www.ultimatehandyman.co.uk

just to keep it simple as there's so many confusing statements flying around i have redone the calculations
assuming a bulb is alight for an average 10 hrs a day over a year and a unit[kw] off energy is 13.75p
for every 1w saved you will save 50p
as an aside any newish product complying with uk electrical regs will be sub 1w on standby
so turning them off will save less than 50p a year
some items that require to function when on standby will use more to far more for example sky box or freeveiw recorder

This needs putting into context - when set against turning your central heating down by 1C the cost savings as far as lighting is concerned pales into insignificance.

Whilst all forms of energy saving will reduce your outlay it's better to start with the higher (more wasteful) systems than 'pick around the edges'.

go for it you do those calculations
i will stick with what i know

going with the above formula for simplicity i compared a standard 100w over a 10w led and a 10w led with a sensor
a "normal" 100w bulb will use 100x50p=£50

an led bulb burning 10w will use 10x50p=£5

a 10w sensor bulb over the 10hrs will be alight for perhaps 10 mins so 1/6th off 10w=1.7w or 84p
plus sensor costs =10 hrsx0.3w =3w so £1.50p a year if left on 24hrs will = £3.60
so iff you turn off the sensor bulb during day it will cost 84p+£1.50= £2.34
iff left on 24hrs it will cost 84p+£3.60=£4.44
in other words its worth turning a sensor bulb off in daylight hours as the sensor uses far more energy than the actual amount used for illumination
if you do turn it off during daylight hours it will pay for its self in around 2 years as compared to a10w led bulb

now the sensor bulb i refer too is in a quiet location on the stars in a hallway without lights and will maybe be triggered for around 8 times in an 10hr session for around 70 seconds
even if its alight for 50% off the time the savings are still worth the cost but pay back may take an extra year

big-all wrote:just to keep it simple as there's so many confusing statements flying around i have redone the calculations
assuming a bulb is alight for an average 10 hrs a day over a year and a unit[kw] off energy is 13.75p
for every 1w saved you will save 50p
as an aside any newish product complying with uk electrical regs will be sub 1w on standby
so turning them off will save less than 50p a year
some items that require to function when on standby will use more to far more for example sky box or freeveiw recorder

You have far too much time on your hands big-all...

i enjoy dealing with figures so no big deal
to me its worth sharing as some people are confused
some people unplug everything and thats great for safety reasons but often fairly fruitless to save money
we used to get shouted at when i was a child 50 years ago for leaving lights on but now with leds its not worth any effort even less so with sensor bulbs
i cant be bothered turning any light off in constant use as the saving are less than the wasted effort