Creative garden lighting has owed its development mainly to 12 volt MR16 halogen reflector lamps for small, easily installed fittings, and it is often forgotten that these lamps are already twice as efficient as old fashioned light bulbs, so energy efficiency is nothing new to garden lighting. MR16 halogen lamps are at least 50% more efficient than 240v GU10 halogen lamps, so these 12v lamps are the best choice for accent lighting, where crisp white beams provide good colour rendering and the power to provide visual impact. 240v GU10 halogen lamps are useful in wall spotlights where their main advantage is that the lights don’t need a bulky base to house a transformer - they also give a slightly warmer colour of light for downlighting in domestic settings. To save significant amounts of energy in designing a garden lighting system the main choices are;
- Use higher power light emitting diodes (l.e.d.s) instead of halogen lamps - they last for 50,000 hours or more and are available for both 12v and 240v spotlights. 12v modules are also available for steplights and underwater lights. l.e.d. options are listed as part of the lamp choice for each light fitting.
- Use compact fluorescent lamps - bollard lights and lanterns have used these to advantage for years, but fluorescent spotlamps are a comparatively recent development. These GU10 spotlamps are 240v and longer than halogen lamps, but Elipta Compact spike spotlights and wall spotlights can now house these to provide low energy garden lighting.
- Use metal halide lighting for trees - it saves about 75% of the energy used by halogen uplights to do the same job. This is a big subject but there is useful guidance on choosing lighting effects and fittings in our Garden Lighting Design Guide
You can save energy just by opting for 12v halogen spotlights as they are more efficient and effective than 240v ones for uplighting shrubs and trees. While 12v halogen spotlights remain the main work horse of garden lighting because they are so cost-effective in initial cost, you can also reduce energy consumption of these by adopting focused beams of light and fitting them to the subject to provide balanced and selective lighting which is easy on the eye, as well as on the planet – have a look at help sheets on lamp choice for more guidance. Don’t just buy a batch of 50w 38 degree lamps because that is the general purpose lamp often sold - use 60 degree lamps to get wider coverage so you use fewer fittings for lighting shrub borders, try 20w lamps for the small courtyard or roof garden, or use lighter coloured focal points and flowers/foliage to reduce the amount of light needed for impact. The Garden Lighting Design Guide gives you more ideas on how to choose lighting subjects and effects. A help sheet on low energy lamp comparisons gives you a visual comparison of lamp types to help you understand the applications - and limitations - of energy saving light sources in the garden.