Use Case: The Office

The short answer

At maximum setting, one HA500 adds about 6–12 equivalent air changes per hour (eACH) to a 15–30 m² meeting room. For open-plan space, adding 4 eACH takes about two HA800s or one HA-C1300 per 100 m². Running one HA800 at maximum for a working year costs approximately £55 in electricity.

How much clean air does an office need?

The Lancet COVID-19 Commission’s task force proposed clean-air targets of 4 eACH (“good”) and 6 eACH (“better”) (Lancet Commission, November 2022). These count clean air from all sources — outdoor-air ventilation, filtration and air cleaners together — and minimum ventilation is still required. Air purifiers count towards the total; they do not provide fresh air or lower CO₂.

How many units?

Ceiling height 2.7 m. Units needed for the purifiers alone to add 4 or 6 eACH at maximum setting.

Space	Floor area	Volume	Units to add 4 eACH	Units to add 6 eACH
Meeting room	15 m²	40.5 m³	1 × HA500 (12.3 eACH)	1 × HA500 (12.3 eACH)
Large meeting room	30 m²	81 m³	1 × HA500 (6.2 eACH)	1 × HA500 (6.2 eACH)
Open-plan zone	100 m²	270 m³	1 × HA-C1300 (4.6), or 2 × HA800 (5.9)	2 × HA-C1300 (9.3), or 3 × HA800 (8.9)
Open-plan floor	150 m²	405 m³	2 × HA-C1300 (6.2), or 3 × HA800 (5.9)	2 × HA-C1300 (6.2), or 4 × HA800 (7.9)

The table shows the clean air the purifier adds at its maximum setting. Existing ventilation also counts towards the total. At quieter settings each unit delivers less clean air than shown. Final selection depends on occupancy, ventilation, room layout, noise and the requirements of the setting. A 30 m² room with one HA500 is only just above 6 eACH at maximum. HA-C800 figures are the same as HA800.

In open-plan spaces, spread units out rather than grouping them, and keep partitions and meeting pods from blocking airflow.

Running cost

At maximum setting for 10 hours a day, 5 days a week (2,600 hours a year), at 26.32p/kWh excluding VAT, electricity costs approximately £31 a year for an HA500, £48 for an HA-C800, £55 for an HA800 and £66 for an HA-C1300, per unit. Lower settings use less power and deliver less clean air: for example, the HA-C1300 delivers 634 m³/h at 16.5 W on its medium setting — about £11 a year for the same hours.

Filters: £150 (HA500) or £240 (HA800) per replacement set, including VAT, typically lasting about two years. For HA-C800 and HA-C1300 filter prices, ask HATL.

What HATL’s evidence shows

Independent office assessment: in CETEC’s six-hour closed-office assessment at London South Bank University, PM2.5 was 1.51 µg/m³ at hour 2 with the HA800 off and 0.34 µg/m³ at hour 4 with it operating in manual mode; PM10 was 22.90 and 3.12 µg/m³. PM2.5 was already low at hour 2. CETEC separately reported 59.1% lower meeting-room TVOC; the sampling periods and analytical method for that comparison are not given (see Case Studies).
Laboratory: HA800 TVOC and gas results are on Evidence & Test Results.

FAQs

How many air purifiers does an open-plan office need?

For the purifiers alone to add 4 eACH, about one HA-C1300 or two HA800s per 100 m², based on maximum setting and a 2.7 m ceiling. Your ventilation also counts towards the total.

Do office air purifiers reduce CO₂?

No. They remove particles and some gases; only ventilation removes CO₂.

How much does it cost to run an office air purifier?

At maximum setting for a 10-hour working day, approximately £31–£66 a year per unit in electricity, depending on model, at the current price-cap rate excluding VAT. Lower settings cost less but deliver less clean air. This is an illustration, not a guaranteed bill.