Cost-benefit analysis and increased productivity: when and why is air humidification worthwhile?

Respiratory illnesses are among the most common causes of sick leave among employees and therefore have a significant financial impact on employers. The illustrative cost-benefit analysis presented here shows that the investment in an additional humidification system can pay for itself in as little as two to three years.

Furthermore, an investment in the indoor climate also pays off in terms of productivity: Studies show that an optimal indoor climate can increase employees’ performance, speed and accuracy. Without complaints about dry air, employees are happier and work with greater motivation and efficiency.

Over 16 per cent of sick days taken by office workers are due to respiratory illnesses (Statista Research Department 2020). In particular, occupational groups that involve a high degree of speaking suffer from frequent respiratory illnesses. The highest rates of sick leave are found among employees in call centres, customer service and telephone support.

In its 2019 Absenteeism Report, the AOK Scientific Institute estimates that cold-related absenteeism among dialogue marketing professionals averages 4.8 days per year. One of the reasons cited for this is the working environment of employees in open-plan offices, where viruses can spread rapidly. Protecting the mucous membranes of the respiratory tract and the vocal apparatus therefore has significant financial benefits in terms of reducing absenteeism and performance limitations. The link between respiratory illnesses and low humidity is now considered proven.

In a multi-year study published in 2019, researchers at Yale University in the US clearly demonstrated the influence of low humidity on the survival and spread of influenza viruses. With an optimal humidity level of between 40 and 60%, it was shown that viral infection is minimised and the transmission process is hindered. Ensuring a relative humidity of at least 40% can therefore be an effective measure for businesses to significantly reduce the spread of respiratory infections, lower the number of illnesses and cut costs.

Video on the right: How does additional air humidification pay off?

For any business, investments must pay off. Employers base their decision-making on business criteria. In practice, however, investments in employees’ health, well-being and motivation are difficult or impossible to quantify in monetary terms. The external factors and individual circumstances are simply too diverse and complex.

Nevertheless, will attempt here to conduct a cost-benefit analysis based on statistical facts and realistic assumptions, which demonstrates the potential savings companies can achieve through preventive health protection.

1. Staff wage costs: €30,000 per year
2. Average of 230 working days per year
3. 4.8 days of absence due to respiratory illnesses
4. Cost of lost working time per day of absence for work not carried out, which must be compensated for, for example, by other colleagues working overtime, weighted by a factor of 1.8.

Based on current medical findings and studies, it can be cautiously assumed that maintaining optimal humidity levels in the workplace throughout the year can reduce respiratory illnesses by at least 25%. Based on a 25% reduction in respiratory illnesses this results in an average reduction in absenteeism within companies of 1.2 days of absence per employee.

The investment costs for an air humidification system to ensure optimal humidity all year round depend on the room size and the number of employees. As a simplified basis for cost calculation, the following values can be used:

1. Space requirements: approx. 15 m² per employee (open-plan office with a ceiling height of approx. 3 m)
2. Investment costs: from €30 per m²
3. Running costs: €300 to €600 per month (including maintenance), depending on the size of the facility

A study by Fraunhofer IAO on the design of the working and office environment, conducted as part of the Office 21 collaborative project, shows that only 20 per cent of office users are very satisfied with their office environment, with a further 42 per cent being somewhat satisfied. Among other factors, a lack of humidity has a significantly negative impact on satisfaction in the office. Over a quarter of office workers frequently or very frequently find the air too dry. Scientists at the Fraunhofer Institute calculated a correlation of -0.30, indicating that a lack of humidity has a clear negative impact on satisfaction in the office. This means that employers and building managers have significant potential for optimisation when designing work and office environments.

The positive leverage effect on performance that can be expected is demonstrated by the influence of satisfaction on the motivation and performance of office workers, as calculated in the Office 21 study. With correlation coefficients of 0.44 and 0.38 respectively, there is a strong positive influence that affects not only performance but also identification with and loyalty to the employer.