ElectricityConsumptionChartMedium

The table above is a brand-new effort to show the results of everything I have done to make our house more energy efficient. It demonstrates that my family has slashed our annual power consumption by 74 percent over the past 16 years.  Taking this long view only became possible when I managed to get my hands on records for electricity use at this house all the way back to 1989. From that year until 1997—the year we took over the house—the average daily consumption was 52.5 kilowatt hours. This year, we are on track to use an average of 13.6 kWh per day. (If you want make your own comparison, every municipal utility bill in Johannesburg—and in most other cities—shows average daily kWh used.)

Moving under the 16.7 kWh/day mark has been a long-term goal for me. Households that use fewer than 500 kWh per month (16.7 kWh/day) qualify for the Lifeline tariff in Johannesburg. The main benefit of the Lifeline tariff is not the very small reduction of about 6 cents per kWh, but the total elimination of R362 in monthly service charges. These annoying fixed fees were often higher than the amount I owed for power used. The municipality has now approved my house for the Lifeline tariff, though I’m told “system problems” have delayed switching the account over. Assuming this is sorted out, I will be paying approximately R5000 total for electricity in the coming year, about R415 per month. If this house were still using 52.5 kWh per day, the annual bill at the latest Jo’burg tariff of  R1+ per kWh would add up to R25,850,  so I am now saving more than R20 000 per year.

What did it take to get here? There are a hundred small, permanent changes and at least a dozen actions I take every day to be vigilant. But I think the bulk of the saving come from a few major changes.

  1. Solar geyser in conjunction with Geyserwise timer. The chart shows a big drop in 2005, the year we installed our solar hot water panels and 2010, the year we connected the tanks for that solar heated water to a Geyserwise timer. There were other changes in 2005 and 2010, but I have no doubt that the investment in this system is the No.1 reason for our 74% reduction in consumption. For more information on my solar system, read here, and for more on the Geyserwise, read here.
  1. Non-electric heat. We have gradually weaned ourselves from electric heaters, and now rely exclusively on wood burned in a closed-combustion fireplace insert and a Rinnai gas heater in the lounge and dining room. For the rest of the house, we have warm slippers, down duvets, hot-water bottles, and passive solar heat through the windows. Click on any of the green links above to read more.
  1. LED lighting. The drop in consumption from 2012 to 2013 is almost entirely because of our switch to LED lighting. We had already been reducing consumption over the years with compact fluorescent globes and IRC Energy Saver halogen lights, but LEDs made the most dramatic impact.
  1. Variable-speed pool pump.  My .75 kW pump stopped working in early 2010, the same year I installed the Geyserwise and saw significant improvements at the electricity meter. I eventually replaced it with a Viron P300 variable-speed pumpthat uses a fraction of the power consumed by ordinary pumps.

 

I’m not satisfied yet. I think that 10 kWh per day is a reasonable goal for the next couple of years, if I can improve the efficiency of my solar hot water system, replace the last few incandescent globes with LEDs and perhaps start cooking on gas. When I reach that goal, I may just frame the chart and hang it on my wall.