Monday, July 25, 2016

insulated refrigerator freezer result negative?

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This graph from last night shows the electrical energy use of my newly insulated refrigerator freezer over about three hours with virtually nothing else on in the house.

I was surprised to find that the energy used last night was greater with the insulation I added yesterday! Until I realized that the last time July 10 I looked carefully at refrigerator usage, the temperature in the house was MUCH cooler. We are having a bit of a heat wave here so the temperature this morning in the house is 21C. You can see the little thermometer in the top right of the graph. Last time it was 12C. I would expect the fridge to be working harder when the ambient temperature is warmer. So I don't know the effect of the insulation yet. I have changed two variables and you can't do that. I'll have to repeat the measurement when the overnight temperature is cooler.

The temperature is measured outside by the Blueline Innovations device on my electricity utility power meter. Since I have the windows open, I would expect the inside and outside temperatures to be about the same. I also had the windows open on July 10.

So last night, I unplugged my small chest freezer downstairs about 10pm and plugged it back in about 5am this morning so it was not running during the recording. The fridge and the freezer have similar signatures so if I want to see one or the other, I unplug the other one for a time.

Everything in the downstairs chest freezer is still frozen solid although most of the light frost is gone from the inside walls and the plastic bags of food. There are still big chucks of ice in there on the walls after seven hours off. I have been watching this fairly carefully since I have been keeping my fridge and freezer OFF with timers during my peak period. They must keep at a safe temperature even after six to eight hours off. If you have a house full of teenagers using the fridge often, this might not work for you.

Other than the refrigerator freezer upstairs, only the network is running (which is how I get the data from my Blueline energy monitor), a couple of night lights and a phone charger. These make up the baseline load of about 70 watts. The base load is a bit lower than the previous tests because I not only turned off the computer but switched off its power bar.

Here is the graph annotated with guidelines and measurements added with CorelDraw. You can use your own favorite graphics program (or a ruler on a printout) to do the measurements and calculation. The Blueline software does not do the appliance calculation.

What I want to know is the area under the curve. The curve in this case is the square wave which represents the time (horizontal axis) that the refrigerator is running. The vertical axis shows the power demand at any particular time. The power times the time is the energy used in kWh.

Looking first at the vertical, when the fridge is ON, the house is drawing about 220 watts. I am eyeballing this by drawing a line through the middle of the tops of the square waves. It's an average, but you can see the fridge is a pretty consistent load when it is ON. When the fridge is not running, the house still draws energy (base load). Again, I am eyeballing this through the troughs of the square wave at about 70 watts. So the fridge is using the difference (220-70)= 150 watts, the same as before.

I would not expect the insulation to affect the amount of power at any time since the motor will draw the same current as before. What should happen is the motor will run less often.

Lookng at the horizontal time axis. It is hard to read exactly the Blueline graph so I am going to use some rulers. CorelDraw lets me lay down these rulers and tells me the distance. I have labeled one hour as being 3.12cm. The units of length don't matter as long as my units are all the same. I am going to use distance to compute time.

Across the top, I see that the fridge is ON an average of (0.92+0.89+0.91/3) 0.90cm or (0.9/3.12) 0.3 of an hour (about 20 minutes). I see the cycle time averages 2.15cm or (2.15/3.12) 0.7 of an hour (about 42 minutes). So I can say that the refrigerator is ON (0.3/0.7x100) 42.8% of the time.

So at this rate, based on these samples, over a whole day my fridge would use (power x time x duty cycle) (0.15x24x0.428) 1.54kWh or (1.54x364) 562kWh per year.

There is more to the story. As I was adding the insulation on the outside of the freezer compartment, I was wondering if I would have to re-balance the controls for the fridge and the freezer. At one point, several hours after finishing, I did adjust the fridge by one notch but then moved it back. I can't honestly be certain that I put it back to the same exact place. Both the fridge and the freezer controls are in the middle of their ranges.

What did surprise me this morning though, was that I had been playing with the "Exterior Moisture Control" and had mistakenly left it in the ON position. There are strip heaters around the door openings that are intended to drive off condensation on the cold door edges. I did not mean to have this on for last nights recording. This would definitely have used more power. I am not sure when the heaters come on but likely they are turned on and off the same as the compressor. But I still see the same 150 watts? Puzzling.

So THREE variables!

Thanks for your interest
George Plhak
Lion's Head, Ontario, Canada

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Sunday, July 24, 2016

superinsulating my refrigerator freezer

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I've spent the better part of the day adding more insulation to the freezer compartment of my refrigerator. It may seem ugly but some experiments are ugly. (click any picture to enlarge)

I am doing this to 1) save energy, 2) have the freezer stay cold longer when I keep it off during my peak period and 3) prolong the appliance life since it won't hopefully be working as hard (as often).

My fridge is a major user of energy. It is older and not as well insulated as those available today. Mine uses only about 150 watts but it runs about one third of the time, 24/7 if I let it. I am intentionally keeping it off during my peak time with a plug-in timer. I've calculated that it currently uses about 412kWh per year (before today). Please see

I've used "superinsulating" in the title in the sense of being on top of or superior to what was there before. Not in the sense of some new technologically advanced stuff. In fact, I am using quite ordinary materials.

The best insulator is a vacuum but we can't economically use vacuum as an insulator for a large appliance like a refrigerator. The result would be heavy and expensive, making a suitable vacuum container to surround the cold space. That would not be practical.

The next best insulator is air that does not move around (convect). Foam is a very inexpensive and lightweight material which traps air and keeps it from moving around. The more foam thickness, the better the insulation.

That's what the manufacturer uses - foam. An 18 cu foot refrigerator like mine in a showroom today is larger by a couple of inches. This is how they have made refrigerators more efficient - thicker insulation. Compressor technology has not changed all that much. The controls might have improved efficiency slightly but the best control improvement I can provide is to keep the fridge from coming on during my peak time. That is a feature not available on today's refrigerators, even the most expensive models.

So I have added insulation on the outside. Adding on the inside would make the space smaller of course but would accomplish the same thing. If I open the door of a current fridge the space on the inside is about the same as mine (18 cu.ft.) but the wall is noticeably thicker and the overall size is larger.

I decided to add insulation on the outside and to check the effect on my old fridge. I can get a new 18 cu ft fridge for $800-2500 and probably have wonderful new features that I don't need except for the increased insulation thickness. I have now added extra wall thickness around the critical freezer section of my refrigerator for about C$20.

I will have to replace mine eventually of course but why NOW when I can do this fine experiment? I have tried to apply the insulation in a workmanlike manner that will be solid for at least a year or two, possibly longer.

For the top and sides, I have used found material, clean and intact surplus styrofoam packaging material that conveniently was in 2" thick block form about a foot square each. I would have used nearly a full 4'x8' sheet if I'd had to buy (Styrofoam SM sheet cost in Canada about C$35).

It might have been easier in some ways to cut from a full sheet but the price was right and the reuse aspect was a plus.

More surplus styrofoam in the form of trays I found at the local recycling depot probably recently carried a large appliance like a microwave oven. They were just slightly smaller than the door and the back of the freezer section.

I filled the trays with a layer of rock wool (Roxul) that I had on hand for the house. I had to split the rock wool down to about 1.5 inch thickness to fit into the trays. The trays filled with rock wool were then attached to the front of the door and the back of the freezer.

The outside is covered with a reflective bubble wrap like material which was really the only thing I bought specifically for this project. A roll of Reflectix Staple Tab Insulation 16"x25'/0.41mx7.6m) cost about $20. I used virtually the whole roll.

Plus lots and lots of packing tape (probably close to a full roll), a few strips of wood and about 10 wood screws to hold the wood to the metal skin of the fridge in a few key spots.

This is not meant to be a complete how to description but rather an overview of what and how I did it. If you would like to know more, please comment below.

I hope to have some preliminary results in a couple of days.

Thank you for your interest.
George Plhak,
Lion's Head, Ontario, Canada

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Tuesday, July 12, 2016


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This is a graph of my freezer's energy use last night. To isolate the freezer from the refrigerator since they look similar in power draw, I unplugged the fridge from about 22:00 to 3:00 so it is not running during the time on the graph. I zoomed on the freezer cycling, not including the fridge startup to get the max zoom on the vertical axis, the energy use of the freezer.

My freezer is an old smaller Woods chest freezer sitting on the cold basement floor. It must be from the 1990s. Sometimes I notice condensation of the top of the door so I don't think it is very well insulated. But it is quiet and does it's job.

I can see on the chart that the freezer follows a regular cycle like the refrigerator, drawing less power about 100watts but for longer, about an hour every couple of hours. This is going to vary a bit, mostly with the room temperature in the basement. These days that is about 23C. In the winter much lower. I don't open the freezer door very often, perhaps once every couple of days.

The fridge and the freezer are like dripping taps. They don't use much power but they are always on. What energy they use goes in cycles on and off. At any moment they might be on or off. Digital? More like Binary?

The shape of the freezer energy signature is interesting as it ramps down slightly as it runs. The spike on the first peak doesn't repeat on the other two. This is probably the freezer compressor motor starting up. Most household motors start with a heavy burst of current known as the "locked rotor current" but that only lasts for a second or less and then the motor current drops dramatically.

I think a limitation of the Blueline equipment is that the samples are taken every minute or so. Blueline may be limited by the hydro meter sample frequency since it gets its data from the hydro meter on the outside of my house. Some guy named Nyquist figured out that the sampling rate had to be at least twice the data rate but thats another story... you can only see slow data with a slow system.

Here is the longer view this morning looking at the past 12 hours.

The freezer you can now see relative to some other appliances. D is the dishwasher. W is the water heater which comes on with the dishwasher and also about 4:30am. You can see that the water heater runs much longer when triggered by the dishwasher. There was no hot water used after the dishwasher. F is the refrigerator being plugged back in. S is me out in the shop with some of the big overhead lights on, doing some painting. T is the toaster oven warming up a bagel.

Here I am in CorelDraw taking a more detailed look at the freezer data and figuring out a yearly consumption estimate from last night's data.

You can use your own favorite graphics program to help with the visualization and calculation. You can be as detailed as you want to be or just eyeball the data to get a sense of what is going on. After I do a couple of calculations, I think I see more in the data. As I said previously, I am disappointed that the Blueline software doesn't do more of this calculation for me but I don't mind doing this for the knowledge I am getting about my actual use real time thought whole house monitoring.

I realize now that I did the calculation incorrectly for the duty cyle for the refrigerator yesterday so I'll go back to correct that.

Looking first at the vertical energy axis I have placed three numbers in watts reading off the rather bad axis which has no tick marks, I see that my baseline last night was a little lower than I expected, about 90 watts. This is probably because I didn't leave any lights on by mistake. The baseline is the computers, the network (which sends Blueline my data from the actual power company meter), a few CO2 detectors and some miscellaneous chargers and power bars.

Next I estimated the peak ppower draw of the freezer at 215 watts, (215-90)= 125 watts not including the baseline. When the freezer has run for a while just before it turns off, the power draw falls to 195 watts or (195-90)= 105 watts. Since the droop is approximately triangular, I will use the rough midpoint of 115 watts for the calculation. About half the time, the freezer uses more, half the time less, so it should be about right.

Now I calculate the time duty cycle, in other words, what percentage of the time the freezer runs. On the chart, 1.21cm = 1 hour. The numbers at the top (0.91, 0.86, 0.85 are samples of run times shown in cm. At the bottom are the lengths of the cycles (2.03, 1.99). I can't find the length of the third cycle since the rising edge of the next ON is off the right of the chart so I'll use only the first two samples. Using the ratio of the lenght to reepresent time, I can say that for the first cycle, the freezer was on (0.91/2.03X100)= 44.8% of the time, drawing 105 watts. During the second cycle, the freezer was on 43.2% of the time. I'll use the midpoint of 44%.

Based on only these two samples, for a whole day, the freezer would use (0.105x0.44x24)= 1.1088kWh or (1.1088x365)= 404.7kWh per year or virtually the same as my refrigerator (412.2kWh)!

Thanks for your interest,
George Plhak
Lion's Head, Ontario, Canada

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Sunday, July 10, 2016


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I got a nice clean recording of my refrigerator energy use last night. This pic is the "Last Three Hours Real Time History" view of my Blueline EnergyCloud software. Recorded in the middle of the night, from about 2am to 5am. I got up shortly after 5am and plugged in the freezer. That's the spike at the right. (click any pic to enlarge)

Normally the freezer and the refrigerator run overnight but that makes a confused recording. With the freezer off, the recording is beautifully clean and shows the regular cycling of my old Fridigaire model IDT186001 against the house background of about 100 watts. The house background consists of my network (necessary for the Blueline hardware to work sending my data to the cloud), a few chargers and wall warts, the light in the basement I forgot to switch off last night plus a few LEDs for path illumination that are on all night but turn off in the day. I think I might have turned on a bedside lamp at 3:30 for a few minutes to check the time. You can see a little upclick at about that time.

Here is a longer view at six hours. That is a water heater peak at about 1:20. Notice that the vertical scale kW changes (steps back) when the water heater is present because of the size of the peak. That's the same refrigerator running in the background but its 150watts looks small compared to the water heater. the refrigerator runs much more often so usage adds up. All the graphs in the Blueline software do this vertical scaling thing automatically. It is important to watch the axes, both time and kW.

Some test conditions: It is the middle of the night in the summer. The refrigerator door has not been opened for at least eight hours.

The energy used by the refrigerator is about 250watts less the background 100watts (which the house is using elsewhere) or 150watts. The refrigerator comes on about every hour for about 20 minutes. Which means as a rough guess, the refrigerator is on ABOUT A THIRD OF THE TIME using 150 watts. I calculate more carefully below.

The temperature shown at the top right of the pic is the outside temperature (12C) at the meter. The inside house temperature is about 21-22C. In the winter, the house temperature will be cooler so the refrigerator is working moderately hard right now. It will work harder still when the house temperature is higher and the refrigerator door is being opened occasionally, new food is being inserted etc. So this should be considered a sort of minimum for the refrigerator.

I should be measuring the inside temperatures of the refigerator and freezer compartments. I should be at least measuirnt the internal temparature at the conclusion of my peak period inhibit.

So now I'd like to turn the graph into an amount, the amount of energy consumed by the refrigerator. I had commented that none of the provided software does that for me so I am going to use a graphics program to help me do the calculation. I am using CorelDraw. I will do it in a bit more detailhere to explain the concept but only present the results on other appliances. I intend to do this for at least my major consuming appliances. Hopefully I will be able to use this information to help me decide on improvements.

Here I am in CorelDraw with the same pic I showed above. I have added guidelines with Corel which I have carefully placed at the edges of the power waveform, where it rises and where it falls. I find it difficult to judge time on the horizontal axis so will use some tools to help me. I will use guidelines to snap dimension tools to I can make fairly precise measurements of the time by comparison. More below.

I have also placed guidelines along the top of the peaks at 250 watts. These are quite uniform so one guideline will do. I have placed another along the baseline at 100 watts. I will use these kW amounts for the calculation.

I have added horizontal dimension lines in cm. Any units will do as long as they are all the same. I want to compare the lengths (times) of the refrigerator power waveforms to compute the time. One hour I have measured as 2.08cm.

I see that the ON time measurements are in the range of 0.64 to 0.67 so I will take the average (0.66+0.67+0.64+0.64/4) = 0.6525cm or (0.65/2.08) = 0.31 of an hour or about 18.8 minutes. This is about how long the refrigerator is ON using 150watts.

I can see from the cycle times that the refrigerator is coming ON every (1.74+1.77+1.73/3) = 1.75cm or (1.75/2.08) = 0.84 of an hour or about (0.84x60) every 50 minutes. This means that the refrigerator is running (0.31/0.84x100) = 36% of the time.

In kWh this would be (0.150x0.36x24) = 1.296kWh every day or (1.296x365)= 473 kWh per year. This is if I don't open the door and don't ask it to cool any new food.

My refrigerator still has the EnergGuide lable showing 691kWh per year expected usage so at least I am on the right page. As near as I can make out, my old refrigerator is from the 1990's.

I notice looking at newer refrigerators the other day that modern units use half the amount of electricity. I also notice that the wall thickness of newer fridges seems twice as thick as mine. The new ones have much thicker insulation in the walls and the door.

Time for a new fridge? Or should I better insulate mine?

Thanks for your interest
George Plhak
Lion's Head, Ontario, Canada

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measuring my home electric energy usage - index

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Same articles with framework Sept 2021

Exploring with my smart meter and a few other tools.

I don't have a very complicated house. It is old with old appliances for the most part. I am looking for sensible upgrade paths that can be measured. I like data. Data does not have to be complicated to be good data.

My writings/pieces/articles often arrive in some random order. Sooner or later, when I've got enough of the pieces, I feel the need to have an index. I occasionally rearrange the index. This is the latest edit (Mar 15 2020).

I am still learning. No intro or conclusion to the writings yet. You can start reading anywhere that interests you.

Thank you for your interest.

George Plhak,
Lion's Head, Ontario, Canada

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Saturday, July 09, 2016

my typical electrical day summer

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This chart recording originates from the Blueline Innovations EnergyCloud software and their sensor device attached to my electric meter outside. I am able to view a recording of my whole house electric use. This is a 24 hour period a couple of days ago. I took a screen capture and added the black and red letters and lines with arrows to explain what I see. (click the pic to enlarge)

Their software and device does not know which of my many electric appliances is using the electric energy. I am shown the total and how it varies very precisely (every minute or so) over time. I have learned to recognize my appliances through the patterns they make in the recording. I can isolate each by switching off as much of everything else as I can or by operating each individually during the quiet times and watching their effect on the recording. Perhaps a bit like recognizing the instruments in a band, each appliance "sounds" different in the pattern it makes in the recording. I've been calling pattern it's "signature". When two appliances operate at the same time, their signatures are added together in the recording.

Let me describe the day electrically.

Starting with the period I've labled A, it is morning the previous day and I am working around the house doing various things, running a vacuum cleaner and a machine or two out in the shop, getting ready to go out for the afternoon. Nothing very significant electrically is going on.

B is my peak period, from 12 noon to 6pm. Electricity during this time for me is five times the non-peak rate. I have recently added timers to my water heater, refrigerator and freezer to prevent them coming on during this period. This seemed obvious cost saving but I have done this only now as a result of being able to see my energy use. I won't save actual electricity since those appliances will have to "catch up" when they come back on, but I will have shifted electric cost to the non-peak period. I will save on my bill by not using electricity in the peak period. My water heater certainly is significant.

Your major user appliance may not be a water heater, it may be something else. Software like this (whole house monitoring) may help you to understand your own consumption, or at least that is what is promised. It does take some study and diligence to apply the data.

I will be out of the house for the afternoon so electrically there should be almost nothing going on during B. There are two peaks I have labeled G! What happened?

What happened is that I came home and opened and then closed both garage doors about an hour apart. G are the garage door motors. Although the spikes reach almost a kilowatt, they don't last long and don't happen often so their contribution to my total is small. Unlike the water heater which persists for minutes once it starts, even though no hot water has been used for hours!

The house starts really using electricity at 18:00. The timers are set for 18:05. The huge peak W is the water heater. There are three W peaks in the recording. The water heater uses a steady 3kW for about 7-15 minutes and comes on usually every six hours or so. The first W, the one after 18:00 has the toaster oven added. The toaster oven uses about a kW and it pulses ON-OFF-ON every few minutes to regulate the temperature. That is the thick blue band on the top of the water heater peak.

At about 22:00 I started the dishwasher. The second W peak occurs just after that, about 22:30. I have learned that stating the dishwasher will almost certainly cause the hot water heater to come on.

The third W peak occurs the next morning about 6:00.

C is overnight. The computers are off and there is only a couple of LED lights on. The pattern during this time is the refrigerator and freezer cycling on and off.

D is morning activity and some work out in the shop. Not much going on electrically but what is there is added to the refrigerator and freezer which are part of the background for the whole recording except for the peak period B when they are inhibited from running by the timers.

I think I have a pretty good idea of where my electricity goes. You might see from the recording why I instantly fixed on the water heater as a major user of my electricity.

It is summer now. Winter will add complexity to the recording because of heating requirements and more lighting due to shorter days. Also the basement and the house temperature will fall so the refrigerator and freezer won't be working as hard but the water heater will need to work harder!

Checking my daily electricity use has become easy and part of my normal routine here, like checking the weather and the news.

I am disappointed so far with the PlotWatt software. McMaster FlexPlan advises "The date on which Plotwatt validated your installation was 2016-05-09 and it takes 30 days for Plotwatt to learn your energy consumption in order to produce meaningful results." I am part of the McMaster study, (Ontario MoE funded project). It is now 2016-07-09 (60+ days) yet I see no meaningful additional information from PlotWatt.

Presumably, the study is paying for my PlotWatt access. You can watch the Plotwatt pitch, which seems primarily aimed to businesses rather than households. I have not received even one notification from Plotwatt at two months and counting.

Readers will also notice that when I wanted to calculate the energy use of a particular appliance that I had to resort to drawing rectangles on a screen capture and calculating the area as a series of blocks. This "area-under-the-curve" function ought to be a part of the BlueLine software I think.

The access to a power utility's data by the way comes about through an initiative called GreenButton.

Thanks for your interest.
George Plhak
Lion's Head, Ontario, Canada

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Monday, July 04, 2016

the base load

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For the next test, I have my refrigerator, freezer and water heater temporarily OFF. These are automatic appliances that come on by themselves if I let them. I want my electricity draw to be as little as possible for this next test.

I don't have air conditioning. My heat source is oil which uses electricity for the compressor, ignition and fan. During summer in Canada I do not need heat. When trying to figure out my energy usage, I find it easiest to have as few appliances coming on by themselves so summer is an ideal time for me. I can concentrate on one at a time.

Today I am going to check my base load, sometimes called "phantom power" but that slightly different. Phantom power in the context of house electric energy is energy to "keep alive" an appliance so that it can come on instantly. More correctly would be called phantom energy. In my case, I need the network to be fully running and the Blueline Bridge to be operation, in order to capture my energy data. I don't need to watch it, I just need to have data captured so the computer and the printers and the scanner and the rest can be OFF and the power bars switched OFF to reduce phantom power. I also went around the house and pulled out a few things that use phantom power. The network is part of what I call my base load, which I need running, not stuff I don't want and can unplug. The base load is always there, always costing money, peak or non-peak, even though it is small.

Base load is the same term that the generators of energy (like OPG and Bruce Power) use. It is always there. They worry about the peaks over the base load.

The sun has gone down. I have only a couple of lights ON and those are LEDs. I visited the washroom using a flashlight rather than the usual house lights. I am not running the microwave, the stereo, a TV, the central vac, or any other major appliance.

For the next test, I am trying to be as quiet as a mouse electrically. What is my electrical energy usage with as little major loads as I can manage?

Over 200 watts! 218 to be precise. Rose to 230 watts while I typed this sentence. I have turned OFF the water heater, fridge and freezer off at 9:45. My background was more in the 350 watt region before that.

This is my electricity usage for the last six hours. The most noticable thing is the spike from the water heater coming on as it should at 6:05pm. As of a couple days ago, my water heater is not allowed to come on (inhibited) during my peak period which is 12:00noon to 6pm.

I was not home during most of this chart. Perhaps just the last 1/2 hour. This is my house doing things on its own. The water heater, the fridge and the freezer, a few lights, a few chargers, two CO2 monitors. All by themselves about 300 watts.

I am typing this one a desktop system, with the network and WIFI running. The Blueline network bridge is relaying my electrical energy information to the cloud. I am connected to the web on machines that eat 110 volts AC from my connection to the grid. Probably my computer and network account for about 150 watts of that, more or less constantly.

And there is a lot of other stuff connected as well. The mobile phone, the microwave oven, a couple of clocks and radios that plug in and are "always on".

I went on a binge and unplugged all of those things about 9:50.

It is shortly going to be 10:15 and I will shut down my computer, but not the network, for (hopefully) 1/2 hour.
This is the result of turning off the compuers and most everything else except for the Blueline bridge and my WIFI and router which are necessary for the Blueline hardware to do it's job.

The small spike just before the shutdown happens because I had to start a second computer from "sleep" in order to shut it down in a true power OFF which included shutting off the power bar which controls some ancillary hard drives and other potential electricity users.

I think I read that as about 50 watts. Not bad to strive for as a minimum during the peak period? Or perhaps even less?

The McMaster study wants to measure changes in behavior with my assigned plan C$0.54 peak/C$0.11 non-peak, no other costs (no delivery cost, debt repayment, etc)

What if my electrical use went to near zero during my peak billing time? This would be worth doing for a 54/11=5:1 ratio in cost! I might be able to achieve that outside of the heating season. A bit of battery backup?

During winter achieving less use will be difficult with the added load of the furnace, water heating (the basement is cooler) and lighting (the nights are longer). Cutbacks in the peak billing period will be more difficult. The base line will probably rise and I will measure it then.

Thanks for your interest.
George Plhak
Lion's Head, Ontario, Canada

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Sunday, July 03, 2016

more TOU and dishwasher continued

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I am doing another run of the dishwasher this morning. The dishwasher and appliances like it (my clothes washer for example) have complicated cycles with several stages. The appliance will draw different amounts of energy depending on the program it is following. This is my software real time monitor showing me that at the beginning of the normal-no-heat cycle, when the dishwasher is heating the water, the my house is drawing 1.7kW.

The actual electricity the dishwasher is using is about 300 watts less than this since there are other "always on" things that use electricity in my house right now. The fridge and freezer are the biggest parts of the background. There are a few lights on and the computer I am typing on, a few charges, some CO2 and smoke detectors, the garage door openers a few radios that even though they are off still draw some "keep awake" power as well the network and the Blueline Innovations whole hose energy monitor itself. The background varies constantly from about 150watts to 300watts. I almost started the toaster oven but stopped since it is a big energy user. I am running this test of the dishwasher and want it to be uncomplicated by other heavy use appliances. The dishwasher is almost done.

The dial on the right in the screen shot shows my total usage for the month. Since it is the beginning of July, that dial has just reset. Briefly it was near zero but now marches forward through the billing month. It does not show peak/off-peak but I can see that elsewhere in the software.

This is the remote readout from Blueline. The pic is taken just a minute or so after the previous one. That's the dishwasher in the background. I suppose the idea of the remote is that you can carry it with you while you are trying out an appliance in another room? There are apps but I haven't loaded one yet.
The bottom part of the display shows me the outside temperature and the date and time? That part is not correct. I don't know yet what the 333kWh "estimate" is yet. I guess I'll have to read the manual? I don't know what the buttons do. Clearly I haven't explored the functionality of the remote.

Another part of the Blueline energy monitor is this sensor unit strapped to my electrical meter. A technician came and installed the meter and set up the software but I suppose it could be DIY. I see that the Blueline hardware is available on for C$110.

Now as far as Time of Use relates to the dishwasher, it is very clear to me that I should be running the dishwasher during off-peak. I am not sure I am going to change my behavior as a result of having this power monitor?

This is this morning's recording of the dishwasher (D) and water heater (W). I have also shown what I consider the background at the left side of the chart.

In an earlier run, I found that the water heater started shortly after the dishwasher. This time, I had resolved to turn off the water heater so that it would not start after the dishwasher. I turned off the water heater at the bereaker panel shortly before 6am. Then I started the dishwasher at shortly after 6am. When I got back the the software, I saw that the water heater had already started and had been running for about 10 minutes before I turned it off.

As I pointed out before, the water heater starts if its internal temperature sensor detects that the water is below the set point. The dishwasher draws hot water and the water heater replaces that with cold water from the water supply. The new water is much cooler than the tank and causes the internal temperature to fall triggering the sensor to call for heat.

It is just a coincidence that my water heater, without any hot water having been drawn from it, chose to come on at about 5:20. Funny thing about a water heater is that unless you have one of these whole house meters, you cannot tell that it is running!

Note that the peaks from the water heater are simple ON-OFF shapes while the dishwasher has a rather more complicated signature. I don't know what the small addition square on top of the second water heater peak is? That might be the fridge or the freezer, which are normally buried in the background, becoming visible on top of the water heater.

Now I am going to calculate the total electrical energy used by the dishwasher during this run. To do that, I have divided the area under the curve into a number of blocks. Knowing that the height of the blocks represents the power (kW) and the width represents the time (h) I should be able to multiply the height times the width of each to find the kWh of wach block then add them up and have the total kWh.

I am having the read the data off a screen capture. I am amazed that the software does not do this for me. It does not even know that this is the dishwasher. Well perhaps Plotwatt will one day figure it out but not yet, so I am calculating the hard way. I will use the millimeter measure of 21.24mm = 1 hour to find the width of each block by comparison using the CorelDraw dimension feature.

Here is the calculations for the blocks:
A 1.4x0.202=0.283kWh
B 0.8x0.056=0.045kWh
C 1.4x0.135=0.189kWh
D 0.25x0.095=0.024kWh
E 0.8x0.083=0.066kWh
(there is a little space
F 0.8x0.036=0.029kWh
G 1.4x0.115=0.161kWh
H 0.25x0.109=0.027kWh
I 0.8x0.78=0.63kWh
Total = 1.454 kWh

This does not include the energy used to heat the water in the water heater, the water that was used during this run. That energy is included in the water heater draw, at least for this run.

So 1.454kWh would cost me during the peak-period (1.454kWh x C$0.54/kWh) = $0.78. During non-peak, my cost would be (1.454 x C$0.11) = $0.16!

A lot of calculation and thinking to show me that the dishwasher does not cost much if run off peak. I don't use it very often, although I did run it three times in three days to get a relatively clean signature. I hope I will be able to use my figure to compare to new dishwashers? I don't think they give the cost per run but per year.

Thanks for your interest,
George Plhak
Lion's Head, Ontario, Canada

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Friday, July 01, 2016

more on time of use electricity

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My whole home energy monitor and software allows me to see what is essentially a strip chart recording of my home's electrical energy use. I can go back in time and zoom in for a couple of months, back to when it was installed. It is summer here so I don't need heat and I don't have air conditioning so my data is relatively simple. I am still learning the software by trying to isolate my appliances, essentially taking pictures of their usage on the chart while I run them.

McMaster tells me that the software is learning about me! It is supposed to provide individualized recommendations as shown in the demo at plotwatt. But I am told that it will take a month or two for it to learn about my usage. I am learning about my usage primarily using the BlueLine software from the maker of the hardware. More about the hardware later.

This is my electricity usage over the last 24 hours. I am showing you a screen capture from the BlueLine software. I have added the black info.

The W peaks are my water heater. How do I know this? I have learned to recognize the water heater from its peak and its timing. The water heater uses 3kW. The vertical axis of the chart at the left is labeled in kW. The water heater senses that its internal temperature has fallen to the set point (which I can vary on the heater) and switches on its heating coils about every six hours for about 10 minutes. If I use hot water, it may come on sooner. If I use a lot of hot water, it may run for longer. It is almost like a clock and it uses a lot of power so it stands out on the chart. Before I installed the inhibit timer, the water heater could end up starting during my peak period. The peak is the rectangle I have drawn on the chart. You can see that the water heater starts when it is allowed to, just after 6pm.

The D on the chart is my dishwasher. Unlike yesterday, I went to the breaker panel and turned off the water heater so that it could not start. Yesterday the water heater came on at the same time, I wanted to run another load of dishes to see the electrical use of the dishwasher alone. More about that test in a moment.

I have also labeled two mystery spikes as ? on the chart. One is during my peak time at about 4:30 and the other is earlier, about 10:30 in the morning. Both are big users but only for a very short time. The first spike is greater than 3kW and the second reaches 4.5kW. I don't think I was even at home when the first one occurred and possibly not when the second happened. I was in and out a fair bit yesterday.

The BlueLine software allows me to click and drag to zoom. When I zoom the second spike, the one during my peak period, I see a single data point that lasts only a minute. This is possibly because the sensor and the BlueLine system takes samples probably about every minute and only that one sample showed this 4.5kW. I have no idea what these are caused by but will continue to watch for them.

This is the dishwasher this morning after turning off the hot water heater breaker. It is a fairly complex looking signature to say the least. I will try to compute the kWh used for one wash cycle and add it below later. So perhaps the no heat dry function works sometimes, sometimes not (intermittent) or I was fooled in my guess about the no heat by the operation of the water heater or another appliance? The BlueLine measures everything connected to my meter. To be sure, I would repeat the exact test again. A good experiment needs careful design and measurement, sometimes repeated measurement..

It occurs to me that having this record of the actual energy use of the appliance will help to evaluate the performance of any replacement appliances. It is the actual energy rather than some computed or implied kwhr per year like on the sticker in the showroom or on the web ratings. The yearly total will depend on how often I use the machine but I cannot change the energy per cycle, per use. For example, if I get a new dishwasher with a more efficient motor or something else that saves energy, I should see the result in the chart.

Speaking of being fooled

The BlueLine sensor which is attached to my electric meter on the outside of the house includes a thermometer to read outside temperature. This is presumably so that the software can know how much heating or cooling might be required. The green line on this chart shows the temperature reaching 40C at about 4-5pm. It was hot that day but no way was it 40C (104F) outside! What is going on?

My electric meter is on the north side of my house, the side that almost never gets direct sunlight, or so I thought. At the red arrow you can see the sliver of sunlight that hits the meter from about 4 to 5pm in the afternoon at this time of year! Just at the time of year that cooling might be important, the sensor gets fooled by some stray sunlight. If it mattered to me, I would add a small screen or panel to block the light from that angle. It would only happen for a short part of the year.

It also occurs to me that today, Canada Day is a holiday so my electrical rates are non-peak all day. The water meter inhibit controller that I added earlier in the week knows about weekends, but it does not know about holidays. So today, being a Friday, my water heater is currently inhibited the same as the other week days, from 12 to 6pm. It doesn't concern me though. I know that the stored water in the tank stays very hot even for six hours after it has last been on.

Thanks for your interest.
George Plhak
Lion's Head, Ontario, Canada

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