UK office buildings waste energy by heating during heatwaves
14 July 2025
Heating systems in UK office buildings are continuing to run during summer heatwaves, resulting in significant and avoidable carbon emissions, according to new data from building analytics firm Demand Logic.
The company’s analysis of live performance data reveals that on a single day of temperatures above 30°C, UK office buildings consumed more than 29.1 gigawatt-hours of natural gas for heating, equivalent to the annual usage of 3,470 homes. This led to the release of over 5,800 tonnes of carbon dioxide equivalent (CO₂-e) in just 24 hours.
“The UK is literally heating buildings during a heatwave,” says Mike Darby, CEO of Demand Logic. “Our data shows this is not an edge case. It’s widespread, and it’s costing the planet dearly. This shows the importance of adapting building operations to match today’s climate conditions, not just relying on legacy settings. It’s totally fixable.”
The issue lies in how office heating and cooling systems are configured and maintained. Occupants requesting cooler conditions during hot weather often trigger air conditioning. If heating systems haven’t been shut off or recalibrated, the building can end up both heating and cooling itself simultaneously.
Demand Logic’s platform, which captures second-by-second data from across millions of square metres of office space, confirms that this paradox is still the norm in many buildings.
“We’re seeing UK office buildings waste the annual energy of an average home every 25 seconds, and that’s just from heating,” adds Darby. “When you add the extra energy needed to cool these overheated spaces, the numbers get even worse.”
Even among environmentally progressive offices monitored by Demand Logic, the company recorded 384Wh of heating energy waste per square metre of office space on a 30°C+ day, costing an estimated £2.6 million in gas nationally. With the wider UK building stock likely performing worse than the more environmentally and operationally conscious sample group, the true figures are likely to be considerably higher.
The root causes range from faulty valves to poorly calibrated set points and misaligned sensor readings. Many buildings also operate on outdated control systems not designed for modern climate conditions.
“Too many building owners think energy savings require massive capital investment,” says Darby. “In reality, it can start with better using what you already have. Buildings need to be re-tuned like a car or an orchestra. Right now, too many are playing out of sync.”
The analysis highlights a broader challenge. Most UK commercial buildings were designed for milder weather. A 2019 study predicted that by 2050, London’s climate will resemble today’s Barcelona. Yet 72% of the buildings that will exist in 2050 have already been built, and retrofitting them to cope with future climate extremes will be vital.
“We’re not just wasting money or energy, we’re undermining our ability to adapt to climate change,” concludes Darby. “If we can’t get this right now, while it’s still optional, the cost of waiting will be far greater.”
