Absenteeism costs UK businesses £26bn a year.
A significant part is an architectural problem.

In 2023, the CIPD — the Chartered Institute of Personnel and Development — estimated that UK employees take an average of 7.8 sick days per year. The total cost to employers, including sick pay, lost productivity, and management time, exceeds £26 billion annually. That is a number large enough to feel abstract. It becomes more concrete when you break it down to the cost per employee per year, and then ask a more specific question: how much of that absenteeism is caused, or worsened, by the conditions inside the buildings where people work?

The honest answer is: more than most employers realise, and considerably more than most buildings are designed to prevent.

The invisible drivers of presenteeism

Absenteeism — people not coming in — is the visible part of the problem. Presenteeism — people coming in but not performing — is considerably harder to measure and, according to most research, considerably more costly. The CIPD estimates that the productivity lost to presenteeism is two to three times the cost of absenteeism itself.

Both are driven, at least in part, by physical environmental factors that are within the control of the building: air quality, thermal comfort, acoustic conditions, and the quality and quantity of natural light. These are not peripheral concerns. They are the operating conditions of the human brain and body.

What the research actually shows

The relationship between physical environment and performance has been studied systematically for decades. The findings are consistent across geography, sector and organisation type. They are also consistently ignored in the specification of most commercial buildings.

Air quality and cognitive function

As explored in our previous article on CO₂, the Harvard COGfx Study demonstrated a 15% reduction in cognitive performance at CO₂ levels routinely found in UK offices. Separately, the World Green Building Council's 2014 report on health and wellbeing in offices found that air quality interventions — improved ventilation, reduced VOC-emitting materials — are among the highest-return investments an employer can make in the workplace environment.

Thermal comfort and productivity

The relationship between temperature and productivity follows a consistent curve. Performance peaks at around 21-22°C and drops off steeply above 24°C or below 19°C. A study by Cornell University found that raising office temperatures from 20°C to 25°C reduced typing errors by 44% and increased output by 150%. Thermal comfort is not about personal preference. It is about operating conditions.

Natural light and circadian rhythm

Exposure to natural daylight regulates the circadian rhythm — the biological clock that governs sleep, alertness and hormonal cycles. Office workers with access to natural light sleep an average of 46 minutes more per night than those in artificially lit environments, according to a Northwestern University study. Better sleep means better cognitive function, better mood, and fewer sick days. The window is not a luxury. It is part of the infrastructure.

Acoustics and concentration

Noise is consistently rated as the single biggest source of workplace dissatisfaction. A study by the University of Sydney found that 30% of workers in open-plan offices cited noise and lack of privacy as their primary productivity barrier. Cognitive tasks involving reading, writing and complex problem-solving take significantly longer in noisy environments — a 2005 study published in the British Journal of Psychology found a 20% increase in task time under distracting noise conditions.

The business case for WELL-informed design

Organisations that have pursued WELL Building Standard certification — or have applied WELL principles without formal certification — report consistent improvements across these metrics. A 2019 meta-analysis of post-occupancy studies in WELL-certified buildings found average reductions in absenteeism of 23%, alongside significant improvements in self-reported wellbeing and productivity scores.

The certification process itself has a cost. But the cost of the physical interventions — better ventilation, low-VOC materials, adequate natural light, acoustic separation — is in most cases modest relative to the total cost of a fit-out. The payback period, calculated against absenteeism reduction and productivity improvement alone, is typically two to four years. Against the cost of staff turnover — which the CIPD estimates at an average of £30,000 per employee, including recruitment, onboarding and lost productivity — it is considerably shorter.

What this means for return-to-office

Since 2020, employers have been engaged in a negotiation with their teams about the value of the office. The argument for coming in — collaboration, culture, spontaneous interaction — is real but difficult to measure. The argument against — commute time, home environment control, flexibility — is also real and is felt daily.

What has changed is that people now have a year-round basis of comparison. If the office environment makes them feel worse than working from home — more tired, less focused, harder to concentrate — that is a data point that accumulates into cultural pressure. Employers who have invested in genuinely healthy workplaces — buildings that support cognitive performance rather than simply housing it — are consistently finding it easier to make the case for being in the office.

The building is not a container for work. It is an active participant in how work gets done. Treating it as an investment rather than a cost is not altruism. It is arithmetic.

Indomo works with employers and commercial property owners across London and Spain to design workplaces that measurably support the health and performance of the people inside them. If you would like to understand how your current space is performing — or what a WELL-informed approach to a planned fit-out would look like — we start with a conversation.