Some 1000 m2 of prepatinated copper is used as the main material for all four facades, applied in horizontal bands of panels and elegantly handling the curves which are central to the design. It was considered important to maintain a consistent appearance for all the copper panels, although those on the south elevation are equipped with the fully-integrated solar thermal function behind (shown light blue on the elevation drawing).
Together, some 80m2 of façade collectors, working in conjunction with 200m2 of roof collectors, provide around 120 000 kWh of heat - as much energy as six average family houses use in the cold Finnish climate annually. This provides about 5% of the annual heat demand of the Swimming Complex. The solar system is used to preheat 4°C cold water coming from the cold pool. This preheated water is then mixed with a larger amount of water coming from the main circulation. The mixed water then passes through the roof collectors before joining circulation from the district heating system.
In summertime, when the Swimming Complex is closed and an open pool used instead, the combined solar thermal system is enough to maintain the pool water temperatures at normal levels without any additional heating. This enables the pool to remain full throughout the year, rather than have to empty and refill it, saving substantial amounts of water. In future it should also be possible to keep the Swimming Complex open for use throughout the summer.
Copper is especially well-suited to solar thermal façade systems because it has the best thermal conductivity of all the usual façade and roofing materials. It also enables architectural design freedom with the invisible integration of collectors behind the copper. In principle, any copper surface is suitable - whether prepatinated or oxidised copper or alloys - although there are some differences in energy production.