How can I calculate my energy use and save?

We’re suckers for research, and enjoy running our home as a personal research lab. One of the biggest things you can experiment with is energy use. Reducing our electricity, water, and gas usage is one of those many intersections between frugality and conservation.

Before we started this experiment, our average usage was 8.22kWh per person per day (lower than the American average of 10.9kWh, but higher than the Australian average of 7.26kWh). I found this ridiculous, given the tiny size of our apartment, the fact that we don’t have airconditioning, a washing machine or a large fridge or a big TV or many other power-hungry appliances that a lot of households do. And we have (unmetered) gas for our cooking. Certainly, there are efficiencies of scale (a family of five and a single person both need to run a refrigerator, it costs no more for eight people to watch a TV than for it to have only one pair of eyes fixed on it). But perhaps the secret was buried in the design of our tiny apartment?

The old house

The house we rented before we bought our apartment was one of the oldest in our suburb, and this was reflected in its design. Each room (lounge, kitchen, bedrooms, study, bathroom, laundry) had one light fixture (a 60w bulb) and one powerpoint. Young and tech-obsessed, our main home ‘improvement’ was the addition of powerboards to give us more sockets for our TV, hifi, games consoles and computers.

Our new(ish) apartment

In our apartment, our lounge/dining/kitchen/entry (which combined is around the size of the lounge at our old house) has not one but FOUR light fittings, each with TWO globes, plus TWO down lights for a grand total of TEN lights in a space that really could be effectively lit by around two.
One switch controls the down lights, one controls the kitchen light, one controls two over the lounge area, and one controls the light over the table.

So, we took out one globe from each fitting except the down lights, leaving us with 6 instead of 10 lights. We have never had a need to switch all on at once either. And we have not noticed a difference at all with the extras removed – especially since our new energy-saving light globes appear even brighter. There a no fewer sources of light, in fact, not even a discernible difference in the amount of light, but the exercise has really woken me up to how much waste was built into this design- and how we blindly followed it!

How we reduced our energy use:

  • Removing extra lightbulbs
  • Unplugging phone and computer chargers when not in use
  • Being more vigilant about turning off the TV, lights etc. when out of the room
  • Wearing extra layers rather than jumping into a hot shower several times a day to warm up in winter
  • Installing energy-saving lightbulbs (courtesy of a government initiative)
  • Using efficient powerboards that turn all peripheral ‘slaves’ (e.g. printer, speakers, monitor/DVD player, games consoles) off when the ‘master’ (e.g. the computer/TV) is off (another government initiative)
  • Turning off the hot water service when away

This lowered our power usage to just 5.22kWh/per person per day – well below the Australian average, and less than half of the American average, and saved us $231 a quarter.

So how can you calculate your electricity use?

It’s pretty easy if you have a stable number of people in your home – simply divide the kWh per day statistic on your bill by the number of people (e.g. 15.23kWh/2 people = 7.165kWh per person per day).

But in reality, we have trips away, guests visiting, and a number of other things that affect our energy use.

Let’s say Abby and Bobby have family come and stay with them for a week out of the month, and are billed for their electricity monthly.

Number of days with 2 people in house = 24. Number of days with 6 people in house = 7.

2×24=64. 6×7=42. 64+42=106 (number of person days in the month) / 31 (days in month) = 3.42 (on average there were 3.42 people in the house each day).

15.23kWh/3.42=4.45kWh per person – just 44% of the average American usage. Apparently if everyone reduced to 10%, there would be enough electricity for everyone in the world.

21EnergyHow do you lower your bills?

Search for your local government’s energy-saving initiatives.

Today’s featured image is the power outlet in my room in Fiji. The last time I stayed at this hotel, there was no power in the hotel or in much of the country following Cyclone Winston (and of course, for many, life without a regular supply of electricity is a daily occurrence).


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