Net zero ready
Heating and hot water throughout the East Range are now provided by six air source heat pumps, located in the second level of the Castle’s vaults. The vaults were added in c1580 and so engineers believe that this may be the oldest building in the world to adopt this technology.
James Cameron of electrical consultants Harley Haddow said: ‘The heat source has been chosen for its excellent sustainability and renewable energy credentials, allowing the castle to be Net Zero ready and removing the need for traditional fossil fuel supplies such as oil or gas.
Greater efficiency
Heat pumps work by taking the low-grade heat in the ambient air and elevating this to higher temperatures suitable for heating and the production of hot water. The ambient air used to drive the heat pumps at Rosslyn Castle is drawn through the vaults by three electric fans located on perimeter walls. To minimise any noise impact within the Castle or the Glen below, slow running fans with large attenuators have been selected.
The ratio of heat produced by the heat pumps to the electricity consumed is in the region of 3.5 to 1. This means, 3.5kW of useful heat is produced for 1kW of electricity consumed. This figure will fluctuate throughout the year with the efficiency becoming greater in warmer weather and reducing during colder spells. The thermal mass of the vaults will help to improve the efficiency during the colder spells.
To help maximise the efficiency of the heat pumps and to provide resilience to the system, four large thermal stores have been provided as part of the design. The thermal stores can be thought of as thermal batteries being charged by the heat pumps. By incorporating the thermal stores, it was possible to reduce the capacity of the heat pumps to work within the confines of the available electrical supply.
The heat emitters within the Castle are a mixture of wall mounted radiators and underfloor heating. The installation is estimated to reduce the buildings heating and hot water energy consumption by 67% and save over 17 tonnes of CO2 per annum.
We believe, Rosslyn Castle may be the oldest building in the world to have adopted air source heat pumps as a sustainable, low carbon technology of the future.‘
