Were energy saving bulbs considered?

If WDC will save £500,000 per year for turning off the lights for 50 per cent of average darkness hours, then presumably the annual bill is £1million before the big switch off.
By The Newsroom
Published 23rd Dec 2012, 08:02 BST

Therefore, if WDC had used the cost of going up to every street light to change the remaining old bulbs to low energy bulbs with roughly 80 per cent less energy usage they would have saved £400,000 per year based on 50 per cent of lights still using old bulbs. After this action they could have gone to a public consultation of also switching some off. Many other local councils across the country have already taken this ‘no-brainer’ step.

Maybe lamp life is affected by the number of times a light is switched on and off which is now twice as many, leading to higher maintenance costs to change bulbs more often, especially the older ones with lower life. Could it be that WDC do not want to change all the other bulbs to low energy because they may have to write off in their accounts the value of stock of the old bulbs which could be a significant number, so would rather use them up over the coming years in lieu of low energy bulbs? - Gary Morgan, via email.