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Developing low carbon heat networks for rural villages in Sussex and Kent

Transforming the way we heat households in rural Britain.

The United Nations’ Intergovernmental Panel on Climate Change has made it very clear that we must reduce carbon emissions to net zero by 2030 in order to avoid runaway global heating.

A crucial strategy for achieving this goal involves decarbonising the way that heat is delivered to rural properties which are not connected to the national gas grid.

BHESCo are developing a number of innovative solutions to heat and power homes in rural areas through a combination of energy efficiency improvements, shared heat networks and renewable energy generation.

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Why we need to re-design the way homes are heated in rural villages

The majority of households in rural England are reliant on fossil fuels as a source of heat, usually heating oil, liquid petroleum gas (LPG) or red diesel.

Burning these fuels releases carbon-dioxide, a key contributor to the climate change crisis, as well as other toxic air pollutants such as sulphur dioxide and nitrous oxides.

In 2017 the UK Government unveiled its Clean Growth Strategy which set out a long term vision to reduce pollution and the use of fuels such as oil and LPG. A key policy proposal was to: 

Phase out the installation of high carbon fossil fuel heating in new and existing homes currently off the gas grid during the 2020s

Build and extend heat networks across the country, underpinned with public funding (allocated in the Spending Review 2015) out to 2021

Connecting rural communities to the existing gas grid is not an option, as the UK Government is planning to transition away from relying on gas as a heat source.

There is already a policy in place which mandates that no new building developments can be connected to the gas grid from 2025. It is clear that over the long-term rural communities will need to find an entirely new way to heat their homes and businesses.

Whilst converting the heat provision for any property is a challenge, the transformation will deliver many significant benefits for villagers, such as:

  • Secure, reliable, affordable heat
  • Community ownership of heat generation
  • Improved local air quality
  • Resilience against global oil market volatility
  • Reduction of climate heating greenhouse gas emissions

The best solution will differ from location to location depending on the requirements of local residents and the unique geographical characteristics of each area.

The most effective outcome will typically involve a combination of  technologies, some of which which are outlined below.

What is a heat network?

A heat network is created by connecting a collection of properties together via a network of pipes which deliver heat from a central generating source.

Heat networks can be very small, consisting of only a handful of buildings, or they can be large enough to cover whole neighbourhoods and cities, such as in Copenhagen. Heat networks can be extended over time, and new properties or heat generating technologies can be added in correlation to demand.

We can divide heat networks into two types;

High temperature heat networks have existed for decades and are common in many parts of the world where urban accommodation will share heat in a district heating system.

These systems require highly insulated pipework to transport heat from the generation source to individual homes and businesses.

Low temperature (or ambient) heat networks provide a continuous supply of relatively low temperature water to buildings. Usually this water is the same temperature as the ground (around 10 °C ) and is used to provide a source of heat for heat pumps.

Although this may initially sound strange a heat pump without a constant source of heat would quickly freeze it’s surroundings.

One of the advantages of a low temperature heat network is that the pipework does not need to be insulated in the ground and there are no heat losses with long pipe runs.

In circumstances where buildings require cooling then a low temperature network can be used to achieve this outcome. Any increase in water temperature will improve the heat pump efficiency for other buildings which are using the network for heating.

Being part of a heat network removes the need for properties to have individual boilers. Each property is fitted with a Heat Interface Unit (HIU) which transfers heat from the shared network to the system within the house. These units are similar in size to a modern gas boiler.

The development of heat networks is considered to be crucial to the decarbonisation of heat in the UK, as they are highly efficient and cost-effective and offer a particularly attractive and viable solution to the replacement of oil heating in rural communities.

What is a heat pump?

A heat pump uses cooled refrigerant to absorb heat from the environment. The refrigerant is then compressed to increase its temperature and the heat is transferred to a water system for use in radiators, underfloor heating, or hot water tanks.

The source of heat in the environment can be one of many things.

Heat from below ground is one of the best sources since the ground temperature (below 1m) remains at around 10°C all year round.

Heat from the air is the most available source, but has the disadvantage of being very cold in the winter.

Heat from water sources, such as lakes or sea water can also provide a relatively warm heat supply all year round.

A typical heat pump can provide 3 to 4 units (kWh) of heat for every unit (kWh) of electricity used to power the heat pump. This efficiency is affected significantly by the temperature difference between source and supply, so a warm source is good and the lower the supply temperature the better so systems like underfloor heating work very efficiently with heat pumps.

Carbon emissions from electricity production have fallen by 50% in the last 10 years and will continue to fall as more renewable electricity equipment is installed. Running a heat pump will already release less than a third of the carbon released by burning oil for heating, whilst delivering the same amount of heat.

What is a shared ground loop?

Ground source heat pumps draw the heat out of the ground through either a series of pipe loops 1-2m under the surface, or from boreholes drilled around 125m into the ground.

Installing these loops or boreholes is costly and requires a reasonably large area of ground. In order to minimize costs and give access to properties without much land it is more efficient to install boreholes at one location and share the heat through a low temperature heat network, or shared ground loop.

Each property has it’s own heat pump and retains the ability to control the temperature of individual rooms in just the same way as having a gas or oil fired boiler.

rural heat network susex kent - brighton hove energy services 2020
An example of a heat network design where each home is fitted with an individual ground source heat pump drawing heat from a shared ground loop and borehole array

The length of piping required for the ground loop will vary depending on the size of your property, the thermal efficiency of the building, and your unique individual power needs.

In circumstances where land available is limited, deep vertical boreholes can be drilled in order to access the heat stored in the earth.

The temperature of the soil remains almost constant throughout the year, meaning the heat pump can generate heat in all seasons.

Solar Power & Battery Storage

Solar panels harness solar power from the sun and convert this into electricity which can be used for our homes, businesses, or other needs such as transport.

This is called ‘Solar Photo-Voltaic’ or ‘Solar PV’ electricity and is generated using solar panels that are usually fitted to a rooftop or ground-mounted in a field.

Over the last 10 years the prices of solar panels have dropped by as much as 75%, making the installation of a solar power system much more cost-effective and available to the general public.

If a property has solar panels as well as a heat pump then some of the electrical energy required to operate the heat pump will come from the solar panels, further reducing the carbon emissions from electricity required to run the heat pump.

When a property is in a position to start generating their own heat through a combination of a heat pump powered by solar panels, they will be protected from the volatile price fluctuations of the international energy market.

For a succesful example of how these technologies can be combined, please see our Case Study on the Montessori Place School in Uckfield, East Sussex.

When considering the introduction of solar power it is worthwhile considering installing a solar battery storage system as well. This allows a property to accumulate energy during the day and release it during the night or whenever necessary.

Having an electricity storage battery also means that energy can be purchased at a low price (by charging the battery) then stored for use at a time when electricity is more expensive (i.e. in the evening).

This stored electricity can be used in order to minimise energy costs, or it can be sold to the national grid when electricity demand is higher.

Energy Efficiency

When we talk about the ‘energy efficiency‘ of a property we are referring to how well it makes use of the energy that is required to heat and power the building on a day-to-day basis. In the UK the energy efficiency of a building is measured by its Energy Performance Certificate (an EPC), which also includes some suggestions on how to improve the property. You can find your EPC using the national EPC Register.

Upgrading the thermal and energy efficiency of a property will significantly reduce the amount of power that is consumed by the building on an annual basis, leading to a corresponding decrease in fuel costs.

In addition to lower energy bills, homeowners who make energy efficiency improvements can expect to enjoy much greater levels of warmth and wellbeing as well as achieving a significant reduction in the size of their carbon footprint.

Typical energy efficiency improvements include loft insulation, cavity wall insulation, low energy LED lighting, double glazed windows, and draught exclusion for windows and doors.

CASE STUDY: Firle Village, East Sussex

BHESCo has received Stage 2 funding from Government to continue our ambition to replace the oil heating in Firle Village with heat pumps. We have permission from the Estate to focus on transforming the heating in Zones B & C first, while we determine how this will work for the properties in Zone A (see map).

BHESCo has already started to survey some of the properties and has prepared a report on our recommendations for four types of properties for the Estate.

We are planning to visit the village again soon to further our assessment of the properties both for energy efficiency upgrades and to measure the heat loads, design the heat delivery systems and start the tender process for a supplier/installer.

Bringing it all together to create a low-cost, low-carbon heating solution for rural communities in Sussex and Kent

BHESCo is working with a number of rural communities across the South East of England to support the emergence of locally owned, low-carbon energy solutions.

We want to empower villages in Sussex and Kent to take control of their heating provision by creating their own heat networks powered by environmentally sustainable sources.

Similarly, we want to assist rural communities to take ownership over their electricity by supporting the development of microgrids and community-owned renewable energy generation.

By combining energy saving measures with heat pumps powered by renewable energy generation and battery storage technology, homes and businesses can achieve a tremendous reduction in the environmental impact of their heating, and in many cases a corresponding decrease in fuel costs.

This is especially important with regards to the decarbonisation of heating throughout rural villages in South East England, many of which currently rely on heating oil or Liquid Petroleum Gas (LPG).

Heat networks and heat pumps are expected to form a fundamental pillar of the UK’s transition strategy towards a net zero emissions economy, and we expect to see a widespread uptake of these technologies over the coming years.

If you live in a village or town in the Sussex and Kent area and are interested in partnering with BHESCo to investigate the economic feasibility of developing a heat network or microgrid in your community then please write to us using our Contact page.

Sources

The Clean Growth Strategy 2017; Leading The Way To A Low Carbon Future, p.13

assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/696273/HNIP_What_is_a_heat_network.pdf