This paper demonstrates that Ireland is potentially the best country in Europe for solar assisted space heating, particularly when seasonal solar energy storage is combined with the exceptionally low space heating demand of Passive Houses. The performance of a real Passive House with a Seasonal Energy Store is examined and presented.

The Critical Success Factors(CSFs) for a real Passive House with an aqueous Seasonal Energy Store are identified and discussed, including climate, solar yield matching with heating demand, optimisation of both the solar energy storage and the heating system, and finally costs. The performance of an installation in Galway, on the west coast of Ireland, is analysed.