What we tested

An R-rated fitting

We tested a range of different types of downlight fittings to see how much warm air was lost from the room. We didn’t test their light output, or all the downlight fittings on the market.

So what the test shows is how different types of downlight fittings – and the bulbs in them – affect the amount of heating required to keep a room warm. 

What the ratings mean

How much hot air escapes into your roof space depends on the downlight fitting’s design and its rating. We tested fittings with RS, CS and CA ratings.

A C-rated fitting

The (R) and (C) ratings refer to the size of the vent to the roof space:

• (R) Restricted. The area of the vent to the roof space is between 5 and 15 percent of the area of the hole cut in the ceiling.
• (C) Closed. This isn’t “closed” in the sense that most of us would think – there’s still a vent but its area is no more than 5 percent of the area of the hole cut in the ceiling.

The (S) and (A) ratings are about the insulation-clearance:

• (S) Specified. The insulation-clearance distance is specified.
• (A) Abutted. The insulation can be abutted up to the fitting but can’t cover it.

Our test

Special room
We built a heated test-room inside another temperature-controlled room – that is, one room inside the other. The heated (inner) test room was insulated as you’d insulate a house. The temperature of the outer room was controlled to 9ºC.

The 3 different non-halogen bulbs used.

The overall set-up simulated a heated lounge with a cool roof space. We then measured the total energy (lights and heating) required to keep the inner room heated to 20ºC.

We then tested several examples of three common downlight fittings with different bulbs:

• R-rated fittings were tested with standard incandescent (GLS) bulbs, then incandescent reflector (R80) bulbs and finally CFLs.
• C-rated fittings were tested with the same three types of bulb. 
• CS-rated halogen fittings were tested as supplied and then again when fitted with the manufacturer's CA kit. In both cases we used standard halogen MR16 reflector bulbs.

We also looked at how much difference there was if we had more than one recessed fitting in the ceiling. To do this, we ran some tests with a single fitting and then with four fittings.