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Zehnder - Energy Savings Using Radiant Heat

Human Temperature Perception -Radiant Heat - Energy Savings - Controllability -Zehnder

The most important consideration when choosing a heating and cooling system is energy efficiency. Zehnder radiant heating and cooling systems can save more than 40% in energy compared to other systems. And all with a pleasant indoor climate.

  • Save energy by achieving a higher perceived temperature than the actual room temperature
  • Even temperature distribution across the full height of the room
  • Very high heat output to EN 14037
  • Short heating & cooling time
  • Free choice of energy source including alternative energies, heat pumps, condensing appliance technology or process waste heat
  • No additional power costs for propulsion energy

The energy costs are mainly dependent on the type of system and the energy source. The biggest cost factor is the inefficient distribution of heat within the room. Zehnder ZBN radiant ceiling panels are particularly efficient and achieve energy savings of over 40%. Numerous facilities equipped with Zehnder provide proof of this, day after day.

1. Human Temperature Perception

Human perception of temperature is the arithmetic mean of the indoor air temperature and the surface temperature e.g. of the walls, ceiling and floor. Due to the radiation and hence the higher surface temperature of ceiling-mounted cooling and heating systems, the indoor air temperature during heating can therefore be kept lower, can be higher during cooling and still be perceived as pleasant. Energy costs are reduced, both when heating and when cooling, due to the lower or higher air temperature.

2. Heat Distribution up to Ceiling Height

Whereas with air heating systems the heated air rises, radiant ceiling panels generate heat whereby the heat radiation comes into contact with objects (walls, floors and people). This results in an even temperature distribution throughout the entire room at ceiling level and therefore a considerably lower energy consumption.

Although the perceived temperature remains the same, the actual indoor air temperature can be up to 3K lower (for heating) or higher (for cooling). The consequential smaller difference between indoor air temperature and outdoor temperature means that heat loss is dramatically reduced.

3. Reaction Time & Controllability

Buildings are becoming increasingly well insulated and thus need less and less energy. Even small variations in the heat load can result in major temperature fluctuations. The result is that users manually intervene in the system and remove the excess heat from the room e.g. via ventilation. The conclusion from this is that systems are required that can react quickly to changes in the heat load or temperature fluctuations in a room - systems with a rapid reaction time and very good controllability.

Test Series

To simulate the miscellaneous inertias of various systems, tests were carried out using a radiant ceiling panel, an underfloor heating system and an active building system. All systems were cooled to a surface temperature of 17°C. The systems were then subjected to the same mass flow and the same flow temperature until each system had achieved a surface temperature of approximately 35°C.

For example, a conference room is heated to 20°C in the winter. The participants enter the room and give off body heat. This, plus additional heat loads from lighting, projectors, computers, etc makes the temperature of the room rise. The result is that in order to quickly bring the sharply increased room temperature back down to the desired 20°C, the windows are opened – and precious energy is wasted.

4. System Temperatures

The future of heating is in the low-temperature field. These systems use less energy, and the energy that they do use is used very efficiently. Heat transfer systems that work using radiant heat and have a low storage mass are ideally suited to low-temperature systems.

Zehnder ceiling-mounted heating and cooling systems are a perfect example of this. Requiring very low flow temperatures is important, especially when pumping heat. For example, if you use a heat transfer system that runs at a flow temperature of 50°C, you will use around 90% more energy than with a system that runs a flow temperature of 30°C.

Sample Calculations

The energy saving potential of over 40% can be demonstrated and determined more precisely in accordance with DIN V 18599. As an example we will use a comparison between radiant ceiling panels and air heaters.

Boundary Conditions: Hall height 20m, room temperature regulation for both systems via PI regulations, air distribution at a normal induction rate, lateral air outlet.

Basic Information: Calculation formula under DIN V 18599

Click the PDF image to view the technical information in full

Heating Solutions

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Zehnder Group UK Ltd
Concept House
Watchmoor Point
GU15 3AD

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Tel: 01276 605800

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