Latest update: 15/01/2017; October to December 2016 usage figures.
This graph displays three years of daily household electricity usage measurements averaged by month. This graph nicely demonstrates my household's journey from complete cluelessness to relative efficiency.
As mentioned earlier, 2014 was a year of observation without much behavioural change (the 'control' year), whilst during 2015 progressive changes were made to behaviour and technology in order to reduce power usage, and then at the end of September 2015 a solar PV system was installed.
The usage figures since the installation of the solar system include usage from both grid and solar so that the comparison remains consistent. I would expect that the difference between 2015 and 2016 will close up by September / October as that's roughly when the behavioural and technological changes became settled in 2015.
- Three bedrooms, two bathrooms, relatively open plan single-storey house
- Gas heating
- Gas hot water
- Ducted evaporative air-conditioning
- Ceiling and walls insulated
- Two adults, two children under 10
- Mini data centre (server room) running two computers and networking infrastructure 24/7
The last item in the list above should be noted as a significant contributor to the behavioural and technological change improvements mentioned below, and also a differentiator between the power usage profile of my household compared to most.
Behavioural and Technological Changes
The decreasing electricity usage shown in this graph is entirely related to behavioural and technological changes which were gradually implemented during the course of 2015 (from around March to September).
- Replacing 25 halogen downlights with LED's ($250)
- Purchasing power boards with on/off switch for TV / entertainment systems ($50)
- Replacing desktop "server" with two low-power draw computers ($700)
- Purchasing power timers for devices that don't need to be on overnight ($30)
- Purchasing thermostatically controlled power switch ($100)
Total cost: $1,130
The last item on the list above allowed me to turn off air-flow fans in the server room and allow them to be switched on only when a pre-determined temperature is reached within the room. Previously these fans were consuming around 50 Watts 24/7, whereas now they're only on for brief periods during summer. This change alone saved over 1kWh per day (around 400kWh per year). Nice to know but, as always, it would have been nicer to know earlier.
- Switching lights off when not needed
- Switching the power off for TV / entertainment systems when not in use
- Closing doors, curtains, and windows to keep heat out or in depending on the weather
- Working out what "things" don't need to be on overnight (ie. some networking equipment)
- Not needing the TV on just for background noise (use the radio if you really need something)
- Post-solar installation: Only charge electronic devices during the day(!)
The family has adapted quite well, and quickly, to these little lifestyle changes. My son asked me just tonight whether he was allowed to charge the tablet overnight since we hadn't been home since school and it was almost flat. I'm definitely happy that their thinking is on the right track.
Measuring the Effects
There are a lot of factors affecting how much power the household uses, such as daytime and night time temperatures, how many people are home, whether it's raining, whether it's footy season, when we take holidays, when the school holidays are on, whether we're spending time in and around the house or whether we're going out. I'm going to ignore that complexity and assume that over the course of a year it balances out.
Electricity usage and cost (not including daily supply cost) comparison between the full year's of 2014, 2015, and 2016:
* These figures are approximated.
From 2014 to 2016 electricity usage is down 35% and cost is down 41%, equating to $875. This means that the payback period of the technology spend is 16 months.
The technological and behavioral changes described above account for an annual saving of around $875 in comparison to 2014, with the payback period of 16 months for the spend on energy saving and energy efficient devices.
Next we'll look at the effects of a solar PV system.
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I should mention that as part of the South Australian Government's Retailer Energy Efficiency Scheme (REES) you can get halogen globes replaced by LED's for $5 per globe (which is cheaper than how much it cost me to replace mine). Here is the site of a company I'm not affiliated with which explains it in a much more user-friendly way than the Government's REES site: Green Home Green Planet.
There is other useful information on energy efficiency at the REES site as well, and I recommend having a read of it.