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One Tonne Life

Tag: carbon dioxide equivalents

Chalmers offers tips to the family

The “Robinson” phase of One Tonne Life means that the family is making a huge effort to get close to the target of one tonne of carbon dioxide per person per year. Fredrik Hedenus and Anna Björk from the Chalmers University of Technology, who have been calculating the family’s carbon dioxide footprint from the very outset, put their heads together and wrote an open letter to the family and included a number of tips and suggestions – and we know that the family have already adopted several of the two experts’ suggestions:

“Hi Alicja, Nils, Hannah and Jonathan!

Today, eating out accounts for a relatively large proportion of emissions in the “food” category. If everyone in the family chooses vegetarian meals at work and at school, emissions from this category can be reduced to 0.3 tonnes of CO2 equivalent per person and year. Previous weeks with mixed dishes for lunch have put greenhouse gas emissions between 0.6 and 0.8 tonnes CO2 equivalent per person and year. Taking a lunch box from home is one way of further cutting emissions; just how much you reduce emissions depends on what your lunch box contains. Both Fredrik and ICA have offered suggestions for healthy and nutritious vegetarian meals on

Meat and dairy products currently also account for a large proportion of your total emissions. If you abstain entirely from meat, you can reduce your emissions by 0.2-0.8 tonnes CO2 equivalent per person and year, which corresponds to the emissions from previous weeks. By replacing dairy products with oats and soya-based alternatives, emissions can be cut still further. For instance, one litre of regular dairy milk produces emissions corresponding to 1.5 kg CO2 equivalent compared with one litre of oats-based grain milk which only produces 0.3 kg CO2 equivalent.

Driving an electric car or cycling instead of taking the bus is a good alternative since the bus currently accounts for about 0.05 tonnes CO2 equivalent per person and year out of the approximately 0.2 tonnes of greenhouse gases for the travel category. If instead this distance were to be covered by bicycle, emissions would be zero and if driven in the electric car, there will only be a small increase since the car is recharged with electricity produced from hydropower. The metro is still a good alternative since it produces low emissions, 0.7 grams CO2 equivalent/person km compared with the bus which gives 27 grams/person km.

Emissions from furniture production are shown in the “Other” category, as part of the “rucksack”. You can choose to do without certain items of furniture, and emissions will decrease proportionately with the amount of furniture the family can do without. At present, emissions for the household’s total complement of furniture are 0.3 tonnes per person and year. If you can do without one-fifth of the furniture in your home, emissions can be cut by about 0.05 tonnes.
Recreational activities currently account for 0.1 tonnes CO2 equivalent per person and year. In order to get rid of emissions from this category, you will have to decline indoor activities.

Good luck!

Anna Björk & Fredrik Hedenus”

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

Climate targets and 1 tonne

One might well ask how the One Tonne Life project came to the conclusion that it is OK to release one tonne of carbon dioxide equivalents per person and year. After all, the project could have picked a different figure. The answer lies in the fact that there are three main considerations determining the extent of emissions we could have here in Sweden without “destroying” the climate.

The first consideration is just what extent of climate change we feel is acceptable. Many of the world’s nations have backed the 2-degree target, that is to say that the global average temperature may not increase by more than 2 degrees over pre-industrial levels. This means the time before mankind started burning fossil fuels, around 1750. To date the global average temperature has already increased by about 0.7 degrees from that base-line. However, the 2-degree target is not a scientific limit, it is actually a political decision. There are experts who suggest we should impose a 1.5-degree limit instead, and others who say that a higher temperature increase would not cause major problems.

The second consideration is how the climate will respond to a higher concentration of greenhouse gases in the atmosphere. This is a scientific issue, but science does not yet have a clear answer. The climate system is highly complex and it has been a couple of million years since the last time Earth experienced the high levels of greenhouse gases we are seeing today. For this reason we do not really know what is likely to happen. Climate sensitivity is a measure we use to estimate how responsive the planet’s climate is to certain factors. It is expressed as the temperature increase that we will have in the long term if the carbon dioxide concentration of Earth’s atmosphere is doubled over pre-industrial levels. Scientific literature indicates that climate sensitivity is probably between 1.5 and 4.5 degrees.

The third consideration is how many people will be living on Earth and how our emissions are distributed. We believe that the planet’s population will stabilise at about 10 billion around the year 2050, but will everyone be producing the same amount of emissions? At present, the average American produces about 20 times the emissions of the average Indian. Does this mean that the American will be allowed to emit more than the Indian in 2050 too, or that by then it will be India’s time to release more per head of population than the USA? Once again a question that science cannot answer but that is instead a political issue.

Using the Chalmers Climate Calculator (CCC) it is possible to see what emission reductions are going to be needed in order to meet various climate targets. Go to CCC and under Emission Scenario enter the year 2010. After that, at Rate of Reduction write 2. Now press the Generate Scenario button. The graph on the left will show that emissions towards the end of the century will be about 10 billion tonnes of carbon dioxide, so if we have a world population of 10 billion people that means emissions of roughly 1 tonne of carbon dioxide per person and year. The graphic on the far left shows that the global average temperature will have increased by less than 2 degrees. This is a rough explanation of how the target figure in One Tonne Life was decided.

However, if you now key in that Climate Sensitivity is instead 4.5 degrees, and press the Generate Scenario button once more, you will see that the temperature will rise by more than 2 degrees. Use this tool to test by how much emissions will now have to be reduced to meet the 2-degree target.

Fredrik Hedenus, Chalmers University of Technology

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