Hull uses heat pumps as part of their eco-efficiency plan
How do you fund renewable energy technologies if they significantly increase the overall costs of a project? Hull City Council and its property management company, NPS, devised a financial mechanism that allowed them to build Green Way School - a low carbon eco-school - that is heated by ground source heat pumps.
In 2008, Hull City Council built Green Way School - the first that the authority had built for 15 years.
The council worked with NPS Property Management on the environmental design of the school. There was no biomass supply chain available at the time. But the school had a big enough land area so ground source heat pumps seemed to be the best heating option.
Ground loop heat pumps were chosen as the water table was too high for boreholes.
The school cost £4.8 million. The Low Carbon Buildings Programme contributed £26,000. This paid half the cost of the wind turbines that generate the electricity to power the ground source heat pumps.
Hull City Council wanted the school to have outstanding environmental credentials and be an exemplar. Councillor Dave Woods says:
"As a council we've been looking at ways of reducing energy costs, energy consumption and carbon emissions. Through the planning policies we now have, we're asking for 10 or 15 per cent energy generation through developments that we're doing. So things like the heat pumps at the school are a way forward."
Renewable technologies tend to be more expensive to install than traditional technologies, and so they tend to raise up-front costs. For this reason the council and NPS looked at what the additional costs were going to be and what potential savings could be made by adopting those technologies.
How do you fund renewable energy technologies if they significantly increase the overall costs of a project? There was a standard cost for building the school and an additional cost for putting the renewable technologies in.
Hull City Council and NPS calculated the financial and environmental savings that were going to be made through ground source heat pumps and other technologies. The public sector is allowed to borrow money through prudential borrowing, providing it makes savings for the council.
The council made a contractual agreement with the head teacher. The school has cheaper energy bills because of its renewable technologies. What it saves it pays back to the council, which enables the council to pay back the loan.
Councillor Woods says that the Hull City Council always lets developers know it wants 10 to 15 per cent energy generation onsite.
"We've found pre-application discussions very useful because we can talk through these things with the developers before planning applications actually come to committee or go through the planning department. And if they know in advance that we want to see 10 or 15 per cent energy generation on site - and things like ground source heat pumps - they can build that into their development."
Once you have installed ground source heat pumps into a building, teach users about the heating system, how it works and how to operate it.
Different renewable technologies suit different builds. Pick the appropriate technology for a site for the right reasons. For ground source heat pumps you must check that the water conditions and ground conditions are suitable.
Ground source heat pumps work best in buildings with long occupancy hours. A ‘conductive screed' will make them more effective in a building with short occupancy hours like a school. ‘Screed' is the concrete that is put over the top of the heating pipes under the floor. A conductive screed will help conduct the heat from the pipes into the room.
Zone the building properly. You need to have very extensive zoning of the building to ensure that you don't get hot and cold spots. This will also help to minimise disruption if repairs need to be done. If the building is zoned well you only need to close down a very small part of the system to isolate it. The rest of the system could continue. This means you can postpone repairs until a weekend or holiday when the school is closed.
Consider how the building may develop in future by documenting where access points to the system are. Ground source heat pumps are hidden so this documentation is very important. Make sure that all relevant departments and bodies have copies of the documentation, for example, the school, children and young people's services, maintenance teams.
At Green Way School there are points where rooms could be divided or walls moved in the future. The heated pipe work does not go across those points.
Ground source heat pumps are very reliable and have a life expectancy of at least 25 years. Compared to gas boilers, ground source heat pumps need very little if any maintenance, which saves money and time.
Elizabeth Wilson, the Head Teacher of Green Way School, says:
"The educational benefits for the children have been wonderful, as the new technology in school has helped them to understand sustainability. Our Eco-Council has used the ground source heating as a study in an attempt to achieve Green Flag status."
John Bell, Energy and Environmental Design Manager
NPS Humber Limited
Earle House, Colonial Street
Hull HU2 8JY
Telephone: 01482 816155
1 May 2012