Benefits to be reaped from saving energy

Lovins gives some examples of Factor Four savings, starting with the hypercar. Only 15-20% of fuel energy used in a car gets to the wheels. Of this around a third ends up heating the air pushed aside as the car moves along, a third heats the tyres and a third the brakes. But looking at […]

Lovins gives some examples of Factor Four savings, starting with the hypercar.

Only 15-20% of fuel energy used in a car gets to the wheels. Of this around a third ends up heating the air pushed aside as the car moves along, a third heats the tyres and a third the brakes. But looking at this in reverse, each unit of energy saved at the wheels results in five times the saving in fuel input.

How the hypercar saves energy:

* advanced composite construction cuts weight by two thirds

* aerodynamic drag reduced by 50%

* better tyres, carrying less weight, reduce losses by a factor of three to five.

These measures double the efficiency.

* By adding a hybrid drive, 70% of braking energy can be recovered. Earlier savings mean that proportionately more energy is lost through braking so a great-er proportion is recovered through regenerative braking.

* Components such as power assist-ed steering, clutch, flywheel, differential and alternator are no longer needed, saving even more weight and driveline losses.

The net result is a five-fold improvement in efficiency.

The capital investment to build the car is less because expensive press tools are not needed.

Lovins says performance will combine `acceleration of a BMW, solidity of a Mercedes, safety of a Volvo and comfort of a Lexus’. Emission performance is better than a battery car – emissions from the hybrid’s internal combustion generator are less than those from a power station to recharge a battery car.

Superwindows

The Rocky Mountain Institute’s headquarters in Colorado grows bananas using passive solar energy in a climate where the external temperature can drop to -44 degreesC.

The building eliminates 99% of its heating requirement by using heavily insulated walls and `superwindows’. These measures are more than paid for by the elimination of a heating system, ductwork and so on.

Superwindows have been the key to many inexpensive buildings on which the institute has advised. They let in visible light and cut down unwanted infra red heat gain, using a transparent film either in the space between the double glazing panes or on the inner surface of one of them.

Films can be tuned to let through or reject almost any proportion of infra red to suit climate and orientation. They also keep in infra red in cold conditions. Krypton between the panes instead of air doubles the insulation.

But they are not widely available in Europe. UK companies have argued that they are not economic to produce because they have to be made horizontally. Double glazing units are normally manufactured with the panes vertical to save land costs, and the extra cost of horizontal assembly was not justified by the gain in performance.

Lovins says they have failed to calculate all the benefits.