Dimplex ground-source heat pumps provide low-carbon heating and passive cooling
A Dimplex ground-source heat-pump system is providing low-carbon heating and passive cooling for a new building at SciTech Daresbury in Cheshire. Vanguard House, a 3600 m2 3-storey office and laboratory facility, was designed to achieve a BREEAM ‘Excellent’ rating and does not use any fossil fuels.
Designed and installed by Dimplex expert partner Ecovision Systems, the system uses two heat pumps to provide 260 kW of heating capacity at a maximum temperature of 60°C. These heat pumps are reversible to provide passive cooling during the summer. In cooling mode, a flow temperature of 18°C is sufficient to cool the building, so no active chilling is necessary.
In addition, a 40 kW high-temperature heat pump provides all the domestic hot water, achieving a flow temperature of 70°C.
Vanguard House is above one of the largest natural aquifers in the UK, the Permo-Triassic sandstone. Groundwater is plentiful, so Ecovision developed an open-loop system drawing water from a depth of 65 m and passing it through a heat exchanger before re-injecting it into the ground at depths of up to 150 m — removing any risk of groundwater flooding into service channels and basements.
Because the system provides heating and cooling, the net change in groundwater temperature is limited.
The average temperature of water from the aquifer is 10 to 12°C, and the heat pumps can achieve a COP of 4.2. Heating and cooling is delivered to offices and laboratories by a concrete core activation system consisting of pipes embedded into the pre-cast concrete planks that form the floors.
Other design features of Vanguard House include part brise soleil, solar glazing and blinds to help manage temperature changes by reducing solar gain.