These lights are not standard 110V AC lights, but use 12V bulbs. In fact, each element consists of the light fixture itself, plus the associated 110V -> 12V transformer.
In any transformer, there will be some loss of energy (no transformer has 100% efficiency), so some heat loss is to be expected. Moreover, in the manufacturer's documentation it is stated that:
Enhanced in heat dissipating cover, to provide noise free operation.
This is good, since a transformer that runs warm will make some noise or "sing". Recessed transformers will tend do this all the more, since they have access to a limited amount of air to take away excess heat.
There are several solutions to this problem. Unfortunately, isolation is not one of them, since all it would do would be to negate the manufacturer's efforts on cooling the transformers, and on the contrary get them all heated up.
Here are some ideas:
- Airflow could be maximized behind the recesses. The name of the game is to ensure the transformers get a fair supply of moving air, to help them cool down. Forget the lamps themselves, they will possibly leak less heat than the transformers. However, you will need to find solutions for where the cool air is to come from, where it will go afterwards, and how to get it moving. Natural convection, or forced? The first is naturally best, since less components would be used, and less noise generated (since no fans are used).
- Other means of heat conduction can be used. We can note that metals are (much) better conductors of heat than air - which is, in fact, quite a good isolation. So connecting the transformers to a metal strip that is then terminated in a cool spot (outside, perhaps) is a practical means of leading the heat produced to where is needs to go. This technique is called a "caloriduct", and is actually used in many laptop computers where there is not sufficient height to place a dissipator on top of the CPU.
- The final solution is probably not what is desired, since it would consist in simply replacing these lamps for a more energy-efficient model. LED enclosures come to mind, which will use much less energy to produce a similar amount of light. Naturally, all the energy saved is not transformed into heat, so our problem goes away. The problem then becomes locating units with a similar shape and size (4" circular) to replace the light part of each fixture - taking care to choose LEDs of a shade that you actually like. This last bit is at times the most complex part, since some people show low tolerance to some types of white LED light.
My own personal preference would perhaps go to solution #2, since it can be implemented with minimum changes. Suitable metallic elements could be aluminum or (more expensive) copper. They do not need to be rigid; instead wire or mesh can be used. Perhaps a large-gauge electrical wire such as that used to ground lightning rods could be pressed into service. Just make sure there is a firm connection between each transformer's existing heat dissipation surface and the metal - and, most of all, that no short-circuits are caused through the new metal.