Jevons paradox

Espousing efficiency is one thing, but energy use for lighting is going up, not down

Growing up in a council house in 1970s Newcastle, the only lighting decision made in our house was whether we should use a new style of lamp shade, and then what size of light bulb should be fitted in the shade – 40, 60 or perhaps push the boat out and go for a 100W.

With the demise of the basic incandescent bulb, the choice would now be a 6, 8 or 12W CFL; perhaps one that looks like a bulb, or maybe one that looks like a corkscrew. Job done, energy efficiency rolled out.

But technology brings new lighting opportunities for all. In the late 1980s there was a crime wave across Newcastle. No car radio was safe.

To counter the effects of the forces of evil, a 500W halogen floodlight became the ultimate weapon. Now, no criminal would be safe, or dare to stray within 15 metres of its cunning infrared detector because they’d be bathed in 5,000 lumens of high quality white light. Enough light to ensure that the car had a Pioneer or a Blaupunkt, not a Saisho or a Goodmans. Enough light to get everyone in the neighbourhood leaping from their beds and phoning the police every time a cat passed or the wind blew.

Technological marvels

These technological marvels became criminal commodities in their own right – we even had one stolen from the wall of the house.

The introduction of the GU10 halogen lamp has probably done more for lighting-related power consumption than any other technology. No new house or retrofit is now complete without the gridiron array of downlights straight from a builder’s lighting design handbook – the acne of the ceiling. In the 1970s everyone was happy with a 100W GLS, but today a basic lighting scheme can easily exceed 500W in the kitchen alone, and that’s before you add the under-cabinet lights and cooker canopy.

What I’ve just described in a roundabout way is known as Jevons paradox.

In 1865, the English economist William Stanley Jevons observed that technological improvements that increased the efficiency of coal use led to increased consumption of coal in a range of industries. He argued that, contrary to common intuition, technological improvements could not be relied on to reduce fuel consumption.

Water lapping at your door

As the world continues to develop and a few billion Chinese and Indian people decide they too want to pepper their kitchen ceilings with GU10s, we have reached the conclusion that it may not have been a good idea after all, and that we should all be tree hugging and fitting lights with miserly energy consumption. Well, we haven’t really decided this, but regulations, ever increasing energy costs and the water lapping at your door galvanise our decision- making processes.

However, according to Jevons paradox, the miserly energy consumption of cool running, compact light sources such as LEDs means that even more lighting applications will spring to mind. No big gypsy wedding is complete without an LED-illuminated wedding dress; you can put LEDs in furniture, toilets, shower heads, or coffee machines – no harmless object is safe from the benefits of illumination.

In one way, we in the lighting industry are in the vanguard of the battle against carbon emissions, delivering solutions that slash energy consumption. Meanwhile, we are plotting away to find ever more cunning ways to find more and more applications for lights. Sure, the power consumption of each unit is minute, but add them all up it’s still the same big number it’s always been. Well done!

People who live in glass houses

Where do you think you’ll find the worst lighting? It might be closer to home than you think

Clarity in the solid state age

The watt is not a very useful measure of a light source – particularly when there are so many available