hmm... except that they're hooded and under the eaves of the roof (I'm familiar with the Dark Sky Association... my father in law is an astronomer). Also by separating the sensors from the lights I can use achieve better sensor coverage using fewer lights. Good points however.
First off, I have to say I agree with the original poster... I too tried to use the Zenith stuff from Home Depot when replacing lights for a friend and the stuff simply doesn't work. Pretty disappointing since there isn't much to this stuff. When I started looking into doing lights for my home I also looked at the X10 stuff but finally decided to build my own infrastructure. Not that there is anything wrong with the X10 stuff... it's affordable, easy to use, and has lots of software support. However, I'm building some custom home automation stuff anyways (such as asterisk integration and a cross platform graphical data-flow language for microcontrollers so you can embed control logic onto a cheap controller board instead of using a dedicated pc without needing to know how to write code) so I figured I'd customize the motion stuff as well. I found some GE motion sensors for about $10 that work great (and actually come with docs covering sensetivity, range, effective angles, etc... which you don't normally get in a packaged unit). I modified them a bit to add tamper detection but otherwise they work great out of the box. These feed back into a controller board which can also control the flood lights (which are just standard floods controlled by relays). And yes, I'm sure all this can be done with X10, I just prefer to build my own stuff (http://www.kondra.com/circuit/circuit.html).
Thanks for the feedback!... always nice to hear...
I wish I had access to some of the systems to poke around a bit but I don't. This system is now installed at several locations... several colo's and several corporate data centers. It's sort of interesting to see the difference in usage patterns between the two however. In the corporate data centers, it's very commonly used for capacity tracking. For example, you might have 200amp service to a panel with 42 breakers in it. Each breaker is rated at 20amps. In this case you can overload the panel (or a phase) before you run out of breakers depending on what you've got plugged in. In one case, the customer kept a clamp-on meter in the data center and before they plugged in a new server, they checked each circuit for the lowest load as they had pretty much maxed out their service.
I've been kicking around ideas for integrating thermal and AC monitoring into the same platform. As planned, it would let you track energy hot spots vs. thermal hot spots which is really much more valuable. For example, say you monitor the temp in two cabinets. If the temp in one is 30deg more than the other, you would naturally figure you found a hot spot. However, this isn't necessarily true. If the hotter cabinet is dissapating a lot more energy then it will naturally be hotter, so once you normalize the temperature using the input energy, you might find that the cooler cabinet is actually a hot spot. Of course no one really talks about this because no one can monitor the energy going into all those cabinets (well, there are a few options, but for the most part they're not usable because they lack useful software). Next, tie in the power consumed by the AC (adjusting for power factor and efficiency, etc...) and you can pretty much close the loop on the entire data center. Once you do this properly, you would have much better control over energy... after all, all that heat that everyone is trying to optimize the cost of eliminating is really just a by-product of energy so if you can better manage energy, you have a better handle on heat (either by reducing energy, or by improving the dissipation efficiency).
At any rate, we scoped this all out a while back, including nifty real-time thermal and energy overlays, etc... but like I mentioned, it's not my product so these types of features wait until someone wants to pay for them.
I built a data center power monitoring system about a year and a half ago for exaclty this purpose (I installed it in my house and posted a writeup to slashdot... the article is now here). This system monitors every branch circuit in the data center and allows you to assign circuits to customers so you can track usage by customer. The first data center it was installed in was a colocation facility and their intention was to start billing for power like they do bandwidth. That is, you purchase power in 5amp blocks and when you spike, you pay for another 5amp block, etc... the thought being that if customers start having to pay for power, they will optimize it just like any other expense.
To this end, the system was designed to let customers login to their accounts and see their power usage (with one minute resolution for a year... the gui is a java applet with real-time graphs, etc..) as well as set alarm thresholds, notifications, etc. The customer I built this product for recently completed a new data board that gathers meter grade current, voltage, watts, power factor, and kwh readings so all this history is now available to the user (and colo). There are independent threshold alarms sets for both customer and admin across all data sets, including panel level, per-phase rollups, etc.. (which amounts to almost 1400 alarm points for an 84 circuit panel).
The folks that use the system have told me it's actually almost more useful for capacity planning and load balancing given the increasing power density of customer cabinets these days.
*disclaimer*:: While I built the system, I don't own it, sell it, or work for the company that does. Anyone looking for more info should visit TrendPoint Systems.
Great discussion! I am of course limited by the capabilities of the board and the board I'm using doesn't provide voltage so I actually pull that in through a different feed (not documented in the article) and compute some of the data in software (with some of the previously discussed limitations). The guys at TrendPoint Systems (the company I wrote the software for) are building their own board that has all of this integrated (including power factor, instantaneous kwh, etc.) The software was designed to have these real feeds available so it will be nice to be able to use them.
As has been pointed out, things 'happen' to work well because most stuff in a house has unity power factor (at least by percentage of total consumption in my case).
Syukton, you make an excellent point. The other thing to think about is all the heat generated by that electricity. I live in a small house with no AC (except for the servers in the attic) and in a warm climate. While electricity consumption can be viewed as simply an economic cost you're willing to bear (ie. you cut back when it costs too much), another impact (which I notice more on a day to day level) is the discomfort caused by the additional heat build up. In this sense it's really handy to know where in the house that electricity is being dissipated.
I see what you're asking... good question. There are two reasons for this:
1. The interface is a java applet launched from a web browser. It is commonly used over home dsl + vpn for network administrators to remotely monitor data centers, etc... so we made an effort to minimize the network payload associated with opening multiple concurrent graphs. By fixing the number of data points in a view (regardless of pixel resolution) we can greatly control the network overhead (which is good since they all update in real time).
2. I've been building stuff like this for a while and more often than not the users get confused by the apparent 'fuzziness' of a full dataset graph. Not that this is my preference, just a common thing we run into. Which is fine since it makes the first problem easier to solve but obviously results in some intersting visual artifacts (which no one ever seems to complain about).
Normally I stay out of these but the article had a typo so I'll clarify. It was actually the washing machine not the dryer that failed. In addition the motor had failed several times before (thermal shutdown) prior to installing the monitoring system. The repair guy I kept calling out said it was fine (since by the time he got there it had cooled and started again). Anyways, the last time it didn't start back up.
I've often wondered how hard it would be to determine which devices in your house were turned on based on the overall circuit data. Certain types of devices have very unique signatures (fridge, dryer, etc...) It would be neat to be able to 'guess' which device is on or off (or failed as you point out) based on analyzing the raw data.
As you can see it's very easy to find this within the data. As you can see from the image I've used cursors to determine the frequency of the compressor cycles. If you look at the cycles over a day however you can see them compress and expand based on the outside temperature.
I suppose this would lead to the next level which is to pre-cool in the morning when cycles aren't so long and electricity is cheaper (depending on where you live) and run less during the day. Overall I would guess that you could save additional energy (certianly extra money) if you could control stuff like this.
Thanks for letting me know... Someone out there should write an article about what it's like to get slashdotted... I know I didn't know what to expect. I had to do a bit of live editing of the site to push things through Coral Cache because things were bogging down. This link had a typo (but it's fixed... thanks again).
I noticed that the graphs shown in the article don't even have a 1 minute resolution; for some reason they are limited to a 4 minute resolution. Seems silly to have such fine measurement resolution and throw it away in the graphs.
Yeah, I didn't really explain that since I didn't want to bog down too much in the software description. The circuit view has two graphs... the one on the top represents the data in the dark grey section of the bottom graph. This makes it easier to navigate (by dragging the grey area) and not have to zoom in and out all the time. The magifying glass buttons are for zooming in and out (which obviously changes the resolution of the view). However, as I think someone else guessed correctly, the data is sampled every 3 seconds and then min/max/mean is rolled up for that minute and stored for a year. All the graphs are derived from this data (although obviously there are other rollup tables for performance reasons as you get to viewing months at a time). The view in the screenshot is not zoomed in completely.
Slashdot Mirror
hmm... except that they're hooded and under the eaves of the roof (I'm familiar with the Dark Sky Association... my father in law is an astronomer). Also by separating the sensors from the lights I can use achieve better sensor coverage using fewer lights. Good points however.
First off, I have to say I agree with the original poster... I too tried to use the Zenith stuff from Home Depot when replacing lights for a friend and the stuff simply doesn't work. Pretty disappointing since there isn't much to this stuff. When I started looking into doing lights for my home I also looked at the X10 stuff but finally decided to build my own infrastructure. Not that there is anything wrong with the X10 stuff... it's affordable, easy to use, and has lots of software support. However, I'm building some custom home automation stuff anyways (such as asterisk integration and a cross platform graphical data-flow language for microcontrollers so you can embed control logic onto a cheap controller board instead of using a dedicated pc without needing to know how to write code) so I figured I'd customize the motion stuff as well. I found some GE motion sensors for about $10 that work great (and actually come with docs covering sensetivity, range, effective angles, etc... which you don't normally get in a packaged unit). I modified them a bit to add tamper detection but otherwise they work great out of the box. These feed back into a controller board which can also control the flood lights (which are just standard floods controlled by relays). And yes, I'm sure all this can be done with X10, I just prefer to build my own stuff (http://www.kondra.com/circuit/circuit.html).
Thanks for the feedback!... always nice to hear...
I wish I had access to some of the systems to poke around a bit but I don't. This system is now installed at several locations... several colo's and several corporate data centers. It's sort of interesting to see the difference in usage patterns between the two however. In the corporate data centers, it's very commonly used for capacity tracking. For example, you might have 200amp service to a panel with 42 breakers in it. Each breaker is rated at 20amps. In this case you can overload the panel (or a phase) before you run out of breakers depending on what you've got plugged in. In one case, the customer kept a clamp-on meter in the data center and before they plugged in a new server, they checked each circuit for the lowest load as they had pretty much maxed out their service.
I've been kicking around ideas for integrating thermal and AC monitoring into the same platform. As planned, it would let you track energy hot spots vs. thermal hot spots which is really much more valuable. For example, say you monitor the temp in two cabinets. If the temp in one is 30deg more than the other, you would naturally figure you found a hot spot. However, this isn't necessarily true. If the hotter cabinet is dissapating a lot more energy then it will naturally be hotter, so once you normalize the temperature using the input energy, you might find that the cooler cabinet is actually a hot spot. Of course no one really talks about this because no one can monitor the energy going into all those cabinets (well, there are a few options, but for the most part they're not usable because they lack useful software). Next, tie in the power consumed by the AC (adjusting for power factor and efficiency, etc...) and you can pretty much close the loop on the entire data center. Once you do this properly, you would have much better control over energy... after all, all that heat that everyone is trying to optimize the cost of eliminating is really just a by-product of energy so if you can better manage energy, you have a better handle on heat (either by reducing energy, or by improving the dissipation efficiency).
At any rate, we scoped this all out a while back, including nifty real-time thermal and energy overlays, etc... but like I mentioned, it's not my product so these types of features wait until someone wants to pay for them.
I built a data center power monitoring system about a year and a half ago for exaclty this purpose (I installed it in my house and posted a writeup to slashdot... the article is now here). This system monitors every branch circuit in the data center and allows you to assign circuits to customers so you can track usage by customer. The first data center it was installed in was a colocation facility and their intention was to start billing for power like they do bandwidth. That is, you purchase power in 5amp blocks and when you spike, you pay for another 5amp block, etc... the thought being that if customers start having to pay for power, they will optimize it just like any other expense.
:: While I built the system, I don't own it, sell it, or work for the company that does. Anyone looking for more info should visit TrendPoint Systems.
To this end, the system was designed to let customers login to their accounts and see their power usage (with one minute resolution for a year... the gui is a java applet with real-time graphs, etc..) as well as set alarm thresholds, notifications, etc. The customer I built this product for recently completed a new data board that gathers meter grade current, voltage, watts, power factor, and kwh readings so all this history is now available to the user (and colo). There are independent threshold alarms sets for both customer and admin across all data sets, including panel level, per-phase rollups, etc.. (which amounts to almost 1400 alarm points for an 84 circuit panel).
The folks that use the system have told me it's actually almost more useful for capacity planning and load balancing given the increasing power density of customer cabinets these days.
*disclaimer*
As has been pointed out, things 'happen' to work well because most stuff in a house has unity power factor (at least by percentage of total consumption in my case).
Syukton, you make an excellent point. The other thing to think about is all the heat generated by that electricity. I live in a small house with no AC (except for the servers in the attic) and in a warm climate. While electricity consumption can be viewed as simply an economic cost you're willing to bear (ie. you cut back when it costs too much), another impact (which I notice more on a day to day level) is the discomfort caused by the additional heat build up. In this sense it's really handy to know where in the house that electricity is being dissipated.
1. The interface is a java applet launched from a web browser. It is commonly used over home dsl + vpn for network administrators to remotely monitor data centers, etc... so we made an effort to minimize the network payload associated with opening multiple concurrent graphs. By fixing the number of data points in a view (regardless of pixel resolution) we can greatly control the network overhead (which is good since they all update in real time).
2. I've been building stuff like this for a while and more often than not the users get confused by the apparent 'fuzziness' of a full dataset graph. Not that this is my preference, just a common thing we run into. Which is fine since it makes the first problem easier to solve but obviously results in some intersting visual artifacts (which no one ever seems to complain about).
Normally I stay out of these but the article had a typo so I'll clarify. It was actually the washing machine not the dryer that failed. In addition the motor had failed several times before (thermal shutdown) prior to installing the monitoring system. The repair guy I kept calling out said it was fine (since by the time he got there it had cooled and started again). Anyways, the last time it didn't start back up.
Here is a shot of my fridge: http://209.10.40.245/circuit/fridge.jpg
As you can see it's very easy to find this within the data. As you can see from the image I've used cursors to determine the frequency of the compressor cycles. If you look at the cycles over a day however you can see them compress and expand based on the outside temperature.
I suppose this would lead to the next level which is to pre-cool in the morning when cycles aren't so long and electricity is cheaper (depending on where you live) and run less during the day. Overall I would guess that you could save additional energy (certianly extra money) if you could control stuff like this.
Thanks for letting me know... Someone out there should write an article about what it's like to get slashdotted... I know I didn't know what to expect. I had to do a bit of live editing of the site to push things through Coral Cache because things were bogging down. This link had a typo (but it's fixed... thanks again).
Here is a screenshot for the last few hours: http://209.10.40.245/circuit/status.jpg