Diseases of the respiratory system are among the most common causes of unfitness for work, and as such have a major monetary leverage effect for employers. The example of a cost-benefit calculation presented here shows that investment in an additional air humidification system can pay for itself in as little as two to three years. Moreover, an investment in the indoor climate also pays off in terms of productivity: Study shows that an optimum indoor climate can enhance the performance, speed and accuracy of staff. In the absence of complaints about dry air, employees are more satisfied and their work is more motivated and productive.
Diseases of the respiratory system are among the most common causes of unfitness for work, and as such have a major monetary leverage effect for employers. The example of a cost-benefit calculation presented here shows that investment in an additional air humidification system can pay for itself in as little as two to three years. The calculation looks only at the potential effects on respiratory problems. The calculations are based on known facts about respiratory problems and on realistic assumptions. All other positive effects of optimum humidity on health (e.g. the voice, eyes, skin) and on productivity are disregarded.
The importance of humidity
More than 16 percent of days lost to illness by office workers result from respiratory infections (Statista Research Department 2020). In particular, professions involving a great deal of speaking suffer from frequent respiratory problems. The frontrunners in terms of rates of absence are employees working in call centres, in customer service and on telephone help lines. In its 2019 report on absence from work, the Scientific Institute of the AOK puts cold-related rates of absence in dialogue marketing professions at an average of 4.8 days per year. One of the reasons for this is the working environment of employees in open-plan offices, where viruses can spread quickly. Protection of the mucous membranes of the respiratory tract and the vocal tract therefore has a major monetary leverage effect in the effort to reduce rates of absence and limitations on productivity. The connection between respiratory complaints and insufficient humidity is now widely acknowledged. In a multi-year study in 2019, researchers at Yale University in the United States clearly demonstrated the influence of low humidity on the survivability and spread of flu viruses. They found that at an optimum humidity of between 40 and 60%, viral infection is minimised and the transmission process is made more difficult. For companies, ensuring a relative humidity level of at least 40% can therefore be a suitable measure to significantly reduce the spread of respiratory infections and the number of illnesses, and to cut costs.
Details on the cost-benefit calculation
Costs of respiratory infections
For every company, investments must pay off. Employers rely on business criteria as a basis for their decision-making. In practice, however, it is difficult if not impossible to measure investments in the health, well-being and motivation of employees in monetary terms. The external influencing factors and individual circumstances are too varied and complex. Nevertheless, on the basis of statistical facts and realistic assumptions, an attempt will be made here to carry out a cost-benefit analysis that shows the savings potential available to companies through preventive health protection.
Assumptions on costs / non-productive employee time:
Employee wage costs € 30,000/year
Average 230 working days/year
4.8 days of absence due to respiratory complaints
Costs of non-productive time per day of absence for work that is not performed and must be compensated, for example by colleagues working overtime, weighted with a factor of 1.8.
Benefits and costs of humidification
On the basis of the medical evidence and studies available to date, it can be cautiously assumed that optimum humidity levels in the workplace throughout the year can reduce respiratory illnesses by at least 25%. At 25% fewer respiratory complaints, there is an average reduction in rates of absence in companies of 1.2 days of absence per employee. The investment costs for a humidification system to ensure optimum humidity all year round depend on the room size and the number of employees. In simplified terms, the following values can be assumed as a basis for the cost calculation:
Assumed costs of humidification:
Room size: Approx. 15 m² per employee (open space with room height approx. 3 m)
Investment costs: From € 30 per m²
Running costs: € 300 to € 600 per month (including maintenance), depending on the size of the system
If only respiratory complaints are considered, the investment in a humidification system can pay for itself in just two to three years. All other positive effects of optimum humidity on health (e.g. the voice, eyes, skin) and on enhanced productivity are disregarded.
Case studies: Benefits and costs of humidification
Protection of the voice at the coffee specialist Jura
Satisfied employees are more motivated and more productive in their work. The indoor climate at the workplace is an important area of action for companies looking to have a positive impact on employees. Relative humidity is therefore not only an influencing factor for perceived “thermal comfort”, it also drives productivity. “Thermal comfort” is the term used when building users do not want the indoor to be either warmer or colder, drier or more humid. The comfort zone, in which the vast majority of room users feel comfortable, ranges from about 18 °C to 24 °C and from 35% to 75% relative humidity. One in four office workers feels frequently or continuously uncomfortable as a result of dry air.
Dry air is a source of irritation
A study by Fraunhofer IAO on the design of the working and office environment conducted as part of the Office 21 joint project shows that only 20 percent of office users are very satisfied with their office environment, while a further 42 percent are more or less satisfied. As a source of irritation with an above-average impact, insufficient humidity is one of the factors that has a clearly negative influence on satisfaction in the office. More than a quarter of office workers often or very often find the air to be too dry. The researchers at the Fraunhofer Institute calculated a correlation of -0.30, with which insufficient humidity clearly has a negative effect on satisfaction in the office. This means that employers and building managers have a great deal of control over the potential for optimisation in the design of working and office environments. The extent of the positive leverage effect on performance that can be expected is shown by the influence of satisfaction on the motivation and performance of office workers calculated in the Office 21 study. With a correlation factor of +0.44 or +0.38, there is a strong positive influence that, in addition to performance, also has an impact on identification with and loyalty to the employer.
Performance, speed, accuracy
Further details on the potential impact of the indoor climate on productivity can be found in the British “Whole Life Performance Plus” study: the study confirms that an optimum indoor climate can enhance the performance, speed and accuracy of staff. In addition, companies that invest in the indoor climate in production and work spaces can expect a range of positive effects among their employees: lower rates of absence, higher product quality, enhanced performance in the workplace, greater employee loyalty and creativity. The study focused in particular on the influence of temperature, carbon dioxide (CO2) and relative humidity in the workplace.
Case studies: Humidification and performance
Fraunhofer Study on air humidity
Fraunhofer Study in a practical information package, including a free Thermo-hygrometer.