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Clean air is one answer to the productivity challenge, says Julie Godefroy.

© iStock
© iStock

04 November2019 | Julie Godefroy

A Harvard University study of architects, engineers, managers and programmers concluded that improved indoor air quality could enhance workers’ cognitive performance. 

And the World Green Building Council’s Health, Wellbeing and Productivity in Offices: The Next Chapter for Green Building document suggests that a well-ventilated office can result in an 8-11 per cent productivity increase. 

CIBSE’s guidance in its Technical Memoranda TM40: Health Issues in Building Services shows that the optimum fresh air rate in working environments is between 20 and 30 litres per second [l/s] per person. This is a significant increase on the current minimum fresh air requirement of 8 to 10 l/s per person for a typical mechanically ventilated space. 

But this is a developing area and most studies support the current guidelines on fresh air rates, avoiding mixing and recirculation, and recommended CO2 levels.

Ultimately, good indoor air quality (IAQ) requires a ventilation strategy supported by monitoring, cleaning and maintenance. Here are five initiatives to improve IAQ.

1 Good maintenance 

TM40 highlights several maintenance issues that can lead to poor IAQ including: 

  •  Badly maintained combustion equipment, such as boilers, which can lead to carbon monoxide poisoning; 
  •  Filters not being changed; 
  •  Unclean ductwork that could introduce pollutants and smells into a space; and 
  •  Poorly drained condensate pans in air handling units and fan coil units. 

2 Reduce pollutants at source 

Good ventilation design should limit exposure to sources of pollution including busy roads, exhausts from neighbouring buildings and other sources. 

In naturally ventilated buildings, operators should look to ventilate through openings on less-exposed façades. When this isn’t possible, use mechanical ventilation and filtering.

Internal sources should also be considered: from the selection of low-emitting materials to the segregation of sources such as printers and cleaners’ stores, in an enclosed space with dedicated extract.

3 Flush out volatile organic compounds (VOCs)

The construction stage is crucial for good IAQ:

  •  Avoid on-site dust;
  •  Protect materials from damage and moisture; and
  •  Protect ventilation systems from dust ingress and clean them on completion.


Flushing the building or the affected rooms should dissipate emissions if high VOC levels are found at the early stages of occupancy after construction, refurbishment, fit-out or installation of new furniture. Flushing could be repeated for the first few months of occupation, particularly if formaldehyde levels are found to be high.

4 Use low VOC cleaning products

High levels of VOCs in a ‘settled’ building are likely because of internal sources such as equipment or cleaning products. Choose cleaning products with low VOC emissions and relocate polluting equipment such as printers to unoccupied well-ventilated areas. A site analysis may also identify sources near to the building’s air inlets, such as industrial or retail premises (hairdressers or nail salons).

5 Check ventilation levels

Check the operation of existing ventilation systems, ventilation rates and controls in relation to occupancy patterns – recommission systems or carry out remediation measures if required. Several voluntary schemes – BREEAM, LEED and WELL – require indoor air quality to be tested and set a limit of 500 micrograms per cubic litre (µg/m3). WELL requires VOC considerations to continue after the fit-out is complete and constant monitoring and testing of IAQ. Ventilation: Approved Document F recommends a limit of 300µg/m3.

A real-world example

Engineering consultancy Cundall trialled WELL certification at its new London workspace. The company says it has seen a 50 per cent drop in absenteeism compared with the year before at its previous office. It also saw a 27 per cent reduction in staff turnover. 

Although a healthy workplace is not necessarily a productive workplace, to be productive office workers need to be well. And even a modest boost in employee wellness will be good for business. 

 CIBSE TM40 will be launched at Build2Perform Live, 26-27 November. For more information on CIBSE TM40 and CIBSE Guide M go to www.cibse.org

Julie Godefroy, technical manager at CIBSE