LED Downlights and normal lights

Dukecaddy · May 23, 2013 3:39 pm

The uninsulated area surrounding the light is only a small proportion of the overall ceiling area of your room. The additional heat transfer through the uninsulated portion would be insignificant overall.

sceen7 · May 25, 2013 8:32 pm

Dukecaddy

The uninsulated area surrounding the light is only a small proportion of the overall ceiling area of your room. The additional heat transfer through the uninsulated portion would be insignificant overall.

No I'm not concerned with the insulation gaps, but the gaps in the light fittings. Heat is leaking into the ceiling cavity. In my en suite this is dramatically demonstrated when I'm having a shower. When the extraction fan is going I can see swirls of air coming in through the light fittings.

my two questions remain as above

Mrs Brown Bear · May 26, 2013 9:10 am

I saw some LED downlights at the Sydney home show that had no surrounding gap in them, so you wouldn't lose heat or allow entry to insects etc. You wouldn't be able to angle them though.

I was hoping to use something like that, and hoping that it is a user serviceable part for changing globes.

daveinthehills · May 26, 2013 10:12 am

I don't know much about the specific problem per-se, but gaps in the insulation have a pretty big impact on it's effectiveness. You can see that by looking at the design and implementation of the totally passive homes they build in the Europe - they are totally sealed with airflow regulated through a heat exchanger. We limited our use of downlights because of this problem. I will be checking and fixing the insulation for the few downlights we do have in the kitchen after handover.

sceen7 · May 27, 2013 10:37 am

yes I agree Dave, Australian standards are very poor when it comes to 'leaky' building practices, especially in the colder states. All of the wall cavities and ceiling roof spaces are open to the outside. I realize there has to be venting so moisture wont build up, but there are dozens of 'leak' points in all new builds. Go around and put your hand on your power points on a very cold day, there's a breeze coming though some of mine.

I have calked and gaped all I can, I'm now just focused on the holes in the roof and how to fill them in.

Dukecaddy · May 28, 2013 1:12 pm

daveinthehills

I don't know much about the specific problem per-se, but gaps in the insulation have a pretty big impact on it's effectiveness. You can see that by looking at the design and implementation of the totally passive homes they build in the Europe - they are totally sealed with airflow regulated through a heat exchanger. We limited our use of downlights because of this problem. I will be checking and fixing the insulation for the few downlights we do have in the kitchen after handover.

Dave, there's a difference between infiltration/exfiltration (i.e. air leaks in the building) and heat transfer coefficient of a wall/roof. Gaps in insulation don't leak air, they just increase the heat transfer coefficient.

Sceen, I now understand your concern is air leakage through the light, apologies.

Like you've mentioned, it is really only feasible to limit building leakage by construction methods, too hard to rectify post-build.

daveinthehills · May 28, 2013 7:25 pm

Dukecaddy

Dave, there's a difference between infiltration/exfiltration (i.e. air leaks in the building) and heat transfer coefficient of a wall/roof. Gaps in insulation don't leak air, they just increase the heat transfer coefficient.

OK, good to know. I suppose the question is, does the energy savings of having LED bulbs beat the gaps in insulation they may have to cause?

sceen7 · May 29, 2013 7:16 pm

daveinthehills

OK, good to know. I suppose the question is, does the energy savings of having LED bulbs beat the gaps in insulation they may have to cause?

It is a shame there has to be any trade off, it gets me cross when I see the sheer joke that is the star rating system. I'll bet there are 6 star rated homes out there that in reality barely scrape past 1 star, and some that on paper are a 3 star in reality score much higher. My builder laughed at me when i started putting foil insulation on the outside walls, now I know why. As insulated as my new extension is there are still massive air gaps all through the structure.

daveinthehills · May 30, 2013 7:27 am

The foil insulation is for radiant heat. Heat bought in/out by airflow is different. The difference between a bar heater and ducted aircon. Both are important I believe but different for different climates