Sunday, December 22, 2013

How to Cut Home Energy Use by One Quarter: "Transition Lifestyles".

Since joining Transition Town Reading, a couple of years ago, we have begun to think carefully about how much energy we use at home. The mandatory installation of a smart-meter has proved a useful aid, as rather like a traffic light system, it goes from green, which is more or less the stand-by situation, through a warning amber, e.g. when we switch the electric kettle on, to red for danger, when the kettle, washing machine and the electric immersion heater have all cut-in together. The price is shown too, which certainly brings home how much of our resources are being consumed at particular moments in time, and by which devices. The figures are given below, so that a comparison can be made for the final two quarters of last year (2012) and this one (2013).

Some figures from our electricity bills:

2013 Q4    Usage 708 kWh cost £105.98
2012 Q4    Usage 942 kWh cost £133.72

2013 Q3    Usage 646 kWh cost £101.06
2012 Q3    Usage 839 kWh cost £121.55

The way electricity is priced can appear to have a somewhat nebulous quality, and so it is more meaningful to look at the kWh figures directly, rather than to try and use cost as a gauge of energy usage. As a matter of fact, we changed tariff in July/August, and while the current tariff includes a standing charge, the previous one did not. Our current tariff charges 12.39p/kWh. The previous tariff charged one price for the first 25% of the electricity used and a different one for the remainder. In price terms, the differential is 20.7% and 16.9%, respectively, for the third and fourth quarters of the years 2012/2013, or an average of 19%, and so we can say that we have knocked a fifth off our electricity bill, which is no mean feat. Yet more strikingly, the kWh figures reveal decreases of 24.8% for the final quarter and 23.0% for the penultimate quarter, and thus we have reduced our actual electricity use by about a quarter, and without experiencing any particular discomfort. So, how have we done it?

As noted, the smart-meter gives a visual alarm of when we are really getting through the juice. Probably this triggers a psychological response to simply switch things off! We have also efficiently draught-proofed the house, putting draught-excluder around the external doors, and closing full-length curtains across the doorways. Another saving is that whereas we used to run the washing machine every day, with just small loads, now we pile it all up and do a (twice) weekly wash, in fact much as folk used to, certainly when we were kids!

We have introduced a "shredded-paper box" which is based on the "hay-box" principle, and we often cook a meal (a stew, say), by getting it started by simmering it on the hob for half an hour, then covering the pot with its lid and putting the whole into the box, which contains shredded paper as an insulating material. The food then cooks (usually overnight) for maybe 12 hours, by which time meat is really tender, and the pot is still warm from the initial input of energy. This is a very efficient way of cooking. Also only one "cook" is involved, it being necessary to merely warm up portions for meals over the next few days, or whenever we want to eat it.

One other deliberate innovation is that, while we used to keep the immersion heater on all the time, now we heat up a tank-full of water and then switch the heater off. The present tank is very well insulated, and will keep water hot for three days or so, by which time we have used most of it anyway. We were alerted to the fact that this tank, which we had installed about a year ago, was much better insulated, and hence gave out much less warmth than its predecessor, when the cat moved out of the airing cupboard. The animal used to spend its winter days asleep in there, kept warm by the water tank, and its energy losses, but now has had to find warmer quarters elsewhere in this domicile.

The main reason for turning the water heater off as much as possible was not to save energy (I have heard the argument that to keep the heater switched on, so that the amount of energy being drawn is regulated by the thermostat, actually uses less energy, but I am not convinced this is true) but rather that since this is a hard-water area, the hot element encourages the lime-scale to precipitate from the water, and onto the element itself. Thus has been the demise of several immersion elements and a few hot water tanks over the past twenty odd years! Only time will tell if this strategy is sound for prolonging the life of the element, which has normally needed replacing every 3 years or so.

The final contribution to using less energy is serendipitous, since we suddenly realised that we no longer (or only rarely) needed to run the dehumidifier. Until about 7 years ago, we had only single-glazing. The result was that when the weather was cold, the moisture from the air used to condense on the window panes overnight, and by morning the windowsills were practically covered by pools of water, which we used to simply mop up with a cloth and wring out into a sink. Then, we had double-glazing installed to provide better insulation. Naturally enough, this worked wonderfully, and to the extent that there was no longer any condensation via the windows, but plenty in the kitchen and especially the bathroom, where mould began to thrive. Thus, for the first time in our many years living here, we bought a dehumidifier, which seemed irksomely ironic, since we were now using more electricity, to cure a problem that we had created by implementing an intended energy-saving strategy in the first place.

On the advice of a local energy consultant and former builder, Dr Tony Cowling, whom we know through being members of Transition Town Reading, each morning, we now open all the windows for about an hour. Although it is counter-intuitive to the uninitiated (as we were) - i.e. thinking that you want to keep the wet, moist air out of the house, especially during the cold, wet, snowy winter period - in fact the air inside the house is always far more humid than that outside. So, open the windows and out it goes! The outcome is that we no longer have mould growing, and there is no need to run the dehumidifier, which saves on electricity.

All in all, this represents an appreciable saving both of energy and money, and really with precious little effort or inconvenience.

What about gas?

As an update (14-4-14) to this article, our gas bill has just arrived for the first quarter of 2014, which compares with the same quarter of the previous year (2013) as follows:

2014 Q1   Usage 1,307.25 kWh  cost £72.39
2013 Q1   Usage 1,927.57 kWh  cost £97.34

Hence, our usage is down 32% on the same period last year which is hardly surprising since we've had mild weather compared with the same period last year. But last year's was slightly down on the previous year as well.

Jumpers and cardigans rule - OK!!!


Theo sam said...

Thanks for sharing this informative post, hope to read more from you.
Save Electricity

home electrical wiring said...

I only able to learn this info in your blog, thanks for sharing. By the way, can I use any kind of paper as insulator?