Another letter from Ron Watts

Ron contunes his debate with peter Bodle regarding climate change

Dear Ray

I think Peter Bodle has got his priorities a little bit wrong worrying about cars using their headlights in daylight. On his drive down to Cornwall he would have used roughly 420kWh of energy. If he had had his headlights on, two 40W lamps for say 6 hours, he would have used an additional 1.5kWh (allowing for the inefficiency of his engine etc). In other words he would have increased his energy consumption by about 0.36%. If he had had his air conditioning on, or a window open, he would have increased his energy consumption very much more.

The UK contribution to global CO2 production is about 2% of the total and road vehicles contribute about 28% of that. Since only about 5% of cars seem to have their headlights on during daylight, the effect of those motorists turning their lights off would be a reduction in global production of CO2 of the order of 0.02 x 0.028 x 0.0036 x 0.05 = 0.00000001 or 0.000001%. I don't think this would make much difference to global warming. I am sure there are many far more significant wastes of energy to worry about.

Furthermore I understand that many Scandinavian cars, i.e. Volvo and Saab, are so wired that their dipped lights come on when the engine is started so that it is not possible to switch them off. There is an argument that cars with lights on are more readily noticed, even in quite good daylight, so that this can be a contribution to road safety. It might also be argued that, since many British drivers fail to put their dipped headlights on at times when they should i.e. when it is misty, raining or just poor light, all cars should have their dipped headlights on at all times that they are on the move.

It does seem probable that developments in lighting technology in the near future will be such that energy consumption for lighting will be very much lower, then any worry about energy used by headlights will disappear completely.

Ron Watts