Night reduction

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With night set is called the transition from the daily target temperature to a lower setpoint temperature at night. The night reduction is used in private and public buildings as well as in aquaristics.

building technology

With night setback, heating continues at a lower temperature level. In public or large office buildings, temperatures can usually be lowered to lower temperatures than in residential buildings, as these buildings have longer vacancy times. If the heating switches off completely, it is a night shutdown.

A timer, which can be programmed in daily and weekly cycles, reduces the setpoint of the thermostat at night . The extent and duration of the evening temperature drop from day to night is determined, among other things, by the building's thermal insulation and storage capacity as well as by the outside temperature and other weather conditions. Falling below the dew point on the inside of the outer walls should be avoided in order to avoid the formation of mold . The lowering is followed by the morning heating to the daily setpoint.

Depending on the size of the system, the switch-off and switch-on times can be individually determined with small computers by entering the special building parameters, weather conditions, heating reserve and user behavior and transferred to the boiler temperature controller ("self-learning control").

Several users of a central heating system have to agree on switching times. Dishes allow the room temperature to be reduced to 18 ° C at night from 11 p.m. (Fridays and Saturdays from midnight) to 6 a.m.

Energy saving

The topic of night reduction has gained in importance in the context of energy saving and building optimization . The actual energy savings essentially depend on the possible breaks in use.

During the night setback, the transmission and ventilation heat losses of the building as well as the losses in heat generation are reduced. However, the cooled down building must be heated up again. Savings are always achieved through the reduced room temperature, but under certain circumstances this can be so low that it is not worthwhile to accept the disadvantage of increased condensation on and in the outer walls, especially in old buildings.

Modern controls ignore the set night reduction when outside temperatures are particularly low, as there is often insufficient power reserve available for reheating the building in the area around the design temperature of the heating system. According to DIN 4702, this period comprises only 20 of 260 heating degree days, on the remaining 240 days a night reduction makes sense.

The savings that can be achieved vary greatly. Its height depends

  • the thermal insulation standard of the building. In buildings with good thermal insulation, night setback does not save enough energy. In old buildings without thermal insulation, the savings are greater.
  • On the amount of standstill losses of the boiler.

In the case of offices and public buildings, the longer breaks in use in the evening and at the weekend allow a significant reduction in temperature and correspondingly large savings.

Aquaristics

In terrariums and aquariums , the water temperature is lowered at night in order to imitate the nighttime temperature drop in the animals' natural habitat. Here, too, thermostats coupled with time switches are used.

Individual evidence

  1. http://www.internetratgeber-recht.de/MietrechtAllgemein/HeizungundWarmwasser/hwa1.htm
  2. ^ Daniel Otto: Modern fairy tales part 1. In: http://www.energieberatung-otto.de . Ingenieurbüro Otto, accessed on December 13, 2017 .
  3. Night-time reduction of the heating output at energieverbübersuter.de