Costs of heating water
There is one simple way to work it out.
You'll use roughly the same amount of energy to heat the water,
Based on my current tarrif, electricity costs about 21p per KWh, while gas costs 8p per KWh.
It takes about 8KWh to heat 40 gallons (US) from 15 to 60 degrees.
I leave the rest of the exercise to the reader!
You'll use roughly the same amount of energy to heat the water,
Based on my current tarrif, electricity costs about 21p per KWh, while gas costs 8p per KWh.
It takes about 8KWh to heat 40 gallons (US) from 15 to 60 degrees.
I leave the rest of the exercise to the reader!
Similar logic applies to new-fangled light bulbs which, lets face it, are mostly used indoors in dark cold weather.
As a result I've largely reverted to bulbs that actually work as the savings seem to be "virtual" not real with low-energy ones.
Different logic for outside lighting and my most recent floodlight is indeed a 10W LED not a 100W linear halogen.
As a result I've largely reverted to bulbs that actually work as the savings seem to be "virtual" not real with low-energy ones.
Different logic for outside lighting and my most recent floodlight is indeed a 10W LED not a 100W linear halogen.
10W floodlight...... wasteful! 
I recently replaced a 150W halogen with a 5.9W LED (covering a modest area at our front porch), the amount of light isn't that much less to be honest.
I don't mind paying for gas to offset the saving of indoor LEDs (I use 1.8 & 3W in many places though some are in 'multiple fitments').
If calculating the cost of heating water remember that a typical boiler is about 80% efficient* so add a bit to the cost per unit of gas, an immersion heater in an insulated tank can be taken as 100% efficient.
* An old boiler could be as low as 55 to 60% efficient, modern condensing boilers claim to be over 90% efficient but most do not achieve this rating when heating water to usable temperatures, so gas is usually significantly cheaper as a heating source (economy 7 overnight can be OK compared with an old gas boiler and oil/LPG is rather expensive so not always worthwhile).
I recently replaced a 150W halogen with a 5.9W LED (covering a modest area at our front porch), the amount of light isn't that much less to be honest.
I don't mind paying for gas to offset the saving of indoor LEDs (I use 1.8 & 3W in many places though some are in 'multiple fitments').
If calculating the cost of heating water remember that a typical boiler is about 80% efficient* so add a bit to the cost per unit of gas, an immersion heater in an insulated tank can be taken as 100% efficient.
* An old boiler could be as low as 55 to 60% efficient, modern condensing boilers claim to be over 90% efficient but most do not achieve this rating when heating water to usable temperatures, so gas is usually significantly cheaper as a heating source (economy 7 overnight can be OK compared with an old gas boiler and oil/LPG is rather expensive so not always worthwhile).
