John, Wollaston asked:
How does the energy use in the new, more efficient energy-saving bulbs compare with older lamp designs of say, 100 watts?
Dave - The efficacy of a light bulb is a measure of how much visible light they produce per watt. So, an old fashioned fluorescent is somewhere between 50 and 67 lumens per watt whereas a compact fluorescent is between 60 and 72. So it's similar, but possibly slightly better because the compact fluorescents are newer.