Meeting Residual Heat Loads in a Passivhaus Using Solar Energy and a Seasonal Store: CIBSE ASHRAE Technical Symposium, Imperial College, London 18th 19th April 2012

A house constructed to the Passivhaus standard, situated in Co. Galway, Republic of Ireland, has seen the heating season for an Irish dwelling drop from a predicted eight months to two. The Passivhaus has a (low) predicted demand for heating between October and May of 1832 kWh, and a year round demand for domestic hot water. To meet these needs a 10.6m2 evacuated tube collector was installed on the south-facing roof. This feeds the DHW tank, underfloor and air space heating and a 23m2 sensible seasonal store buried in the garden. This paper reviews performance of the installation over an 18 month period.
A space heating Solar Fraction of 0.72 was achieved for the heating season from September 2010 to April 2011. The seasonal store provided a significant 556kWh of energy in 2010, despite losing 50% of the peak stored energy of 1111kWh through sensible heat losses. The financial analysis shows that direct solar heating combined with the ISES is the most economical solution for heating especially when the proposed UK RHI incentive is considered.