If you've ever found yourself locked in a silent battle over the office thermostat, science has finally delivered a verdict. New research reveals the precise temperature that keeps British workers happiest, calmest, and most productive, potentially ending workplace climate conflicts for good.
The Science of the 'ThermoState'
According to a comprehensive study by home heating experts BOXT, which surveyed 2,000 British adults, the magic number is a balmy 21°C (70°F). Scientists have dubbed this the ideal 'ThermoState' – the sweet spot where both brain and body function in harmony.
Clinical psychologist and mental health expert Dr Sophie Mort explains the concept. "The ThermoState is like emotional central heating, the point where the brain and body work in sync," she says. "Temperature regulation isn’t just about physical comfort; it is closely tied to psychological wellbeing, influencing memory, emotional processing, stress response and how relaxed or tense we feel."
The Narrow Window for Peak Performance
The research indicates that our comfort and performance follow a shallow 'mood-heat curve', peaking within a surprisingly narrow band. The optimal range for wellbeing is between 19.5°C and 20.6°C (67.1-69.1°F). Straying outside this zone leads to a rapid decline in both working ability and emotional state.
When temperatures dip below 17°C (62.6°F), mood and alertness begin to suffer. At just 16.7°C (62.1°F), people report losing focus and experiencing poorer sleep quality. A 2021 study supports this, finding that cold exposure led to "significantly disturbed" cognitive responses, with increased blood pressure and heart rate indicating activated stress responses.
"When indoor temperatures fall too low, the body naturally shifts into heat-conserving mode," Dr Mort notes. "This can increase stress hormones, subtly reduce cognitive performance and make emotional regulation more difficult, which is why many in colder environments feel more tense or irritable."
Why Turning Up the Heat Isn't the Answer
However, cranking the thermostat to tropical levels is counterproductive. The study found that when temperatures exceed 21.6°C (70.9°F), mood and alertness decline once more. At 22°C (71.6°F), people become more irritable and combative, with feelings of fatigue emerging any hotter.
"Once we push beyond this ThermoState zone into overheating, reaction time and mental sharpness begin to decline, and fatigue or restlessness can set in," warns Dr Mort. Research confirms that temperatures above 24°C (75.2°F) impair cognitive performance, particularly processing speed, meaning an overly warm office could be the reason for afternoon slumps and colleague frustration.
Regional Variations Across the UK
While 21°C serves as the national average, the ideal ThermoState isn't one-size-fits-all. BOXT's survey uncovered notable regional preferences. Residents of Brighton and Glasgow typically favour temperatures up to 1.2°C (2.16°F) hotter than the average. Conversely, people in Plymouth prefer a chillier environment, opting for settings about 1°C (1.8°F) cooler.
Dr Mort emphasises the importance of these findings, particularly during the winter months. "Even relatively small shifts in indoor warmth can affect mood, energy, sleep quality and motivation, particularly during winter when emotional resilience is already under pressure," she states. The research ultimately suggests that finding and maintaining that personal and collective ThermoState could be a simple yet powerful key to a happier, more effective workplace.
