The Mayor of London must reform planning rules to make it easier for sweltering new build homes to have air conditioning installed, experts and campaigners have said. City Hall are currently consulting on London’s Heat Risk Delivery Plan in a bid to cool down residents despite summers becoming hotter and drier every year.
The plan, currently in its public consultation stage, will lay out a series of measures that can be taken to combat the impact of heatwaves. The Mayor has already talked up ‘cool spaces’ around the city, thousands of water refill points and plans to plant thousands more trees to reduce the temperature for Londoners moving around the city.
But experts have now warned that the real danger could be an effective ban on installing air conditioning in highly insulated new build developments. The London Plan, drawn up in 2021, instructs developers to prioritise “passive ventilation”, such as shading from trees, high ceilings and utilising airflow.
It says the use of air conditioning is not “desirable as these have significant energy requirements and, under conventional operation, expel hot air, thereby adding to the urban heat island effect”. If such systems are “unavoidable”, developers must design them in order to “reuse” any waste heat produced.
Similarly, the London Climate Resilience Review recommends that “mechanical ventilation is prioritised over air conditioning”. When it comes to new build homes, however, passive cooling measures may not work as effectively as needed.
Developers often add extra fire resistant insulation and thicker windows to ensure buildings are kept warm in winter – but leaving residents helpless in the hotter months. Dan Wilson Craw, Deputy Chief Executive of campaign group Generation Rent, told the Local Democracy Reporting Service (LDRS): “Excessive heat in homes is becoming a bigger problem, particularly in London.
“With new legislation expected to set out new decency standards for private rented homes, this is a good opportunity for the Mayor of London to make it easier for new homes to meet tenants’ needs.
“In many cases it will be easier to provide air conditioning instead of complicated ventilation systems. The growing solar power sector can provide the energy to run this at minimal cost to the environment.”
Kane Emerson, Head of Housing Research at the YIMBY Alliance, told the LDRS: “The Mayor is absolutely right to take action to make London liveable during hot weather. But it cannot stop at passive measures. Mediterranean towns are designed with the passive cooling principles that are being consulted on but they still struggle during heat waves without air conditioning.
“Overheated homes are a serious health risk to children, older people and pets. Yet London’s housing rules mean new homes are being built without modern technology like air conditioning. Allowing new homes to have air conditioning built-in is an easy first step to creating a more heat-resilient London.”
In June, polling from More in Common found that 46 per cent of those in Greater London supported the effective ban on air conditioning, with 38 per cent suggesting it was not a “sensible policy”.
A report from the Centre for Cities the month before also claimed that the London plan was “neglecting the helpful potential of air conditioning.” Referring to the energy cost of air conditioning systems, it added: “It is not obvious why spending energy and emitting carbon to keep buildings comfortable is unacceptable in summer but tolerable in winter.”
Ed Hezlet of the Centre for British Progress told the LDRS: “It is encouraging to see that City Hall is actively engaged with the risks associated with overheating in London. However the survey’s exclusive focus on passive cooling measures will limit the effectiveness of London’s heat plan when temperatures are at their highest.
“Air conditioning in domestic settings must also be part of the conversation, rather than being relegated to the bottom rung of London’s cooling hierarchy.”
Air conditioning also has the potential to become a political issue in London. Thomas Turrell AM, the Environment Spokesman for the City Hall Conservative group, told the LDRS: “Londoners are baking alive in new builds because of the Mayor’s aircon ban, and no doubt will be slightly at a loss to hear that the Mayor’s suggestions to cool them off include tree planting and ‘Heat Watch groups’.
“We are a developed country that has invented aircon and can afford to install it in homes – sometimes the most straightforward solution is the best. Sadiq Khan is living on a different planet to Londoners.”
Professor Mehri Khosravi, an Energy and Carbon Senior Research Fellow, at the University of East London, warned that air conditioning alone is not the answer. She told the LDRS: “New builds in London are particularly at risk of overheating. Many are designed to be airtight for winter energy efficiency.
“Installing AC seems the easy solution, but if London relies only on AC, we risk high energy use, rising bills, and even more strain on the electricity grid during heatwaves.
“AC can also worsen inequalities, as not everyone can afford it. A smarter solution is to reduce cooling demand first through passive cooling strategies such as shading, shutters, reflective materials, and natural ventilation.
“The remaining demand can then be met by efficient AC units or reversible heat pumps. This is how southern European countries have managed for decades. Improving heat risk communication with Londoners is also vital to reduce health risks.”
A spokesperson for the Mayor of London said: “The London Plan allows for air conditioning to be installed in new builds but requires developers to maximise the benefits of passive cooling measures, which includes helping reduce carbon emissions and lowering energy costs for households.”
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