Since the Industrial Revolution, argue the authors, progress meant an increase in labour productivity. People worked efficiently and produced more. But in doing so they overused resources such as energy, materials, water, soil and air. Most technology introduced in the last two hundred years has led to the wasting away of the earth. Take electricity for instance. Only 3% of the energy from a nuclear or coal-based power station is converted into light in an incandescent lamp. 70% is wasted before it gets to the lamp which in turn converts only 10% of the electricity into light. Or the 80 to 85% of a car’s petrol which is wasted in engine and drivetrain before it gets to the wheel. Or water which evaporates and dribbles away before it gets to the root of a crop.

But this wasting disease is curable and the authors have a good prescription. Better technologies, policies and designs gleaned from the ingenuity of engineers, chemists, farmers and every person, based on good science, economics and common sense can usher in a new industrial revolution, the "efficiency revolution".

This would make it possible to double the global standard of living while cutting resource use in half.

"We would make money, pollute less, live better in a more equitable society", say the authors.

The book is replete with examples of wondrous technologies which can change the way we live.

Super windows-high tech films which allow visible light through and reflect away infrared - will change the way buildings are designed. At the Rocky Mountain Institute at Colorado, in the US, a solar banana farm produced a harvest even in cold January. There is no heating system here. Super windows trap solar energy and light and don’t let the heat escape. And at no extra cost. In Singapore, a Chinese engineer, Lee Eng Lok, has designed an air conditioner which uses 65% less electricity than a conventional one, simply by making the same fans, pumps and chillers in the air conditioner work better.

Organic farming using perennial grain crops instead of high yielding but resource intensive agricultural seeds can provide a more sustainable agricultural system. Grown in combination with other plants, they could look after each other. One plant could fix nitrogen, and the other guard against a pest attack. Drip irrigation can save water and direct it to the plants roots.

Roland Belz, the German engineer, has developed Belland material which looks like plastic but is water-soluble. By rinsing the collected contents with basic water, all Belland material can be recovered from the effluent water by adding a few drops of citric acid. This can be collected and turned into chemically pure granules for further processing.

By the year 2005 we can expect to travel in light hybrid cars which will run on electric propulsion thereby eliminating the need for cumbersome batteries. And people will be using them not just because they save 80 to 95% of the fuel and don’t cause smog, but because they will be superior cars. Worldwide governments have tried to get people to use public transport. But citizens cannot give up the pleasure of driving. In Curitaba, the capital of Parana in Brazil, an innovative private bus service, is used by 70% of the city’s population. It combines the efficiency of an underground metro with the convenience of a bus system. Developing countries could learn a few lessons from them.

The authors share with us a great vision of the future. But this is one road which has not yet been travelled. Implementing sound policies is a tough task and not always successful. Good scientists have to understand psychology too.

Then, sharing technology between the North and the South has never been easy. In today’s patent protected world how will the third world, have easy access to such state of the art technology?

The authors espousal of the informal sector and home production will not find favour with feminists who have fought long and hard to be accepted into the mainstream. Women will always prefer technology which cuts down the time spent in the kitchen. But Factor Four is not an exercise in utopia. It is based on sound practical ideas. Every person can help usher in the efficiency revolution by being inventive and resource conscious. The book is also a good read. It is written in a simple and interesting style and has a certain raciness. q