Why Ventilate? Controlling Pollutants and Humidity in Living Spaces
Why is ventilation necessary?
Composition of Breathing Air
In its natural composition, air consists of approximately 21 percent oxygen and about 78 percent nitrogen. About one percent of the air we breathe consists of noble gases, carbon dioxide (CO2), and hydrogen. The primary source of oxygen for humans is the air we breathe. Oxygen is transported through the blood to the entire body and is essential for all metabolic processes in the human body, making it a prerequisite for energy, health, vitality, and well-being. Humans can survive for days without water and for weeks without food, but only a few minutes without air to breathe. This makes the quality of the air we breathe all the more important.
WHAT DOES VENTILATION DO?
Other substances also continuously accumulate in indoor air such as dust particles, aerosols, sulfur and nitrogen compounds, volatile organic compounds (VOCs), ozone, neon, helium, and carbon monoxide. Due to these pollutants often does not have an optimal composition for humans. In addition, the moisture content of the air increases over time, which can lead to negative consequences in the form of mold growth. In a 4-person household, for example, a daily amount of water vapor ranging from 6,000 to 12,000 grams is produced, i.e., up to 12 liters of water vapor per day.
As a result, it is of fundamental importance that the air in a room is regularly exchanged and fresh air gets in, thereby reducing the concentration of moisture and air pollutants. There are basically two different ways of achieving this air exchange: window ventilation (opening the window) and mechanical ventilation.
The moisture extraction through the air exchange with window ventilation amounts to an average of around 900 – 1,500 g of water vapor per ventilation process. With three ventilation processes per day, that is 2,700 – 4,500 g of water vapor per day. Since around 6,000 – 12,000 grams of water vapor are produced daily, three burst ventilation is not enough to achieve a complete moisture balance.
Requirements for a ventilation concept
Current living situation in Germany
For years there have been reports of structural damage and damage to health from mold. According to the study “Wohnen und Leben” (Innofact, 2012), 17 percent of Germans live in an apartment contaminated with mold. At least 7 percent of children are affected by mold damage.
In 55 percent of the cases, the bathroom is affected, in 38 percent of the cases the bedroom, in which the residents spend a particularly long time. Once mold damage has occurred, control and remediation are often expensive and time-consuming. Accordingly, the motto should be: “Prevention is better than aftercare”.
Requirements by DIN 1946-6
Normative requirements are made by DIN 1946-6. This regulates the ventilation of apartments with general requirements as well as requirements for dimensioning, execution and labeling, handover / acceptance and maintenance.
The nominal ventilation (NL) describes the ventilation necessary to guarantee building protection as well as the hygienic and health requirements when a usage unit is used as planned – i.e. in normal operation. Here you can find the concept of hygienic air exchange (according to EnEV §6, paragraph 2). The hygienic minimum air exchange rate is a minimum to ensure fresh air. Below this, there can be odor problems, dust and microorganism pollution and high radon concentrations. For a healthy living climate, a ventilation concept should be designed in terms of hygienic air exchange after the nominal ventilation.
The so-called reduced ventilation (RL = 0.7 x nominal ventilation) is user-independent ventilation which, under normal conditions of use (moisture and pollutant loads), meets minimum requirements for indoor air quality even when the user is temporarily absent. This would come into play, for example, if the residents of an apartment go to work in the morning and only return home in the evening. Here, too, you should always keep an eye on the living situation, because this design level might no longer be sufficient, especially on weekends and during sleeping times, and moisture and pollutants can accumulate in the living rooms.
The ventilation for moisture protection LFS (0.3 / 0.4 x nominal ventilation) describes user-independent ventilation in minimum operation, which under normal conditions of use – based on reduced moisture loads and room temperature – aims to avoid mold and moisture damage in the building.
In other words, it is the necessary ventilation to ensure building protection under normal conditions of use with partially reduced moisture load. This reduced moisture load comes into play, for example, when a building is uninhabited.
Neither reduced ventilation nor ventilation designed to prevent moisture damage provides effective protection against moisture damage in apartments, since residential units are, in reality, always occupied. Appropriate caution should be exercised when planning ventilation systems: It is essential to design them based on the nominal ventilation rate. Ask your planner!
Relationship between energy efficient buildings and ventilation
Building fabric and energy saving
“Saving energy” has been an important issue in Germany since the 1970s. From an economic perspective, the oil crisis was responsible for raising energy awareness. In this context, the term “sufficiency” emerged: It describes the goal of minimizing energy consumption across all sectors. Consequently, the construction industry also began striving to reduce energy consumption. You can find more on the topic of energy-efficient construction at here.
Requirements for energy-efficient buildings
Various factors affect the total heating requirement in a building. Its aim is to keep the primary energy requirement (final energy requirement for heating and hot water as well as expected losses for processing and transporting the energy) for a property as low as possible. This value is known from the energy certificates for real estate. Nowadays, for example, this must always be stated in advertisements for residential buildings in order to create a comparability and an energetic overview for the end customer.
As a rule of thumb, the lower the value, the better the building and the lower the annual operating costs due to the energy sources required for heating and hot water. If you compare existing buildings with new ones, they differ most clearly in terms of the heating requirement, which is often only a quarter.
As a rule of thumb, the lower the value, the better the building and the lower the annual operating costs due to the energy sources required for heating and hot water. If you compare existing buildings with new ones, they differ most clearly in terms of the heating requirement, which is often only a quarter.
Airtight construction of buildings
When considering heat loss within buildings through their various components, there is enormous potential for savings. 82 percent of energy consumption in private households is used for heating and hot water production, with 66 percent of that going toward space heating. Given the number of existing buildings in Germany, there is enormous potential in building renovation.
New construction methods for masonry, windows, roofs, floor slabs, and their joints can, through proper sealing of buildings achieve high energy efficiency. This airtight construction method was already mandated in 1984. Even in the years prior to that, buildings were constructed with the requirement for joint tightness, though this was still limited to airtight windows and doors.
Within residential buildings, the goal of energy conservation is addressed in new buildings and renovations by making the building envelope increasingly airtight to prevent heat loss. As a result, the topic of ventilation is becoming increasingly important, as hygienic air exchange must still be ensured (EnEV § 6, para. 2).
While in older buildings, simply opening windows used to be sufficient to achieve adequate moisture protection—since windows, doors, roofs, and masonry were less airtight—modern new buildings and buildings renovated according to energy efficiency criteria must be ventilated differently and more reliably. A ventilation concept tailored to the building standard and the building’s use prevents the formation of moisture and thus mold growth, and ensures hygienically sound, clean, and low-pollutant indoor air.