The opening of the two million pound development comprising film and dance studios and new kitchens and dining rooms marks a deliberate move by the school into seriously ‘green’ territory. At nearly nine hundred square metres, the new building would take a great deal of energy to heat by conventional means, to say nothing of the summertime requirement to cool it. Yet both requirements have been met through the use of ground source heat transfer technology, a highly efficient, carbon friendly alternative to burning fossil fuels. The Ground Source Heat Pump system, though technically far more complex, is in reality a very close relative of the humble fridge! We are all familiar with the working of a fridge – the heat from the inside is extracted and dispersed into the room from a panel on the back. Thus we benefit from the coolness in the fridge and the warmth in the room.
Extend this principle just a little further and extract the heat from, or put heat into, not air but a large volume of water, and you have the Hurtwood system. Where is our water source? It’s the original spring-fed water tank for the oldest building on the campus, no longer used, and it contains some seventy tonnes of water. How does the heating (or cooling) get into the building? Via a blown air system which contains fan coils not at all unlike the condenser on the back of your fridge!
And it’s unbelievably efficient – about five times that of conventional means to be precise. So in terms of heating, for around twenty kilowatts of energy running just motors and pumps, we benefit from a hundred kilowatts of energy which magically appears inside the building, all extracted from the water source. Which equally magically gets neither warmer nor cooler – such is the mass of water, its contact with mother earth and its constant replenishment from the spring. In the UK, the earth - a metre or so below our feet - keeps a constant temperature of about 10-12C throughout the year, and it’s all around our tank, and along the 200 metres of pipe from the tank to the new building. To us, a hot summer's day feels many times "hotter" than a freezing mid-winter. But in reality the Earth's surface does not vary in "heat energy" as much as we might imagine. Scientifically speaking, there is only 11% less energy in cold water at 5°C compared to hot bath water at 40°C. It’s an inexhaustible source of energy, and Hurtwood House now has the means to exploit it, to the benefit of the environment and the accounts! Major donors please note that naming rights for the new building are now available!