Energy audit and reducing consumption
Principle 6: Produce no waste
|Small energy meter used to measure the watts used for our 23 year old washing machine
During the last 12 months we used about 2.9kWh of electricity per day, this has not varied much over seasons, which surprised me somewhat. The Jan - Mar quarter is the hottest time of year when we were running the ceiling fans frequently, electric bread maker and also an electric fruit drier which helps explain the higher usage.
July - Sep 2010 (87 days) 238 kWh = 2.74 kWh per dayI purchased a small energy meter that allows me to see how much power an appliance draws and uses over time. I have been monitoring some of our major appliances so that I can see where our energy is being used.
Oct - Dec 2010 (91 days) 250 kWh = 2.75 kWh per day
Jan - Mar 2011 (98 days) 315 kWh = 3.21 kWh per day
May - June 2011 (89 days) 245 kWh = 2.75 kWh per day
Total power usage for the year 1048 kWh = 2.87 kWh per day
Electric fruit drier - 4180W for one batch (plus time in the sun)Standby power consumption
Electric bread maker - 330W for one loaf
Fridge (150lt) - 690W per day (before being moved)
Washing Machine - 100W for a load and approx 40W / 70W for water pump (small / extra large load), probably do about five loads per week as we wash nappies.
Water Pump (water pressure for household rainwater supply) - 610W per day average
Computer and peripherals - 1435W (with nine hours 'on-time' during the day)
Entertainment system (TV, DVD and amplifier) - 510W (3 hrs use 4.5hrs on - heavy use for us)
While I have been aware of stand by power consumption I didn't realise how much power it actually consumed. I discovered the following:
Water Pump - 19W per hourReducing energy use further
Computer and peripherals - 41W per hour
Entertainment system - 14W per hour
We have been considering and applying the following:
Electric fruit dryer - We have decided to limit our use of this appliance and use a solar dryer as much as possible.With these simple measures I estimate that we will save about 1kWh per day / 380kWh per year, over a third of last years energy use. A saving of A$89.30 per year with our new higher electricity rate (assuming all power charged at 23.5c per kWh which it probably wont be).
Bread maker - We use this during the summer months when the wood oven is not running. 1-2 loaves per week. I'm investigating whether we can use it to make sour dough bread by just using the bake setting as we are not impressed with the quality of the standard loaf that this makes with home ground flour. This will reduce our use slightly, as we wont be using the mix cycle - also we wont need any ingredients other than home ground flour, water and salt.
Fridge - This 150lt bar fridge was given to me when my grandfather died. It was made in the USSR in May 1988. It was positioned in a enclosed space and allowed to frost up considerably. I have since moved it to a more open location that receives little winter sun and have got into the habit of defrosting it every couple of weeks (or when needed). It works much better than it did before and I'm sure uses less power than indicated about (but I haven't measured it yet).
Washing machine - I was surprised at how little power our Maytag washing machine actually used, especially considering that it was made in June 1988, some 23 years ago. It's water use is considerable though, 75lt for a small load, and 150 for a large one. Since we use water collected on site and have had plenty of rain, this has not yet been an issue. I imagine that we will reduce usage later next year as Sen gets out of nappies.
Water Pump - I've been thinking of using a timer to switch off the pump from 11pm - 7am, saving about 152W per day / 55.5kWh per year (A$12.76 saving per year at 23.5c per kWh).
Computer and peripherals - We have been changing our usage pattern, turning the computer off during the day when not using it, rather leaving it on all day and relying on sleep mode. Another issue has been the three external drives that are connected, each with it's own power supply, I will only leave the one that I use for back up connected when the computer is on from now on. We also now switch the computer and all peripherals off at the power board, so that there is no standby consumption. This will save us 615W per day / 224.5 kWh per year (A$52.76 saving per year at 23.5c per kWh).
Entertainment system - My electrician suggested that I add an extra switch on my light switch that controls a power point, which I did. We were using this for controlling a lamp. I have since changed this so that it can control the entertainment system. We now turn off the system when it is not being used, which will save us 273W per day / 99.6 kWh per year (A$22.90 saving per year at 23.5c per kWh).
I feel that using old appliances, the 23 year old fridge and washing machine, is better that throwing them out and buying new 'low energy' ones. The embodied energy in these needs to be valued, and their actual use of power is not huge compared to other areas.
I'm actually surprised at how valuable an exercise this has been, and has made me much more aware of how and where we use electricity. Installing the solar PV system has been a real motivator in exploring and reducing energy use further.
While numbers vary a lot, the typical Australian household uses around 20kWh per day, with the changes mentioned above we are looking at using about 10% of that without compromising our lifestyle, more like 7% (1.4kWh per day) if we were using mains water and not pumping it ourselves. Anda that's with a family of four, which not typical of Australian households.