The swimming pool as thermal storage

The home is located in the Vienna hills on a sloped site with excellent south exposure. The exterior walls and roofs are super-insulated and air-tight to limit heat loss. The south facade is completely glazed and fitted with exterior adjustable blinds and overhangs; this enables generous solar heat gains in winter and adequate shade in summer.

The 350m2 home is conditioned by a unique, innovative solar thermal heating system. A conventional solar system with collectors on the roof and a domestic hot water tank in the basement has been modified to incorporate in-floor heating and an indoor swimming pool. The pool itself serves as a large-volume, moderate-temperature storage; on sunny days it acts as a temperature buffer, absorbing excess heat from the solar system and on cloudy days, when the solar loop is operating at lower temperatures, it has the advantage that can still extract some warmth from the system. Further, in the heating period, the moderate temperatures stored in the pool are adequate to serve in-floor heating on the one hand and to provide pre-warming of municipal water supply for domestic hot water use on the other. The system effectively increases the capacity of the solar system to store solar heat from the summer for use in the winter.