Thermal component activation
Thermal component activation (also: concrete core activation or building core activation) is a term from air conditioning and describes systems that use the building mass to regulate temperature. These systems are used for sole or additional space heating or cooling . Such a system is, for example, the thermoactive ceiling (TAD) or cooling ceiling or the energy pile .
When constructing solid ceilings or occasionally solid walls, pipes, mostly plastic pipes , but also capillary tube mats are laid. Water flows through these pipes as a heating or cooling medium. The entire solid ceiling or wall that flows through is thermally activated as a transmission and storage mass: To reduce comfort-reducing radiation asymmetries , heating water temperatures should not be above 28 ° C when heating and cold water temperatures should not be below 18 ° C when cooling.
With a pile foundation , heat and cold can be taken from the foundation piles as required. These then serve as geothermal probes . Depending on the groundwater and soil conditions, the soil can be used as a seasonal energy store.
The solid component absorbs or releases heat over its entire surface, depending on the heating or cooling situation. Due to the comparatively large transfer area, the system temperature differences can remain low. This means that when heating, the medium does not have to be heated as much as the water in the central heating system, for example, whose radiators offer a much smaller transfer surface. Because of these lower flow temperatures, z. B. heat pumps can be used efficiently. Environmental energies such as free recooling, base plate cooling or groundwater cooling are suitable for cooling .
The solid component absorbs the heat from the medium or the room, stores it and transfers it to the room or the medium with a time delay. So there is a phase shift between energy generation and output as well as in the heating curve . The daily load peaks are thereby "smoothed", i. H. they are lowered and sometimes postponed at times when there is no room utilization. In summer, night cooling can be used to cool the medium and to extract thermal energy from the component. During the day, the rooms are then cooled by heat dissipation into the cold walls. The cooling takes place during the day as required, when otherwise the maximum daytime temperature could lead to overheating of the rooms. The thermal component activation is particularly suitable for office buildings in which the main usage time coincides with the phase of highest outside temperatures and maximum solar radiation.
Thermal component activation in comparison with surface heating and night-time ventilation
The thermal component activation causes a large-area heat emission via radiation as does surface heating . It also acts as underfloor and ceiling heating and in winter the same positive physiological effects can be achieved as with wall heating .
The difference is that the usual surface heating systems are laid as close as possible under the component surface in order to enable rooms that are not used continuously to heat up quickly. This is usually the case with living spaces, as these are often only used in the morning and evening on workdays.
Laying the heating and cooling coils inside walls and ceilings leads to a significantly delayed release of heat and cold. The thermal component activation can therefore only be used to cover a basic load that either occurs uniformly every day or can be calculated and controlled in advance. It is therefore better suited for large and compact buildings in which the heating and cooling loads of the individual usage units are mutually balanced and for commercial buildings with (factory) daily use than for single-family houses that are not used evenly.
The use of the building's storage mass through thermal component activation is particularly advantageous if cooling loads occur regularly in summer. The heat from the inside of the building can then be conducted at night to the outer skin of the building and dissipated there so that the cooled walls and ceilings can absorb the heat load that occurs during the day. In this way, the operation of very energy-intensive air conditioning systems can ideally be dispensed with.
A simple alternative to using night-time cooling would be to automatically ventilate the building with cold outside air at night. In comparison with thermal component activation, however, this does not allow the ideal, uniform temperature profile to be achieved. The rooms will always be a little colder in the morning and will gradually warm up during the day. In addition, walls and ceilings - depending on how they are constructed - often do not cool down sufficiently through pure night ventilation in order to be able to fully use their storage effect.
The pipes can be placed in the component using two methods:
- The manual laying of the pipes on a carrier mat.
- The laying of prefabricated pipe modules. This variant leads to a rapid construction process.
The selected control strategy should be checked for profitability using building simulations. The regulation of the thermoactive blanket takes place via the self- regulating effect , which considerably reduces the amount of control technology required. The mass flow rate and supply temperature are set in such a way that the surface temperature is constant at 23 degrees Celsius. If the room temperature is higher, the thermoactive blanket acts as a cooling system; if it is below that, the blanket gives off heat. Since the maximum cooling capacity of thermoactive ceilings is approx. 40 W / m², it can only be implemented in conjunction with facades that effectively limit the entry of radiation.
- Bernd Glück: "Spatial model - definition of the radiation temperature asymmetry"
- Federal Geothermal Association: Energy Pile
- Research on energy-optimized building - model project
- Federal Association of Surface Heating and Surface Cooling eV
- Book: Glück, B .: "Thermal component activation - use of environmental energy and capillary tubes"
- Research report and simulation model: Glück, B .: "Dynamic room model for thermal engineering and thermal physiological assessment"
- Thermoactive component systems (BINE information service)