Q:

Better life span for halogen bulbs in ceiling lighting?

The halogen bulbs for our recessed ceiling spotlights  have to be replaced quite often. 
Could we be using the wrong transformer/bulb combinations? How would I find out? Does the number of bulbs attached to any one transformer influence the life-span of the bulbs or the transformer? Are these bulbs drop-in replaceable by LED bulbs?
Transformer output: 11.5V, 35-105W
Bulb specs: 12V, 30W
The situation: Due to their location in the room we have 2 bulbs connected to a transformer. We have a total of 6 transformers and 12 bulbs.
Please leave a comment if more specs are needed to answer this question, then I will try to look them up. NB: The grid voltage is extremely stable in our neighbourhood.

A:

These bulbs can fail from overheating. If there is insulation in the space around them you may need to remove some to give them some ventiation, and it may even help to cut a small hole in the attic flooring.

