Keeping your home warm / heating / energy crisis / insulation etc

I'm running a dehumidifier and in that time the last number has gone from 2 to 4.

My usage rate is 25.21p/kWh.

Does that mean it's cost me 50p?

Well, going from 2 to 4 could mean it's gone anywhere from xxxx2.0001 to xxxx4.9999 (almost 3, or 75p) to it having been xxxx2.9999 to xxxx4.0001 (just over 1, or 25p).

50p would be ~2kWh.

My dehumidifier draws about 150W on average, so 2kWh would be 13.3h of my dehumidifier alone, however the rest of the stuff in my house (computers, lights, fridge/freezer, stuff on standby) also draws a reasonable amount.

Also remember that dehumidifiers also generate a reasonable amount of heat in the form of warm air, so some of that money being spent will mean you need to use your heating a little less, so it's not wasted electricity. We only really need to run our dehumidifier when the temperature outside drops enough that we need to stick our heating on, so it's rarely wasted heat.

The old rule of thumb (before the energy crisis) was that 1W left on for a year costs £1. With that 25.21p/kWh that's more like 1W all year = £2.208.

A 150W dehumidifier running for 6h will cost a total of 25.21p * (150*6) / 1000 = 22.69p for that 6 hours.