Which IAQ parameter has the biggest productivity impact?

CO₂ as a proxy for fresh-air-per-person is the single most reliable productivity lever. Cognitive function scores degrade above ~1000 ppm and fall sharply above 1400 ppm. Thermal comfort runs a close second, especially in cooling-dominated buildings.

What does a productivity-focused IAQ improvement look like in practice?

Demand-controlled ventilation tied to real CO₂ data, low-VOC procurement for finishes and furniture, particulate filtration to ePM1 ≥ 50%, and a thermal comfort strategy delivering PMV/PPD within BS EN 16798-1 Category II across the working day.

Guidance

Indoor Air Quality and Productivity

Cognitive performance, absenteeism and presenteeism all respond to measured changes in workplace air quality. The evidence base is large, peer-reviewed and increasingly board-relevant.

Cognitive function Measurable ROI Peer-reviewed

The evidence

Air quality is a productivity input — not a soft benefit

The 2016 Harvard CogFx double-blind crossover trial (Allen et al.) placed knowledge workers in identical workstations under three IAQ regimes. Cognitive function scores rose 61% under "Green" conditions (typical green-certified ventilation and low-VOC materials) and 101% under "Green+" conditions (doubled outdoor-air rate). The largest gains were in strategy, information usage and crisis response — exactly the high-value cognitive domains employers pay for.

The mechanism is straightforward. Elevated CO₂ and accumulating bioeffluents impair the brain's prefrontal performance under sustained cognitive load. Thermal discomfort imposes a parallel cognitive tax. Together they explain the well-documented afternoon performance dip that ventilation upgrades reliably eliminate.

Translating evidence into action requires measurement, not aspiration: the productivity case is built on per-zone CO₂ traces, particulate counts and thermal comfort indices, set against measurable cognitive and absence outcomes.

FAQ

IAQ and productivity

Yes — measurably. The Harvard CogFx studies (Allen et al., 2016) showed cognitive function scores were 61% higher in green-certified buildings and 101% higher with doubled ventilation rates, in double-blind crossover conditions. WGBC's 2014 review found ventilation and thermal stability are the strongest IEQ predictors of workplace productivity.

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Independent IEQ baseline, ranked interventions, post-intervention verification. Call 01322 555566.

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