An office building of approx. 35,800 m² BTA, with two basement floors below ground, is now under construction at Campus Ullevaal in Oslo. Increased use of heat storage and heat recovery in buildings represents a local initiative for development towards a more sustainable society and contributes to achieving the UN's and EU's goals for sustainable and energy-efficient buildings.
The project will show that the utilization of ground heat from soil masses can have good profitability and be a real alternative to other energy solutions in areas with thick soil masses in Norway.
Background
The building site for Campus Ullevaal is mainly on clay with a thickness of 15-40 meters, and due to the building's two basement floors, piling is required as far as 15 meters below the ground surface to stabilize the construction pit during construction. Sheet pile walls are a common stabilization method in Norway and it will take 580 tonnes of steel to cover over 5,600 m2 of loose material around the construction pit.
In Norway, the sheet piles are often left in the ground when the building is completed. The volume between the sheet pile and the basement wall is backfilled, and the sheet pile remains in the ground without any function. At Campus Ullevål, this sheet pile will be prepared for further life and will have an additional function as an energy sheet pile.
Energy sheet piling has not previously been used in Norway, and operating experience from reference projects in the rest of Europe is very limited or not published. There is a need for a full-scale installation to verify the calculations that have been carried out so far and to speed up the technological development of energy scrap as thermal energy storage.
Stable thermal effect
Preliminary calculations estimate an energy storage capacity in the order of 150 – 250 MWh and a power output of between 25 – 75 kW stable thermal power depending on the operating strategy. This will help to recover energy locally and cover part of the building's energy needs, as well as contribute to peak shaving in periods of high power demand in parts of the year.
The solution has an estimated net negative greenhouse gas emission after 3 – 5 years of operation, depending on which energy performance is used as a basis. These estimates have the project as a goal and must be documented through follow-up and operation of the facility over the next 5 years.
