Lowering of the room temperature

In public buildings, the room temperature in offices should be lowered to 19 °C. Corridors, foyers, etc. should not be heated at all. In circulation areas, the university meets these requirements in most buildings because no radiators are installed in these areas. However, lowering the office temperature will definitely have an impact.

Many of our buildings are supplied with district heating, which we either produce in our own power plant or purchase from the municipal utilities. In the buildings, usually down in the basement, there is a heating system that distributes the heat throughout the building. In order to achieve a temperature of 19 °C in all offices, building management has to make a considerable effort: To do this, the temperature is measured in the office furthest away from the heating system. The heating system is then adjusted so that 19 °C is safely reached in this office. This process may well take a few days per building. Theoretically, a higher room temperature can be reached in all rooms located in front of it.

To set the temperature in these rooms as well, there are thermostats on the radiators. The graduation on them indicates the temperature that can be adjusted: setting 3 corresponds to 20 °C, 19 °C is a line below it. All thermostats should be set to this temperature. However, the thermostat on the radiator only measures the ambient air temperature. When a radiator gets warm, the air in the room is set in motion. It flows up over the radiator, sweeps along the ceiling, then down the opposite side of the room and back across the floor. This gradually increases the air temperature. The thermostat measures the temperature of the passing air. When the set temperature is reached, the valve in it closes or reduces the supply of heat.

If there is furniture or a thick curtain in front of the radiators, the system will not work properly. The air around the radiator gets warm but cannot enter the room. The thermostat reduces the heat supply because it measures the warm ambient air. However, people in the room are feeling cold because the room has not warmed up. If the thermostat is then turned higher, the room around the radiator heats up very strongly, for which a lot of energy is consumed. If the room is then ventilated, an excessive amount of heat energy that has collected in the window area above the radiator escapes, especially if the radiator is not turned down in the process, because the thermostat immediately reacts to the cold air and increases the heat supply accordingly.

Please note that it does not make sense to turn up the radiator valves in the office fully after the weekend, for example. Whether you turn the heating to a line below 3 (19 °C) or to 5 (28 °C) does not change the heating speed. The valve in the thermostat opens completely every time, and the heating gets warm very quickly. But if you turn to 5, there is no stop at 19 °C air temperature, the thermostat heats the air temperature up to 28 °C. This is way too warm to work, thus opening the door to the hallway or a window to cool down wastes a lot of energy as well.

Many employees are concerned that a temperature of 19 °C is too cold for working - especially when sitting in front of a computer for hours. This is where the perceived room temperature comes into play, which is made up of two components: firstly, the air temperature, which is set via the thermostat, and secondly, the radiant heat of the walls. Currently, after many summer days, the walls of most buildings are still quite warm - a set air temperature of 19 °C can even seem quite warm there. This only changes when the buildings slowly cool down, which takes longer in modern, well-insulated buildings. It is important to know that the cooling of buildings can be prevented to some extent. Therefore, do not leave windows and doors open for a long time, as this will allow a lot of heat to escape.

Reducing the use of the heating obviously saves the most energy. If you want to be particularly energy efficient, set the thermostat to a value between 2 and Moon (15 °C) for days when your office is not in use. During normal operation, when you are back in the office, please set it again to a line below 3 (19 °C) so that the room can be brought back to the predefined temperature.

At night, the heating system in each building is automatically lowered. When the heating is reduced, the heat from the walls passes into the room until the set night temperature is reached. The heating system is set to achieve a room temperature between 15 and 16 °C. This means that the temperature difference between outside and inside is smaller, and less heat is lost to the outside. In the morning, the heating is regulated up again so that you reach your temperature set with the thermostat in the room when the walls have absorbed the heat again. The lowering and raising of the temperature cancel each other out, savings are only achieved over the length of the night temperature period.