Office Ventilation: 7 Signs It Is Not Keeping Up
Nobody submits a formal complaint about ventilation. They open a window, move to a different desk, take the meeting outside, or quietly conclude that the afternoon slump is just how offices are.
That is why this particular problem persists for years in buildings where everything else is well managed. It produces no incidents, generates no reports, and shows up instead as a low background hum of headaches, tiredness, poor concentration and people avoiding certain rooms. Meanwhile it is one of the few environmental factors with an explicit statutory requirement attached.
Seven signs worth taking seriously, and what each one usually means.
1. The room everyone avoids
Almost every office has one. A meeting room, usually internal, usually with a glass wall, that people book last and leave early.
This is the clearest diagnostic signal available and it costs nothing to notice. Small enclosed rooms with high occupancy and no dedicated supply are where inadequate ventilation shows up first, because the ratio of people to air volume is worst there.
Regulation 6 of the Workplace (Health, Safety and Welfare) Regulations 1992 requires effective and suitable provision to ensure that every enclosed workplace is ventilated by a sufficient quantity of fresh or purified air. A room that becomes unpleasant within forty minutes of four people entering it is not meeting that standard, whatever the building's overall specification says.
2. Afternoon drowsiness that tracks occupancy
If concentration reliably drops on busy days and not on quiet ones, the variable is people rather than the time of day.
The symptoms associated with poor ventilation are unglamorous and easy to attribute to other causes: tiredness, headache, difficulty concentrating, stuffiness. Individually they look like lifestyle. Collectively, correlated with occupancy, they look like a building.
HSE publishes practical guidance on ventilation in the workplace, which is a reasonable starting point for anyone trying to establish whether they have a problem.
3. Nobody has measured anything
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The most common finding, and the easiest to remedy.
Carbon dioxide is a useful proxy. It is not itself the hazard at the levels found in offices, but because people exhale it, the concentration indicates how well the air is being replaced. HSE's guidance on using CO2 monitors explains the approach and the levels that suggest adequate or inadequate ventilation.
Two cautions worth carrying into any measurement exercise. CO2 is a proxy for ventilation rate, not a measure of air quality generally, and it tells you nothing about contaminants from other sources. And a single reading proves very little: what matters is the pattern across occupied hours, in the spaces people actually use, on days that reflect real occupancy.
Measuring is cheap. Not measuring means every conversation about the building is an argument between opinions.
4. Density went up and nothing else changed
The sign most organisations have created for themselves in the past two years.
Ventilation systems are specified for a design occupancy. A floor designed for two hundred people, run at eighty for several years, and now running at one hundred and eighty on mandated core days is being asked to do something it has not done in a while, by a system that may have been maintained on the assumption that it never runs near capacity.
Anyone who has reduced their footprint while keeping headcount, or introduced attendance requirements, has changed the input to that calculation. The same applies to space that has been reconfigured: desks added, partitions installed, or a breakout area converted to workstations without anyone revisiting the air supply serving it.
The same arithmetic applies to regulation 7, which requires a reasonable temperature. The approved code of practice L24 supports both provisions and is worth reading alongside them.
5. The kit has multiplied
Specific to technology businesses, and frequently overlooked because it arrives gradually.
Comms cabinets, local servers, test rigs, workstation clusters and charging benches all generate heat, and heat load competes directly with occupant comfort for the same cooling capacity. A room that was adequate as an office is a different proposition once it also contains equipment running continuously.
The failure pattern is that equipment is installed by people thinking about power and network capacity, and nobody asks about air. Where a space contains both people and significant equipment load, the ventilation question needs asking again.
6. Your building is shared and nobody owns the answer
In leased, multi-tenant and serviced buildings, the system belongs to the landlord or operator and the occupants belong to you.
That split is where the issue stalls. You cannot adjust the plant, they cannot see your occupancy, and the person best placed to notice the problem has no route to the person who could fix it. This is the same structural gap that affects other duties in coworking and serviced offices: the infrastructure is theirs, the duty to your employees remains yours.
The practical step is to ask, in writing, for the design occupancy of the space you occupy, the maintenance regime and its most recent completion, and whether the system supplies fresh air or substantially recirculates. Those three answers resolve most disputes, and an operator who cannot produce them has told you something useful.
7. Maintenance is assumed rather than evidenced
The final sign, and the one that most often explains the others.
Systems degrade quietly. Filters load, dampers stick, controls drift, and a unit can run for years delivering a fraction of its design performance while appearing to work. Nobody notices because nothing stops.
Ask for evidence rather than reassurance: when the system was last serviced, what was found, what was done, and what the measured performance was. In shared buildings this is a question for the operator. In your own premises it is a question for whoever holds the facilities contract, and the answer is frequently that the contract covers reactive repair rather than performance verification.
What to do about it
| Sign | What it usually means | First step | |---|---|---| | A room people avoid | Local supply inadequate for occupancy | Measure that room specifically | | Drowsiness tracking occupancy | Ventilation rate below what the density needs | Measure across occupied hours | | Nothing measured | No basis for any decision | CO2 monitoring in real conditions | | Density increased | Design occupancy exceeded | Recalculate against actual headcount | | Equipment added | Heat load competing with occupants | Reassess spaces with people and kit | | Shared building | Nobody owns the answer | Request design occupancy and maintenance record | | Maintenance assumed | System underperforming silently | Ask for evidence, not assurance |
The sequence matters. Measure before you specify remedial work, because the most common outcome of measuring is discovering that the problem is concentrated in two or three spaces rather than distributed across the floor, which changes the cost of fixing it by an order of magnitude.
The international dimension
For groups, ventilation requirements are set nationally and the standards differ, which matters if you are writing a single specification for offices in several countries.
Some jurisdictions prescribe minimum air supply rates in detail, others set the duty in general terms as Great Britain does and leave the detail to guidance and standards. Occupancy rules differ too, which means the same fit-out can be compliant in one country and marginal in another. The approach that works is a group standard describing what good looks like, verified locally against the national requirement rather than assumed to transfer.
Keeping measurements, findings and remedial actions for every office in one register rather than in local email threads is where health and safety consultants and software are worth more together than either alone, and periodic health and safety audits test the environment as occupied rather than as designed.
Where Arinite fits
Arinite assesses offices as they are actually used, which for ventilation is the only assessment worth having. We support 1,500+ businesses across 50+ countries and protect 100,000+ employees, with 95%+ client retention over 15+ years. Our health and safety consultants work extensively with IT and software, finance and banking and legal organisations, including many occupying space they do not control.
Where offices span several countries, our global health and safety consultants confirm what each jurisdiction requires, and our international health and safety consultants keep that current as you add or reconfigure space.
If people are complaining about the air and nobody has measured anything, a free gap analysis will tell you whether you have a building problem, an occupancy problem or a maintenance problem, which are three different bills.
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Written by
Arinite Health & Safety Consultants
Health & Safety Expert at Arinite
