One factor you might consider when choosing downlights, is how energy effeicent they are. LED's are the most popular choice for this reason, however one factor not considered in choosing these lights, is the requirement of cutting holes in your ceiling, and moving insulation away. As can be seen in the diagram below, standard style globes (GU10 and MR16 for example) are completely unsealed, and as such allow your air-conditioning (whether for cooling or heating) to leak into the ceiling, reducing it's effectiveness.
One of our suppliers, Brightgreen, have conducted some excellent research on the effect of this, and have published their findings here.
The results of this paper, show that by making the switch to a sealed light, the average Australian home could stand to save 390kWh per year.
There are a few ways to combat this air leakage. A popular method, is to use lights that mount to the ceiling, preventing the need to cut holes in the ceiling and remove spots of insulation. Another method is to use completely sealed downlights with an IC abbuted certificate. IC certification is an Australian standard that regulates what requirements need to be met for recessed lighting, when in or near contact to insulation (the abstract for which can be read here). IC-F abutted certification allows recessed lighting to be covered/underneath insulation; which in combination with being fully sealed, will not allow air-conditioning to leak through them.
You can view Brightgreen's 'surface series' downlights here.
Or, some of Atom's IC-F abutted certified downlights here.