Save energy using LED lamps with G4 fitting in spot lights instead of halogen G4 lamps.Retrofitting Halogen Light Fixtures with the installation of LED lamps. How can 12 Volt, G4 LED’s (12V AC/DC G4 Led Bulb/Lamp) be mounted in existing substructure spot lights? An energy saving of 85% can be reached. Make sure you use the right leds. The current available LEDS are very different in characteristics like: lumen, colour temperature. Even if you buy 5 LED’-lamps from the same manufacturer their can be a difference in colour and the amount of lumen emitted. Some LED’s make an amount of noise. If you need to replace halogen lamps of 20 Watt, 12 Volt, you need LEDs of about 150 lumen. In some cases existing transformer must be replaced as well. Existing transformers can have a minimum load of for instance 50 Watt, but the LED load in my case was only 15 Watt 230V AC to 12 Volt DC transformers (15 Watt) can be bought for around € 10,-. De LED modules (warm white: 2700K) are available for about € 17,- a piece. The new version however only costs you arround € 7,- (Corpro LEDCapsuleLV G4 827) How to upgrade Halogen Downlights to Energy Efficient LED Lighting? With the MASTER LEDcapsuleLV 3-20W G4 827 or MASTER LEDcapsuleLV 3-20W 827 G4 (This one is not available any more so you should choose the Corpro LEDCapsuleLV 2-20W G4 827. Make shure you do not choose the dimmable version since this one is to high (48mm) and costs more. The MASTER LEDcapsule radiates warm light in all directions, making it a true alternative for the halogen capsule. It is particularly suitable for task lighting and decorative applications in homes, shops, hotels and restaurants. Compatible with existing fixtures with G4 holders and designed for retrofit replacement of halogen capsules, MASTER LEDcapsule delivers huge energy savings and minimizes maintenance costs without any compromise on light quality. The patented intelligent driver in the 2.5-10W version enables broad compatibility with existing electromagnetic and electronic halogen transformers.