Controlled natural ventilation

from Wikipedia, the free encyclopedia

Of Controlled natural ventilation (KNL) occurs when the natural air exchange user independently by an electric motor powered windows in the building outer shell in combination with an automated is demand-driven control.

reasons

To save heating energy , better and better insulation of building walls and roofs is no longer enough. Rather, it is about reducing the heat losses in buildings - and not just those that result from incorrect ventilation behavior of users, e.g. B. in the case of too seldom or too often recurring burst ventilation , but in particular also the heat losses due to infiltration volume flows. This is prescribed by the Energy Saving Ordinance (EnEV). Due to the denser building envelope, however, the usual, uncontrolled and constant exchange of air from the previously existing joint leaks in windows, doors and their connections to the building envelope is no longer necessary. This means that moisture and pollutants in the indoor air can no longer be broken down sufficiently.

The EnEV addresses this issue and, in addition to the air-impermeable building envelope, requires an exchange of air that is hygienic and physically necessary. This combination ensures that the air exchange does not take place in an uncontrolled manner, but has to be dimensioned according to planning. This is the only way to ensure the hygienic minimum air exchange required in the EnEV and more precisely defined in DIN 1946-6 (for residential buildings) . In the area of ​​non-residential buildings, there are additional requirements for the energy efficiency of ventilation and air conditioning systems as well as room cooling systems, taking into account thermal comfort conditions.

Intelligent, user-independent ventilation concepts - such as KNL - can be useful in order to prevent the increase in the concentration of pollutants and moisture and the resulting mold infestation on the one hand, and to save energy on the other . Particular attention should be paid to the comfort and convenience of the residents or users of the building. "Used" air and the associated excessively high CO 2 concentrations can be B. lead to tiredness and reduced concentration and performance. For this reason, in addition to the use of KNL in residential buildings, its use in non-residential buildings - such as office buildings - is often useful.

Areas of application

KNL systems or solutions show their advantages in particular where an automated, needs-based fresh air supply of rooms with sustainable energy and cost efficiency is to be ensured - taking into account the user requirements for hygiene, comfort, comfort and safety, e.g. B. in:

  • Office and administration buildings
  • schools
  • Universities
  • Educational centers
  • Leisure and sports facilities
  • Day care centers
  • Hospitals and rehabilitation clinics
  • Retirement and nursing homes

In addition, KNL is also used in residential buildings.

Working principle of (controlled) natural ventilation

In the study "KonLuft - Energy Efficiency of Buildings through Controlled Natural Ventilation" by the Stuttgart University of Applied Sciences , which was carried out in cooperation with the project partner ZVEI - Central Association of the Electrical and Electronics Industry and the project sponsors Federal Ministry of Economics (BMWi) and Projektträger Jülich (PTL) , it has been proven that a very good indoor air quality can be achieved with all natural ventilation concepts, but the thermal comfort is strongly dependent on the dimensioning of the openings and the selected control strategy.

Natural ventilation is based on physical principles: The air exchange is driven by temperature and pressure differences between the inside of the building and the outside environment. This and the wind pressure on the building cause a thermal lift ( chimney effect ) - without electrical expenditure for air movement.

In the KNL, the automated, user-independent regulation of the room climate depending on the climatic indoor and outdoor parameters (e.g. temperature, rain, solar radiation) is recorded by sensors and automatically "adjusted" to the set values ​​by the control unit. Thus - without the involvement of the resident or the user of the respective room - for z. B. sufficient night cooling or morning fresh air can be provided. In addition, the indoor air quality has an influence on the ability to concentrate at the workplace, ensures a restful sleep, pleasant temperatures and the right room humidity.

Buoyancy ventilation.svg

Components

To implement an KNL concept, various evaluation and regulation units (control centers, controllers) are required, depending on the system and system configuration, via which the ventilation of the rooms can be centrally controlled individually or in groups. They have connections for sensors to record a wide variety of data such as weather, room climate and window position as well as for controlling the electromotive windows, the shading system and the radiators. Displays, buttons and remote controls complete the range of operating options.

Normative requirements for residential and functional buildings

The functionality and efficiency of controlled natural ventilation via electrically operated windows is confirmed in numerous national and international studies. Nevertheless, this type of ventilation has not yet been taken into account as a binding planning basis in the relevant laws, ordinances, standards and guidelines for structural engineering, e.g. B. in DIN 1946-6 for ventilation of residential buildings.

Links / sources