Glossary Space Heating Technology


Heating for agricultural applications


Agrarnox is a radiant heater made by Kübler that stands out for its very low NOx-emissions. Additionally, its flue gas can be used for target-oriented CO2-fertilization of plants in greenhouses. The slender design guaranties that hardly any unwanted shade is produced in the greenhouse. A new, prism-shaped burner casing makes this agricultural heater highly resistant to humidity and dirt. Therefore, this energy saving system can also be ideally used in stables or pens.

Building services engineering

Building physics, technical utilities or building services are different terms to describe all technical devices and installations that are fixed to the building and from an integral part of it, i.e. they are necessary to run the building.


One of the main components in infra-red heaters. Burners turn chemical energy into thermal energy. In the burners a gas-air-mixture is burnt producing heat.


CAD planning means computer based comprehensive drawings of the heating system and the hall itself. Lists of all parts needed can be generated from these drawings and mounting is based on them.

Ceramic plaque heaters

Ceramic plaque heaters are one variety of infrared heaters. Infrared rays are produced by a visible gas combustion process causing ceramic plaques to brightly glow up. The disadvantage of these infrared systems lies in the fact that they are indirectly flued via the air in the building and do not dispose of a closed flue gas system exiting to the outside. Thus radiant heating systems may be ceramic plaques heaters characterised by flare combustion or radiant tube heaters, which, by contrast, always make use of a combustion chamber.



A system developed by Kübler to allow quick, rough estimates of saving potentials for primary energy consumption and emissions based on individual input value options.

Control system

Modern control systems allow individual temperature levels in different heating zones, e.g. programming of differing day and night temperatures, of holidays and vacation times.


Convection loss

The air that heats up e.g. on hot heating tubes rises upward and is therefore no longer useable near the floor of the premise, where human beings typically are, is called convection loss.


Corrosion protection

Radiant tube heaters or infrared heating systems, respectively, can be used to prevent corrosion of stock material due to two effects:
1) by reducing the relative humidity of the air
2) by heating up the surfaces of all stock items above air temperature. Condensation and with it corrosion can only happen on stock items with surface temperatures lower than their surrounding air temperature.


Direct heating

Solid or liquid bodies absorb infra-red or electro-magnetic rays and are heated directly (internally) by this radiation. By contrast, indirect heating means, that those bodies are heated from the outside by warm air.

Ducted fresh air supply

In buildings with a marked high or low pressure or in production halls with very dirty or dusty air, the radiant heaters can be run independently from the inside air. In this case the combustion air is sucked in from the outside which can be done either using a double layer roof or wall terminal or using two separate ducts.

Electromagnetic radiation

By electromagnetic radiation we understand waves of electrical and magnetic fields that spread out uniformly from the source of radiation in all directions into space. Depending on the energy level, electromagnetic radiation can include gamma rays, visible light, infrared radiation and radio waves.

Infrared radiation

Energy Consumption Certificate

The energy consumption certificate is a document that evaluates a building’s energy performance including its air conditioning system, hot water supply and lighting. Who is authorised to issue such a certificate, how it is used, its fundamentals and basic principles are laid down for Germany in DIN V 18599 – “energy evaluation of buildings”. For non-residential buildings the following persons are authorised to issue the certificate: university graduates of architecture, structural design, civil engineering, building services engineering, building physics, mechanical engineering or electrical engineering. Moreover, professionals with special qualifications in the field of energy-saving structural design or other authorised persons may issue the certificate.

German Energy Saving Regulation (EnEV)

Energy conservation

Measure to reduce the consumption of a given primary and/or secondary source of energy.

Energy saving

Devices and objects that allow an especially high ratio of energy conservation compared to average systems and thus work very energy efficiently.

Exhaust gas loss

By exhaust gas loss we understand thermal energy that is contained in the exhaust gas and that after leaving the heating system is ‘lost’ without further making use of it to atmosphere.

Farm applications

Heating systems designed specifically for usage in stables and livestock breeding. Radiant tube heaters have proved to be especially suitable because they will not provoke dust to be swirled up and therefore create a comfortable climate for raising young livestock.



Floor heating

Floor heating is part of the panel heating systems. Ducts are installed underneath the floor and filled with a heating medium, e.g. hot water, thus giving off the heat from below into the room.


Flue gas damper

A damper is a device to control a volume flow rate, mainly flue gas.

Flueing System

A closed, combined manifold system for infra-red heaters or radiant heaters, respectively, to evacuate the products of combustion to atmosphere. In general, several heaters are linked into a common manifold system and exit the building together.

Combined manifold system / herringbone syste

Gas heaters

A gas heater is an infrared heater fired with gas. It can be both a ceramic plaque model (i.e. glowing when in operation) and a radiant heater with tubes (i.e. “dark” when in operation). Hence the German term of “dark heaters” for radiant heaters that burn gas in closed tubes.


German Energy Saving Regulation (EnEV)

Regulation on energy saving insulation and systems engineering for buildings. The current Energy Saving Regulation has been in force since Oct. 01, 2007. In steps, the Energy Saving Regulation, abbr. EnEV, will introduce the Energy Performance Certificate as mandatory from July 01, 2008.


Gross Calorific value

By gross calorific value we understand the amount of thermal energy that is emitted by the total combustion of one fuel unit, given equal temperatures of both fuel and combustion products (usually that temperature is 25°C) and under the assumption, that the total amount of water resulting from the combustion process is present in liquid form.


Heat is a physical value that is understood as transmission of thermal energy.

Heat load

The heat load is the amount of heating needed to achieve the desired temperature in a given building or room. It can be calculated mathematically taking into account the usage patterns of the building, its insulation and its dimensions.

Heat transmission

The transportation of heat within a body or liquid by diffusion due to a temperature difference.

Heat radiation

Heat radiation is electro-magnetic radiation emitted by all matter according to its temperature.


Heating system

A heating system comprises all technical installations that can be used to heat up a given space.

Herring bone flue gas system

In contrast to single flueing applications the flue gas pipes of several infrared heaters or radiant tube heaters, resp., are connected. The herring bone flue gas system needs only one roof or wall exit for several radiant tube heaters. In total up to 20 heaters may be connected. A flue gas fan ensures correct pressure conditions within the system.

Hot water heating

Heating systems using hot water as a medium for heat transmission. These are mostly convective systems or ceiling panels, feeding hot water into the grids from a central boiler room.

Individual flue gas system

For individual or double flue gas system one or two radiant heaters are connected and their flue gases exited directly to the outside atmosphere. The entire flue gas system is regarded as a secondary heating surface and thus is part of the radiant tube.

Indoor climate

By indoor climate we mean the temperature, draft etc. that are felt inside such buildings as industrial premises, exhibition or event halls, sports halls and other big buildings. Heating with infrared systems proofs to be especially comfortable (infrared heating) as these systems come closest to the natural heating principle of the sun.

Induced draught burner

When using an induced draught burner the low pressure in the burner is induced by a fan at the other end of the piping.


Industrial heating systems

Space heating systems


By infrared, abbreviated IR, formerly also called ultra red, we understand the invisible part of the electromagnetic spectrum, which follows the long-wave part of visible light (red) and lies in the area of approx. 800 nm to1 mm of wavelength. Infrared rays will develop heat on solid or liquid bodies exposed to them.

Infrared heating

Heating systems that produce Infrared radiation and use this as heat source. These systems stand out due to their minimal heat loss. Among other advantages they also boast up to 54% energy savings compared to standard systems, a comfortable room atmosphere (similar to natural heating by the sun), low investment costs, brief return-on-investment, even heat distribution also in poorly insulated buildings, short heating-up periods, as well as the dust- and draught-free heating principle. Being especially suited for big spaces infrared heating systems can directly warm up the objects inside and doesn’t warm up the air, which in high rooms will elude towards the ceiling. Thus, to heat from top to bottom is not necessary.

Infrared rays

Infrared rays are light waves beyond the visible spectrum. This thermal radiation can be compared most easily to that of the sun.

Infrared radiation efficiency

The infrared radiation efficiency is a criterion to quantify how effectively infrared heaters make use of energy. It specifies the ratio of emitted radiation compared to the thermal input into the heater and thus it states that percentage of energy which is actually usable for human beings on the floor. Kübler introduced the infrared percentage and thus the infrared radiation efficiency as a decisive criterion to judge modern heaters’ quality. Of international importance is the system for performance measurement of infrared heating systems called RayLab – the automatic system to quantify the infrared radiation efficiency of industrial heating systems (both radiant tube systems and ceramic plaque systems). The RayLab system, which was developed by Kübler, has become part of the European norm (method B) and continues to be the most reliable way for measurements according to the new norms EN 416-2 and 419-2. Owing to the assessment of the heating system as a whole on the basis of its infrared radiation efficiency enormous savings potentials both concerning energy consumption and CO2 emissions can be detected.


Measures and procedures to ensure the good upkeep and servicing of technical devices and systems. Regular maintenance (usually once a year) will secure reliable operational availability of the premises during the cold season, constant economical operation mode, defined prices rather than incalculable costs in case of a technical failure, prolonged life time of the system as well as secure warranty.

Maintenance contract

Under A maintenance contract the producer of a good is liable towards the buyer to check the good regularly and if necessary also to repair it. Kübler offers a number of lucrative maintenance models, cost effective and individually adaptable.
By the way, this is also offered for third-party products. So really, regular maintenance is not a cost factor but an economy factor that may pay back even in

Net Calorific Value

By net calorific value we understand the amount of thermal energy that is emitted by the total combustion of one fuel unit, given equal temperatures of both fuel and combustion products (usually that temperature is 25°C) and under the assumption, that the total amount of water resulting from the combustion process is present in gas form.

I.e. the net calorific value is lower than the gross calorific value by the amount of vaporisation heat of water.


High performance system of Kübler GmbH (principle: infrared heating, specifically radiant tube heaters), winner of the international prize “industrial heating system of the year” in 1996. Since then this product line has set the trend concerning maximum infrared efficiency. The Optima series is also the first heating system of its kind to meet design requirements. Optima’s special features in a nutshell: reduction of convective losses, drastic improvement of heat transmission and tube temperatures plus further optimisation of infrared efficiency to allow better direct heating of work places, using less energy. All of this leads to energy conservation ratios of more than 50% compared to conventional systems.

Payback period

Payback period means the time after which an original payment (investment) will be covered by the savings induced by this investment.

Primary energy

Primary energy is energy in naturally existing energy sources such as fossil fuels (crude oil, coal, gas, nuclear fuels) or other natural energy sources (water, wind solar energy, etc.) This energy can be transformed by combustion or other physical or chemical processes to secondary energy (heating, electricity, motion).

Radiant ceiling panels (water based)

Water-based radiant ceiling panels are a type of infrared heating systems. Waterway grids for hot water are incorporated within flat metal panels to produce high surface temperatures. This means that the whole structure is heated up. However, compared to gas-fired radiant heaters, the ceiling panels’ surface temperature is far lower making very large radiant surface areas necessary to achieve even heat distribution.

Radiant heater

Radiant heaters are tubes, mainly u-shaped, through which flue gas with temperatures of up to 800°C is conveyed. A burner installed at one end of the tube burns natural gas while a vacuum fan at the other end of the tube produces the necessary low pressure to transport the flue gas through the tube. The heat emitted from the tubes in an upward direction is re-directed into the area to be heated by means of a reflector over the whole length of tube. Due to the u-shape of the tube the average temperature of 250 – 500°C is nearly even over the entire length of the heater.
Nowadays, high performance radiant heaters by Kübler may well work with their tubes partly glowing. So the old German term “dark heaters”, that used to distinguish the tube heaters from so called “glow heaters” or “plaque heaters” (emitting infrared from a glowing plaque) has become obsolete. The main difference between plaque heaters and tube heaters is the fact that radiant heaters composed of tubes form by a closed combustion system, i.e. allowing controlled exiting of flue gases from the building.

Radiant heating systems

A decentralized heating system transferring the heat it produces by infrared radiation. This technology has proven its worth as a cost effective and environmentally friendly way of space heating.

 Radiant heating
 Infrared heating
 Radiant tube heater


R.O.S.S.Y® is Kübler’s control system for heating systems designed to optimise the use of recourses. This intelligent and self-learning system optimises the turn-on times after a night setback and thus the energy consumption and sets new standards of ease of use and functionality. Due to its outstanding capability and its measurable contribution to a more economical operation of hall heating systems R.O.S.S.Y® was awarded the Innovation Prize 2004 by the German Federal Ministry of Economics.

Secondary energy

Secondary energy is the energy form that will remain after transforming primary energy in so called effective energy.

Stainless steel turbulator

Stainless steel turbulators are devices inside infrared or radiant heaters that increase heat transmission from the flue gas to the tube surface.

Space heating systems

These are heating systems that are used mainly to heat big, spacious buildings, like warehouses, sports halls, industrial premises, etc. There are convective systems, like warm air heating systems (convection) and radiant heating systems such as ceramic plaque heaters and tube heaters (infrared radiation).

Thermal energy

Thermal energy is the energy that is stored in the free movement of a matter’s atoms or molecules.

Warm air heating system

Heating systems that heat up a building by emitting warm air into it, using a blower. The disadvantage of such a convective system is the fact that warm air will raise. Especially in high buildings this will lead to a so called warm air layer under the ceiling, causing significant energy loss while the warm air is lacking in the floor area where human beings could benefit from it.