Comparing BTU to kW

BTU to kW

The question of how many “BTU’s” (British Thermal Units) do far infrared heaters produce is frequently asked in order to determine “standard” heat-loss calculations. These calculations are widely accepted since these have evolved over a period of well over a hundred years.

The problem is that conventional formulas don’t completely apply to this “new” heating technology.  With far infrared energy there is no direct correlation between Watts of energy used and BTUs.

Far infrared technology is unique; it is different from traditional convection technologies.  Far infrared heat is based on the principle of energy storage and emission, not by heating the air.

The far infrared heat energy travels through the space and is absorbed and stored in the floor, walls, people and all objects within that space.  As a result, heat energy is emitted back into the space, which creates an overall saturation of far infrared warmth.  When this effect is achieved, the natural response is to lower the thermostat.  The energy is stored and because we do not send a mass of hot air to the ceiling, or to the outside world when a door opens, much less energy is used compared to traditional methods.

Energy conversion facts:

  • It is a fact that 1 kW of electrical energy produces 3412 BTU’s.
  • Ducoterra far infrared panels, like any other “electric heater” convert 100% of the electrical energy into heat, but how this heat is used is what sets the products apart.
  • A baseboard heater (for example) also “technically” converts 100% of the electrical energy into heat, but yet it is only 25-40% efficient (60-75% are “convection losses”), since the exposed coils or elements are subjected to the oxygen in the air they have a very short life expectancy and burn out after 3-5 years of heavy use.
  • Most heaters, including many baseboard heaters, use fans which use more energy to operate – this is also lost energy.

The differences between far infrared technology and traditional heating systems:

  • Depending on placement (actual location of panels), Ducoterra’s panel technology provides a 15-45% energy advantage over traditional heating.

Energy efficiency relative to panel placement-

    • With far infrared energy (invisible light) coming from the ceiling we have a dynamic efficiency of 80%, i.e. 80% of the electrical energy supplied is converted into “usable heat energy” while 20% of the energy supplied is “lost”. Most of this “lost energy” is attributed to conduction to other parts of the building and a small amount to convection.
    • When the panels are mounted on the walls the dynamic efficiency is reduced to 60% because the air flowing past the unit creates a convection flow, which both cools the panel and takes some of its energy as “hot air” to the ceiling.
  • If we could place the panels in the floor this would be 50%, as there would be 10% more convection losses than wall mounting.
  • A forced air system has a “starting efficiency” of 60-95% depending on the type of heater (older, newer, straight transfer of hot gases, or secondary heat exchanger). Even a 95% efficient heater (after fan losses, duct losses, convection losses and ventilation requirements) is typically 35% efficient, just because it heats the air.  Regardless of the performance rating of these types of heaters, unless the floor is warm, people can still have very cold feet even if the room is 24C or 27C degrees.
  • A good “hydronic” (in-floor) geothermal system can approach our efficiency, but it is very expensive, and won’t work at all temperatures; in many cases it needs our panels as a supplement.  A good geothermal system is generally (and incorrectly) touted as a system so efficient that it has a *COP (Conversion of Power) of 3, meaning that under certain circumstances it uses 1/3 of the energy of a traditional (inefficient) heat source.  However, when we look at losses associated with various heating methods, far infrared heating stands alone as the star energy saver.
      * For energy efficient systems the industry has established a “COP” (Conversion of Power). A COP of 1 means that a system is 100% efficient according to existing standards for filling the space with hot air (it does not mean 100% of the energy is converted to heat; in practice it is around 25-30% of the energy supplied)

Although there is no direct correlation between BTU and far infrared energy requirements, depending on the type of building and the particulars of the installation, the typical “equivalent COP” based on many installations worldwide is between 1.5 and 3.

To address this further we can make a comparison between geothermal, a system that uses a similar amount of energy, and Ducoterra’s SolaRay far infrared heating panels.

The operating costs of Ducoterra heaters and a good Geothermal system in mild winters are very similar.  The industry claims that geothermal operates at a COP of 3.  But as the temperature drops for prolonged periods, far infrared heating panels can easily outperform geothermal by as much as 2:1.  With far infrared heating panel acquisition costs at only a fraction of what one would pay for a reasonable geothermal system, and when one adds the maintenance expenses to the operating costs of geothermal, far infrared panels clearly come out the winner.  Many Geothermal customers who are dissatisfied with the performance, augment their systems with far infrared heaters for this very reason.

Caution:
As with any type of heating or heating product, if the energy is carried away faster than it can be stored, the system will not work correctly; never cut corners by under-installing as the system would need to work “all the time”.  A properly installed system will shut off and cycle to save energy.