Granlund is helping to increase the amount of solar energy in Helsinki

Solar power and renewable energy sources are important parts of the City of Helsinki's climate goals. Granlund has been responsible for the electrical design of several solar power plants.

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In recent years, the City of Helsinki has made significant investments in building solar power, and new sites are being identified all the time. For example, Finlandia Hall now has 180 solar panels on its roof, while Hiidenkivi Comprehensive School has 178 and the meat wholesale hall at the wholesale market has 243.

"The City of Helsinki is committed to promoting the use of renewable energy sources. The City is preparing an emission-reduction programme named Carbon-neutral Helsinki 2035, which will require major investments, particularly in increasing the use of solar energy. Buildings could save 2–20 per cent of the amount of electrical energy they use annually by fitting a solar power system," says Sirpa Eskelinen, Senior Energy Expert at the City of Helsinki.

Granlund has been involved in preparing the electrical design of building services and monitoring implementation in Finlandia Hall, the wholesale market, Hiidenkivi and Torpparinmäki Comprehensive Schools, and Mellunkylä emergency response station. The solar power systems were supplied by GreenEnergy Finland Oy, which was also responsible for dimensioning and simulating the solar power systems.

The City's targets are to reduce carbon dioxide emissions and to save electrical and heating energy, which will also reduce the City's energy bills.

Solar power systems for old and new buildings

The City of Helsinki intends to increase the amount of solar energy and other renewable energy used by new and existing buildings.

In terms of electrical design, incorporating a solar power system into a new building does not really add to the workload, but older buildings require more work. The structural designer inspects the condition of the roof and prepares a study that is used to decide whether it is worth retrofitting a solar power plant.

"One challenge is to identify and plan the cable routes, which must correspond to electrical and fire safety regulations while being technically and financially viable. Special attention must also be paid to the lead-ins for electrical cables to ensure that the building's conditions are not jeopardised. Cable routes must be carefully considered, particularly in buildings with a high cultural historical value like Finlandia Hall," says Antti Kulmala, Granlund's Project Manager.

As solar power plants become more commonplace, more common guidelines will be required for designing and implementing them. Solar power systems always have live DC power, and this needs to be taken into consideration in the event of a fire.

"When the solar power plant was designed for Mellunkylä emergency response station, the fire safety of the solar power systems was a concern. How can fires be extinguished on sites with solar power systems? The Mellunkylä solar power plant employed optimiser panels, a new technology that can be de-energised," Kulmala says.

Solar power has a bright future ahead of it

The price of solar power plants has decreased dramatically over the last ten years, and the price of solar energy is also following a downward trend. For this reason, solar power is almost always considered when renewable energy sources are reviewed for new-build and complete renovation projects.

"The energy analysis conducted during the project planning phase involves simulating 2–3 energy design solutions for the building, one of which is typically solar energy. The simulations focus on technical and financial viability," Sirpa Eskelinen explains.

The City's targets are to reduce carbon dioxide emissions and to save electrical and heating energy, which will also reduce the City's energy bills.

"Selling electricity to the grid does not have a major a impact on the electrical design. However, it currently makes sense to design solar power systems in such a way that as much energy as possible from the system is consumed on the site where it is installed," says Kulmala.

5 ways of reducing the carbon dioxide emissions of buildings

  1. Adjusting the controls for lighting and building automation
  2. Utilising heat recovery
  3. Deploying appropriate ventilation
  4. Replacing bulbs with LED lights
  5. Using renewable energy
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