How do you achieve the highest possible indoor comfort with the least possible impact on the environment? And: How can thermal comfort in buildings be provided sustainably? We have compiled a catalogue of measures for you.
In addition to this topic, we recommend the lecture "High Comfort - Low Impact" by Prof Thomas Auer. The Managing Director of Transsolar specialises in sustainable climate and energy concepts for buildings and their rooms and conducts research at the Chair of Building Technology and Climate-Friendly Construction at the Faculty of Architecture at the Technical University of Munich.
Humans feel heat and cold through receptors in the skin. These thermoreceptors inform the brain that it is "too warm" or "too cold", although many more receptors are programmed for cold. The sense of temperature is the only human sensory system that exclusively reports information to the brain when discomfort occurs.
The body generates heat through metabolic processes, but at the same time it has to keep its core temperature constant. The body is therefore in constant heat exchange with its environment. This happens through
In principle, thermal comfort is achieved when the body's overall heat balance is in equilibrium. Six factors are regarded as the primary and dominant factors for thermal comfort:
In the 1970s, the Danish scientist Ole Fanger researched people's perception of warmth in a series of tests with numerous test subjects and developed a static comfort model depending on the six primary factors (see above) based on empirical investigations of individual perception.
This resulted in the so-called Predicted Mean Vote (PMV) - a scale of +3 (too warm) and -3 (too cold) with 0 as neutral. The PPD (Predicted Percentage of Dissatisfied) can in turn be determined from the PMV. In line with the human sensory system, we are also talking here about the number of dissatisfied rather than satisfied people. The lower the PPD value, i.e. the lower the percentage of dissatisfied people or the closer the PMV value is to 0, the better the comfort in a room is by definition.
On the other hand, there are adaptive comfort models. In addition to the user's thermal perception, they also take into account measures for adapting to the environment and different expectations regarding the indoor and outdoor climate. Here, temperature limit values for the indoor temperature are defined as a function of the outdoor temperature, the type of room air conditioning and an average of the outdoor temperature over the last seven days of the building. These upper and lower limits for the air temperature thus define a comfort range. As the criteria and requirements increase, the limit values change and the comfort range becomes narrower. However, narrow comfort limits throughout the year are neither legally prescribed nor healthy.
Leaving the comfort zone means, among other things, allowing more room for manoeuvre for individual user comfort!
Nevertheless, both methods in combination with indoor air movement form the basis for many German and international standards and certification systems for evaluating thermal comfort in buildings. In this respect, the question arises as to whether this method is the right approach for providing thermal comfort in buildings in a sustainable manner.
Particularly in view of increasing requirements due to greater flexibility and individualised working conditions and assuming variable levels of clothing and activity as well as more air movement, a wider comfort band means more scope for individual user comfort. A wider comfort band therefore saves considerable energy on the building technology side and reduces the level of technical installation in the building.