How many excess deaths does heat cause in England?

The UK Health Security Agency (UKHSA) reports 1,504 heat-associated deaths for 2025. 2026 started hotter, with 2,877 deaths reported as an interim estimate by June.

For context:

• 534,020 total deaths were recorded in England in 2025

• ~3,000 cold-related deaths were reported for the winter of 2024/25 (or around half after adjusting for flu)

  • Only giving rough numbers here for context, because UKHSA initially reported incorrect figures

  • Overall excess winter deaths are about 10x higher

It’s hard to measure heat-related deaths

Heat is not generally recorded as the cause of death. Instead, heatwaves increase deaths for people with existing health conditions.

So the heat-related mortality figures are not a count, but rather a statistical estimate of excess deaths during hot days.

The UKHSA chart below shows how daily deaths are slightly above baseline during hot periods.

The pattern isn’t super obvious, which is also reflected in the broad confidence interval reported by UKHSA. Based on their method, they report a 95% confidence interval for the number of heat-associated death between 936 and 2,072.

What is a heat episode?

UKHSA uses an England-wide definition for heat episodes:

Heat episodes are defined as days on which the mean Central England Temperature (CET) is at least 20°C. One day either side is also included; an extra day can also be included if merited by a sudden change in temperature.

Central England Temperature records the average of three locations around England.

How are excess deaths during a heat episode calculated?

UKHSA calculates the average number of deaths for a baseline period 14 days before and after the heat episodes (skipping any days that belong to a different heat episode). This average is then compared to the average during the heat episode.

I had Claude reconstruct this for a heat episode in 2022. It reported 179 excess deaths compared to 187 reported by UKHSA. This is likely because UKHSA excludes COVID deaths from its data.

Note that this is an early episode that doesn’t show very clearly in the chart. This is shown by the -27 to 401 deaths confidence interval.

The second heat episode that year shows a clearer pattern of rising deaths. (Although the rebuild overstates it compared to UKHSA figures, likely due to high COVID deaths at the same time.)

Who dies from heat waves?

Mostly old people. Over half of additional deaths in 2025 are from people 85 or older. 89% were at least 75 years old.

Young children are often reported as being especially at risk from overheating. However, the 2021 to 2025 UKHSA monitoring data only shows about an average of 23 heat-associated deaths for the entire age range from 0 to 24. I think one factor contributing to that figure could also be a higher number of drownings during heat episode days.

Are heat-related deaths increasing?

That would make sense:

• The UK is getting hotter

• There are more older people who are impacted

Better healthcare and heat adaptation are unlikely to have fully counteracted those factors. (I think?)

Here’s a simple chart showing the increase, based on data from the Office for National Statistics (ONS).

This shows a nice pattern. Then you zoom out and the data starts looking slightly less clear.

Since 1988 the number of people in the UK over 80 years old has also increased from just under 2 million to 3.8 million, so you might expect higher peaks today.

UKHSA only started publishing data based on the current methodology in 2020, so you can’t really see a trend yet.

Statistics in development

It’s also worth noting that the ONS statistics on climate-related mortality are “statistics in development”, previously called experimental statistics.

We advise caution when using the data and to consider the uncertainty around the estimates in the associated data table.

My understanding is that the UKHSA heat mortality data is not experimental, while the cold mortality data is considered statistics in development.

How many years of life are lost due to heat-related deaths?

UKHSA reports 5,109 years of life lost (YLL) for those aged 75 to 84, and about 2,978 for those ages 85 and over.

However, YLL uses standard life expectancy data for a given age. So if there are 793 excess deaths in those 85 and over, that shows that they used an average life expectancy for this cohort of 3.76 years.

Importantly, this assumes that the people that die sooner from heat-related causes are average for their age group. However, if their life expectancy was adjusted for existing frailty, then the years of life lost would be lower.

For example, the ONS states the following about the 2022 data:

Each heat-period peak, most notably that on 19 July 2022, was followed by a fall in deaths to below the average over the following days; this suggests a short-term mortality displacement, where deaths among vulnerable individuals are ‘brought forward’ to within the heat-periods.

The 2023 Health Effects of Climate Change report also points out that some of the deaths may be related to short-term shifts.

Previous studies have estimated that between 10% and 70% of heat-associated mortality may be associated with short-term (up to a month) mortality displacement

The 45 to 64 age interval interesting because it shows roughly a hundred deaths with potentially long remaining lifespan. However, UKHSA does not calculate YLL “for younger age groups as they did not see statistically significant heat-associated mortality in summer 2025”.

This article takes a closer look at where the emissions estimates come from.

Plans for new datacentres

The article discusses two planned data centres in England:

• Wapseys Wood: 300MW IT load

• Quest Park: 720MW IT load, 1GW of generation capacity

IT load covers just the power consumed by servers, without cooling and other energy consumption.

Both data centres would have on-site gas power plants. As The Guardian explains, that’s because of “the long wait to connect to the grid”. The Quest Park request statement says it “has signed an agreement for delivery [of a 200MW grid connection] in October 2034”.

Nationally Significant Infrastructure Projects (NSIP)

NSIPs are large developments that can avoid the usual local planning process. Instead, central government issues a Development Consent Order (DCO).

Both data centres are considered NSIPs, though neither has yet applied for a DCO.

Timelines

The Guardian states that the NSIP regime “allows developers to rapidly deliver infrastructure projects by bypassing local planning authorities with decisions instead handled by central government”.

Quest Park data centre expects a DCO decision by mid-2028. Operations could start around 2030.

CO2 emissions from gas power plants

Foxglove analysis predicts that the two data centres “will produce more than 4.5m tonnes of carbon emissions”.

I’ve not been able to find the original analysis, but the maths basically works on these numbers:

• 365g of CO2 per kWh from natural gas plants, or 365kg per MWh

• 8760 hours per year

• 1.3GW of capacity

Based on that we end up with 4.157 million tonnes of CO2 per year. That’s pretty close to the Foxglove number. I’ve not been able to find any estimates by the data centre providers or the government (which might be because the DCO application hasn’t been submitted yet).

The exact numbers will depend on what conversion factor you use for gas power plants, and whether you assume that the full plant capacity is used.

Contextualizing the numbers

According to Foxglove, the plants “will spew out more planet-heating carbon emissions than the entire UK operations of ExxonMobil”.

Ember Energy reports CO2 emissions by company, showing 3.9 million tonnes of emissions in the UK for ExxonMobil.

The Office for National Statistics puts total emissions in the UK at 367 million tonnes of CO2e. So the two proposed data centres alone would be 1.2% of that.

Based on consumption, the ONS reports UK emissions at 699 million tonnes of CO2e.

Are the figures misleading?

Someone working for the government says they are:

A government spokesperson said these figures were “misleading” because of the assumption that both projects will run at 100% utilisation from day one, which they said was “not accurate”.

Foxglove provides no justification, calling it “standard industry practice”. This line of thinking is unfortunately common, for example “Carbon Brief assumes a data-centre “load factor” of 90%, which is in line with other analyses”.

In contrast, one study estimates a 62% to 75% load factor for AI training facilities:

electrical infrastructure is routinely sized for worst-case cooling conditions, design-case PUE (power usage effectiveness), and a firm-specific contingency factor, plus headroom for future IT-load expansion

It also notes that electricity draw “varies over the year… because cooling-system response depends on ambient conditions”.

Still, I’m not sure why the government spokesperson focusses on “day one” emissions rather than when sites are fully operational.

Even if more accurate figures were half the reported ones, the overall emissions would still be significant.

In the article, The Telegraph reports on three different cases where retrospective planning permission was refused for air conditioning units in Camden.

Let’s take a look at what happened in each one, and review some of the additional coverage in The Telegraph and other news outlets.

Case 1: Rejected due to sustainability requirements – appeal rejected

In August 2022 a retrospective planning application for two air conditioning units was submitted. They were installed on the roof at the rear of the building.

An acoustic assessment confirmed that noise levels at neighbouring properties would be acceptable. The conservation officer stated that the AC units would “not be considered harmful” to the local character of the conservation area.

The planning application was rejected only on sustainability reasons:

The proposal has failed to justify the need for active cooling by reducing and mitigating the impact of dwelling overheating through the application of the cooling hierarchy, thereby failing to minimise carbon dioxide emissions

The property owner appealed and the appeal was rejected in January 2024.

An overheating analysis produced in June 2023 found that “the flat passes the relevant tests… on the basis that windows can be opened to allow for cross ventilation“.

Air conditioning might still be allowable if opening windows isn’t practical. The appeal decision considers potential security concerns, but dismissed them.

There would be security concerns associated with leaving windows and balcony doors open when the flat is unoccupied or at night, but there does not appear to have been any examination of how these could be addressed.

Such security concerns would not be as great as those associated with ground floor windows, as mentioned in the [overheating report].

Case 2: Rejected due to sustainability requirements – appeal allowed

Three air conditioning units were installed on the roof in September 2023. In August 2024 a planning application was submitted, followed by an overheating risk assessment in December 2024.

Camden rejected the application in December 2024 because the proposal failed to show that “all feasible passive and other design measures to reduce overheating” were incorporated before air conditioning was considered.

The council stated its case in response to the homeowner’s appeal:

The applicant’s assertion that ceiling fans cannot be factored into the assessment contradicts the provisions of TM59:2017, which explicitly state that ceiling fans must be considered when they are proposed as part of a new build or refurbishment.

The council acknowledged that solar shading might not be viable at the front of the building due to design concerns, however it pointed out that “such measures could feasibly be introduced on the rear extension”.

In February 2026 a planning inspector allowed the appeal:

Whilst I am not persuaded that there is sufficient technical justification for the three AC […], it is clear that the appellant has considered and implemented where practicable the provisions of the cooling hierarchy.

[There] are material considerations that lead me to conclude that the appeal scheme would not be inconsistent with the broad aims and provisions of [Camden’s] policies

Case 3: Rejected due to design, noise, and sustainability – appeal refused

In July 2020 two air conditioning units were installed in the front garden, as well as two in the rear garden. In February 2021 the owner submitted a planning application.

Planning permission was refused in November 2021 based on three reasons:

1. A “detrimental impact on the character and appearance” of the building

2. Noise levels impacting the adjoining buildings

3. Failure to demonstrate the need for air conditioning through dynamic thermal modelling

On appeal, the planning inspector was “satisfied that the two front units do not harm the character and appearance of the property nor the wider CA [conservation area]”.

However, the noise and sustainability objections were upheld in September 2022:

I therefore find that it has not been demonstrated that the development has an acceptable impact upon the living conditions of occupiers of existing properties, […] with regard to noise disturbance.

A cooling hierarchy has been submitted […] However, no thermal modelling has been submitted and therefore the clear need for the units [has] not been demonstrated

What the three cases show

Camden Council has repeatedly refused planning permission for AC units on sustainability grounds. It has not always been successful on appeal, as the most recent case shows.

The cases where Camden was successful ended in 2022 and 2024. In 2025, England-wide permitted development rules were extended to no longer require planning permission for air to air heat pumps for some homes. However, I think the cases covered here are mostly outside the scope of those changes.

I also don’t think Camden has changed their policies over the last few years.

Were perfectly operational AC units removed across London?

After discussing example cases from Camden, The Telegraph reports that AC installers they talked to have reported removing functioning AC units across London:

Air-con engineers told The Telegraph that they had been called out to remove perfectly operational units worth thousands of pounds across London.

In an article discussing a “net zero clampdown” you might think this refers to AC units being removed for sustainability reasons. But if you read carefully, the sentence makes no reference to climate change policies!

AC units are removed frequently, but mostly for noise and design reasons.

Planning rules in Islington

The Telegraph mentions air con policies in Islington:

Other London councils have also attempted to restrict the use of air-con on climate grounds, including Islington, which says it “must only be considered as a last resort”.

This is stated in the Islington Local Plan:

Full-building mechanical ventilation and active cooling systems must only be considered as a last resort.

…

[For minor home extensions] the use of active cooling measures will not be accepted, unless it can be demonstrated that other methods higher up the hierarchy cannot be used to deliver sufficient heat control.

While I’ve not read the Islington Local Plan in full, I think the language is very concerning if you’re an Islington resident and want to install air conditioning in a flat (where permitted development rules mostly don’t apply).

But from what I can tell, Camden’s climate change policies and their enforcement for existing homes is unique.

The Sun, The Mirror, and GB News: an unjustified plural

The reporting in The Telegraph prompted articles by other news organisations. For example, GB News states:

Planning officials at councils have told residents to take down their cooling units over concerns about carbon dioxide emissions.

As I explained, this does not follow from a careful reading of the Telegraph article, which presents no evidence that other councils have ordered the removal of AC units for climate change reasons.

Is air con just not permitted because of how it is installed?

Techradar claims the news stories about AC planning refusals are mostly not due to environmental restrictions on air con:

If you look at the detail of the newspaper stories you’ll typically find that the problem wasn’t the air con itself, but how and where it was installed.

No examples of this are cited in the article, but the prior paragraph mentions the reporting by the Telegraph.

As I’ve shown earlier in this article, sustainability was cited as a refusal reason in all three cases. In one case this was ultimately overturned on appeal. In another, it sits as one of two reasons along with noise concerns.

However, the London borough of Camden has taken a particularly strict stance on AC, even for retrofits. Home owners need to show that they really need air conditioning and that alternative cooling methods can’t solve the problem.

In this article I’ll take a closer look at AC planning rules in Camden.

Adapting to climate change: CC1 and CC2 of the 2017 Camden Local Plan

The 2017 Camden Local Plan outlines the council’s development vision and sets out the policies that guide planning decisions in the borough.

Beyond the usual rules on noise and local character, the document contains two policies in the “Sustainability and climate change” chapter that impact air conditioning installations:

• CC1 Climate change mitigation: buildings should reduce carbon dioxide emissions

• CC2 Adapting to climate change: encourages measures like green spaces and sustainable construction

When does Camden permit air conditioning?

To get planning permission for air conditioning units, Camden residents need to show that:

1. They’ve explored other steps on the cooling hierarchy (like increasing shade or ventilation)

2. Dynamic thermal modelling shows that their home is still too hot

CC2 of the Camden Local Plan explains that AC should only be permitted in these specific circumstances:

Active cooling (air conditioning) will only be permitted where dynamic thermal modelling demonstrates there is a clear need for it after all of the preferred measures are incorporated in line with the cooling hierarchy.

This is due to the energy use of air conditioning units as well as their contribution to the urban heat island effect.

In addition to increasing the demand for energy, air conditioning and plant equipment expel heat from a building making the local micro-climate hotter.

Camden blocks AC installation purely for sustainability reasons

Unlike in other councils, in Camden AC retrofits can be refused purely on sustainability grounds.

For example, in this planning application (refused in 2023), there are no noise or design concerns:

The conservation officer was consulted and the air condenser units in this location in terms of design and heritage would not be considered harmful to the character and appearance of the host property or the wider conservation area.

…

Based on the results of the environmental noise survey, the applicant proposes adequate levels to be achieved at 1 metre from the nearest noise sensitive window

However, the applicants failed to take the necessary steps to demonstrate why air conditioning is necessary.

The proposal has failed to justify the need for active cooling by reducing and mitigating the impact of dwelling overheating through the application of the cooling hierarchy, thereby failing to minimise carbon dioxide emissions

In this case, the planning application failed to show that other steps of the cooling hierarchy were followed first, and didn’t submit a thermal model to prove that cooling was still required.

Does this policy really apply to existing homes?

London’s anti-overheating rules usually only apply to new developments. Is this the case in Camden?

When residents appealed the decisions of their local council, planning inspectors have not interpreted this consistently. For example, in this appeal from 2024, the planning inspector states:

However, I agree with the appellant that this requirement appears to refer to proposed buildings and to ensure that such new buildings are designed and modelled to mitigate the effects of possible overheating.

… the cooling hierarchy seeks, for instance, to reduce heat entering the building through orientation, and manage the heat within the building through exposed internal thermal mass and high ceilings.

These are all matters regarding the initial design of the building…

However, in another case from 2022, the planning inspector affirmed that Camden’s rules also apply to existing homes:

This policy is not restricted only to major developments.

The supporting text to the policy sets out that the Council will discourage the use of air conditioning and excessive mechanical plant as, in addition to increasing the demand for energy, such measures expel heat from a building making the local micro-climate hotter.

Newer guidance makes it clear it applies to all development

Overall, my impression is that the restrictions don’t just apply to new builds.

The Local Area Requirements for Planning Applications 2025 are most clear about this requirement:

All new-build development, and any development where air-conditioning is proposed, must demonstrate how the London Plan ‘cooling hierarchy’ has been applied and informed design. Development at risk of overheating (for example, single aspect units within 90 degrees of due south) should submit dynamic thermal modelling demonstrating risk of overheating has been mitigated.

Inconsistency in how the policy is applied

Camden’s unusual requirements have caused confusion for applicants. But planning officers have also not been applying the rules consistently.

For example, here air conditioning was approved without clearly demonstrating need:

Whilst AC units are not typically supported for environmental reasons, in this case the building is an existing dwelling with limited scope to retrofit

However, this precedent is not a reason to overturn the council’s planning refusal on appeal:

The appellant has submitted numerous examples of approvals within the Borough of similar recent development where a cooling hierarchy or thermal modelling were not required.

Such inconsistency in the application of policy is regrettable, however, this does not alter the clear wording and requirements of the policy before me.

Do you really need dynamic thermal modelling?

Notably, in this case a cooling hierarchy statement was submitted with the planning application in the example above. It mentioned several existing overheating mitigations, for example:

• Overhanging eaves

• Additional wall and roof insulation

• An efficient boiler to reduce internal heat generation

• Use of high thermal-mass materials

• Mechanical ventilation

The applicant stated that these measures “have not been effective in maintaining comfortably cool temperatures”, however this was not deemed sufficient:

A cooling hierarchy has been submitted by the appellant and I am satisfied that, as development serving an existing flat, the preferred measures set out in the policy and Policy SI 4 of the London Plan have been addressed.

However, no thermal modelling has been submitted and therefore the clear need for the units have not been demonstrated. The requirements of the policy have not been met.

Camden’s home improvement planning guidance is confusing

Camden’s home improvements guide from 2021 explains that air conditioning is discouraged and that other options should be “considered”. That’s a much weaker standard than what is sometimes required by planning officers.

If you are concerned that your home overheats in summer beyond comfort levels, you should consider passive cooling measures which do not rely on an energy source like air conditioning.

The guide explains that planning applications require a noise assessment and a statement of what other cooling measures have been taken.

Air conditioning units require planning permission and the submission should include a Noise and Vibration assessment as well the table in Appendix 1 completed stating all the other measures that have been taken to address overheating in your home.

This table is not specific to cooling measures. Dynamic thermal modelling is never mentioned in the guide. I can understand why someone might submit a planning application with just the documents outlined here, without checking additional council guidance.

Extensive effort, but still a technical breach

The Telegraph’s reporting mentions a case where an applicant successfully received planning permission on appeal in early 2026, a year and a half aftre their initial application.

The applicant documented numerous steps that were taken to achieve cooling through passive means, as well as submitting a dynamic thermal model to show that further cooling was required.

The council challenged the lack of ceiling fans and an MVHR+ system to achieve cooling without air conditioning. However, the applicant argued that these measures would not be effective:

Ceiling fans … will only have the effect of moving warm air around the room in any case

…

The installed MVHR system provides external air tempering by its very nature, it will exchange warm internal air and exchange it for cooler external air.

If the incoming air was to be mechanically tempered, this would require an outside air conditioning unit to run through an internal coil within the MVHR unit, this would constitute by very nature an air conditioning system.

Despite this, the planning inspector did not conclude that this clearly met Camden’s requirements:

The appellant’s commentary on the appeal scheme and measures already taken at the appeal property against the cooling hierarchy goes some way to explaining the absence of both ceiling fans and the MVHR+, both of which the Council consider should have been incorporated prior to the AC system.

I find the appellant’s reasoned justification in these respects to be compelling.

However, it seems to me that there remains limited technical justification for the 3 AC units and the need for that level of system to cool the building.

In the absence of such the appeal scheme would amount to a technical breach of the provisions and aims of CLP Policy CC2.

However, the appeal was ultimately granted because the extensive prior work showed a “continued commitment to the principles set out by the cooling hierarchy” and that installing AC “would not be inconsistent with the broad aims and provisions of those policies”:

Furthermore, although not decisive, it is clear that the extensive combination of measures and steps already taken, together with the AC system, suit the appellant’s particular needs and the constraints of a retrofitted property.

…

I am satisfied that material considerations exist sufficient to justify a decision otherwise than in accordance with the development plan.

This highlights that, when planning rules are rigorously applied, Camden residents need to go to extraordinary lengths to get AC approved.

Planning permission granted only with the cooling function of a heat pump disabled

When heating, heat pumps are significantly more efficient than gas boilers and their emissions go down as the electricity grid decarbonises. That’s why they are generally considered to be sustainable technology.

Reversible air-to-air heat pumps can also act as an air conditioner.

I found one case where a building extension was approved, however as one of the conditions the cooling option of the heat pump had to be disabled:

Prior to first use of the air source heat pump hereby approved, the active cooling function shall be disabled on the factory setting and the air source heat pump shall be used for the purposes of heating only.

Reason: To ensure the proposal is energy efficient and sustainable in accordance with policy CC2 of the London Borough of Camden Local Plan 2017…

Opposition to AC from local groups

It’s not just planning officers interpreting Camden’s AC rules strictly. The Hampstead Neighbourhood Forum also objected to air conditioning on sustainability grounds on several occasions.

For example, from a comment on one planning application:

We also question whether the applicant has provided enough justification for the proposed air conditioning unit, which is discouraged by Camden Local Plan Policy CC2, and wonder if the applicant has considered more sustainable heating and cooling methods as recommended by Camden guidance.

Or, from the planning application above where the cooling function was disabled:

The emerging Hampstead Neighbourhood Plan supports the green heating and cooling hierarchy, which emphasises energy conservation, followed by the utilisation of renewable energy sources and efficient technologies, to achieve environmentally friendly and sustainable heating and cooling systems. Active air conditioning would be contrary to this policy.

In a 2021 comment, The Camden Square Conservation Area Advisory Committee also expresses concern about the number of AC units proposed and their environmental impact:

There are two air conditioning units placed at the front and two at the rear of the property which seems an excessive number for the size of the flat.

…

The application form (under “Environmental Impacts” section) indicates that the units are heat pumps.

Whilst A/C units can be considered to be a form of heat pump. In this instance the form is for describing energy efficient air source heat pumps or similar, providing a positive, sustainable solution. However, air-conditioning units are not energy efficient choices.

Does this still matter after the 2025 changes to permitted development rights?

Permitted development rights allow owners to make changes to their property without requiring permission from their local council. Since May 2025, installing a reversible air source heat pump is allowed across England (including Camden), under certain conditions. Prior to the change, permitted development rights only applied to heat pumps that were “used solely for heating purposes”.

The current permitted development rules allow one heat pump per block of flats. However, in practice it’s difficult for an individual owner to get freeholder consent and comply with noise regulations. Flats account for 84% of homes in Camden.

There are also additional restrictions in conservation areas, which cover 70% of Camden’s built-up areas. There are 5,600 listed buildings where planning permission is still required.

This map shows conservation areas in Camden:

Overall, I think most people in Camden would still need planning permission to get air conditioning.

Permitted development doesn’t apply to cooling-only devices – but I don’t think that matters

Permitted development rights do not apply to pure air conditioning units:

Development is permitted by Class G subject to the following conditions… the air source heat pump is not solely used for the purpose of cooling

However, I get the sense that this doesn’t matter in practice since cooling-only devices are rare:

Modern air conditioning systems are reverse cycle heat pumps, not simple cooling units. Cooling-only systems are now very rare in the comfort cooling market.

Therefore, this requirement does not add any extra cost.

Camden’s new draft local plan

Camden is developing a new local plan and published a draft in 2025. Chapter 8, “Responding to the climate emergency” reaffirms that residents need to demonstrate the need for active cooling.

The chapter discusses overheating and cooling specifically:

…it is important to ensure that buildings and spaces in Camden are designed to promote cooling and reduce overheating, while avoiding the use of mechanical cooling, which often has significant energy requirements and, under conventional operation, expels hot air, which adds to the risk of overheating.

This will reduce the impact of overheating in the borough and reduce inequality in the experience of heat impacts.

The new policy CC8, “Overheating and Cooling”, takes a strong stance against air conditioning in new builds and clarifies that restrictions also apply to existing homes:

Proposals for active cooling in new residential developments are unlikely to be considered acceptable

…

[We will] only permit applications for new and/or additional active cooling systems or units where all other feasible measures in the cooling hierarchy have been integrated into the development and there is still a clear need for active cooling demonstrated by dynamic thermal modelling.

In addition to demonstrating need, applicants should also offset the energy use of AC through additional measures.

Where applications for active cooling are considered acceptable, the energy used to operate the active cooling system should be offset through the installation of solar PV and greening, to help cool the local environment, where feasible

This suggests that, unless permitted development rights apply, it will get even harder for Camden residents to install air conditioning.

However, these restrictions don’t apply when installing air conditioning in an existing property. What stops owners who want air conditioning from getting it?

Do you need planning permission to install air conditioning?

In May 2025, the UK government expanded permitted development rights in England. In many cases, it is now possible to install reversible air-to-air heat pumps without applying for planning permission, at least when a suitable site is available on the property. These heat pumps can provide air conditioning in addition to heating.

However, you still need planning permission in some cases. For example:

• Pure air conditioning units without heating

• Individual flats

• Listed buildings

In conservation areas (~10% of properties), you also still need planning permission for a street-facing installation.

Common refusal reasons in planning decisions

I used Landcycle to search for rejected planning proposals to install air conditioning units or air-to-air heat pumps.

Out of 31 applications I reviewed, 64% included noise as a refusal reason, and 48% mentioned design or local character. I wasn’t fastidious selecting a representative sample, but this analysis should give a directional idea of the challenges in getting planning permission.

The 2025 changes introduced tighter noise rules for permitted development. At the same time, siting rules were relaxed. I also included pre-2025 applications, so today I would expect slightly more noise refusals and fewer design ones for heat pump installations.

I’m mixing pure air conditioning units, reversible air-to-air heat pumps, and heating-only units in my review. However, assuming planning permission is needed in the first place, I don’t think this makes much difference in practice.

Noise concerns

To get planning permission for air conditioning units, property owners need to show that the noise and vibration won’t negatively impact neighbouring properties.

This is done using a BS4142 noise assessment. It looks at factors like how much noise the device can produce, how the noise travels, and how far away the neighbour’s closest door or window is.

If this assessment fails, planning applications generally get refused:

The proposed air source heat pump would generate unacceptable levels of noise pollution, causing significant harm to the living amenities currently enjoyed by neighbouring residents.

Design & local character

After noise issues, the visual impact of the air conditioning unit is the most common refusal reason, especially if the device can be seen from the street.

For example:

The proposed air source heat pump would be sited in a prominent position and would be readily visible from the street to the front of the property.

As a result, it is considered that the addition of the heat pump at the front of the garage would result in an incongruous addition that would harm the character of the property and wider street scene.

However, outside of conservation areas, ground-level front-facing heat pumps are now allowed under permitted development.

What about sustainability?

Recent reporting covered cases where air conditioning units were refused because climate change adaptation policies required applicants to demonstrate a need for air conditioning.

I’ve never seen this happen outside of Camden, despite spending quite some time looking. So it may not impact more than 0.4% of England’s population.

I’m hoping to write more soon about how Camden’s policies differ from those of other councils!

The Ministry of Housing objects:

Air conditioning can be installed in both existing and new homes.

And yet, I have never experienced a home in the UK that has air conditioning.

What I’ll look at: air conditioning in rented flats in London

I’ll focus on rented flats in London since that’s what I’m most familiar with. This study also shows that Londoners are most likely to report overheating at home.

Do Londoners not want air conditioning?

Maybe flats don’t have air conditioning because people don’t feel the need for it?

Surprisingly, one of the authors of the study above claims that 30 per cent of Londoners use air conditioning at home.

It was not surprising, said Dr Khosravi, that Londoners were found to be the most likely to have air con in their homes (30 per cent), “because air con use is about affordability.”

This is much higher than I expected. But I suspect it doesn’t mean that 30% of flats have installed proper air conditioning.

Instead, it’s likely to be janky portable air con setups, like my one in the photo below. I also found an old photo from March 2022 where it was 32 degrees inside.

I want air conditioning, and clearly many people living in London feel the same.

Is affordability the reason homes don’t have AC?

The quote above suggests cost as a big factor. I’m skeptical for a few reasons:

1. The survey asks about the most important consideration when buying AC, not about why don’t people buy AC. Though maybe the data comes from a different survey?

2. Only 20% of respondents with an income over £70,000 report home AC use, compared to 15% with an income below £10,000.

3. If I search on Rightmove, I don’t think I can just spend a lot of money to get a flat with AC? They seem extremely rare, unless you’re looking to buy a £10M apartment.

Property ownership does make AC use easier, but I don’t think cost is the reason for low rates of AC installation.

Even if cost was a concern, a substantial number of people could afford air conditioning. In 2020, 16% of London households had an income over £100,000.

Are developers building new blocks of flats with AC installed?

Overheating is a big problem in London and people are willing to pay to address it. If air conditioning isn’t banned, do new developments finally have AC installed?

I had Claude look through planning documents across 4 London councils. It didn’t find a single new build that has air conditioning.

Why do developers not build homes with AC?

It comes down to planning rules and building regulations.

Planning permission: the cooling hierarchy

The 2011 London plan introduced the cooling hierarchy. Air conditioning is only allowed as a last resort.

The increased use of air conditioning systems is not desirable as these have significant energy requirements and, under conventional operation, expel hot air, thereby adding to the urban heat island effect.

_{Image source: the overheating report for the Pudding Mill Lane development.}

Building regulations: Part O

In 2021, the housing ministry introduced Part O of the UK building regulations. It introduces requirements for new residential buildings to mitigate overheating, which came into effect in June 2022.

Part O also prohibits air conditioning unless the developer can show that there is no other way to prevent overheating.

The building should be constructed to meet requirement O1 using passive means as far as reasonably practicable.

It should be demonstrated to the building control body that all practicable passive means of limiting unwanted solar gains and removing excess heat have been used first before adopting mechanical cooling.

Additional reasons AC isn’t allowed

On top of environmental concerns, councils also deny permission to install air conditioning for noise and conservation reasons.

For example, there’s this refusal from Newham Council:

The proposed development fails to respect the character and appearance of the area and lacks application clarity on the impact of the noise produced on the living conditions of neighbouring properties

Conclusion

While residential air conditioning is not banned outright, in practice it is not permitted for new residential developments.

This encourages overheating, inefficient portable air conditioning units, or water-cooled air conditioners that have no external unit but use a lot of water.

Retrofit of AC is possible in theory as Part O doesn’t apply to existing properties. However, this runs into problems with noise and design concerns that could have been avoided with upfront planning.

Caveats

Maybe AC-cooled blocks of flats are being built, but I wasn’t able to find them? I would like to learn that this is the case.

Maybe air conditioning really isn’t needed in new buildings that comply with Part O? Maybe Part O would work but isn’t sufficiently enforced?

I also don’t have a good understanding of UK planning rules and maybe there are loopholes that would allow AC.