Home Economics

Back in June 2006 my interest in household energy came from a desire to go green, as 2009 approaches, I more concerned with not going broke.  Utility companies send me demands for large amounts of money printed on bits of paper with a picture of a wind turbine.  As my teenage children became increasingly bored with my ranting and gas and electricity bills in the range of £1,000 - £2,000 appear on the horizon a number of things became clear:

At current energy prices its worth learning to read the meter.

Unlike a petrol pump that demands eye contact whilst it drains money from your debit card, gas and electricity meters skulk in cupboards, hide behind bushes and mug you by direct debit.

Think about what you do with the energy you buy

The utility company wants £150/month, what habit am I feeding with this amount of money, back in 2006 this is what mine looked like:

Without any change to the way we use energy, the difference in the bills between 2005 and 2008 is frightening:

From the graphs, the logic of "don't sweat the small stuff" is obvious, unplugging your mobile phone charger over night is a long way second to managing your heating better.

Understand the Processes which use energy in your home.

At this time it's probable that the average homeowner's grasp of economics is ahead of that of a Wall Street banker and this combined with some school science can save you money.

In the early part of the 20th Century, value-for-money was part of the home economics syllabus taught in schools, but after decades of cheap energy, it has been dropped.

There's no shortage of products which claim to cut your bills, some of them  actually work.  However, better use of what you have already got costs you nothing and and understanding the claims made for a given device allows you to make an informed decision.

Think about your Lifestyle

Whilst most of this part of the site is about processes, don't ignore the impact of your lifestyle.  The way you use central heating time switches, is a good example.  If your life has a steady pattern and you need to be warm, using a timer to turn the heating on and off makes sense.  However, if you keep odd hours, simply turn it on (and off again) when you need it.  It can cost 60p/hour to run a gas boiler, leaving the thing turned off for a few hours buys you a nice woolly jumper from Oxfam.

Think about the lifetime costs of appliances

At 3p/kwh there was no incentive to think about lifetime energy costs.  Say a cheap, planet destroying fridge costs £100 and uses 1 kwh/day, over a year that fridge will cost £58 to run.  A lovable, tree hugging fridge costs £150, but uses only 0.2 kwh/day, and costs £12/year to run.  In just over a year, the more expensive fridge has saved the extra money, after that is just cheaper to run.

Efficiency

Efficiency is the ratio of what you want out of a process (i.e. I want to make a mug of coffee) to what you have to put in to get it (the energy required to boil the kettle).

Lets think about a gas central heating boiler (domestic water heater would be a better name).  A typical three up/two down semi with two adults and 2.5 children might use 15,000 kwh per year of central heating and hot water.  An old non-condensing boiler might have an efficiency of 80%, thus the household will be buying:

Gas Purchased = Energy Used/Efficiency = 15,000/0.8 = 18,750 kwh

A modern condensing boiler might achieve an efficiency of 90%, in which case the gas purchased will be:

Gas Purchased = 15,000/0.9 = 16,650 (approx.)

Thus a boiler upgrade will reduce energy consumption by 2,100 kwh.  at 3.5p/kwh, this represents a saving of £73.50 per year.  The potential savings need to be compared to the capital costs involved.

The numbers in these examples are simply for illustration, but the logic is the same for houses great and small and will provide you with a way of making  informed decisions.  Recently built or renovated properties will probably have a condensing boiler (for details consult an expert on building regulations), however, there are still a lot of the older non-condensing variety around.

These pages are work in process and opinions and conclusions may not always be consistent -  just like life.

Page Updated: 14-Mar-07

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