IQ Radiant Glass Window Heating Systems - Testing Analysis and Conclusions

Due to continuous innovation, the quality and characteristics of IQ Radiant Glass improve constantly. Testing over 20 years has been performed with increasingly higher performance glass. IQ Radiant Glass U-values constantly evolve and vary according to the composition of the number of sides of the glass, the low e coatings, the inert gases, and recent improvements in buss bar innovations.

There are many variables in actual applications but our experience in testing and installations has averaged 25-35% savings over forced air and oil-fired radiator systems.


  • 32 to 38 % less power required with IQ Radiant Glass compared to a traditional double pane unit & radiator to obtain the same resulting temperature of 69.8 ℉ (21 ℃).

  • With traditional double pane units & radiator the air temperature was 71.6 ℉ (22 ℃) in order to obtain a resulting temperature of 69.8 ℉ (21 ℃)

  • The air temperature in the case of IQ Radiant Glass was lower than 69.8 ℉ (21 ℃) as a result of pure radiant heat, resulting in better energy efficiency

  • With IQ Radiant Glass, the average radiant temperature is substantially higher than the air temperature

  • With traditional double pane units & radiator, the air temperature is much higher than the radiant temperature

  • This effect inevitably results in more power required to heat up the air using a traditional radiator

  • Since the radiant air temperature is much higher than the air temperature with IQ Radiant Glass, the air temperature can be lowered whilst remaining the same comfort level for the occupants

  • The surface temperatures were obtained for all the objects

  • The surface temperature of all objects using IQ Radiant Glass was much higher and closer to the resulting temperature than the surface temperature of all objects using a traditional radiator and double pane units

  • This dramatically improves the comfort level

  • The temperature gradient of the glass is significantly smaller with IQ Radiant Glass than with traditional heating systems

  • The IQ Radiant Glass window forms the best ‘cold shield’. The consequence is a more constant air temperature in the room, which increases the comfort sensation

  • Due to the radiant heat effects of IQ Radiant Glass, a lower room temperature can be sufficient to reach the same level of comfort feeling

  • During a normal heating season, IQ Radiant Glass can produce energy savings of 25 %, compared to a convection heating system

Check out the following publication for more detail:

2007 TNO Built Environment and Geoscienc
Download • 101KB


Rhodes, Greece, August 20-22, 2008

Abstract: In areas where heating requirements are significant, an innovative solution exists to counter the physical discomforts caused by windows – electrically heated windows. At first sight, installing heated windows would somehow appear not to make sense from an energy standpoint since the initial perception is to think about the energy consumed by a heated window as being dissipated towards the outdoors. In order to examine the effects of an electrically heated window on a building’s energy needs, a model was developed and validated. The model is applicable to both conventional and heated windows. Compared to standard double-glazed windows, the model reveals that using heated windows actually reduces the space heating and cooling loads. It also increases the thermal comfort in a building’s perimeter zone by preventing cold temperatures on the indoor side of the window from occurring. On the other hand, compared to energy-efficient double pane windows, the results demonstrate a slight increase in the space heating load but a decrease in the need for air conditioning. Furthermore, in cold climates and from an energy standpoint only, the results demonstrate that it is more advantageous to install a heated window on the north and east (or west) walls of a building as opposed to the south because, among other things, the solar heat gain coefficient (SHGC) of a heated window is lower than that of windows normally used in the building sector.

Read the full document here:

HTE'08 Research
Download PDF • 550KB

17 views0 comments