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Smart guide

Smart lighting choices

Cutting your power use can be as easy as changing a light bulb.

New lighting technology looks smart and is smart

A nationwide study in 2005 showed that lighting accounts for up to 8 percent of household energy use in the average New Zealand home. Since then technology has rapidly developed.

Light-emitting diodes (LEDs) have historically been an expensive but highly efficient alternative to conventional lighting technology. Since 2011 LEDs have reduced in cost worldwide by 80 per cent making them an attractive alternative widely available in supermarkets and DIY stores.

That means that you can easily save money by changing to energy-efficient light bulbs. As well as cost-savings you’ll be reducing greenhouse gas emissions (less electricity use means less burning fossil fuels to generate electricity).
Energy-efficient light bulbs may cost more to buy, but are a smart decision in the long run. They last far longer and can save you up to 80% on your lighting power – meaning they are cheaper overall. It's an easy change to make, and your options are increasing all the time.

Two lighting metrics that are very important to consider for residential applications are:

  • CCT: or Colour temperature. Living rooms ideally should feel warm and inviting while garages, kitchens and bathrooms should be bright and clear.
  • lumens: ie ‘the overall quantity of light produced’. The amount of light will change according to your space.

Also important are:

  • length of life
  • is it dimmable?
  • lifetime cost = purchase + running costs


LEDs (light emitting diodes)

LEDs are many times more energy efficient than standard incandescent light bulbs, give off very little heat and are very cheap to run. Good quality LEDs last at least 15,000 hours. They still cost a bit more than a compact fluorescent light (CFL) to buy, but last longer. Overall, they have the lowest lifetime cost of all lights.

LEDs come in various colours and their light has a high level of brightness and intensity, making them ideal for use in applications such as path lighting. They come in a range of fittings and can replace incandescent, halogen and fluorescent lamps.

In household lighting, LEDs can now be used for just about any situation, due to recent advances in technology, but they are especially good for:

  • difficult to access locations
  • decorative lighting, especially the new filament-types that are very popular
  • areas where a low level of lighting is required for long periods of time – such as down stairs or night lighting along a hallway
  • lamp shades.

LED technology is constantly improving with new products coming onto the market. Quality and efficiencies can vary. Currently, the very best commercially available LED efficiencies get up to 200 lumens/W (for linear tubes), but the more common ones for household application achieve around 70 lumens/W (in 2017).

It is best to get advice from a specialist lighting supplier on bulb quality, light colour, warranties and whether LEDs are appropriate for the light fitting. 

LEDs emit no harmful UV or IR rays.

LED lighting on the Gen Less website has more information.

Fluorescent lights

Fluorescent lights are the most commonly used energy-efficient form of lighting for households. They are a little more expensive to buy than standard incandescent light bulbs but are much cheaper to run and last longer.

They're available as fluorescent tubes or as CFLs that can fit in a normal light socket.

CFLs can give as much light as incandescent bulbs yet use 80 per cent less energy. Quality CFLs last at least six thousand, and should withstand at least three thousand, switch on/off cycles. The savings can amount to $15 per year for each light. Overall, they have the second to lowest lifetime cost.

CFLs increasingly come in a wide range of shapes, sizes and colours, including a 'warm white' that is very close in colour to the light from standard incandescent light bulbs.

With all the choice in CFLs, choosing the right light bulb for the job is very important:

  • Not all CFLs are suitable for dimmers and other electronic switches, including proximity sensors – use special dimmer versions.
  • Although CFLs produce much less heat than standard incandescent light bulbs, the electronic control components in the base do not withstand heat well. So not all CFLs are suitable for all enclosed fittings that have limited air circulation or heat dissipation (for example, outdoor bulkhead lights).
  • CFLs need a short time to reach maximum light output – up to three to four minutes for older types – so they are not ideal when instant light is needed.
  • CFLs are unsuitable for recessed downlights with built in reflectors, unless the fitting is designed to take them.
  • CFLs are good for places where you want general background lighting and where the lights are on for a long time, such as the living room and kitchen.
  • They're also good for security lighting, but may be less useful for directional lighting or for places where you may only want light for a short time such as the bathroom, toilet or laundry.

Fluorescent tubes and compact fluorescent lamps contain mercury and cadmium. They should be disposed of as hazardous waste. Contact your local council or landfill about your disposal options.

More information:

Halogen globes

Halogen bulbs are a type of incandescent lamp. They cost twice as much as standard incandescent lamps but will last twice as long and are 30 per cent more efficient. Although they look similar to standard light bulbs, they use a small halogen bulb encased inside a traditional glass globe rather than a filament.

Halogen bulbs can be used with dimmers and other electronic switches such as proximity sensors and they are fine in areas where the lights are frequently switched on and off. They have no warm-up time so can also be used when instant light is needed.

However, these bulbs are still not as efficient as CFLs or LEDs and will not last as long.

Halogen lamps

Halogen lamps are a modified form of incandescent lamp, available in two voltages – 12-volt MR16 versions, which require a transformer, and mains voltage GU10 MV versions. They are more expensive to buy than standard incandescent lamps but last about twice as long. Although halogen lamps are not nearly as energy efficient as a CFL or LED, new IRC (infrared coated) models can provide 30 per cent savings compared to a standard halogen lamp and a longer life of two thousand hours.

All halogen lamps require special light fittings. Halogens lamps are often recessed and this may require holes in ceiling insulation through which heat can escape (see Downlights/Recessed lighting for more information)

They're often used for spotlighting paintings or for task lighting directly over a cooking area or desk.

If you use halogens:

  • fit lower wattage and more efficient bulbs – an efficient 35W lamp can produce as much light as a standard 50W lamp
  • don't touch the lamp with your hands – its life will be reduced. Mains-voltage halogen 'torchiere' lamps can get very hot and have started fires
  • Replace old halogen bulbs with modern LED replacements when they blow – these use far less energy and last a lot longer. Check with an electrician first before you replace 12V MR16 halogens with LEDs.

Standard and speciality incandescent light bulbs

Incandescent or tungsten bulbs have been around for well over one hundred years. They are cheap to produce and dispose of, but they are very inefficient, turning only about 5 per cent of the energy they use into light. The remaining 95 per cent is turned into heat. They also have a short lifespan, typically one thousand hours. Typically, they have the highest lifetime cost.

Note that this document is published by the Ministry of Business, Innovation and Employment Chief Executive as Guidance under Section 175 of the Building Act 2004. This is a guide only and, if used, does not relieve any person of the obligation to consider any matter to which the information relates according to the circumstances of the particular case.