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“The greenhouse effect and global warming are indisputable facts today, and our emissions disturb nature’s balance. We have to live in a more resource-efficient way, but we have to think carefully and choose the right methods,” says Mattias Gustafsson, researcher in energy systems at the University of Gävle.
Among other aspects, Mattias has studied how making a building energy efficient affects the district heating system and global CO2 emissions.
“Say that we reduce the use of heating in a building by additional insulation or change of windows and that we buy a heat pump. Then we reduce the amount of heating we purchase substantially. However, electricity use increases and that electricity might come from a coal power plant. My doctoral dissertation shows that producing electricity means more global CO2 emissions compared to using heating from a district heating system.”
Mattias Gustafsson claims that the district heating system in Gävle is unique, as the collaboration with Billerud-Korsnäs provides heating from residues in the form of biofuel; no trees are cut down.
“This district heating system uses residual heat. When producing electricity, we use primarily fossil fuels, whereas almost no fossil fuels are used in the district heating system in Gävle.”
“I am not saying that we shouldn’t make heating more energy-efficient, because we have to be resource-efficient. But to reduce global CO2 emissions, we have to reduce electricity use and instead increase electricity production.”
In studying how common electric meters function if we have solar cells on our houses, Mattias discovered that the configuration of the electric meter matters a great deal to homeowners. Results concerning the amount of internal use of electricity versus export of excess electricity to the network may differ. In this way, the value of the electricity you produce may vary.
“We need regulations on how to manage and use excess production of electricity. Today, there is a tax reduction to compensate for the lower financial value of exported electricity, but if that tax reduction is reduced or discontinued, there may be a number of solar cell owners who cannot break even.
Mattias has suggestions that could improve how the Swedish National Board of Housing, Building and Planning calculates the energy efficiency of a building. When calculating the energy efficiency of a building today, their regulations favour heat pumps over district heating and solar thermal systems in district heating system over solar panels.
“But since our district heating system here in Gävle is extremely good with low CO2 emissions, we should perhaps prioritise solar panels that produce electricity above solar thermal systems producing heat on the building. Adding electricity to our electricity network to replace fossil fuels is beneficial. This means that if the district heating system has low CO2 emissions, it is better for the environment to invest in solar panels rather than in solar thermal systems.
In simulating a future scenario about how our electricity distribution network would be affected by charging of electric vehicles, Mattias could determine that, in general, our electricity distribution network can handle a large proportion of electric vehicles. However, electricity distribution networks in the countryside may run into difficulties.
“But how we charge makes a difference; we shouldn’t charge during peak- consumption hours in the evening. Instead, we should charge after we have gone to bed. Then, even the performance of the networks in the countryside will suffice.”
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Mattias Gustafsson was an externally employed doctoral student at Gävle Energi in the industrial post-graduate school Reesbe (Resource-efficient Energy Systems in the Built Environment). He is their first doctoral student of the school to defend his doctoral dissertation. He now returns to Gävle Energi, but will be employed part-time also by the University of Gävle.
“I am employed by Gävle Energi and worked there even before I started studying for a doctorate. Our collaboration is very good and this is also a good way to connect research more closely to businesses.
Mattias Gustafsson defended his doctoral dissertation Energy efficiency measures in the built environment – some aspects to consider in Sweden on Friday 14 December at the University of Gävle.
For more information, please contact:
Mattias Gustafsson, externally employed doctoral student at the University of Gävle
Phone: 070-414 04 85
E-mail: mattias.gustafsson@hig.se
Text: Douglas Öhrbom
Photo: Marie Hägg
