Heating Efficiency

Whether you are heating hot water for the sink/bath or radiators for your heating, the same basic rules apply and if you understand these, it will help you decide what system is the most efficient or the most cost effective. Generally the two are related but there are two other factors that need to be considered. The general expression to understand efficiency is:

Total Cost = (Average Energy Unit Cost x Size of system x Time used x Efficiency) + Installation Cost + Maintenance Cost

Hopefully most of these will make sense but what is worth noting is that some of these you have control over and some you don't.
The Average Energy Unit Cost (£/Kwh) is the amount it costs you for 1 unit of energy (gas/oil/electricity) for your system. Although the unit costs are different for each fuel type (and bottled gas is more expensive than mains gas) the unfortunate truth is these prices generally increase all the time so an average cannot really be based on todays price but perhaps double todays rate for something that might last 20 years.
The Size of system (Kw) is not something that is likely to vary, you need X amount of heat for a given size building and trying to save some money here is unlikely to be helpful. Likewise a bona-fide heating engineer should not over-spec the system so much that it costs you lots)
Time used (Hrs) is something that you can vary. This is the total hours over the lifetime of the system. For example 20 years at 8 hours per day over 6 winter/spring months = 29,200 hours. Obviously the less the system is running, the cheaper it will cost. It is NEVER cheaper to keep the system on 24 hours as opposed to letting it cool down during the day if you are out. Work out roughly how long it takes to heat up from cold (usually about an hour) and time it to come on. The system loses less energy when it is colder so it is more efficient.
Efficiency is a ratio of how much energy you put in via your energy source is turned into heat. Electrical appliances might be close to 100% efficient. Gas systems vary from around 70% to 90% but should be specified on the boiler on in the boiler manual.
The installation cost (£) is a one-off but is usually higher for gas systems which require gas work, plumbing and water whereas electrical systems are easier to install. If you are considering work, there is no harm in getting a few prices for electrical vs gas to see what the difference is here. It is also worth mentioning that you might want to spend extra on a system which will involve a longer payback period but which is more efficient just to lessen your reliance on fuel and the price increases.
Maintenance Cost (£) is something else worth considering. Electrical heating is often fit-and-forget and you generally don't get these units regularly serviced (unless you are a school/hospital in which case proactive work might benefit) whereas a boiler is worth having serviced once per year to ensure it is in good condition. You can find out how much a single service or an ongoing contract costs by contacting a plumber or gas company like British Gas.
My own view is that electricity will eventually be cheaper than gas since natural gas is running out whereas electricity can be produced using renewables and nuclear. However, for the time being, I like gas systems. They are well understood and you can fit a lot of heating power into a smaller space. I also like the idea, however, of keeping hot water cylinders (which most people remove) and using solar panels and wood-burning stoves to heat water in order to save gas or electricity costs.

Heating your house and saving energy

My energy bills are really low, I average £20 per month for gas and electricity. I have gas central heating and an electric oven. I wanted to share how my bills are low and suggest that many of these are within reach of a normal person in a normal house.

1. I don't run my heating to keep my house at 24 degrees. My thermostat is set to 20. I will wear a jumper before switching the heating on (although I am quite warm as a person). It might sound undesirable but honestly, it will save you a packet.
2. Make sure you have thermostatic radiator valves, the ones that are quite large and usually have red or green coloured numbers on them. They are no use if turned all the way up in every room but for instance, keep a spare room at 2, perhaps the bathroom at 4 and most rooms at 3. Why pay to heat a room you hardly use? Also, you might very well not want the bedroom at too high a temperature which will cook you when you are under the duvet.
3. Make sure you have a room thermostat that will switch off your heating when you house is warm. You might think that having loads of thermostatic radiator valves will do the job but if the boiler is still running when all the rooms are warm, you are quite simply paying to heat nothing. Honestly, this can save loads.
4. Make sure you seal any drafts around windows etc. They don't always make your house very cold but they can make it feel cold which makes you turn the heating on. Use curtains and draft excluders if required.
5. Make sure you have good loft insulation. It might seem expensive but it quickly pays back. The recommended amount is now about 250mm (almost a foot!) which can be annoying if you have a boarded loft but do what you can and make sure it looks cosy like a jumper!
6. If you have any cold rooms (or if you are like me) fix some rigid insulation to the inside of the outside walls and then plasterboard it and skim it. This works well on cavity or solid walls and can reduce some drafts as well as heat loss. It doesn't cost a massive amount and can be cheaper than cavity wall insulation (as well as not bridging the cavity and causing damp.
   

How to Calculate your Energy Consumption

It's the flavour of the day but saving the planet is all very well unless you have no idea how to work out things like energy consumption. For many people, energy consumption simply means whether the gas and electric bills are higher than expected. This is how you can calculate the energy consumption of your electrical appliances:

1. Look for a plate on the equipment that says what the maximum power requirement is. It might be in Watts, KiloWatts (1000 Watts) or in Amps.
2. If it is in watts, divide it by 1000 to find out how many units (KiloWatt Hours) it will use when running at maximum power. For instance, your fridge says 250 Watts. Divided by 1000 is 0.25 or a quarter of a unit per hour at full power.
3. If it is in Amps, multiply it by 0.23 to get the kilowatts and kilowatts over the course of an hour makes units. e.g. A 3Kw tumble dryer will use a maximum of 3 units per hour.

If you do this for a range of items, you might be surprised that things like tumble dryers and electric showers use vast amounts of power compared to things like TVs and mobile phone chargers. You might not.

After you have these, you need to work out how much is actually used. This can be hard for things like fridges which are always switching on and off and for washing machines, which only use large amounts of power when heating the water inside. You have two options to work this out:

1. For things like TVs, work out how many hours per month you use it and then multiply this by the power consumption. e.g. a TV might use 0.1 units of power and you might use it for 40 hours per month = 4 units. Again you might be surprised that low power things when used frequently add up to a lot of power.
2. For items like fridges and washing machines, their usage might be found in the instruction manual or otherwise you can measure it with the electricity meter. With everything else switched off at the mains (you can leave your clocks plugged in!) read your electricity meter and then go out somewhere for a while - do not open your fridge or turn anything else on. If your washing machine, you must obviously wait until it finishes the cycle. After the cycle finishes or perhaps 2 hours, read the meter again. Most of this amount will be your appliance (some might be things that you have not switched off like clocks, chargers etc). Divide this amount by the number of hours you have watched it for (fridge) or simply use it as an amount per cycle for the washing machine and you can then look down your list and find out where you can make savings in electricity.

Bear in mind that a washing machine uses much more power on a hot wash than a cold one so if you regularly use a hot wash, measure that and measure a 40 degree wash too.
For most people I expect that lights being left on, washing machines and tumble dryers being used too often and a poor quality fridge are where most power savings come from. I can't imagine your children will be pleased if you suggest a maximum of 5 minutes of TV every day!!