Lamp type

Power

W

Light output

Lumens

Efficiency

Lumens/W

(higher is better)

Pros

Cons

Notes

240V, 50W GU10 downlights

Also available in 35W

  50

525

10.5

Cheap

No transformer required

 Dimmable

Stone age efficiency

Light is not as crisp as dichroic 12V halogen lamps and the choice of beam angle is limited

If you care at all about saving energy, you have to think twice before using these lamps. There are so many alternatives that are so much more efficient.

240V, 60W pearl GLS bulb

 Also in 25, 40 and 100W

 60

 700

12

Cheap 

Dimmable

Low efficiency

Consider more efficient halogen versions which are direct replacements, although the gains are marginal. However, consider whether you want the extra light as you will still be using the same amount of energy.

12V, MR16 Halogen downlights 

Also available in 20W, 35W and 50W  versions. Smaller MR11 version (35mm diameter) is also available for pin-spots in 10, 20 and 35W

20

35

50

320

630

1000

16

18

20

Cheap

Good quality of light and range of powers and beam angles

Long life versions available

Dimmable

Low efficiency, but much better than mains halogen

Requires transformer

Buy a good quality lamp from a specialist supplier and insist on a brand name, such as Osram, Sylvania, Edison, Philips, GE. Look for 5000 hour life rather than 2000 or even 1000 hour.

 Do you need 50W? Would 35W provide enough light? If not, consider Philips Masterline ES 35W lamp for 40% greater efficiency.

12V, 35W Philips Masterline ES high efficiency downlights

Philips part: 413970 71  (24°)

35

980

28

40% more efficient than normal halogen downlights

Direct replacement of normal 12V, 50W lamp

Quite difficult to obtain

More expensive than normal 50W lamps

Must be used with an electronic transformer to make the most of efficiency.

 Probably the best choice, if you are using halogen lamps.

Osram have a similar product using their IRC technology

240V, linear 300W halogen

Also available in 200 and 500W  versions as well as 60, 100, 150W in shorter package

300

4550

 15

Cheap

Good quality of light

Dimmable

Low efficiency

Do you really need 300W for your application? How about 200 W lamps?

Best used in conjunction with motion detectors, but consider metal halide for all-night illumination.

Integrated compact fluorescent

Philips Master PL Dimmable

Philips part: 660596 10

20

1200

60

Dimmable down to 10-15% with a normal dimmer switch

High efficiency

Light quality poor compared with tungsten/ halogen

Launch Q4 2007

This is a new product from Philips and, if you believe the blurb, should be the first energy efficient bulb to be dimmable with a normal dimmer switch. Very interesting, if it works as advertised.

Compact fluorescent

Available in powers from 9W to 55W and in various shapes

10

13

18

26

32

 600

900

1200

1800

2400

 50

60

60

64

70

allowing for control gear

High efficiency

Available in a range of shapes, sizes and outputs

Dimmable with the correct ballast

Light does not show colours accurately

Takes a few minutes to reach full brightness

The only practical choice for high efficiency in domestic environment where it is necessary to switch on and off regularly.

 Linear fluorescent tubes are about the same efficiency.

70W Metal halide

 Also available in 35, 150 250 and 400W

 70

6200

78

allowing for control gear

High efficiency

Crisp white light

Dimmable to 50% with correct ballast

Start time up to 12 minutes, during which time colour changes markedly

Cannot re-start when hot – must cool down first

Good replacement for floodlights that are on all night or for floodlighting trees, garden etc.