Ventilation regulations in the EnEV

For the purpose of long-term energy savings, modern buildings are designed in a particularly tight construction method that noticeably reduces the escape of heated air. However, since this also eliminates natural ventilation via joints and other openings, the EnEV stipulates that new buildings be constructed "in such a way as to ensure the minimum air exchange required for the purposes of health and heating." Since these statements open up some room for interpretation, the requirements can be met in different ways.

Hintergründe zur EnEV

The increasing understanding of climate protection and the careful use of natural resources has led to a large number of new energy requirements regarding the condition of residential and commercial premises. These are laid down, among other things, in the Ordinance on Energy-Saving Thermal Insulation - the Energy Saving Ordinance (EnEV) for short.

The EnEV is part of German economic administrative law and in this position prescribes building requirements for energy-efficient building operation to building owners. The scope of the EnEV primarily covers residential and office buildings. The background to the regulation is the energy policy goal of ensuring an almost climate-neutral building condition by 2050.

The requirements of the Energy Saving Ordinance

For manufacturers of ventilation systems, tradesmen, but also for planners and architects, Section 6 (1) and (2) is particularly decisive. This deals with the tightness of buildings and the required minimum air exchange.

• EnEV § 6 para. 1: "Buildings to be constructed must be designed in such a way that the heat-transferring enclosing surface, including the joints, is permanently sealed in an airtight manner in accordance with the recognized rules of technology."
• EnEV § 6 para. 2: "Buildings to be constructed must be designed in such a way that the minimum air exchange required for health and heating purposes is ensured."

The paragraphs state that constructed buildings should be as impermeable to air as possible and limit natural air exchange by infiltration and exfiltration. At the same time, a sufficient minimum air exchange from a hygienic point of view must be ensured. In most cases, this double requirement can only be met with a modern ventilation system.

Development of suitable ventilation concepts

Among the most widespread solutions are ventilation systems, which are used in centralized and decentralized designs, depending on local conditions. They extract the humid air, which is rich in carbon dioxide, from useful rooms and bring in fresh, oxygen-rich air from outside. Sometimes, however, ventilation systems in the windows are sufficient to ensure regular air exchange. Widely used are, for example, window rebate ventilators, ventilator window ventilations and electric tilt ventilation systems integrated into the window fittings.

Whether a ventilation system or window ventilation is the solution of choice can be determined with the help of a ventilation concept. Factors such as the size of the room, the type of use, the building layout, but also the exposure to pollutants in the ambient air are taken into account.

Regardless of which solution is chosen, controlled ventilation is indispensable. This is not only because air quality deteriorates when people breathe in oxygen and breathe out carbon dioxide, but also because pollutants are emitted from carpets and furniture.

Different types of pollutants in the air

Pollutants occurring in the air play an important role in the EnEV. Of particular note here are volatile organic compounds, such as those contained in solvents, cleaning agents, adhesives or paints. Fortunately, they gaseousize comparatively quickly, usually within a few weeks to months.

The situation is different for low-volatile organic compounds (SVOCs). These include plasticizers in plastics. They off-gas much less, but over many years. They are also deposited in the body, where they can act like hormones and lead to problems such as infertility and premature births.

Heat recovery pays off

Even if the installation of a ventilation system is not explicitly prescribed in the EnEV, it is recommended in self-interest alone. Especially in new buildings, experts emphasize the importance of heat recovery systems. In well-insulated buildings, up to 30 percent of the total demand for hot water and heating can be recovered. Some experts even speak of up to 50 percent. Another advantage of heat recovery is that warm air is better distributed in the room and does not sink heavily to the floor like cold air.