The Heat / Cool System at Stockwood
This ambitious project will make our business park less dependent on fossil fuels, contribute to achieving UK climate change targets, as well as significantly improving the standard of life at the Business Park for all that work here in a cost-effective manner. An all-round winner!
With a heat pump, up to 80 percent of the total energy demand is taken from nature, using highly
effective and environmentally responsible technology. Only electrical power is required to drive the heat pumps, and we will be generating some of that from the sun with our photovoltaic system; The solar energy stored in the ambient air and in the ground water is used in combination to efficiently provide heating water.
40% of CO2 emissions are derived from the heating and cooling of buildings and only about 1% of heat currently comes from renewable sources in the UK. Government projections have set the challenge of increasing this to 12% by 2020. In total, the UK is committed to generating 15% of its energy from renewables by 2020.
Ground source heat pumps: What is it?
The principles of ground source heat pumps were first described by Lord Kelvin in the 1850s and continuous development since they were first used commercially more than 50 years ago, has greatly improved their efficiency. GSHP systems are common in the USA, Canada, Sweden, Switzerland and Germany.
A ground source heat pump extracts heat from the ground to heat water by circulating a mixture of water and antifreeze around a loop of pipe – called a ground loop – which is buried in the ground. Beneath the surface, the ground stays at a constant temperature, so a pump can be used throughout the year. Modern ground source heat pump systems are very efficient. For each kilowatt of electricity used to run the heat pump, three to four kilowatts of heat can be delivered to the building.
The CO2 saving depend on what sort of home-heating fuel system you’re replacing. Maximum annual CO2 savings are 7 tonnes if replacing an electric heating system, 6.5 tonnes if replacing solid fuel, 1.8 tonnes if replacing oil and 1.2 tonnes if replacing gas. Stockwood previously relied on a combincation of electric and gas.
The specific heat pump to be installed is shown below. It is a Viessmann Vitocal 300-G Pro and two are housed in two containerized units.
At the heart of the heating and cooling system is a pair of Swiss-made heat pumps, which give a
combined heat output of nearly 300 kW. In order to generate renewable heat, the heat pumps collect low-
grade heat from the nearby field using an 11km network of pipework that forms the horizontal ground collector array.
The array is filled with 18,000 litres of special heat transfer fluid which is used to collect the low-grade heat from the ground before it is converted to useful high-grade heat by the heat pumps. The heat is transferred to a 5,000 litre insulated buffer tank, before it is circulated around the business park through the new district heating network.
In the summertime, the system will be switched into reverse, and heat will be extracted from the units via the district heating network and stored back in the ground again, ready to be recovered the following winter.
Although the heat from the ground is free and renewable, some electricity is required to power the
heat pumps and circulation pumps. In order to offset the purchase of electricity from the grid, we
have installed 170 solar panels on the roof of Unit 1B, which can generate 50 kW of clean electricity to power the system.
The system is one of the largest of its kind in the UK, and we are proud to be using this innovative
technology to bring us closer our goal of making the business park the most environmentally friendly in the UK.