Healthy room climate

Anyone who speaks of well-being in the living room can not ignore the subject of thermal comfort. This refers to the narrow temperature range that lies between body sensations of blood fullness and sweating and the feeling of freezing. If thermal equilibrium can be maintained without regulatory effort, a person will experience thermal comfort.

"Depending on the local culture and climate, adapted clothing may accept temperatures between 16 and 32 degrees Celsius as acceptable, as evidenced by numerous heat and comfort studies conducted around the world in different cultures and climates. An ambient temperature is perceived as "comfortable" when the skin perfusion is at a medium level and neither sweat gland activation nor tremor need be used to control core temperature. This comfort temperature depends not only on the ambient temperature, but also on clothing, physical activity, wind, humidity, radiation and physiological condition. The comfort temperature for the seated, lightly dressed person (shirt, short underpants, long cotton trousers) with low air movement (below 0,5 m / s) and at a relative humidity of 50 percent at about 25-26 degrees Celsius, "says the study "Comfortable sustainability - studies on the comfort and health value of passive houses", firm.

Energy-efficient buildings have a clear advantage: high comfort, cosiness and pleasant living climate can be achieved with minimal energy consumption. The study authors: "Through consistent insulation heat losses are reduced so much that even very small amounts of heat sufficient to maintain the room temperature. The heating requirement of a passive house is therefore lower by a factor 10 than the average of the building stock. In the passive house, the high internal surface temperatures in winter cause a radiant climate, which is perceived as very comfortable. This high level of comfort is only achieved with radiators under the window, wall heating or underfloor heating in houses that are not built to the energy standard of a passive house. "

Bad indoor air makes you sick

The same applies to the indoor air: it also has a strong influence on the well-being and health of people. By cooking or cleaning we influence the quality of the air as well as through building materials, technology or textiles. From the study "Comfortable sustainability - Studies on the comfort and health value of passive houses": "So-called bad air is not caused by a lack of oxygen, but primarily by an excessive CO2 concentration. The overwhelming majority of users consider the indoor air quality as good if the CO2 concentration does not exceed the values ​​of 1000 ppm ("Pettenkofer number"). The outdoor air has a CO2 concentration of 300 ppm (up to 400 ppm in city centers, editorial note). Humans exhale the air with a CO2 concentration of approx. 40.000 ppm (4 Vol%). Without exchange with the outside air, the CO2 concentration in inhabited rooms rises rapidly. An increased CO2 concentration is not directly hazardous to health. However, from certain concentrations, you may experience disorders such as tiredness, difficulty concentrating, feeling unwell and headache, and impaired performance. A synopsis of studies on the health effects of carbon dioxide shows that decreasing CO2 levels also reduce so-called sickle-building syndrome-related symptoms (eg irritation and dryness of the mucous membranes, fatigue, headache). "

Home ventilation helps

Away from regular ventilation, a high-quality, controlled ventilation of the living space is a remedy in particular: with the controlled ventilation of the living space, cold fresh air is sucked in and filtered. In the geothermal heat exchanger and in the ventilation unit, the heating of the fresh air takes place. The air flows through a pipe system in the living and sleeping rooms and passes through staircase and hallway in the kitchen, bathroom and toilet. There, the used air is extracted via the pipe system and led to the ventilation unit. The heat is transferred in the heat exchanger to the supply air, the exhaust air blown into the open air. Of course, despite the ventilation of the living space, it is also possible to ventilate the building manually and windows may be opened. "Without a ventilation system, the windows would have to be opened at least every two hours to lower the CO2 rate to below the hygienic limit (1.500 ppm), a practice that is impractical in practice, especially at night," the study says , In addition, the window ventilation in winter ensures increased energy and heat loss, drafts and noise pollution.

Lower pollutants

The study "Ventilation 3.0: Occupant Health and Indoor Air Quality in Newly Built, Energy-Efficient Residential Buildings" by the Austrian Institute for Building Biology and Construction Ecology IBO has set itself the goal of improving the indoor air quality on well-being as well as the residential satisfaction of residents of single and multi-family dwellings ( 123 Austrian households) with and without residential ventilation system. Among other things, the living spaces were examined for harmful substances. The subject study collected data three months after referral and one year later.

Conclusion: "The results of the indoor air examinations, the data on user satisfaction and health as well as on the subjectively perceived indoor air quality show that the concept of buildings with residential ventilation systems has clear advantages over the" conventional "concept of the low energy house with pure window ventilation. The use of a residential ventilation system in residential buildings therefore, if the planning, construction, commissioning and maintenance of the current state of the art, generally recommendable. "

In particular, the recommendation is to combine the room air hygiene advantages of high-quality ventilation systems with maximum energy efficiency. And, according to the study on prejudice: "Various views on" forced ventilation systems "such as mold, increased occurrence of health complaints or increased drafts were not confirmed in the present study. On the other hand, it should be noted that there is a definite need for action with regard to the low air humidity in buildings with domestic ventilation systems. Technical solutions are available for superior ventilation concepts. "

Room ventilation: Prejudices checked

And the study goes on to say: "In general, significantly lower levels of pollutants in the indoor air were detected on both the first and the follow-up date in objects with residential ventilation systems compared to objects with exclusive window ventilation. [] The results show that the use of a residential ventilation system on average achieves significantly better room air with regard to health-relevant air constituents, but the dispersion of the values ​​is high in both house types. "

Pollutant concentration

In detail, the exposure to various Volatile Organic Compounds (VOC) and other pollutants compared to conventional window ventilation was investigated. The results of the study showed that the type of ventilation (with or without residential ventilation system) had a highly significant influence on the VOC concentration in the room air and that in the case of objects with exclusive window ventilation more frequent guideline overruns occurred at both measurement dates. Significant influence was observed with respect to the concentration of formaldehyde, carbon dioxide, radon and mold spores. The type of domestic ventilation for dust mite allergens has no influence.

New building: higher load

"Based on the results of the pollutant measurements of indoor air can also be said that especially at the beginning of the use in both types of objects in many cases increased VOC emissions of building materials and materials of the interior took place, which is a hygienically unsatisfactory situation. In some cases, the operation of the residential ventilation system is not sufficient as the sole measure for reducing exposure. The VOC values ​​were to a large extent (also in properties with residential ventilation systems) above the results of quality-assured objects built using chemicals management. The reasons for this are on the one hand presumably the use of solvents in construction chemicals and interior materials as well as secondarily the low supply air volume flows in the rooms. More emphasis must therefore be placed on reducing emissions by selecting low-emission, pollutant-tested building materials and materials. "

Room temperature & draft

With regard to the indoor climate, room temperature and air movement were considered to be significantly more pleasant by the occupants of dwellings with residential ventilation systems than by the residents of objects with exclusive window ventilation. The opinion with regard to so-called "forced ventilation systems for residential objects" that the room temperature is considered to be more unpleasant and drafts may therefore not be upheld.

Allergy & germs

The opinion that ventilation systems are "spitting germs" could not be confirmed. Conversely, it can be assumed that ventilation systems even function as a sink for mold spores, while residential ventilation systems can significantly reduce the concentration of allergens (spores, pollen, etc.) and particulate matter entering from outside.

humidity

However, the opinion has been confirmed that the air in ventilation systems tends to be too dry, due to the increased volume of air transported through the entire system, which in the cold season leads to dehumidification of all materials and, as a consequence, indoor air. If just the same amount of air was released into objects that were ventilated exclusively via windows, there would also be comparably low humidities.
Technical solution for improving the situation (demand regulation and moisture recovery) are well known and are already installed in modern plants.

Mold

It is true that in all utility buildings, whether insulated or not insulated, moisture is created which has to be released outside. Mold is also formed in new buildings, which are not completely dried up after the construction, and especially in buildings in need of renovation. An external thermal insulation - assuming a professional planning and implementation of the structural measures - reduces the heat losses to the outside very strong, thus increasing the surface temperatures of the inner walls. This significantly reduces the risk of mold growth.

The study: "Both too high and too low values ​​for the relative humidity should be avoided. The study showed that low levels of 30 percent relative humidity were found almost exclusively in homes with residential ventilation systems, high levels above 55 percent almost exclusively in objects with window ventilation. It can therefore be assumed that efficient mold prevention is possible by means of a residential ventilation system. "

1 - thermal comfort

An ambient temperature is perceived as "comfortable" when the skin perfusion is at a medium level and neither sweat gland activation nor tremor need be used to control core temperature. The comfort temperature for the seated, lightly clad people with low air movement and at a relative humidity of 50 percent is about 25-26 degrees Celsius.

2 - indoor air quality

So-called bad air is not caused by a lack of oxygen, but primarily by an excessive CO2 concentration. The overwhelming majority of users consider the indoor air quality as good if the CO2 concentration does not exceed the values ​​of 1000 ppm ("Pettenkofer number"). The outdoor air has a CO2 concentration of 300 ppm (up to 400 ppm in city centers).

3 - Pollutants - VOC

Above all, VOCs, volatile organic compounds, burden the health of the living space. Many building materials contain these VOCs and release them into the indoor air. Emissions are high, especially in the case of new construction or repainting, but they decrease over time. Studies show that a controlled ventilation of the living space helps to remedy this situation and ensures healthier indoor air.

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