The Klöber Klimastuhl: a field test
Four months after the market launch of our Klöber Klimastuhl and during a seemingly never-ending summer, our innovative office chair is more relevant than ever. In the first part of the “Living Lab smart office space” blog post, Prof. Hoffmann, research director at the Technical University of Kaiserslautern, already answered a wide range of questions on her sensational project. Now we want to find out about her three-month field trial of the Klöber Klimastuhl in more detail, and we are delighted to be interviewing her a second time.
Prof. Hoffmann, can you explain the structure and procedure of the Klimastuhl study for the benefit of our readers?
We began our field study within the structure of the Living Lab smart office space initiative in the very hot summer of 2015 at the German Research Centre for Artificial Intelligence. As I specialise in the research area of “thermal comfort”, my team and I were keen to find out how the Klimastuhl would perform under real-life conditions. The first step was putting together a representative mix of participants, taking into account relevant parameters such as age, gender, body mass index and height. A total of 26 people took part in the field study, of whom 16 were men and ten were women. They were allocated to individual and group offices with four to six occupants.
The testers put the chairs through their paces for approx. 21 days. During this time we measured the ambient air temperature in the offices and recorded when each function – heating or ventilation – was used and what effect that function had on the individual’s sense of wellbeing. To find this out, participants were questioned twice a day via an online questionnaire as to their perception of temperature and personal comfort, both before and during use of the Klimastuhl. This data was then statistically evaluated.
How did the participants respond at the different temperatures? Can you identify a pattern?
Yes, it was possible to establish a significant correlation between the room temperatures measured and the use of the climate function. From around 24 °C most people used the ventilation function on Level 1, and above 26 °C they switched to Level 2. During cooler weather the heating function was used even when room temperatures reached 24 to 25 °C. There are different possible reasons for this:
- The season and prevalent weather conditions affect people’s thermal preferences
- In autumn and winter the external walls are colder, meaning that heat is lost through radiation
- In many cases the heating function has a soothing effect on the back, so people use it for that reason
- Individual comfort temperatures can vary widely, and depend on a range of physiological parameters
And what effect did the use of the ventilation and heating functions have on the comfort of test participants?
The most important findings clearly indicated that the heating function resulted in considerably improved thermal comfort, and that around one-third of participants achieved an increase in wellbeing – in some cases significantly so – thanks to the ventilation function:
The cooling effect of the Klimastuhl can be attributed firstly to the latent heat dissipation caused by evaporating perspiration, and secondly to the fact that the ambient air is channelled past the body, taking heat with it. This heat transfer effect is more noticeable the greater the temperature difference between skin and ambient air.
On a six-point scale – of very uncomfortable (-3) to very comfortable (+3) – it was possible to achieve increases of up to five points with the ventilation function.
The comfort ratings also increased considerably when the heating function was used – by up to 3 points on the scale. The explanation: if someone tends to feel cold, the Klimastuhl works exactly where people react most sensitively to cold – in the trunk, where the vital organs are located.
Quite often different interpretations of cold and heat are down to gender. This theme was also addressed in the blog post “Why women are always freezing in the office – and men aren’t!”. Were you able to observe this phenomenon during the field study, and what’s your opinion as a scientist?
The verdict was positive overall, with only a slight difference between men and women. Both genders appreciated the chair’s heating function equally. Our observations showed that people who are generally more sensitive to the cold, including men, use the heating function more frequently, which is after all to be expected. The fact that a higher percentage of these people who react sensitively to cooler temperatures is female is both borne out by statistics and can be explained in terms of physiology.
With regard to the ventilation function on the other hand, we were able to identify a clear preference amongst male testers. The men spoke particularly highly of the perspiration removal, which causes noticeable cooling as well as a pleasant “drying” effect thanks to the heat released through evaporation.
Can you give a statement regarding the effect of the Klimastuhl on productivity in the workplace?
In most cases it is difficult to measure the productivity of office-based work in a truly objective manner and therefore arrive at quantitative statements regarding the effectiveness of a particular method. But in any case it is possible to identify a qualitative relationship between satisfaction with the working environment and productivity. The principle is this: the higher the dissatisfaction, the greater the negative influence on work performance. In other words, the more you can correct compromised thermal comfort with the Klimastuhl, the more it promotes productivity at work. “Too cold” or “too hot” rank amongst the top complaints faced by facility managers in office buildings. So the Klimastuhl has great potential to contribute significantly towards employee contentment and therefore productivity in the company.
So where do you think the Klimastuhl will be needed most?
I see three main areas of application for the Klimastuhl:
- In open space or combi-offices where people with differing temperature preferences share a working space.
- In buildings where it is not possible to create ideal conditions with regard to thermal comfort in the workplace – for instance because of ineffective heating and ventilation (inadequate design) or structural issues (lack of insulation, poor windows etc.), or because of the use (for example supermarkets with air conditioning set to high). The Klimastuhl® is also recommended for individual workstations in these situations.
- In all buildings where energy-saving strategies are practised, because operation of the Klimastuhl is highly energy-efficient thanks to its rechargeable lithium-ion battery. The Klimastuhl can help to prevent “over-heating” in winter and “over-cooling” in summer – which has the effect of reducing peak loads when running the heating or air-conditioning.
Thank you very much for the interesting interview, Prof. Hoffmann!