Shared Ground Loop Arrays

How are Shared Ground Loop Arrays different to district heating?

Kensa’s Ambient Shared Ground Loop Arrays (SGLAs) design out the issues of traditional district heating and heat networks, which can be energy wasting, financially front loaded systems, which are complicated, admin heavy, liable to heat provider exploitation, and require large amounts of space for plant room equipment and a backup system in case of failure.

Whilst Fifth Generation District Heating and Cooling (5GDHC) networks remove some of the negatives of traditional district heating schemes, such as reducing heat losses and the need for energy centres, and allow for the introduction of waste heat for more efficient heating and cooling, Kensa’s 5GDHC system featuring SGLAs goes a step further, by providing an individual heat pump to each dwelling and so removing the need for a plant room, complex billing and restrictive energy supplier contracts, safeguarding against whole system failures, whilst utilising a ground array to provide flexibility for integrating additional energy sources and permitting inter seasonal heat storage.

Kensa’s decentralised Shared Ground Loop Array approach results in an even more efficient system as high-grade heat is only generated at the point of use by the ground source heat pump, and only when required; unlike traditional Heat Networks and some 5GDHC systems where heat is generated in a central plant and then circulated inside the building continually, thus leading to heat losses and overheating particularly in risers and communal areas.

Ground Source Heat Pumps

A Ground Source Heat Pump offers non combustion space heating, cooling, and hot water, whilst producing approximately three times more energy than it consumes.  The heat pump is an electric appliance which transfers heat from the ground or water – a constant and renewable solar heat source, unaffected by air temperatures, compresses it and delivers it to the building at the required temperature for heating and hot water production.

Environmental Benefits

This system offers national planners a way of helping to meet CO₂ reduction targets, moving away from fossil fuel, combustion heating to a system which exploits the decarbonisation of electricity production in the most efficient way.  Its effectiveness as a low carbon technology can be enhanced when used in combination with other renewable technologies such as;

• Phase change heat storage;
• Town scale battery storage;
• Utilising cheap, low carbon electricity at low demand parts of the day and night;
• No local atmospheric pollution increasing air quality in urban areas.

Electricity Grid Benefits

The energy source for ground source heat pumps – the ground – is stable all year round, which makes it extremely useful for decarbonising the grid. Naturally, ground source heat pumps offer greater grid balancing capabilities than air source heat pumps due to this stable heat source.

By using time-of-use tariffs and thermal storage, ground source heat pumps can be turned on and off to not only balance the grid and reduce peaks and troughs, but also to lower the carbon intensity and running costs of the heat pump; a heat pump is now a key component to a broader household energy system.

By electrifying the grid via ground source heat pumps, overall investment in electrical generation goes down. Once at scale deployment of heat pumps, they will offer even greater grid balancing opportunities.

*Daily average cost and carbon graph: Base electricity charges based on Sheffield averaged on the Big Six once a month – average electricity cost per kWh (www.ukpower.co.uk/home-energy/tariffs-per-unit-kwh, www.nottenergy.com/energy_cost_comparison). Octopus Agile Tariff (average over 24hrs). Average CO2/kWh over 24hrs in winter (www.carbonintensity.org.uk)

Developer Benefits

The individual ground source heat pumps connected to a shared ambient loop offer a straight forward solution to a number of M&E issues;

• Uncomplicated solution which uses existing internal controls and standard plumbing;
• Easier and cheaper compliance with SAP 10 building regulations;
• System architecture is completely scalable and can be installed with project phases;
• Installation does not impact visual appearance and does not reduce kerb appeal;
• Will not add to overheating problems;
• Can offer passive/active cooling;
• Increase useable space in developments which otherwise would need plant rooms;
• Uncomplicated schematics and no need for expensive pipe insulation;
• No requirement for heat meters and admin of providing heat to individual users;
• No expensive maintenance of plant room.

End User Benefits

The home owner or tenant living in the dwelling with a heat pump benefits enormously from;

• The lowest running costs of heating
• Very low maintenance cost
• No annual servicing
• Familiar controls

Peer Reviewed

In light of London’s drive to become a zero-carbon city by 2050, the Greater London Authority (GLA) commissioned a report by Etude into the scope and opportunity for ‘Low Carbon Heat: Heat Pumps in London’. The report features Kensa’s Shared Ground Loop Array scheme at Enfield, and is well-timed to provide an invaluable resource to guide the specification of low-carbon heating in London’s new builds.

The report concludes that: