Measure first, change second
Every improvement programme starts with two to four weeks of baseline measurement. Without it you are guessing. The baseline tells you which pollutants are actually elevated, which zones are worst, and what the cost of the status quo looks like in productivity terms.
Increase fresh air, then control it
The biggest single lever in most UK offices is fresh air supply. Confirm the AHU is delivering its design rate; rebalance supply against extract; replace time-expired filters; recommission VAV terminals. Where the data supports it, retrofit demand-controlled ventilation linked to breathing-zone CO₂. The combination consistently delivers a 20–40% reduction in steady-state CO₂ and a measurable reduction in occupant complaints.
Upgrade filtration
For urban offices, upgrading AHU filters to ISO 16890 ePM1 50% or ePM1 70% typically halves indoor PM2.5 with no increase in fan energy where the AHU has spare static pressure. Where it does not, in-room HEPA units in high-occupancy meeting rooms are a quick targeted fix.
Manage VOC and material sources
Specify low-emission paints, sealants, adhesives and furniture for new fit-outs; plan a bake-out period with increased ventilation; relocate printers and high-VOC operations away from breathing zones; switch to low-VOC cleaning products. Source control is cheaper than removal.
Keep monitoring continuously
The improvement programme closes with continuous monitoring — CO₂, PM2.5, TVOC, temperature, humidity — dashboard-visible to facilities and senior leadership. The data trail demonstrates the outcome, supports lease evidence and tenant communication, and catches drift before it becomes a complaint.
Frequently asked questions
Do plants improve office air quality?
Marginally. Indoor plants have a measurable but small effect on VOCs at realistic densities. They are not a substitute for ventilation. They are excellent for biophilic and wellbeing outcomes.
How long before staff notice an improvement?
Where ventilation is the lever, occupant feedback typically improves within two to three weeks. Productivity and absenteeism outcomes show in monthly data.
What's the cheapest meaningful change?
Replacing time-expired AHU filters and rebalancing supply / extract. It costs little, requires no capital approval, and is often the largest single improvement in an under-maintained system.