London Offices Without AC Face New Price Risk Due to Heat Waves

London’s office market is weighing the possibility of lower prices for properties that don’t come with cooling options such as air-conditioning, according to real estate brokers and consultants.

“Heat is now up there as a red flag,” said Chris Cummings, a director at Savills, one of the largest real estate consultants in the UK capital. Buyers looking at office properties that get too hot in the summer — because of an absence of air conditioning and an outdated design — increasingly see “an opportunity to actually negotiate down,” he said.

Demand for London offices without AC was already lower than for buildings that had it as of 2024, according to property consultancy Knight Frank. That gap now looks set to widen meaningfully, industry professionals interviewed by Bloomberg said. Offices with no AC “will prove extremely challenging to let” as London temperatures continue to rise, says Dominic Pozzoni, head of national offices at Colliers.

The UK capital has already sweltered through multiple heat waves this summer, with temperatures hitting record highs for both May and June. Since the 1980s, the number of days on which the mercury tops 30C (86F) in London has quadrupled, a development for which the city is unprepared and that will require billions of pounds in investment to address, the Mayor of London’s office has warned.

While having air-conditioning is generally a basic requirement for corporate tenants seeking high-quality “Grade A” buildings in the city, it’s far less of a certainty in older, lower-grade real estate in some of London’s central districts.

Worries about heat can hinge not just on AC, but also on the extent to which a building has been designed to cope with high temperatures through a range of measures including insulation, ventilation and shading, Cummings said. For a poorly-insulated 20th century office not built for increasingly hot summers, an absence of AC is a problem.

Heat is now an even bigger worry for investors in London than flooding, according to Cummings, who oversees sustainable design at Savills in the UK. But efforts to protect the metropolis from high temperatures are falling short.

“We don’t have a heat equivalent to the Thames Barrier,” he said, referring to the flood gates built to protect London from storm surges.

There’s no recent public data on how widely air conditioning has been adopted across London’s offices. A 2016 BRE Group study estimated that around 65% of office floor space in England and Wales was air-conditioned in 2012, based on estimates rather than reported figures.

Though well above levels seen in private homes across the UK, where AC adoption is below 10%, it remains far below the US, where more than 90% of office floor space is in buildings that use electricity for cooling.

US vs UK

Charles Ingram Evans, head of project and building consultancy at Knight Frank, says he’s currently trying to help a large US corporate client negotiate acceptable temperature parameters with the landlord before they move into their London office. Ingram Evans, who declined to identify the company by name, said the client’s perception “is that London buildings aren’t as good, particularly the older-stock London buildings,” as their equivalents in the US where offices are less likely to overheat.

Ingram Evans says he has another client who’s currently trying to figure out whether they’d find any buyers for an un-air-conditioned building that’s over 100 years old in Pimlico, close to Westminster where Britain’s Houses of Parliament sit.

A key part of the concern is that employees in hot offices are less productive, Ingram Evans said.

“They haven’t got air conditioning and their productivity goes down.” On hot days, the client — a think tank — finds staff just want to work from home, he says. Knight Frank is now trying to help the client figure out what to do with the property.

A 2025 meta analysis of 30 studies found that when temperatures rise above 25C, there’s a “significantly negative impact on work performance, and especially on response time.” The effect was “more pronounced in skilled tasks requiring higher cognitive functions,” the study also found.

More specifically, office workers enduring temperatures slightly above 25C tended to see lower accuracy levels in the tasks they were performing, with effects becoming significant as soon as workers spent more than an hour in such environments, according to the analysis.

A separate study conducted as far back as 2006 found that office workers start to become less productive as soon as the mercury rises above 23C-24C, with 22C the temperature at which people were found to be most productive.

During the latest heat waves in and around London, the temperature in May hit a record 35.1C, followed by a record of 37.7C for June. And forecasters agree that temperatures are set to continue rising in the years to come. The UK Health Security Agency says that heat waves in England are expected to become more intense, last longer, and happen more often.

Meanwhile, landlords and investors in London offices without adequate cooling options may face substantial costs if they want to improve the market value of their property.

Charlotte Ashton, head of London leasing at Colliers, says especially for older buildings, such a project can be both challenging and expensive.

“For those landlords who manage estates that include period assets with more complex floorplate configurations and access than newer purpose built office blocks, planning is prohibitive for adding condenser units on the roof,” she said. “And the costs for installing into these types of properties are not viable.”

In such situations, landlords sometimes need to resort to freestanding AC units, “in order to get deals over the line,” Ashton said.

Photograph: A worker sits on an office chair outside a building during a heat wave in the City of London; photo credit: Chris J Ratcliffe/Bloomberg