08-04-2019, 05:01 PM
I haven't attempted the sums, but for now obsolete 100W GLS lamps, the cost of the lamp is negligible compared to the energy it will use during its life. 1000 hours at 100W is 100kWh, £10-£15 at today's prices. The lamp costs much less than £1.
The life of a GLS lamp goes up a lot as you reduce the voltage by a little. But the light output goes down a lot too and so does the efficiciency. I haven't done the sums but for a given design of lamp, it may well be more economic to use fewer of them and run then brighter but with a shorter life.
I haven't accounted for the cost of re-lamping. Usually not critical in domestic applications, highly relevant in commercial. Which is why LEDs are taking over from fluorescents in shops etc. More light for less electricity (payback is usually less than 2 years) plus much lower re-lamping costs.
The life of a GLS lamp goes up a lot as you reduce the voltage by a little. But the light output goes down a lot too and so does the efficiciency. I haven't done the sums but for a given design of lamp, it may well be more economic to use fewer of them and run then brighter but with a shorter life.
I haven't accounted for the cost of re-lamping. Usually not critical in domestic applications, highly relevant in commercial. Which is why LEDs are taking over from fluorescents in shops etc. More light for less electricity (payback is usually less than 2 years) plus much lower re-lamping costs.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
