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: energy

Heating system

In the One Tonne Life house, it is important to demonstrate that it’s possible to live energy-efficiently without compromising on either comfort or function. The Lindell family keep the heating going on cold days by utilising the building’s two separate systems. One consists of an energy-efficient underfloor heating system. This has been supplied by Uponor and features an intelligent control system called the Uponor Control System. This technology helps to efficiently distribute energy between the various rooms to ensure the maximum possible comfort while at the same time contributing to an energy saving of about 5%, thus also cutting carbon dioxide emissions.

Underfloor heating is only installed on the ground floor, where a cold floor would otherwise make a noticeable difference. On the first floor, the only heating source is heat distribution via the incoming air. This preheated incoming air heats up the first floor via valve-operated diffusers in the bedrooms and living-room. Before the air enters the house, it passes the ventilation unit which harnesses 84% of the heat energy in the outgoing air from the kitchen, bathroom and laundry room and uses this to warm up the incoming air. If this supplementary energy is not sufficient to maintain the required indoor temperature, an additional heating system linked to the accumulator tanks steps in. This takes place on exceptionally cold days.

These two heating systems are both based on solar energy, since they are both linked via the accumulator tanks to the house’s solar panels. If the sun cannot meet the building’s heating needs, for instance during the dark winter period, an immersion heater in the primary tank is activated. The primary tank is always in use and supplies the Lindells with heating and hot water throughout the year. When the sun shines most brightly, the house produces more energy than the family needs, and that energy is diverted to the building’s slave tank from where the stored energy can be used for a longer length of time throughout the year.

Christian Axelsson, A-hus

Dry your hands the energy-smart and eco-smart way

Jonathan asked how best to dry his hands at home in an eco- and energy-smart way. He got his answer on Tuesday. What’s the best way in a public toilet?

Many public toilets have replaced paper towels with electrically-powered hand dryers. The arguments for and against vary depending on the industry presenting the arguments. Energy, cost and spread of bacteria are all arguments that have been used.

There are different types of electric hand dryer. In one model the hands are dried in a current of air at more than 600 km/h. How much electricity does it use to dry one’s hands with this type of dryer?

The answer is very little indeed: the electricity consumed costs about 0.05 kronor/drying session, which is a mere fraction of the cost of paper towels.

So what do we want when we visit public toilets? According to one survey carried out on behalf of the European Tissue Symposium, 63 percent prefer paper towels, 28 percent hot-air dryers, while the rest want cloth towels.

What then is the answer? If we think in terms of carbon dioxide and energy, the clear winner is the hot-air dryer!

Lars Ejeklint, Vattenfall

What can you do with 0.15 kWh of electricity?

I live in south-east Göteborg and commute to Volvo’s Torslanda plant every day. That makes a round trip of 40 km a day. A Volvo C30 Electric consumes 15 kWh of electricity per 100 km in mixed driving conditions, so if I had a C30 Electric I would use about 6 kWh of electricity per day (for the 40 km daily commute). For the same distance, a C30 DRIVe would use 3.8 litres of diesel per 100 km, which means 15 kWh of energy. In other words, more than twice as much energy. This is because an electric motor is far more efficient than an internal combustion engine.

But the question was what we can do with 0.15 kWh of electricity. Drive a Volvo C30 Electric a distance of 1 km, for instance. But it is of course possible to use that power for other things too. The table below offers a few examples by way of comparison.

There are naturally considerable variations between different household machines. This can be seen, for instance, in the Siemens products with which the house is equipped – they are particularly energy-efficient. What is important to demonstrate when we now start using electricity to power our cars, is that the energy that we use in the house is also used for the car. So by how much will our electricity bill increase when the car runs on electricity? If the car is driven 15,000 km/year, it will consume about 2250 kWh. This corresponds to an increase of 10% in the average Swedish villa (22,000 kWh according to the Swedish Energy Agency).

The following table presents an interesting comparison between different fuels. 1 km in the Volvo C30 Electric consumes 0.15 kWh. This corresponds in terms of energy content to:

However, internal combustion engines have a much lower efficiency rating, so to cover 1 km they will require more than twice as much of each fuel, depending on the type of engine fitted. The exact figures for Volvo’s car range can be found at www.volvocars.se

David Weiner, Volvo

Aviation’s climate impact

Aviation is often seen as a major source of greenhouse gas emissions. And it is true that as a private individual, flying is the single most climate-impacting activity you can undertake (if we disregard space travel). Having said that, we don’t fly all that often, and most people in the world never fly at all. From the global perspective, aviation accounts for only about 2% of total carbon dioxide emissions.

Last week an estimate was made of how much carbon dioxide the family saved by not flying to Switzerland for a skiing holiday. However, the real difference is actually less than the figures given in last week’s presentation. That’s because it is rather difficult to calculate exactly how much climate impact a flight causes. The amount of energy needed to fly one person over a distance of one kilometre depends to a considerable extent on the total length of the flight. Flying from Göteborg to Stockholm requires almost twice as much fuel per kilometre than flying to Beijing, for instance. And of course another vital parameter is how full the aircraft is.

The calculation only takes into account the CO2 emitted during the flight itself, but producing the fuel also requires energy. To this should be added the fact that airports and their various peripheral activities also cause emissions, but these emissions are seldom taken into account when calculating aviation’s total climate impact.

What is most complicated with aviation, however, is the warming caused by aviation apart from the carbon dioxide effect. For one thing, aircraft produce nitric oxide emissions. Nitric oxides have both a warming and a cooling effect on the climate. Warming comes from the fact that they help create ozone. When we talk about ozone we usually refer to the ozone layer in the stratosphere that prevents the sun’s ultraviolet (UV) light from penetrating through to the earth’s surface. However, ozone that is formed at lower altitudes in the atmosphere functions as a greenhouse gas. Furthermore, nitric oxides are also part of a process that breaks down methane, which is a greenhouse gas. If we take all these effects into account over a hundred-year perspective, nitric oxides from aviation will have a slight overall warming effect.

Aviation also causes contrails (also known as vapour trails, seen as white streaks in the sky). The density of these contrailsvaries with factors such as the aircraft’s altitude and ambient temperature. Just how much warming effect this has depends on whether you are flying at night or during the day, and whether the ground below is dark or light.

If we add together the effects of nitrogen oxides and vapour trails, we find that aviation causes an overall warming effect that is about 30% higher than that caused solely by carbon dioxide over a hundred-year period. This time perspective is important: carbon dioxide remains in the atmosphere for a very long time. Ozone remains for weeks, while contrails disappear after a few hours. However, while they are present, they have a significant warming effect. If we were to examine this comparison on a shorter time frame, we would have to increase aviation’s emissions by more than 30%.

To this should be added that contrails can later turn into more long-lasting cirrus clouds high up in the atmosphere. These clouds cause a rise in temperature down on the surface of the earth, although there is some uncertainty as to the extent to which these clouds are caused by aviation. If we also take these clouds into account, the warming effect of aviation is about 70% higher than that caused solely by carbon dioxide. But there are large uncertainties present.

If we now try to calculate the family’s trip to Geneva, the journey is 1680 km long, and flights of that length require about 0.40 kWh fuel per person-km. If we examine aviation fuel from a lifecycle perspective but disregard emissions from airport operations, we end up with 410 kg CO2/person for a return trip. If we now add in the effect of nitric oxides and contrails, the final figure is between 530 kg CO2 eq/person and 700 kg CO2 eq/person.

Emissions per km for the flight are about 158 g CO2 eq/km, which is comparable with doing the trip alone in a large car.

Fredrik Hedenus, Chalmers

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