In 2009 Castle Howard was one of the first historic properties to enter into the emerging renewables market and pioneer the use of renewable energy heating at its site. A 199kW heat pump was installed which draws its energy from collectors placed in the Dairy Pond to the North front. This system was used as a case study for many historic properties and estates taking their first steps into renewables thereafter.

The system operates through circulating water through 56 coils pipes which are submerged in the lake. The water absorbs the heat from the lake which is pumped to the house and compressed to generate higher temperatures which are used within the wet heating system in the Castle and also to heat the hot water for the kitchens serving the Fitzroy Café. As a result of this project 85,000 litres per annum of oil consumption were eliminated along with a 70% reduction in carbon. The Estate, being committed to reducing its reliance on fossil fuels, also has a wood chip biomass system in order to heat our Estates Office and we have four properties within our estate which benefit from heat generated from air source heat pumps.

Our commitment to improving our environmental credentials doesn’t stop there however. During lockdown we have been busy planning to expand our lake source heat pump system. Since the system was installed our visitor numbers have grown, thus causing demands for hot water in our kitchens to increase. We found that the heat pumps couldn’t cope with demand and we were relying on electric immersion heaters which are not only expensive but are also not an energy efficient method of generating heat. Furthermore, only part of the Castle is connected to the wet heating system. Those spaces which don’t have radiators are heated by plug in oil filled radiators which again, are costly, likely to come from energy generated by fossil fuels and can contribute to higher humidity levels within the building.

We have therefore designed an additional 150kW heat pump system which will sit alongside the existing pumps. Through increasing our capacity we will be able to install more radiators to spaces currently heated electrically along with meet 100% of our hot water demands. Heat pumps operate at lower temperatures to conventional gas and oil fired systems which is good news for historic houses. Through operating the system constantly at the lower heat output of 55 degrees it helps us to provide a steady environment for our precious contents and collections which can be at risk of irreversible damage from both high humidity and fluctuations in humidity.

When you visit over the forthcoming weeks you may therefore see some equipment along the North shore of the Dairy Pond. This a new array which is being constructed to accommodate over 5 km of pipes which will be floated out into the lake and submerged so that we can draw the heat required for the extended system.

Any savings made as a result of the new system will help fund the upkeep of Castle Howard along with going towards vital conservation work.