Ground heat keeps new castle warm

Riverstone Castle is being made of 20,000 concrete blocks laid on 540cu m of concrete.

How to heat a castle? That was the challenge for Christchurch engineer Alan Cooke when he got the job at Riverstone Castle being built by Dot Smith outside Oamaru.

The castle comes complete with moat, drawbridge, dungeon and secret tunnel. The big stone and brick structure is rising near the much-awarded Riverstone Kitchen restaurant, gift shops and extensive organic vegetable and flower gardens.

Cooke, a senior mechanical engineer in consulting business Babbage's Christchurch office, said he hadn't faced anything as difficult as the castle.

"It's one of the more unusual requests of my career. How do you efficiently heat a castle made of 20,000 concrete blocks laid on 540cu m of concrete?"

Cooke has had a state-of-the-art ground source heat pump installed which he said would provide cheap heating via underfloor coils which draw energy from the ground.

"They cost more to install but for a large facility like a castle, they're the most efficient heating option in the long run."

A book has been published on the castle and other ventures.

Dot - Queen of Riverstone Castle by Dot Smith with Nathalie Brown tells how she lives on the property owned with her husband Neil where they have six dairy farms running more than 4000 cows but also of their struggles to get the farms established, her interest in travel, gardening, cooking, retailing and building the castle.