Boiler bans for off grid homes-a rural design challenge?

Reducing energy and associated carbon emissions from the built environment is critical to meeting our climate targets. A key part of the Government’s strategy for this in England (energy policy is a devolved matter), is to decarbonise heating in residential properties by shifting away from fossil fuels. 

Announced by the Government as far back as 2019 and confirmed in the recent Heat and Buildings Strategy, is a ban on fossil fuel boilers in new homes from 2025 and a target to ‘phase out’ fossil fuel boilers for existing homes from 2035. Phasing out appears to mean that after 2035 when current boilers break they should be replaced with low carbon heating systems which should lead to a gradual shift, decarbonising heat over time. 

There are approximately 23.9million homes in England and around 1.1million (4.6%) do not have access to the gas grid and rely on fossil fuel heating. These homes are mostly in rural areas as can be seen from this map. Until the 12th of January 2022 the Government is consulting on plans to phase out fossil fuel boilers in off gas grid homes from 2026 (see here for consultation). That is, ten years earlier than for those people with access to the gas grid. 

Shows a map of the England with districts shaded by the percentage of off gas grid properties, Cumbria, East Anglia and Cornwall
Percentage of homes off the gas grid

One of my research participants who lives off the gas grid asked me if I’d seen any good sources of information about this issue. I had a bit of a search but it mostly seems to be passing under the radar. The only organisation that had picked it up was Farmers Weekly who were quite clear in their views. So I thought I’d have a look at the consultation and share some of my own views. 

Farmers weekly have strong views on the proposals

Some reasons

Now there is some logic for this proposal from a carbon intensity perspective because the main fuels used in households without access to the gas grid are oil, bottled gas (mainly LPG) and occasionally coal, all of which have higher carbon emissions than natural gas (Table 1). Getting these homes onto low carbon heating is therefore disproportionately better than getting the same number of gas grid homes to switch.  

 

Table 1: Carbon intensity of fossil fuels based on UK Government carbon factors for fuel 2021 

Fuel type Coal Oil  LPG (liquid petroleum gas) Mains gas
Kg/CO2e per kWh 0.3446 0.2418 0.2145 0.1832
kWh for a tonne of carbon 2,902kWh 4,136kWh 4,662kWh 5,458kWh

A second reason, mentioned in the consultation, is that there are hopes that houses on the gas grid might eventually be able to take advantage of renewably produced hydrogen which might be able to use the existing gas infrastructure network. I’ll leave it to people more qualified than me to discuss both the feasibility and probability of this actually happening however. 

One does wonder about a third reason however. When the ‘gas boiler ban’ was first announced it caused quite a bit of noise and there had to be a lot of emphasis on the fact that it only applied to new builds from 2025 and that no one would have to take out a working boiler. Part of this was due to general outrage at the government interfering in people’s lives and partly due to real concerns about the current lack of affordability of low carbon heat sources in comparison with fossil fuel boilers. The idea is that by setting a date of 2035 it gives the industry time to respond and for the cost of low carbon heating to benefit from economies of scale. However what is the situation for off gas grid homes, are they ending up as guinea pigs to help reduce costs for the rest of us? And is this because they just can’t shout as loudly because there are less of them and they are dispersed across the country? Is this another area where ‘levelling up’ needs to be whispered?  

 

The heat pump first strategy…

The current, low carbon heating technology of choice is heat pumps, which extract heat from the ground or the air and then use a heat exchanger powered by electricity to raise it to the required temperature for use, generally to heat water for circulation in radiators or underfloor heating. This can be much more effective than direct electric heating, with each unit of electricity for a heat pump providing between 2 and 4 units of heat. 

The electricity needed for the heat pump will come from the national grid, unless households have their own renewable micro generation such as solar PV panels. Grid electricity has been decarbonising rapidly in recent years as a result of increased renewable generation. However there is some concern that if we suddenly and dramatically increase electricity demand (by electrifying heating for example) then this additional demand will have to be met with fossil fuel power plants pushing the carbon intensity of electricity back up and making it not quite as low carbon as it needs to be. Part of the challenge is that air source heat pumps in particular are less efficient in cold weather when there is most heating demand, this increases the ‘peak demand’ on the grid especially if everyone is plugging their electric cars in as well. 

…Needs to be a retrofit first strategy

Luckily there is a solution, retrofit! Before trying to decarbonise the heat supply to a home what we really need to do is reduce heat demand. Currently UK buildings on average use around 132 kilowatt hours per square meter of floor space per year (132kWh/m2/yr). Stock modelling by the Association of Environmentally Conscious Builders (AECB) suggest that to reduce the electricity demand for heating to a workable level for the grid we need to get heating demand per existing house to an average of 50kWh/m2/yr, which means a 62% reduction in heating demand, mainly by making the building fabric more efficient. 

From a cost perspective having lower demand means that smaller heat pumps can be installed which are significantly cheaper and also have less embodied emissions from their manufacture and require less carbon intensive refrigerant. For an additional incentive for retrofitting, heap pumps are most effective when they are designed to provide low temperature heat. This isn’t generally compatible with current high temperature radiator systems and to make it work either underfloor heating or oversized radiators are required. Since most people don’t want radiators as big as the wall, underfloor is really the main option and is likely to entail quite a lot of disruption and cost. Unless of course the current heating demand can be reduced to the extent that the current radiators are by comparison ‘oversized’ as a result of, yes, you guessed it, retrofit! 

 

What’s missing?

The level of retrofit required to get a building to this scenario is likely to be quite substantial. Unfortunately this doesn’t appear to be reflected in the proposal for consultation. There are a few mentions of the probable need for ‘energy efficiency measures’ such as cavity wall insulation alongside the heat pumps but very little detail on how this will be encouraged or how household are expected to finance these measures alongside the heat pump that at the moment costs two-three times as much as their current oil boiler. These costs should absolutely reduce as heat pumps become more common but are still likely to be significant for early adopters which is what off gas grid areas are being volunteered to be. 

There is some recognition that low temperature heat pumps won’t be practical for some homes: 

For instance, we do not propose to apply the heat pump first approach to replacement heating systems where major upgrades such as external wall insulation would be needed at the point of boiler replacement to meet the heat demand of the home with a low temperature heating system. (p.12)

Although it would be interesting to see what proportion of 1.1million off gas grid homes are solid walled as I suspect it may be quite a high proportion because many of them will be older buildings. 

The proposed alternative solutions are high temperature (and highly inefficient) heat pumps, biomass boilers in rural areas where air quality isn’t as problematic and a mention of the potential that liquid biofuels could have in the future, although the current links with deforestation don’t make this the most attractive option at present. Finally, and rather amusingly in the context of rural areas, district heating is also suggested…

Picture of Lake district valley with dispersed houses and farms
A district heating system wouldn’t be very effective in this area, there’d be a lot of distribution loss…

In terms of costs the government are proposing to give £5,000 vouchers towards heat pump installation to help bring costs closer to a parity with current fossil fuel systems. However the current cost of ‘an air source heat pump for an average house’ is £12,000 while replacing an oil boiler is currently around £4,000 (figures from the consultation) so the arithmetic isn’t positive at present and importantly these costs don’t include any retrofitting.

 

Recommendations

It is undeniably important that we decarbonise heat and given the carbon intensities of off grid fossil fuels maybe this is a good place to start. It is also positive that the government are providing long term dates and targets to give industry more certainty about what is going to happen so that it can plan accordingly. Given that ‘phasing out’ rather than an outright ban is proposed perhaps it could start earlier for all homes given that in the context of the fight against climate change, 2035 is a long way off. 

However, decarbonising heat and a heat pump first strategy won’t work effectively from a carbon or a cost point of view as a single measure in a vacuum. It needs to be part of a holistic approach that considers the building fabric, the heating system, opportunities for micro generation, oh yes, and the values and behaviours of those pesky occupants who are actually living in and using the buildings and the heating systems. 

If this proposal goes through there also needs to be much more support for occupant of homes without access to the gas grid, both in terms of financial support and information. People generally replace their boilers when they break, and this is usually a matter of some urgency. Most of the ‘normal people’ that I’ve spoken to don’t really understand how heat pumps work and getting a system designed and sized for a house, if done properly is a complex business that requires some time to get right. Maybe the government should subsidies this preliminary work so that all homes get a ‘heat pump plan’ including what retrofitting they should undertaken first, so that when the boiler breaks they already have their replacement planned and lined up. 

The retrofitting that is currently mentioned in the proposal is what it termed shallow retrofit which doesn’t dramatically reduce energy demand compared with ‘deep retrofit’. Deep retrofit is advocated by many, not just for it’s energy and carbon saving potential but also for it’s ability to improve the comfort, wellbeing and even health of occupants, and to address fuel poverty which can be a significant issue in off grid rural areas. These co-benefits should be recognised and efforts made to support these types of positive outcomes from retrofit and decarbonising heating. 

Rural house with rainbow above

Conclusion

In conclusion, it is important that we decarbonise heat but it does need to part of a much larger strategy for reducing carbon emissions and energy demand from residential buildings. It would be great to see this policy on phasing out fossil fuel boilers as part of a much broader and more articulated strategy on retrofitting, and while we’re at it, maybe linking with efforts to reduce rural deprivation as well. 

If this post has sparked your interest please read, and maybe even respond to the consultation yourself here is the link again: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1026356/domestic-offgg-consultation.pdf

 


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