The One Tonne Life project has ended and the content on this web page is static and is not updated any more. The project was unique and pioneering, making the conclusions and all information connected to the project just as interesting and up-to-date today as when it was run. Read more about the project and get inspired! (March 2017)

One Tonne Life
Vattenfall

Tag: solar cells

Reassessment

Ignorance? Journalists often ask if we think differently now that we’ve lived in the house for some time. What’s the biggest difference? What has been most difficult? Do we have to make big sacrifices? My answer is usually: no, modern technology has made it easy and enjoyable. The difficult sacrifices are probably still ahead of us. The last stage down to one tonne is what’s going to be the real tough haul.

Now I’ve noticed that I’m gradually beginning to think differently and reconsider my views. When I think about helpful and fun technology, I have to admit that white-goods don’t exactly spring immediately to mind, at least not during the winter months. They are pleasant to use and attractive to look at. But what difference does it make that they are energy-lean in the winter months, if the house still needs a continuous supply of supplementary energy in order to stay warm?

Well, naturally a kitchen extractor fan that works just as well without blowing the warm air out of the house, or a dishwasher that drains off a bit less hot water by being extra-efficient, are welcome features. Important, perhaps, but nonetheless only relatively modest as tools for CO2 reduction. Quite a lot of the energy that is saved is instead diverted to a different part of the house so we can have a warm and cosy indoor climate. In the summer, the benefit of energy-lean appliances is immense when we need to cool rather than heat the house.

Reassessment I’ve gradually begun to realise where we can perhaps make our biggest CO2 savings. And it’s not where I imagined they would be. An energy-lean refrigerator – can that really make a major difference in the winter when the house still has to be heated up? Now I’ve started to realise the significance of the high-tech refrigerator’s ability to keep the food fresh. In the beginning I didn’t really absorb the full implication of what was being said about vitaFresh compartments and cold zones and moist air … one fridge is pretty much like another, I thought; perhaps one is more attractive to look at than the other, but when all is said and done it’s just a fridge …

After spending two months in the house I’m beginning to appreciate that it actually does make a difference. Our groceries stay fresh for much longer, it’s like the old-fashioned root cellars that houses used to have, where root vegetables and other vegetables could be stored throughout the winter. This together with the realisation that the average family throws away up to one-third of its groceries, has caused me to totally reassess the significance of the refrigerator. Of our total carbon dioxide footprint today, food accounts for about 60 percent, so in our “CO2 battle” the refrigerator’s ability to keep food fresh is very important indeed – it is perhaps the most important technical aid at our disposal in the coming months! (Apart from the car and the solar cells.)

Food for thought Another question we get is what habits and solutions we will take home with us at the end of the project. I have now begun to seriously consider this business of the refrigerator. Let’s say we have a food budget of 6,000 kronor a month, and that 1,500 kronor of that is never consumed but instead ends up in the bin. Half of that may perhaps never need to be discarded if we have a high-tech fridge. This means we would save 12 x 750 kronor a year if we invested in an advanced refrigerator, in addition to the energy saving we would make in the summer months. A reasonable calculation gives a saving of about 10,000 kronor a year. To be on the safe side we can halve that figure and expect a saving of 5,000 kronor a year. An advanced refrigerator probably costs about 20,000 kronor. A shocking amount of money, one might well think. But if the above calculation is correct, it would pay for itself in just four years. There probably aren’t that many household investments that can be recouped in such a short time.

Real food for thought, in other words: failing to throw out our old-school refrigerators is nothing short of downright wasteful.

Nils Lindell (lives in the One Tonne Life house)

The house’s solar cells

The Lindells have solutions that will make things easier for them on their journey towards one tonne of carbon dioxide emissions per person per year. One of the challenges the family are facing is to reduce their electricity consumption. In order to further cut their energy usage, the One Tonne Live house will produce its own energy. Firstly via solar heating and secondly via solar cells that generate electricity. The electricity is produced by the house’s own solar cells which are fitted on the south-facing roof and façade. This electricity is used by the Lindells for cooking, recharging the family’s electric car and for powering other equipment at home. The solar heat that the house stores will produce most energy while the house is empty, for instance during the day while everyone is at work and school or while they are away during their summer vacation. Since solar heating produces a surplus of electricity, this will be fed into Vattenfall’s grid, with a corresponding amount of electricity fed back into the house when the sun is not shining.

The cells, made by Sulfurcell, are what are known as thin-film solar cells. All told, the One Tonne Life house’s 96 square metres of solar panelling will produce about 5000kWh/year in a normal year. Factors that affect actual output are how sunny the weather is during the year, the angle of the panels facing the sun, and the direction they face. The geographic location of the house itself is also a major factor – a house in the southern Swedish province of Skåne will produce more electricity than one in Norrland in the north of the country.

There are several different types of solar cell technology and thin-film is one of them. The advantages of the thin-film solution are its design and the fact that it creates a uniform, neatly integrated impression, as well as its price. This is an important consideration in order to recoup their cost over the years.

Christian Axelsson, A-hus

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