewable Heat Incentive starts this spring it will be an excellent return on money.

Saving energy and wasting less is far more important than renewables. In our example, we eliminated let’s say 40 MWh of primary energy use with insulation, airtightness and mechanical heat-recovery ventilation, as opposed to generating 3 MWh using solar thermal or 4 MWh primary energy with solar PV on your roof! What you can generate is 10 percent of what you could save by not wasting.

Why no grants are available for making real changes I believe is down to two main factors: First, there are huge construction companies who do not want strict building regulations; they just want to build for today and they are not interested in the long running costs of the building. A building normally takes 10 percent of the overall energy for the construction and the other 90 percent is used during the 100-year lifetime of the building. These companies work with subcontractors and implementing high-quality and airtight buildings would be a challenge for them. They lobby against any low-energy regulations. The second is government: they buy and resell gas. Easy money and looks good on the GDP, too. Huge money I am talking about! Just look up the top 100 companies with the highest revenues—most will be energy companies. The government is not directly interested in changing for you to use less, actually their interest is the opposite, even if the planet is struggling. So it is up to us to make those changes.

Can you tell us a little about your open house tours? How often do you do them?

We’ve done four of them so far and will do more if needed. I was thinking about starting them again in the next heating season.

In the meantime I am continuing my blog, starting a free Passivhaus Certified Consultancy from April and helping some ongoing projects, training builders, and so on. In general I am available for advice, preferably to ambitious retrofits to start with, for families who want to do a radical change but don’t know where to start. Through them and by monitoring those I hope we will also learn how to make small but very efficient steps too, for those who can only change a little at a time.

For more information visit: transitionhomes.info