Here's a link:

http://en.wikipedia.org/wiki/Laws_of_thermodynamics

Basically, in this context, imagine two exactly identical boxes, completely sealed and 100 percent insulated, except for their power cables. One power cable is 432W and goes into one box. The other power cable is 400W and goes into the other box. Neither box is transforming their respective energy inputs into kinetic energy (e.g., motion, spinning blades, moving turbines, whatever).

The laws of thermodynamics dictate that the 432W box will get hotter, no ifs ands or buts about it. Read the Wiki for an overview of the laws of thermodynamics, or search Wiki for 'Conservation of Energy'.

Now, if that's not the case with a 400-watt HPS light as compared to a 432watt (or whatever) Teklight -- if the heat output isn't greater -- then there must be a reason for that to be so that does not violate the laws of thermodynamics, especially the law of Conservation of Energy, which to date has been deemed irrefutable. The only way I can think of how that could be is if the Teklights have significantly more moving parts than HPS lights (moving parts would transform some of the incoming energy into kinetic energy, rather than light or heat -- small fans for example, do they have fans in them?). That would also explain why they generate less light for more energy - some energy would be diverted into kinetic energy. Otherwise, I have no explanation if they are, in fact, cooler.