y t i l a u q r i a m o o R l i g n n n a p r o f s s a B i i g n n n a p l l a c i t c a r P l i g n n n a p e p m a S l 1 Healthy room air quality in homes A pleasant room climate and hygienic room air quality are essential for healthy living and well-being. And this is the main job of domestic ventilation. Unpolluted outside air sets the standard for “good air”. Pollution of room air comes from various sources, including harmful substances which enter the room with the outside air, the persons themselves, as well as construction materials, fittings, home furnishings, heaters, cook- ers, pets, plants, textiles, foods and household chemicals emit a number of substances. The most important substances include: f carbon dioxide (CO2), that is produced by human metabolism or combustion processes (gas stove, candles, smoking). f water vapour, some of which comes from people and some of which is produced from water evaporated by plants, when cooking, washing, showering etc. A humidity level of between 40 % and 60 % is considered comfortable. f odours from human perspiration or domestic activities. f toxic gases and vapours (nitrogen oxide, hydrocarbons, aldehydes, solvents), which escape from objects and materials or are produced from combustion processes. f micro-organisms, such as bacteria, viruses, mould spores or house dust mites. f radioactive substances from construction materials and the earth. Achieving a good room air quality requires emissions in the building to be mostly prevented, efficiently re- moved and adequately diluted. Research into humidity, CO2 and odours has found that 30 m³ of fresh air an hour per person is a good guide for the volumetric flow needed to achieve good hygiene levels. This figure is also based on DIN 1946-6 “Ventilation for residential buildings”. Depending on the size of living space per person, this means air exchange rates1 of between 0.3/h and 0.8/h. Taking into account the unavoidable amount of indoor air pollution from construction materials and furnish- ings as well as the fact that many materials buffer water vapour and odours, requires a minimum volu- metric flow to be designed depending on the size of the home. If the air volume of a home is used as the gauge for this, the air exchange rate should not fall below 0.3/h. Controlled domestic ventilation is currently considered to be the only way to ensure a hygienically adequate air exchange, with the sealed building envelope design prescribed by law. MAICO Ventilatoren develop and produce very efficient and smart ventilation systems with heat recovery at the company’s headquarters in Villingen-Schwennin- gen, southern German - “Made in Germany”. i w e v r e v o t c u d o r P 1 The air exchange rate is the ratio between the exchanged volume of air per hour and the total room volume. 4