ExclusivesThinkingHow Indoor Environmental Quality impacts health, wellbeing and productivity at work

Curtis Gubb, Environmental Consultant at multi-disciplinary engineering firm, Cundall, discusses the importance of Indoor Environmental Quality.
Content Team2 weeks ago12 min

Curtis Gubb, Environmental Consultant at multi-disciplinary engineering firm, Cundall, discusses the impact of Indoor Environmental Quality (IEQ) on health, wellbeing and productivity in the workplace, and how employee perception plays an important part in the holistic assessment of a healthy space.

Why Indoor Environmental Quality is important

Indoor environmental quality (IEQ), which encompasses various factors that influence comfort like temperature, daylight, noise levels and air quality, has been shown to directly affect our health, wellbeing and productivity. This is especially prevalent in the workplace since we spend 90% of our time indoors and a large percentage of that at work.

A large body of research has found occupant perception of IEQ to be inconsistent — likely due to the intricacies of how we each individually experience the environment around us — and although occupants can frequently identify a problem, recognising the specific cause is often difficult. As engineers, we are able to monitor IEQ in use, and by coupling monitoring with occupant perception we have the ultimate tool for assessing a healthy space – once we know there’s an issue, we can find a solution.

Indoor Air Quality

In indoor air quality (IAQ) terms, pollutants, such as particulate matter and certain volatile organic compounds, are often measured indoors at concentrations harmful to our health; this causes either long or short-term impacts depending on the pollutant’s toxicity and concentration, and directly affects our wellbeing. Numerous strategies can be utilised by designers to reduce internal pollutant concentrations. Broadly, these look to either reduce the number of sources, or ensure fresh air is introduced to a building, via filtration or by increasing the ventilation rate.

Unfortunately, there is no guarantee that a building has a good quality, or a well-designed and maintained ventilation system providing enough fresh air to keep pollutant concentrations at a safe level. Additionally, many buildings – such as houses and schools – are naturally ventilated and at the mercy of whatever pollutants are present in the ambient air. Furthermore, a lack of fresh air often gives rise to an increase in CO2 indoors, which can impact on decision making and cognitive performance at elevated, but commonly experienced concentrations.

Thermal Comfort

As thermal comfort often depends on personal and environmental factors, predicting an optimal range of temperature and humidity is challenging, but paramount. Alongside controlling energy consumption, increasing workplace efficiency and performance is why it’s so important to understand comfort.

Cundall’s Work on IEQ

Effective monitoring strategies of both thermal and air quality parameters allow for mitigation measures to be implemented immediately, alleviating possible health, wellbeing and productivity impacts on occupants. At Cundall, we first investigated this during the fit out of our London office – One Carter Lane. Helping us become the first building in the UK and Europe to achieve the WELL Building Standard Gold certification – and only the seventh in the world.

We now continuously monitor IEQ inside all of our offices with the help of desktop IEQ sensors that measure elements like temperature, CO2 and relative humidity. We’ve then passed on what we’ve learnt to our various clients, helping them to enhance occupant health, wellbeing and productivity in their buildings. Inside our own office, a number of years after we moved in, we noticed an increase in CO2 concentrations from an average of approximately 700 parts per million (ppm) to a much higher 1300 – 1400 ppm. On a different floor within our building, a fit-out was taking place and with it a re-balancing of the ventilation system – effectively robbing us of our fresh air. If we were not monitoring our IEQ, we would have been oblivious to this and our health, wellbeing and productivity would have suffered as a result.

For a high-profile asset manager, we have done extensive long-term monitoring of numerous pollutants, temperature and humidity. We found that CO2 concentrations were exceeding the optimal range 80 per cent of the time and with some small modifications to their ventilation and cooling system, we managed to reduce the concentration dramatically. Furthermore, with our bespoke productivity mapping tool, we calculated improvements in productivity by 5.8 per cent, equating to up to £2 million a year in savings.

Light and Noise

In addition to air quality and thermal parameters, light and noise levels are also important in terms of wellbeing and productivity. In a recent Leesman workplace review, noise levels were found to be one of the key drivers influencing an employee’s productivity, enjoyment and pride in the workplace. Light also plays a vital role in the wellbeing of occupants, promoting employee engagement, presenteeism and productivity, so it is important to ensure we’re exposed to the right light at the right time; namely, coordinating the indoor light with our natural circadian rhythm — moving from blue during the day (the dominant colour in daylight) to a warmer colour in the early morning and evening. Designers can achieve this by optimising a space to ensure maximum daylight penetration and supplement this where needed with high-quality architectural lighting.

In terms of monitoring, both light and noise levels are beginning to be integrated into commercially available IEQ sensors, alongside air quality and thermal parameters. However, initial testing by our specialist in-house light and acoustic teams has shown the results to be unreliable. This is to be expected with a relatively new integration and improvements will follow as the technology develops. In the meantime, we recommend the results be used as a guide only and specialists should be consulted for accurate measurements.

Occupant Perception

Alongside monitoring, an employee’s perception of their indoor environmental quality aids in identifying and effectively mitigating issues. We’ve found that this can be achieved through post-occupancy evaluations (POE), such as the Building User Survey (BUS) or the Leesman workplace review, which are effective ways for occupants and facilities managers to communicate building issues. Alternatively, utilising smart services — where instant feedback can be inputted into apps or the building management system — can help to immediately highlight relevant issues to the facilities management team.

As workplace wellbeing continues to push to the forefront, the need for continuous monitoring of all aspects of IEQ alongside occupant perception will be of critical importance. If landlords and tenants alike fail to uptake this fast enough, leasing a building or attracting the best staff will become incredibly challenging.


Curtis Gubb joined Cundall in October 2019 and has contributed to the sustainability team’s ongoing research into IEQ in the workplace and managed several ongoing monitoring projects. As part of Cundall’s air quality team, he has undertaken ambient assessments and written strategies for clients on how to enhance indoor air quality. He is an Environmental Health PhD candidate from the University of Birmingham and also a member of the CIBSE air-quality working group.

Curtis Gubb, Environmental Consultant at multi-disciplinary engineering firm, Cundall
Curtis Gubb, Environmental Consultant, Cundall

Content Team

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