GSHP's to improve London's air quality - web yellow

How innovative heating systems can combat climate change & local air pollution

In light of Government’s Clean Air Strategy, the city of London’s Cleaner Heat Cashback scheme, and the Royal College of General Practitioners announcing they are to cease investment in the oil and gas sector due to its impact on climate change, air quality, and health, Kensa investigates the role of ground source heat pumps in our buildings and how they can combat local air pollution.

Air Quality

According to current estimates by the UK Health Alliance, outdoor air pollution contributes to around 40,000 premature deaths, over 6 million sick days and an estimated total social cost of over £20 billion per year. In 2017, the Royal College of Physicians (RCP) revealed that 44 of the 51 UK cities in the WHO’s ambient air pollution database exceed WHO’s recommended limit for air particulate matter.

Air pollution comes in three main forms: particulates; Nitrogen Oxides (NOx); and Sulphur Oxides (SOx). Much of this air pollution is caused by vehicle transport but there is also a contribution from combustion heating systems that burn gas, oil, LPG or biomass to produce heat.

In particular, air quality in the UK’s cities is a major issue. In London, the NOx pollution contribution directly from domestic and commercial gas boilers is estimated to be 16%, but that percentage is set to grow as transport becomes cleaner.

The correlation between air pollution, climate change, and health has been widely publicised recently following the Royal College of General Practitioners (RCGP) announcing they are to cease any future investment in the oil and gas sector (1st August 2018) due to climate change being a “clear risk to the health and wellbeing” of patients, placing the NHS under severe strain.

The public health charity Medact describe air pollution as “comparable to tobacco in terms of the number of deaths per year for which it is responsible”.

Dr Katie Clare – Public Health Doctor and Medact member, says:

The RCGP’s decision to divest could not be more timely. This sends a strong message that fossil fuel companies that damage our population’s health through air pollution and climate change have no future.

Medact spokesperson Deirdre Duff says:

The fossil fuel industry is driving the climate crisis and their actions have led us to the brink of a public health emergency. Gas, oil and coal companies continue to push false climate solutions and their lobbying is a huge obstacle to climate progress.

The RCGP decision to divest shows up the fossil fuel industry for what it really is – a rogue industry that is claiming patient lives today and putting the future health of people and the planet in even more danger.

Addressing our approach to heating and cooling existing and new buildings is therefore vital to deliver the air pollution and carbon reductions needed to improve the health and well-being of us all, and our planet.

The role of GSHP on air quality

A ground source heat pump extracts naturally occurring heat from the ground (or water) and uses it for space heating and hot water production in buildings (domestic and commercial). The heat pump itself is an electrically driven device with no combustion. There are therefore no point of use emissions of any pollution – particulates, NOx or SOx (and no point of use CO2 emissions either).

A particular benefit is the use of ground source heat pump systems in cities. As an example, if a typical three- bedroom property that consumes 12,000 kWh per year of heat was heated by a modern condensing gas combi boiler it would produce approximately 480g of NOx emissions. For older, non-condensing boilers this could be over 2kg NOx per annum.

Whilst ensuring that all gas boilers in London are modern condensing boilers would produce significant air pollution savings, it is worth stating again that ground source heat pumps produce no point of use emissions. There are estimated to be 900,000 domestic gas boilers in London. If these were all replaced with ground source heat pumps, we could reduce the NOx emissions in our city alone by over 400 tonnes per annum compared to even the best gas condensing boilers.

Ground source heat pumps could reduce the NOx emissions in London alone by over 400 tonnes per annum compared to even the best gas condensing boilers.


It is important to note that there are some NOx emissions associated with electricity generation and therefore that used to power the heat pump, however power stations are typically located outside of cities where air pollution is greatly reduced and they are much simpler to monitor, measure and control local pollution effects.

The air pollution effects of UK grid electricity is also reducing due to the decommissioning of coal fired power and the increasing role of renewables in the UK energy mix.

Also it is worth remembering that the efficiency of ground source heat pump systems is high – with the heat pumps producing three to four units of heat for each unit of electricity they consume.

Simon Lomax, Managing Director of Kensa Heat Pumps comments:

Thankfully, Government is now acting on air quality issues linked to heating systems: the Clear Air Strategy poses the question as to whether biomass installations in urban locations should even be eligible for the Renewable Heat Incentive.  As an alternative, ground source heat pumps are the perfect solution, especially in cities.

Fuelling the change

The Cleaner Heat Cashback scheme, which offers small businesses in the capital up to 35% cashback when they switch their gas, oil, LPG or old biomass system to renewable heating systems, such as ground source heat pumps (GSHPs), supports London Mayor Sadiq Khan’s ambition to have a zero carbon capital city by 2050.

Biomass fuels produce more air pollutants compared to other renewable technologies, therefore the scheme does not support the installation of new biomass boilers.

Businesses located in London’s Air Quality Focus Areas will be able to claim an additional 5% cashback.

With Kensa’s shared ground loop system architecture there is also the potential to co-fund ground source heat pump projects with the Cleaner Heat Cashback scheme and the Government’s Non Domestic Renewable Heat Incentive (RHI) scheme, provided the grant funded elements are limited to non-RHI parts of the work.


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