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Friday, 28 December 2007

Stats Update (Updated)

I last read my electricity and water meters 37 days ago. Some interesting things have happened between then and now including the installation of the electric pump that enables us to use captured rainwater in our washing machine and toilet. There'll be a separate post about the pump and related matters, but I have been very curious about how much impact that system would have on our consumption of external energy and water.

Today's reading won't give the whole story. For one thing, I can't recall exactly when the pump was installed but I'm pretty sure it was after that last reading. And our whole family went away for a week's holiday during the period so our consumption was artificially low during that time - I'll do some math to compensate for it but even that won't be accurate because the fridge was running for the week and I don't know how much power it would have used when nobody was opening it.

And speaking of the fridge... it's not well. Either it has a blocked drainage channel or leaking door seals. There's too much Christmas food in it to try and fix the problem right now but I wouldn't be surprised if it's using more power than usual. (Update: only hours after I posted that, the electrical safety switch in our fuse box tripped. The fridge was the culprit - all that water building up must have short-circuited something. Emptied it out and pulled it apart a bit, found the decomposing remains of some corn kernels blocking the condensation drainage pipe. Cleaned, reassembled, tested, OK now.)

So then: Tariff 11, the standard domestic electricity supply. Over 37 days we used 265kWh, averaging about 7.15kWh per day. (Our average for the 94 days to 10 Dec, which includes our week away, was almost exactly 7kWh.) Compensating for our time away brings the figure to more like 8.8kWh per day, a fairly significant increase. I'll have to do some work here to understand where the extra power is being used. Probably I'll connect the fridge and the pump to my two power meters and find out precisely how much of a contribution they're each making.

Next up is Tariff 31: Night Rate. I'm including this one just for comparison, because since the installation of our solar water heater we've switched to a different tariff. But energy is energy, and on this bill we see that over 21 days we used 90kWh. This included a few days where we had no hot water system at all and then a few more after the solar system was installed but before the electricity company came to reconfigure our meter for the other tariff.

Tariff 33, "Controlled Supply", works similarly to the night rate system except that it's available for 16 hours each day instead of just 8. I decided that made more sense for a hot water booster because we'd likely need it in the late afternoons and evenings when night rate supply would still be unavailable. Our total consumption over the 73 days covered on the bill was...

2kWh. That's not per day, that's total. We had to flick it on for an hour or so sometime in October if I recall correctly. It hasn't been on since, so of course the consumption over the past 37 days is a flat zero. I love my solar hot water system.

OK, so on to the water. I want to put this into perspective.

For the previous 39 days (that is, prior to the last time I read the meter) we had averaged 381L per day. For the 37 days just ended our daily average is 200L per day!

Even taking out the week we weren't here gives a figure of 247L per day. Again this is something that will need some monitoring during the coming weeks to work out our ongoing rate of consumption but I'm pretty pleased about that. Tank water is now being used for all outside requirements, all laundry, and most of our toilet flushing. The Shower Saver would account for a sizeable reduction in mains water use as well.

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