Night cooling
With night cooling (in Austria also night flushing ), the cold night air is conducted into the building in the summer months and stored there in the building in order to achieve a pleasant, beneficial room climate on the following day. The aim is to compensate for the daily heat input into the building at night. The night temperatures in Central Europe are mostly below 21 ° C for 5 hours.
Night cold is a renewable energy , since only the interplay of solar radiation, air and water is used as inexhaustible natural sources to generate cold , see also night cooling .
Active / passive night cooling
A distinction is made between active and passive night cooling. With active night cooling, the cold is transported with mechanical support (fans, pumps) and with passive night cooling through free ventilation (thermal, draft / cross ventilation).
Passive night cooling is air-bound and always depends on the weather and wind. Due to the loss of comfort in terms of temperature and draft, passive night cooling is ideal for buildings (office buildings, warehouses, etc.) that are empty from midnight to sunrise.
Active night cooling is used to avoid these problems. In the simplest case, the existing air conditioning system is operated for night cooling purposes in ventilation mode - possibly also with minimum supply air temperature limitation - mostly with reduced air volume. To increase the cooling capacity, adiabatic cooling can also be integrated.
The active night cooling of multifunctional heat recovery systems (GSWT) is more efficient, in which , in addition to the night cold , its evaporative cooling is also used. For this purpose, adiabatic cooling is not operated with exhaust air, but with outside air. The night temperature falls below around 17 ° C and the duration of night cooling is increased. To save the energy-consuming air transport, the cold is transferred to a liquid and used for direct component cooling (including cooling ceilings, etc.). There is also the option of storing the cold water in a buffer and only discharging it again when it is actually needed. This only enables effective night cooling if the building does not have sufficient storage mass and also saves heating energy if, contrary to the original assumption, the following day does not become summery.
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Active night cooling for component cooling with multifunctional heat recovery
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literature
- Dieter Thiel: Possibilities and limits of natural night cooling as a means of cooling in the air conditioning of office buildings , Düsseldorf, 1991, ISBN 3-18-145419-2
Web links
- Air conditioning plus climate protection: University of Applied Sciences saves energy with passive cooling (report on a building of the Bonn-Rhein-Sieg University of Applied Sciences in St. Augustin)