I've got a Worcester 24i Greenstar boiler and just being on, it dissipates around 10W. Normally this wouldn't bother me too much but it's on 24 hours which is 240W everyday and at 8p/KWH costs 1.92p a day or =A37 a year. Not much I'll admit but I'm sure the deisgn engineers could have got the power dissipation down to less than 1W when the bolier is doing nothing and then fired up the rest of the circutry when it needs to.
Likewise, my washingmachine, dryer, cooker oven, dishwasher dissipate
15W together for just being pluged in which is no big deal providing they can be switched off easily and don't need dismantling of the kitchen to get at the switch which the burke that installed my kitchen forgot about.
Thankfully I have a Hotpoint fridge which takes virtully no power on standby because it's isolated from the mains via a power relay which switches when necessary.