Queen's Policy Engagement

Decarbonising residential heating in Northern Ireland

Retrofitting various solutions has the potential to deliver a multitude of benefits for Northern Ireland's approach to heating our homes says Ryan Madden and Prof John Barry.

Decarbonising residential heating in Northern Ireland

Introduction to the issue
Irrespective of age, class, ethnicity, nationality or race, heating our homes is something that unites us all. Heat allows us to live comfortably, cook, provides us with warm water and boosts our physical and mental wellbeing. In essence, it is absolutely critical for our day-to-day life. With a relatively colder climate compared to continental Europe, combined with an increasing amount of excess winter deaths, residential heating is particularly important in Northern Ireland (NI).

However, our relationship with heating is inherently paradoxical, as it is the biggest source of emissions globally, thereby exacerbating climate change and threatening our day-to-day life. Heat accounts for around 50% of global final energy use and contributes to roughly 40% of global CO2 emissions. The residential heating sector’s (RHS) contribution to this total is substantial, with many studies indicating that the commitment made in the Paris agreement of keeping global average temperature increase to 1.5°C cannot be achieved without a near total decarbonisation of the RHS.

As of 2019, the residential sector accounted for 14% of NI’s total greenhouse gas emissions, primarily through the use of fossil fuels for heating.  For comparison, the agriculture and land use sector is the region’s biggest emitter of greenhouse gas emissions (GHGs)– contributing around 30% (its 10% in the rest of the UK).  This figure has declined since 1990, however progress in emissions reductions has been slow, with only a 21% decrease in emissions from the residential sector since 1990. To compensate for this slow rate of progress, the UK Governments statutory body for Climate Change – the Climate Change Committee, has recommended that at least 25% of heat supply in NI should come from low carbon sources by 2030, which underlines how much work needs to be done.


Why is Northern Ireland’s residential heating sector so carbon intensive

A majority of industry experts highlight NI’s dependence on oil to be extremely problematic, as 68% of homes are still fuelled by oil, along with the fact that 72% of the population here use open or closed fires as secondary heating solutions, with coal and peat common fuel sources in the region. This statistic becomes truly startling when we compare it to other areas of the UK, where only 4% of households in England and Wales rely on oil for household heating.

There are a variety of reasons why NI is so dependent on such carbon intensive heating sources, including a shortage of gas network infrastructure and a lack of political will, which will be touched upon later. It can also be linked to the region’s lower level of income compared to the rest of the UK and Republic of Ireland (RoI) [1]. Lower incomes mean that many householders in NI feel unable to pay the upfront capital costs for efficient gas boilers or other low carbon heating sources (such as heat pumps or solar panels), so continue to purchase small quantities of oil at inflated prices.

It is estimated that 50% of houses in NI were built prior to minimum building thermal performance standards in 1973. The poor energy efficiency within NI homes means that potential heat energy is lost at a disproportionately high rate (with climate and affordability implications). This not only increases the amount of fossil fuels being used to heat homes, but also means homeowners spend a significant amount of income on heating their home. This is linked to fuel poverty which is a huge issue in NI, as 22% of households are classified as being in fuel poverty.

While a complex issue, a few key drivers can explain our high levels of fuel poverty (households spending 10% or more of their income to stay warm). Firstly, there is an overdependence in NI on oil for space heating and a high proportion of the housing stock being poorly insulated, as well as lower wages and households dependent on welfare transfers.

At the time of writing, the UK as a whole is currently in the midst of an ‘energy crisis’, which amongst a variety of factors has been caused by demand for natural gas outstripping supply, unseasonably low winds for renewable electricity production and geopolitical tension over the distribution of natural resources between Russia and the rest of Europe. This threatens to exacerbate fuel poverty in NI and highlights the importance of ensuring energy efficiency within homes is high, or to use a well-known term within the industry – taking ‘a fabric first approach’. There has been an overwhelming response from industry experts regarding the NI Executive’s lack of action on residential heating decarbonisation strategies. The absence of a Climate Bill, an up-to-date Energy strategy, and inadequate building regulations have all been cited as factors for the lack of progress in NI.

Followers of politics in this part of the world will be no stranger to the lack of political will to address climate change, with former Environment minister Sammy Wilson previously labelling the scientifically proven phenomenon as a “con”. Aside from climate change denial at the highest levels of local government, some of the hesitancy to introduce new climate change related policy in NI was linked to the lack of a functioning devolved government between January 2017 to January 2020, the collapse of which was infamously caused by a failed Renewable Heating Incentive (RHI) scheme. Whilst the main talking point around the RHI scheme was the loss of taxpayers money, the closure of the scheme meant there is now no publicly available financial support for new renewable heat projects in the region and has paused heat decarbonisation initiatives. Meanwhile, the Department for the Economy is in the process of producing a new Energy Strategy for NI, with the hope that this will set the foundation for energy targets well into the next decade. However, there has been no indication of whether a renewable heat target will be included in the strategy, which again casts doubt on how serious government departments are in addressing this issue.

The transition away from oil

So, we have addressed the carbon intensive nature of residential heating and its root causes, but how do we go about tackling it? The progress NI has made in moving away from coal and oil is undoubtably a positive step, as both have significantly higher emissions than natural gas, producing approximately 0.4kg and 0.3kg of CO2 for every kilowatt hour of energy delivered, compared to just over 0.2kg for natural gas. Natural gas is often touted as a cleaner fuel source and its proponents claim that it is a ‘bridge fuel’ that will allow society’s heating needs to be met whilst we make a full switch to zero carbon sources of energy.

However, this transition to natural gas is problematic, as it is recognised that to reach decarbonisation targets, a shift from natural gas to alternative low carbon sources is required as soon as possible. It’s not even clear if using natural gas as a bridging fuel is necessary given the progress made by smaller and less developed nations in adopting renewables compared to NI such as Latvia. This has been reaffirmed by the International Energy Agency who have advised that to reach net-zero emissions targets by 2050, no new fossil fuel boilers should be sold from 2025. Conversely, the gas network continues to expand within NI as the region seeks to catch up with the rest of the UK and RoI. One such example is the on-going ‘Gas to the West’ project, which is aiming to connect 40,000 additional residencies and businesses to the gas network.  However, an investigation by the Irish News revealed that the main beneficiaries of this scheme (thus far) has been a handful of big businesses, including Moy Park, rather than households.


Decarbonising the gas network

But what if we were able to leapfrog natural gas and substitute it for a less carbon intensive fuel source? Some have suggested using the gas infrastructure to pump green hydrogen into homes. Provided the electric current used in the production of green hydrogen comes from renewable energy, it can be categorised as a zero-carbon fuel, as aside from the infrastructure no greenhouse gases are released from its production. Or perhaps a more feasible alternative could involve injecting biomethane into the gas network. Given the predominance of NI’s agriculture sector there is significant potential to use agricultural and food wastage in anaerobic digesters to provide a low carbon source of fuel to homes.

However, industry experts I spoke to questioned both technologies scalability in the near future, highlighting that hydrogen has not been used to heat homes anywhere in the UK yet. One respondent underlined this doubt, noting that a project at Keele University in England was the only evidence of meaningful hydrogen use within UK, “which says everything about where it’s at in terms of its development”.

Whilst biomethane is beginning to enter the heating mix in the RoI, it is untested in NI and there is a distinct lack of infrastructure for biomethane injection here. Additionally, both technologies would cost hundreds of millions to implement on a regional scale, with costs likely to be pushed back on to local consumers who are already bracing themselves for the dilemma of ‘heating or eating’ as a result of the energy price crisis. Implementing these technologies would require NI to take a leadership role, however as anyone reading will be aware, this would be unchartered territory for a region that has historically followed Britain’s lead.



Electrified heat

Of course, we don’t have to become totally reliant on utilizing the gas infrastructure. Electrified sources of heat such as heat pumps have long been promoted as having a prominent role to play in the decarbonisation of the RHS. Studies carried out by researchers at Ulster University on the predicted 2030 heat pump supply on the island of Ireland show that heat pumps have the potential to reduce CO2 emissions from fuel source heating in residencies by 40%. Given the significant wind and tidal resources available to NI, electrification through heat pumps would appear to be an attractive option (not least since NI produced almost 50% of its electricity from wind in 2020). Heat pumps, recently heavily promoted in the UK government’s Net Zero strategy, could also remedy the problems that will be faced in rural areas that are unlikely to be connected to the gas network.

Despite their high efficiency rates, industry experts have noted that a transition to heat pumps will put increased strain on the electrical grid as demand for electricity rises, which will necessitate investment to upgrade the grid’s infrastructure so it can meet the demand. Given the correlation between domestic heating demand and electricity demand, electrified heat could potentially increase unsustainable peaks in electricity demand compared with current levels. In simple terms, this could result in electricity outages or consumers not being able to access their electricity in times of need.


The best of the rest

Studies which have included NI in an ‘All-Ireland heat map’, show that if governments on both sides of the border made appropriate investments in infrastructure and created complimentary policies, district heating could potentially meet 57% of the island of Ireland’s heat demand.

There are currently 94 district heating schemes in NI, only one of which supports an area that exceeds 100 homes, underlining heat networks distinct lack of scale of in NI. Conversely, it evidences that there are no knowledge or technical barriers to overcome unlike alternative low carbon heat sources and could be uniquely suited to the growing urban hubs of Belfast and Derry.  Unfortunately, similar to other low carbon heat technologies in NI, the theme of a lack of framework or support mechanism for district heating continues. This also holds true for Carbon Capture and Storage technology. Whilst studies have shown that there is potential to store close to 100,000 tonnes of carbon in the region, it has not been proven in practice and may encourage society to continue emitting greenhouse gases from residential heating in the expectation that we can simply store it under ground.  The Climate Change Committee has noted that there is limited CCS potential in NI, suggesting nature based solutions from rewetting peatlands and reforestation are better options for the region.


Fabric first approach

When thinking about decarbonisation strategies it can become easy to develop an unhelpful obsession with emerging technologies to tackle the issue. However, the way forward may be a lot less complex than that. Implementing retrofitting initiatives within homes has been cited as one of the most feasible options towards heat decarbonisation and is an avenue NI could pursue given that the resources to retrofit residencies are widely available. Numerous studies carried out on the island of Ireland have shown that even basic retrofit measures such as having more insulation put into loft spaces or upgrading to a boiler with heating controls, can deliver huge energy savings and be installed into homes with minimal disruption.

From an estimated 780,000 domestic properties in NI, over half have a Standard Assessment Procedure (SAP) rating below band C, with only 4% of houses achieving a Band B or above. When combined with the fact that roughly 60% of houses in NI were built before 1980, housing in NI can be categorised as old and inefficient. This is very much a ‘low hanging fruit’ on the quest to decarbonise residential heating, as significant emissions reductions could be achieved in a short time frame.  This is in keeping with the Belfast Climate Commission’s Net Zero Carbon Roadmap for Belfast which highlights that decarbonising residential and commercial buildings is the most cost effective and carbon effective strategy for the city.

In order to reach net-zero targets by 2050, the rate at which retrofitting measures in the region are being implemented will have to at least double and perhaps treble annually. Given the scale of the task, the industry experts I interviewed advised that a targeted approach would be best suited for any mass retrofit scheme, with one individual stating, “you’re going to have to look at something like only retrofitting homes that meet a certain criterion, e.g. homes that are ‘X’ age, ‘X’ energy efficiency”. Cross-border collaboration with the RoI could also be leveraged to counteract any potential labour or skills shortages.

Despite its challenges, respondents repeatedly came back to improving energy efficiency and focusing on retrofitting homes throughout our discussions, as this would ensure that when technologies such as heat pumps have matured, that they are working at their optimum and not having to compensate for a lack of energy efficiency within the home.  Given that an extensive retrofit of the housing stock to improve energy efficiency was such a recurring theme throughout the discussions, it was deemed appropriate to carry out further research on just how effective common retrofit options could be for decarbonising the RHS in NI.


Research into retrofit

Recently completed research used decision making software known as the Analytical Hierarchy Process tool to carry out a desk study on the effectiveness of common retrofit options. A comparison of the retrofit options is outlined below, in terms of their performance in relation to potential CO2 reductions, capital cost, annual fuel cost reductions and ease of installation in an archetypal NI home [2] :

  • Loft insulation (300mm thickness)
  • Double glazing windows (Post 2006)
  • Cavity wall insulation
  • Heating controls for wet central heating
  • Suspended floor insulation


* – Denotes the relative weighting and importance of each category Potential CO2 reductions if implemented in all suitable NI homes (tonnes of CO2e)
Average capital cost of one installation (£)
Average annual fuel cost reductions from one installation (£)
Ease of installation (average time taken to install by two labourers)
Loft insulation (300mm thickness) 218,654 £225 £165 5 hours
Double glazing windows (Post 2006) 193,112 £4900 £79 2-3 days
Cavity wall insulation 88,160 £1000 £183 5 hours
Heating controls for wet central heating 399,744 £400 £187 7 hours
Suspended floor insulation 103,600 £1000 £87 2-3 days


This study revealed that heating controls for wet central heating were the most preferential option in relation to identifying the retrofitting solution that would be most effective in decarbonising the RHS in NI. Heating controls performed well when measured against all criteria, outperforming other options by a considerable margin.

It is interesting to compare what the theoretical impact on total greenhouse gas emissions would be if every home suitable for heating controls in NI were to adopt them. Emissions attributable to the RHS in NI totalled 2.9 MTCO2e as per most recent estimates. Therefore, on the basis of the data in the desk study, if heating controls were adopted in every potential home, this would lead to a 13.78% reduction of emissions from the RHS.

If this was extrapolated to NI’s total greenhouse gas emissions (21.4 MTCO2e) it could lead to a reduction of 1.86% of emissions. These calculations were based on the potential savings from homes with an average SAP rating of C and below meaning the same CO2 savings are unlikely to be achieved in a more efficient home. However, they do evidence what can be done with a smaller financial output compared to other technical solutions listed in this piece. Whilst 1.86% may not sound like much on the surface, that is huge impact for just one piece of technology and when used in conjunction with complimentary retrofit measures, it’s impact would be amplified.

For example, if heating controls were implemented alongside suspended floor insulation and loft insulation across all applicable homes, theoretically total greenhouse gas emissions from the RHS would be reduced by almost a quarter [3]. Considering this combination of measures would cost the homeowner on average under £1700, this is a very feasible way of beginning the decarbonisation process.

The blog has discussed how NI is a region with a lower level of income, historically high fuel poverty levels and a lack of supply chains to undertake deep decarbonisation of the RHS. The results from the study suggest that heating controls, and by extension, other retrofit measures could counteract this. They are not only affordable, but they would also help reduce fuel poverty and would not require significant government support to support their development, as the technology is already in use across the region.



Overall, retrofitting clearly has massive potential to help decarbonise the RHS in NI and in my view, should be of the upmost priority for any decarbonisation strategy. However, as already stated and reaffirmed by the industry experts, there is no ‘silver bullet’ approach, and any strategy will likely have to include a combination of measures alongside retrofitting. Therefore, a diversified strategy that focuses on the points below would be most effective in ensuring a deep decarbonisation of the RHS.

  • In the short term, emphasis should be placed on adopting a ‘fabric first’ approach and engaging in a mass retrofit program of residential buildings over the next 7-10 years. This should include a timeline of targets that will help drive efforts towards energy efficiency across the housing stock
  • Increased subsidies to encourage low income households to implement energy efficiency retrofit measures should be prioritised –particularly heating controls and insulation
  • Beyond this, pilot testing should be undertaken to understand how emerging low carbon heating technologies perform in different types of NI homes, particularly biomethane, district heating and heat pump technology
  • Local government should develop a replacement for the RHI scheme which can deliver financial support to households for low carbon technology without repeating the mistakes of its predecessor
  • As many rural homes off the gas grid as possible should change their primary heating source to heat pumps or alternative low carbon heat sources
  • Finally, all-Island collaboration with the RoI should be utilised to overcome the skills shortage and lack of supply chains for low carbon technologies in NI, as well as sharing competencies and resources to maximise decarbonisation potential. This will be particularly important for alternative fuels being moved around the island’s gas network


Concluding remarks

This blog post was based on a dissertation I completed over the Summer as part of my MSc in Sustainability and Environmental studies at the University of Strathclyde, examining how best to decarbonise residential heating in Northern Ireland. As part of my dissertation, I was fortunate enough to speak to ten individuals working close to the residential heating sector in NI. This allowed me to gather their thoughts and opinions on what challenges society would face when decarbonising residential heating, whilst also seeking to identify the most feasible and promising methods of doing so. The consensus from the industry experts was that retrofitting homes represented the most promising solution to decarbonise this sector. From a list of common retrofitting options (as outlined within the table within the article), heating controls for central heating were identified as the most effective retrofit solution for decarbonisation of the RHS in NI.

It is important to reiterate that the findings from my research are theoretical and it is highly unlikely that heating controls will be implemented across all homes in NI over the coming decades. However, I believe this study makes it clear that the retrofitting solutions have the potential to deliver a multitude of benefits for NI. This will not only enable us to meet our decarbonisation targets, but also ease our dependence on increasingly expensive, unsustainable fossil fuels and ultimately tackle the social inequality created by fuel poverty in the region.



[1]  NI’s median average salary of £28,000 is £3,000 lower than the UK average, with studies also estimating that on average residents in the RoI earn over $4,000 more in annual household disposable income (Bergin and McGuinness, 2021; NISRA, 2020).

[2] The data employed for this study was extracted from Building Research Establishment reports on the Cost of carbon savings in NI’s housing stock and the Cost of making dwellings in NI more energy efficient, the Northern Ireland Housing Executive’s latest Housing Condition report and a Scottish Government report into Developing the regulation of energy efficiency of private sector housing

[3] Based on adding ‘Potential CO2 reductions if implemented in all suitable NI homes (tonnes of CO2e)’ for the aforementioned retrofit options together and dividing by the residential sectors contribution to greenhouse gases in NI


About the Author

Ryan Madden works as an Energy Auditor for an Irish energy consultancy which specialises in energy efficiency and renewable energy. Ryan recently finished his MSc in Sustainability and Environmental studies at the University of Strathclyde and will be graduating later this year.


The featured image has been used courtesy of a Creative Commons license. 

Professor John Barry
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John Barry is a Professor in the School of History, Anthropology, Philosophy and Politics at Queen's University Belfast. His research interests include: green political theory, politics and political economy of sustainability, greening the economy, environmental and sustainable development policy-making, environmental ethics, transition to a low-carbon/renewable energy economy.

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