Hjorthagshus’ plots, streets and the Motala Park cover a land area of 38,000 m2. Every year, we receive large amounts of energy from the sun, approximately 41,000,000 kWh/year. Solar energy is free, completely without climate-impacting carbon dioxide emissions and easy to harvest.
The association currently uses totally around 4,200,000 kWh/year, i.e. we get almost ten times more solar energy for free than the energy we today use. If we improve energy efficiency, we will need about 1,200,000 kWh/year, which the sun easily provides. If we completely switch to solar energy, we will not have to buy energy at all – we will become self-sufficient!
The City of Stockholm allows us to also use land outside our property boundaries for energy extraction. It can be heat pump systems using the bedrock or the soil, energy storage in the ground or other equipment deemed necessary for our buildings energy supply.
In connection with the transition to solar energy, the association’s running costs will fall sharply because the equipment for harvesting solar energy annually costs significantly less than the energy annually purchased by the associations.
Above our roofs from the north on a sunny day. The roofs are large in relation to the flat surface and are – after some adjustments – excellent for solar energy extraction. Electricity and heat can be stored from the sunny half of the year to the less sunny one. Solar heat can also be harvested in winter. The film below shows a conventional solar thermal collector which in February makes the water boil even though the outdoor temperature is minus 16 degrees.
Even in early mornings, the sun from the east can be converted into electricity or heat.