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Reducing gas consumption in the home

boiler picture Inspired by the energy consumption research of a neighbour, Chris Gare, I started recording my gas (and electricity) consumption daily at the start of 2010 by simply reading the meter each day. I had moved into a new, larger house and I was curious to know how much more expensive its energy costs would be.

Tracking my gas consumption helped me to understand how I could contain its cost. I use gas for central heating, cooking, and heating the hot water. It's the largest of my energy bills so any savings I can make on consumption are beneficial. I hope my findings are of interest to you.

I have a floor standing, semi-commercial Osprey boiler rated at 36kWh that was installed by a previous owner in 2001 along with a Ferroli hot water tank. It is over 10 years old, is not "energy efficient" in the modern sense, and is much larger than a normal domestic boiler. However, my boiler servicing gas engineer points out that the savings I would make from upgrading to a new energy efficient boiler would be so small as to not make it worthwhile. I need to wait until my current boiler becomes unrepairable. In the meantime, the boiler is serviced periodically to ensure it's as efficient as possible.

The chart below shows my gas consumption in 2010 and 2011, illustrating well the costs of space heating in the winter months relative to cooking and water heating.

average gas consumption July 2012

My latest estimate suggests that I use 62% of my annual gas consumption for space heating (over five months of the year) and 38% for cooking and water heating of which most is water heating. This is equivalent to £470 per year for winter heating and £290 for cooking and water heating (of which £80 per year is simply keeping the pilot light lit!) That's about 80p per day for cooking and hot water and about £3.00 per day for heating the rooms.

My total gas consumption last year of 18,077 kWh was well below the national average for a five bedroom house, 31,500 kWh, and the result of a number of energy saving measures. These mainly relate to my behaviour and simply getting used to living in colder temperatures. This may sound extreme but it's not and it's worth over £430 per year in savings - far more than I would get from switching to another gas supplier.

The chart below shows how my average daily gas consumption changes by month and reveals that I am continuing to reduce my consumption (weather permitting).

average gas consumption 0ctober 2012

Space heating

The biggest saving is made by turning the central heating on as late as possible in the year and then off again as soon as temperatures warm up. I aim to turn it on only once the average minimum outside temperature at night has fallen to about 5 degrees centigrade. Research by Chris Gare, a neighbour, suggests this is the critical temperature to take account of and - in this part of the world - would mean that the heating is only on for about four to five months of the year, typically late November to late March.

I can cope with turning the central heating on late in the year because I also use a wood burning stove for heating the living room from about late October. This ensures the main room I occupy in the evenings is warm enough when I'm generally less active, i.e. watching TV. By leaving the doors to the hall open, some of the heat is allowed to escape upstairs thereby taking the chill off the bedrooms - but certainly not making them warm!

All radiators have manual thermostats that are individually set depending on the use of each room. A more sophisticated approach would be to use electronically programmable thermostats, provided their additional savings covers their cost and the cost of fitting. My neighbour, Chris Gare, is experimenting with these.

Setting the right time for the heating to switch on and off is important as is the right setting for the hall thermostat and individual radiators. This all requires some experimentation to get right and it depends on whether doors are generally left open or closed. The more people there are in the house, the harder this is to control!

Wood burning stoves can sound appealing but they have significant drawbacks. If you have to pay for wood, the stove and its installation then a woodburner is unlikely to be more cost effective than gas.
Read more


Insulating the house adequately is, of course, important and a much easier place to start. All my windows are A-rated double glazed and all cavity walls are insulated. Although the loft is insulated it is not to the standard I would like. The previous owners boarded the loft and this all has to be lifted to allow me to fit double thickness insulation.

The Energy Saving Trust reports that introducing insulation where you have none will pay for itself within about two years. If you are increasing the thickness to 270mm from about 100mm then it will take four or more years to pay for itself. Nevertheless still worth doing if you plan to stay in the property for long.

Shutting curtains in the evening and closing doors to little used rooms helps appreciably and is worth doing if you can remember to do it.

Wearing warmer clothing from late autumn makes a significant difference and allows me to inhabit a house that is probably colder than average quite comfortably. The return on investment from an extra layer of clothing, thicker socks or a "woolly" is extremely high! Much higher than most other energy savings measures.

However, eliminating drafts, particularly where you sit is particularly important. These drafts may be through windows or under doors but they can also be due to normal air movement in the room, particularly if you have a stove or open fire that is drawing air from the room.

Cooking and water heating

I have a range-style gas cooker with two ovens and two grills. The smaller oven/grill is sufficient for most purposes and consumes significantly less gas. Efficient use of the hob and the oven reduces overall gas consumption - but only modestly.

Water is heated twice a day for about 20 minutes on each occasion and I have a well insulated hot water tank. The water only needs to reach 66 degrees for a few minutes to kill disease. Importantly, I do not draw hot water throughout the day. It is mainly for washing in the morning and evenings so this is when the water is timed to come on. I have set the timer so that the boiler is no longer heating the water during the short periods when I am likely to be drawing hot water. This means that the water isn't being constantly reheated, unnecessarily when cold water is being drawn into the tank. When I'm away on holiday I switch the water heating off altogether.

Fitting solar water heating panels would reduce my gas consumption but I would need a new hot water tank with a second heating element. I would also need to find suitable space on the roof or a wall and a route for the additional pipes that is not too disruptive to my bedrooms.

However, the Energy Saving Trust estimates a solar hot water heating system costs about £4,800 including installation. With this, their research suggests I could make savings of 39-60% on that part of my gas bill associated with heating water. At most this is likely to be about £140 in my case. Although the UK Government's Renewable Heat Premium Payment scheme is now operating, a grant of £300 does not reduce the capital cost significantly and I would have to wait over 30 years before the system pays for itself (ignoring inflation). Until such time that I am forced to change my hot water tank and/or system prices reduce, this option does not seem financially attractive although it would reduce my CO2 emissions.

Another possibility would be to fit a Quooker or similar instant hot water tap in the kitchen. Most of these instant hot water taps do not produce water at 100 degrees centigrade so can't replace a kettle. The Quooker does. It takes about 10 minutes to heat 3 litres of water and stores it under pressure in a highly insulated container under the sink.

This has its attractions not just in eliminating kettle usage but would allow me to switch off the boiler completely for long periods of time. Also, because the kitchen is on the opposite side of the house to the hot water tank, I consume 5 litres of water simply waiting for the hot water to reach the kitchen. However, at present the Quooker costing about £830 plus installation is unlikely to pay for itself anytime soon.

Written November 2011