Making an AGA more efficient

If you are keen to minimise your household's outgoings, one important area to monitor carefully is energy consumption.

With a good record of how much energy and water you use throughout the year ( we take readings on a weekly basis ), you can identify patterns of use, and try to reduce your consumption where possible. This exercise can help to pinpoint the greadiest appliances.

AGAs are right up there on the greed scale. They have been receiving some bad press in recent years, with the increased focus on green issues, and the rising cost of fuel. Many owners are trying to decide whether to replace theirs with something more efficient.

We found ourselves in a similar position towards the end of 2009. Although we find ours to be a very useful appliance, love the way it cooks, and would find it very difficult to find a replacement as a consequence, we were finding it increasingly difficult to justify its monthly running costs.

AGA Intelligent Management System ( AIMS )

Doing a bit of research, we discovered that AGA had launched a retro-fit service for their AIMS product. This was originally fitted to electric versions, to reduce consumption, but has since been made available as an option on all fuel types.

The system consists of a new, more efficient burner, and separate controller which allows you to program it to come up to different temperatures at different times on different days, two time settings per day. AGA claim that the system can help to reduce consumption by 20%.

Testing the claim

We were quoted £1,800 to retro fit the system to our old, reconditioned mains gas unit, which was originally built in the late 1950's. That's quite a bit of money to spend on a system that may or may not reduce running costs significantly, so we decided to try replicating the job of the AIMS system manually, to see how much money we might save, and to find out what the payback time might be.

We started the experiment in January, a month when guest numbers are lower, allowing us to switch the AGA thermostat down low overnight, turning it back up in time for cooking in the evening. We took daily readings, to be able to compare consumption with and without central heating on, so as to try and isolate the cost of running just the AGA.

We did this for a couple of months, and discovered that by turning the AGA down when not in use, we were saving between £1 and £1.50 per day, an annual saving of between £360 and £540, or a payback time of between 3.5 and 5 years. And that was with an old, inefficient burner.

Why not just make the effort to do this all the time then, and not bother spending out for a programmable system ?

Two reasons. First, the old burner didn't like being turned down for sustained periods. It coked up, went out, and was a pain to relight. Second, if you need the AGA up to temperature for breakfast, you need to leave it on all night because it takes so long to come up to that temperature.

Why spend that amount of money on an appliance that some people view as a wasteful lifestyle statement ? Why not simply buy a new, efficient oven ?

There is no singular way to answer this very reasonable question. Here is our answer, based on our personal circumstances.

AGAs cook in a very particular way. The ovens' surrounding heat retains moisture within the cooking food, leaving it more succulent. They can produce food that, unless experienced, is very difficult to define, to describe. Cooking quality alone, however, wouldn't be enough to justify such an expense.

Once up to temperature, because they work on the principle of stored heat, you have a long period of slowly decreasing heat in which to cook a variety of foods, a period that doesn't require gas to be burnt. Running a bed and breakfast in Cornwall, we take advantage of this period to bake biscuits for the guest bedrooms and afternoon tea, and to prepare evening meals, amongst many other things.

AGAs radiate a certain amount of their heat, even if packed properly. This feeds one of the arguments for them being wasteful. However, given that the heat is radiating, you may as well make use of it. We dry all of our laundry above it on an old fashioned hanging air dryer, and need no central heating radiator on in the kitchen.

The original unit was built some 50 years ago. The carbon footprint of its production has long since been spent. Replacing it with a new appliance would create a new footprint, and would lead to the existing AGA being tipped into landfill.

You might have guessed that we decided to invest in the new system.

We had the AIMS unit installed at the beginning of April 2010. Using the figures for May, June and July, when we rarely need to use the central heating, and so can assume that any difference in consumption would mostly be down to the AGA, we calculated that it had consumed 33% less gas than the previous year.

Over the first 12 months our overall gas consumption was down by just over 20%, which at today's gas prices works out to a saving of just under £300. Obviously usage will vary slightly from one year to the next, central heating being the greatest cost ( the 2010/11 winter was a particularly cold one ), but these figures seem to suggest that the system will pay for itself within six years. Take rising gas prices into account, and that payback time will drop further.