Feeling the heat? How to transform your school into a beacon of sustainability

Heating accounts for around half of all the energy consumed in the UK and is responsible for roughly half our carbon emissions. With this in mind, the government announced its £860 million Renewable Heat Incentive in March which it hopes will transform the way we heat our buildings. We investigate how you can take advantage of the incentive and transform your school into a beacon of sustainability.

With the warm summer sun flooding through the classroom windows, the heating systems at your school may be the last thought on your mind. However, if you are not already doing so, you could be harnessing those precious rays of sun to reduce your fuel bills both now and in the depths of winter. You could also greatly reduce your carbon footprint – something which every school in the country should be actively pursuing as an example for children and local communities.

If reducing your fuel bills and your environmental impact weren’t already enough incentive, the government is introducing what it hopes will be the final push which starts a revolution in the way we heat our buildings and homes.

Described as the first scheme of its kind in the world, the Renewable Heat Incentive (RHI) is a new government-backed measure which aims to encourage us all to switch over to renewable heating technologies.

The new incentive is projected to reduce our total emissions by 44 million tonnes by 2020, the same amount of carbon as emitted by 20 gas power stations in one year and is being introduced in two phases, with the first phase focused on the non-domestic sector – including schools.

Schools who install one of the eligible heating technologies – or who have completed an installation since15 July 2009- will be entitled to claim quarterly payments for 20 years. Payments will be based on the tariff level set for that technology and the size & output of their system.

Those who do claim their slice of the £860 million fund are said to expect a healthy rate of return on their investment of up to 12 per cent. For example, a ground source heat pump installation costing £300,000 would receive a subsidy payment of £27,600 a year.

School-friendly technologies which are currently eligible for RHI payments are biomass boilers, ground source heat pumps and solar thermal installations.

There are several renewable heating technologies are currently excluded from RHI eligibility, most notably Air Source Heat Pumps. The government says that complex issues remain over their inclusion; however, it is reviewing all the candidates and will revaluate their eligibility in 2012.

Biomass boilers

Biomass boilers are run on biological material, such as a wood, which is considered to be a carbon neutral fuel since the carbon which is released is the same as removed during the plant’s life.

In striving to meet carbon emissions targets, many schools have been quick to take advantage of the benefits of biomass since the technology is relatively simple to install in place of an existing boiler.

When considering biomass boilers it’s important to address key practical issues, says Martin Murrish, technical manager of Hoval Ltd., which has extensive experience of working with schools to help them choose the best option for their particular needs.

“Our experience has shown that it’s important to evaluate a range of day-to-day practicalities that accompany any biomass system”, he says.

A key issue, for example, is the overall suitability of the site in relation to fuel storage and deliveries; both of which influence the choice of wood fuel to be used – typically either wood chips or wood pellets.

Wood chips vary more in their combustion efficiency than wood pellets and are also larger with a lower calorific value, so this impacts on storage volumes and frequency of deliveries. On the other hand, wood chips cost less than pellets so it’s important to take this into account. However, it’s worth noting that the cheapest chips will usually produce higher volumes of ash, which has implications for everyday maintenance.

Chips are normally delivered by large tipper lorries, so access routes and turning circles also need to be considered and, typically, a tipper lorry dictates that the fuel storage be below ground. Chips also need more robust handling equipment, so this can have an impact on capital costs.

Pellets are usually delivered by a smaller ‘blower’ vehicle and the best results are achieved by using a vertical storage silo, which can be sited indoors or outdoors. Because of their height, outdoor silos may require planning permission.

All biomass fuels produce particulate emissions so it’s also important to include mechanisms to eliminate these. Experience shows that the most effective way to comply with the latest air quality legislation is to use special ceramic filters.

Just as important is getting the buy-in of the people who will use the boilers. In particular, they need to understand how maintenance requirements differ from more familiar gas or oil.

For all of these reasons it’s vital to consider the full ‘biomass picture’.

Ground source heat pumps

Ground source heat pumps are a popular choice for schools, which normally have a large amount of suitable land available nearby for installation. These can be laid, for example, beneath the school playground or field.  Many schools are considering heat pumps for both new and retrofit situations.  With new builds, this is a great opportunity to fit underfloor heating systems, which provide the most effective distribution of this more natural form of heat energy.

The way ground source heat pumps work is by circulating a refrigerant fluid around a circuit containing four elements: evaporator heat exchanger, compressor, condenser heat exchanger and expansion valve. Heat absorbed from the ground is transferred to the liquid refrigerant which evaporates to form a gas. This gas is then compressed which causes its temperature to rise. The hot gas passes into the condenser where it starts to change back to a liquid as heat is transferred into the building.  After passing through the expansion valve, the liquid refrigerant returns to the evaporator and the cycle begins again. Heat pumps are effective both in summer and winter, day and night because the ground temperature remains constant at only a few feet below the surface.

When existing schools are looking to fit heat pumps then there may be a need to upgrade the level of insulation in a building to ensure the heat pump can operate to maximum efficiency.  It may also be necessary to install new radiators, as sometimes older-style radiators can provide inadequate distribution of heat.  In some school retrofits, the school keeps the boiler as a back-up supply, as this can offset requirements in times of peak demand, however this is not normally necessary.

Danfoss, a leading producer and installer of heat pumps, recently completed a project for a school inMansfieldwhich had ground source heat pumps fitted for a new extension – that provided all the school’s heating needs in one of the coldest winters on record!

Large expanses of land are not essential either – another Danfoss project used boreholes at a school in Lytham in the North West, to provide the energy source for the heat pumps using the depth to source the energy, rather than ground loops being set in trenches.

Solar thermal

Have you ever sat in a conservatory or your car on a cold sunny day and enjoyed the heat from the sun?  If so, you were experiencing Solar Thermal heat in practice.  Now imagine if you could capture that energy and use it to heat your water.  That’s exactly what a Solar Thermal system does!

From a distance, Solar Thermal panels look similar to their ‘electric cousins’, solar PV panels, and are typically fixed to the roof of a building using a light-weight metal frame. The system contains a mixture of water & glycol (to stop it from freezing at night) which is driven around the system using a pump, which is itself sometimes powered by electric solar panels. The heat from the mixture is then passed to your hot water storage tank to relieve your conventional water heating requirements.

According to Alternative EnergyUK, an approved Solar Thermal installer, these are some of the issues you need to consider when investing in a system:

•        Make sure the installer and the products they use are registered under the Government’s Microgeneration Certificate Scheme.

•        Can you position the panels so they are facing between SW and SE at a tilt of approx. 35 degrees?  The more you move away from South the more you move from the optimum.

•        If there is shading caused by buildings or foliage then this will have an impact on the performance of your system.  Trees may need to be maintained over the lifetime of the system.

•        Although Solar Thermal systems can provide hot water all year round it is clear that a greater amount of heat will be provided during the summer months and less so in the winter months.

•        Does your pattern of demand for hot water match what the system can deliver. Remember: a Solar Thermal system will not provide all your hot water needs and must only be considered as an addition to the primary heating system, such a biomass boiler.

Many schools are combining multiple sustainable technologies, in addition to those covered by the RHI, such as wind turbines and solar PV, which generate some or all of the green electricity to drive their newly-installed solar thermal or ground source heat pump systems.  When these technologies are combined with upgraded insulation, it can offset the electrical energy used to power the new systems, leading to a carbon neutral installation.

Professional advice

For those schools who have yet to take the plunge, the RHI now means that investing in renewable heating technologies is an undeniably excellent way to reduce heating bills, reduce your environmental impact and set the right example to children and local communities.

For more information and professional advice about the feasibility of installing technologies which the RHI supports, here are some useful contacts to help you on the path to transforming your school into a beacon of sustainability:

Biomass Boilers

Hoval Ltd
Tel. 01636 672711

Ground Source Heat Pumps

Danfoss Heat Pumps
Tel. 0114 270 3900

Solar Thermal

Alternative EnergyUK
Tel. 0800 012 6826

Renewable Heat Incentive

Department of Energy & Climate Change (DECC)
Tel. 0300 060 4000

Carbon Trust

Tel. 0800 085 2005


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