Around the world the question of how we respond to climate change is a controversial topic.

Much of the debate is focused around economy-wide measures and international agreements like those discussed at the UN Climate Change Conference in Cancun last year.

While solutions at that level have been hard to come by, a good part of the answer lies with a simple solution: the humble light bulb.

The case for change is clear. Globally, lighting uses 20 per cent of all electricity. And two-thirds of lighting installed is based on old, inefficient technology.

New energy-efficient lights use up to 80 per cent less energy than incandescent bulbs, which waste 95 per cent of their energy on heat.

Philips' research shows even achieving an average energy saving of only 40 per cent using energy-efficient bulbs would reduce global carbon emissions by 630 million tonnes each year - the equivalent of 1.8 billion barrels of oil.

So while international debate continues on answers to climate change, we can all do our bit.

Most people are unaware of the extent of the energy savings that energy-efficient bulbs achieve. According to government website Rightlight, if every household in New Zealand were to change four incandescent bulbs for four energy-efficient bulbs, enough energy would be saved to power 20,000 homes for a year - a city roughly the size of Nelson.

Even replacing a single light bulb with its energy-efficient equivalent would save half a tonne of carbon emissions over the life of that bulb.

The question then is, how many people does it take to change our light bulbs?

Globally, many governments are legislating or regulating incandescent bulbs out of existence.

The European Union has started phasing out the bulbs, and in the United States the bulbs are due to be phased out by 2014.

New Zealand had thought about going down the same path, but the Government gave the bulbs a stay of execution, preferring to let consumers choose for themselves.

The problem is that many New Zealanders are still in the dark when it comes to the facts about energy-efficient light bulbs.

Compact fluorescent lamps became readily available to consumers in the mid 1990s. Since that time there have been continual breakthroughs which now offer consumers an ever-widening selection of energy-efficient alternatives to standard incandescent bulbs. Many people are also unaware of what today's energy-efficient bulbs actually look like.

Due to the speed of change in this area, even consumers who trialled energy-efficient bulbs five years ago will find new versions provide much greater flexibility.

For those concerned with aesthetics, advances in design mean it's no longer necessary to compromise on style.

Compact fluorescent with their distinctive coil hidden within a frosted globe look similar to incandescent bulbs. Smaller coils can sit flush in special fittings and, with a variety of shades of light available, switching to energy-efficient bulbs won't result in a loss of 'warmth' in the quality of light.

But the lighting technology that is really going to revolutionise the way we light our homes, offices and outdoor areas is LED lighting - an LED light bulb uses light-emitting diodes as the source of light.

Major breakthroughs in this technology over the past few years have resulted in lighting solutions that are far more efficient than standard incandescent bulbs. They have added benefits of providing a cool beam of light, no mercury content and more dimmable options.

They also can last up to 25 times longer than a standard incandescent bulb. That's a lot fewer light bulb changes for all of us.

One of the reasons governments have been reluctant to impose outright bans on incandescent bulbs is due to concerns that energy-efficient bulbs are too expensive. In reality, choosing a cheap, inefficient light bulb may be false economy.

It's true that a typical compact fluorescent lamp bulb costs around six times more than a standard incandescent bulb, but such a CFL bulb will also last five to six times as long and use one-fifth of the electricity over its life time.

Over that 5-6 year period, using a "cheap" incandescent bulb works out being around $110 more expensive. Add up the number of bulbs in your house, and the cost begins to mount quickly.

Over the 25-year life of an LED light, the savings are even greater.

As well as benefiting individual households, energy savings from energy-efficient light bulbs mean New Zealand also stands to benefit from reduced growth in energy demand.

At a time when the economy is under pressure, any opportunity to make savings needs to be seized.

In the longer term, every efficiency improves New Zealand's competitiveness on the world stage.

Of course we will all ultimately have to make some hard decisions on climate change. Economy-wide changes such as emissions trading schemes and international agreements will be an essential part of addressing those issues.

But more energy-efficient lighting is the low hanging fruit that's within our reach right now when it comes to reducing our carbon emissions. We are fast running out of reasons not to make the switch.

* Michael Downie is general manager of Philips Lighting New Zealand and Australia