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0 pointselectromagnetic16y ago0 comments

But what scale of measuring is necessary? Do I need to know what devices drain what power when it's simple to assume that electric heaters consume a vast amount of energy during winter and that air conditioners consume a vast amount of energy during the summer.

I believe the OP was asking is what is the benefit of this additional measuring and monitoring. What will it provide beyond the KW/h information I can get from my own meter?

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5 comments · 1 top-level

gridspy16y ago· 4 in thread

But how much energy? Do you know how many $$ of your power bill are down to AC and how many are due to hot water? If you turn down your AC one degree, can you tell at the end of the month how much you saved?

It is hard to isolate particular elements of your house's usage without either a lot of legwork or a decent sensor solution. Knowing how you use your power lets you make smart compromises and invest in power saving measures such as better lights, solar hot water heating, insulation or smarter appliances.

It is especially important if there are many people living or working in the same building, making it hard for any one person to get an accurate picture in their minds of the power consumption.

electromagneticOP16y ago

I know exactly how much electricity my devices use, and I certainly don't need a meter to figure out how or what they use. I worked as an electrician, I can work out the power consumption of every device, so yes personally I know where virtually every penny of my money is going.

I also have an induction meter (IIRC accurate to ~10W, I've used ones accurate to ~1W) that cost ~$60, so I seriously don't see the value in a $200 system that can't do much more than me, a pencil and time.

I see the system as a bit dishonest when you can tell people to look at a plug and read the amperage draw and tell them to times by 110. It's especially dishonest when the majority of devices now tell the wattage due to EnergyStar requirements.

sparky16y ago

I agree that eyeballs + a calculator can go a long way. However, the amperage draw on the back of your power supply or device is typically worst-case (maximum) current, not average current. Similarly, EnergyStar numbers do a little better, but everyone's usage pattern is different. For instance, what is the wattage consumed by your computer? It is certainly not the summed TDP of all components in the box. It is also not the rated wattage of your power supply. For things like this that are not "dumb loads", you need a more sophisticated way of measuring power consumption.

Personally, I'm with you in preferring a different solution. I use a Kill-a-Watt (http://www.p3international.com/products/special/P4400/P4400-... ) to measure actual average power consumption over a few days for each major device in my home. Seems to work fairly well.

mseebach16y ago

That's like a race-driver saying that ABS brakes are inefficient because he can brake better than the computer (true, but 90% of the rest of the population can't).

Or an amateur-chef scoffing at someone going to a steakhouse to get a good steak, because he knows how to make them good at home, much cheaper.

Or, say, a geek saying that graphical UIs are bad because he can work much faster on the command line and in vi.

I have two electrical heating devices, but both have a thermostat. I can read the label and do the math and tell you exactly what they cost to have running. But I can't tell you how often the thermostat turns them on and off, and I'm not going to spend a day with a stopwatch, looking at the light going on and off. I can't tell how the temperature outside might affect my heating usage. I can't tell how two persons showering affects the floor-heating in the bathroom, over one or none.

A logger like the one Wattvision offers could offer some input to that.

gridspy16y ago

Many many people will pay $200 dollars for the time component in your example.

You cannot read your meter as you walk around the house switching appliances.

Many (if not most) home-owners are far less aware of the power usage of common appliances than we are. They probably don't even know what a kWh is.

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