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### Do you have a formula that would enable someone to work out the cost per minute/hour/day of running an electrical appliance? So we could calculate the cost of boiling the kettle, running the central heating or having the TV on standby. Each appliance has a kW rating, maybe even kWh, it's just the cost of electricity used I'm having difficulty finding.

power (in kilo Watts) x time (in hours) x price per kWh

current average UK price is £0.145 per kWh

so for example

a 3kW kettle on for 6 minutes (0.1 hours)

3 x (6/60) x 0.145 = 3 x 0.1 x 0.145 = £0.0435

please be aware that this can only be applied if the power consumption of the device is constant. So it cannot easily be applied to a washing machine where the spin takes more power than the wash for example. Heaters with a thermostat cannot be treated in this way either since power demand fluctuates. The kettle is fine! Lights are fine. Cookers have thermostats so it will be tricky.

### With police advice, I have a dusk to dawn sensor light in the front of my house and one at the back. I am anxious about the annual cost of these 10w low energy bulbs. Can you reassure me please.?

The light I guess will only be on for a few hours a day, when it senses movement.

For one light, even if it were on 24hours each day for a year it would cost £12.70 calc below:-

10 Watts = 0.01kW

.01kW x 24hr x 365days = 87.6 kWh

with a cost of about 14.5p / kWh

14.5 x 87.6 = 1270 pence or £12.70

more likely it will cost £3 a year, with intermittent use

### How up to date are the prices on the site?

The prices are all updated automatically once a year using latest data from government sources and fuel retailers. Once the prices are updated all the site calculations automatically recalculate. So the site never significantly goes out of date.

### Can an electric space heater be low consumption?

We have looked around the various claims on a few sites on the internet on this issue. Simply put no, but with one qualification. Electrical space heaters are all very efficient at converting electrical energy to heat, close to 100%. So they will all consume the same amount of electricity for the same heat output. The qualification is thermostats; a good thermostat is very useful at maintaining a room at a set temperature rather that continuing to heat a room which is already warm enough, having said that most space heaters have got thermostats on them.

So beware of claims on highly efficient low consumption electrical space heaters.

### Your calculations on the PV solar energy miss out FITS, why?

FITS is the Feed in Tariff. This is where an artificially high price is paid for electricity generated by solar cells. We have left it out until now because it is an artificial government construct to encourage PV electrical generation and could go at any time, the reality of the economics of PV is all that is shown.