Image Credit: LiftMaster
More Musings of an Energy Nerd
If your home has a garage, there is a good chance that you have an automatic garage door opener. Because these electrical appliances operate for only a few minutes per day, they don’t use much electricity to open and close your garage door. But there’s a catch: most garage door openers use three to five times more energy during the 1,437 minutes per day when they are “off” than they do during the 3 minutes per day when they are on.
Like any appliance that has a remote control, a garage door opener is always on. Even when it isn’t operating, it is warm and humming, listening for the radio signal that will tell the machine to spring into action. This type of electrical draw is called a “phantom load.”
Back in the 1950s, electrical appliances didn’t have phantom loads. When you turned them off — by flipping a toggle switch or knob that made a satisfying click — they were really off. Since then, however, appliance manufacturers have gotten sneaky. Even though the switch position may be marked “off,” the appliance is still warm. The only way to really turn it off is to pull the plug out of the wall.
Appliances with phantom loads include anything with a remote control, as well as any appliance that has a clock display or glowing LEDs. Appliances with phantom loads include a few obvious candidates, like set-top cable boxes, and several less obvious ones, like some washing machines and kitchen ranges.
In 2002, Mark Pierce, an energy expert at Cornell University, estimated that phantom loads cost the average U.S. household $200 per year. Other estimates are much lower, ranging from 329 to 569 kWh (about $40 to $70) per year. According to a web page on phantom loads maintained by the…
Weekly Newsletter
Get building science and energy efficiency advice, plus special offers, in your inbox.
This article is only available to GBA Prime Members
Sign up for a free trial and get instant access to this article as well as GBA’s complete library of premium articles and construction details.
Start Free TrialAlready a member? Log in
20 Comments
LiftMaster 3595
We have the LiftMaster 3595 (3/4 HP) and it draws 3W.
On a related note, you know you're an energy-efficiency geek when you leap out of your chair and hunt for your Kill-a-Watt to measure the phantom load of your garage door opener, all before breakfast.
Response to Andrea Lemon and Eric Sandeen
Andrea and Eric,
Thanks to both of you for sharing your Kill-a-Watt readings. What a great community of geeks and nerds.
New garage door opener
Maybe not the cheapest, but no phantom loads.
https://www.youtube.com/watch?v=UJwN4QYcs7c
My "three little pigs"
I'm pleased to see this category of phantoms given some attention as well as being able to provide useful data for discussion.
Kudos to Ron Brogle and Liftmaster for contributing to this discussion and offering products that address the problem. All my home energy audit reports contain information about phantom loads. I will add specific advice about garage door openers. My own trio comprise about 25% of my total phantom load, an outsized chunk given the total number of phantoms 5 fully wired people have in our home.
Moving on to other phantoms - I have refused to activate our doorbell's transformer. I'm tempted to order and post a placard reading "knock, remove headgear, wait for permission to enter", but I doubt I'd be allowed that.
We have a dozen or so smoke alarms, some with CO sensors, scattered throughout all 4 levels of our home. I went well past code on those. All share a 14/3 Romex cable arranged in a great loop and powered by a dedicated circuit breaker. It is on my to do list to measure that circuit's load. I learned the hard way that if the breaker is inadvertently off or tripped for a month or so, the smokes start eating pricey 9 Volt alkaline batteries by the bucketload. The buggers seem to be time aware, since they inevitably start their low battery chirping at around 2 AM.
Some 24/7 loads are arguably not strictly phantoms - we cherish always-on high speed internet, so that gear stays powered 24/7. A recent addition is a mobile phone WiFi extender to mitigate perennially weak mobile phone signals within our steel reinforced ICF house, something of a Faraday Cage. Similarly, the trickle charger for the standby genny's cranking battery, measured at 5-7 Watts, is a small but critical bit of infrastructure in our rural, storm-prone area.
Response to David Martin
David,
Q. "For someone who had to have a garage door opener, why couldn't they come up with a switch in the drive that opened the door when you ran over it with your car, eliminating the need for the radio signal?"
A. They used to have rubber hoses on the asphalt at the old service stations, hooked up to a doorbell, so the attendant could come running out to wash your windshield. But you never see those guys any more. The main reason you suggestion isn't used -- in addition to the cost-effectiveness issue -- is security. You don't want the door to open for strangers.
My article quoted the LBNL estimate that “5-10% of residential electricity use in most developed countries.” Other estimates, as you note, as significantly higher; the LBNL website notes that this category of electrical use appears to be rising.
UK Study - "Powering the Nation"
Thanks for the article, Martin. I didn't think about my garage door opener. I've got a two car garage, but I usually park under the carport. I use one garage door occasionally, the other never. I'll definitely unplug the one I never use. I might just unplug them both. They're not that heavy to lift by hand. I need the exercise anyway.
For someone who had to have a garage door opener, why couldn't they come up with a switch in the drive that opened the door when you ran over it with your car, eliminating the need for the radio signal? Not cost effective, eh?
Phantom loads--
I wonder what the US estimates is its total phantom load consumption for households, if there is such an estimate. Brian Keane, of the energy efficiency think tank SmartPower, was quoted in a USNWR article in 2009 as saying it is between 5 and 10% of total consumption.
The UK's Energy Saving Trust conducted a detailed study of home energy consumption, titled "Powering the Nation", which concluded the actual phantom load problem of 9-15% is about twice the previous estimate of 5-10%.
TV watching --
I wonder how often the TV is on with no one watching it, which is much worse than a phantom load. That used to be common in my large family as a kid.
The study found that TV's were on about 6 hours per day. The previous estimate was 5 hours. I knew that flat screen plasma's use a lot more energy than LCD's, but it was a surprise to find out that they both consume more energy than older CRT's. In kWh per year,
CRT 118
LCD 199
Plasma 658
Single person households--
Another troubling finding had to do with single person households, which were 29% in 2010 of all households in the UK, and increasing. The study found that for cooking and laundry, lone dwellers consumption was equal to or greater than that for families.
There's a lot of interesting points in the report. There's a link to 2 hour presentation on the website.
I wonder if similar findings would come up if such a study was conducted here.
http://www.energysavingtrust.org.uk/Organisations/Working-with-Energy-Saving-Trust/The-Foundation/Our-pioneering-research
I love you guys
It's so nice to know there are other geeks who measure garage door idle power. ;) Back in 2010 I measured my LiftMaster (sorry, not sure which model) at 3W as well.
On a related note, my doorbell transformer also measured at 3W. Here's one guy's solution to that problem; I haven't done this yet.
LBL's Home Energy Saver web tool accounts for both of these and more on their other appliances input form...
Hoses & doorbells
The hose idea for the garage door wouldn't be bad if it could simply engage power to the garage door when you run over it, and then require the normal remote to operate the door. But then you'd have a standby circuit waiting for the signal from the hose!
I did think about putting the garage door opener on a heavy-duty rotary timer. On the off chance that I need to get into the garage at 3am there is always the key lock & manual cable to take it off the opener track.
Regarding doorbells, I looked at prices for 16V toroidal transformers for a doorbell retrofit. They aren't terribly expensive, I found one for about $11 retail. If LiftMaster was receptive to phantom-elimination efforts, I wonder if NuTone might do the same, offering more efficient doorbell transformers?
3W always on at $0.10/kW is about $2.50/year. So $10 extra for a toroidal transformer would pay back in 4 years...
Or maybe we should just go back to the manual/twist doorbells which are actually bells!
Response to Eric Sandeen
Eric,
My off-grid house runs on 12 volts DC, so my doorbell is an inexpensive $4 buzzer from Radio Shack, wired to a push-button (momentary) switch at the door. No phantom load.
I find it handy / easy to show / remember...
...that every Watt of phantom / standby / 24/7 usage costs about a buck per year. Obviously that varies with electricity rates, but at the national average it is pretty close, and a real handy way to explain. A Watt doesn't sound like much, but most folks would rather not part with any more dollars than they have to.
Is it really worth 30 minutes labor at minimum wage just to power a conventional doorbell? Why not just knock?
Confused
Another great article, Martin. I too immediately dug out my Kill-a-Watt meter and plugged it in to my garage door opener. I also hadn't thought about measuring it. We have a pretty old Stanley 1/2 hp opener and I thought I would have very high standby power readings. This is what I came up with.
Standby: 0 watts
Operating: around 490 watts
Closed with the lights on: 175 watts, I have (2) 100 watt light bulbs in it. (not good, I know) :)
After 8.5 hours of sitting idle the total KWh reading was 0.00
Is the standby power so low that it doesn't register with the Kill-a-Watt? It has a remote so it must use some power all the time, right?
About confusion on Kill-a-Watt readings
Todd. The Kill-a-Watt meter is a very good tool, and accurate to 0.2% plus or minus 1 Watt. This means at the bottom end of its range it can be off by about 5 Watts. When I need very low Watt measurements I use an old electro-mechanical power meter, and loop the current sense wire through the current transformer ten times, then divide the reading by ten.
Does it make sense to not have a garage door opener
Unless you drive a Prius, Volt, or similar vehicle with low idle energy use (not zero energy use because you probably are running lights, heater or air conditioner, sound system, vehicle information systems, etc. off a battery even though there is not a gasoline engine idling), there is increased vehicle idling time plus and additional stop and acceleration if you stop, get out of your car, open the door and get back into your car.
I know, you could shut off the engine before you get out of the car, but, realistically, how many people actually do this. For the real people who will let their cars idle, I will assume one minute if idle per door opening or closing for 500 trips (one opening and one closing) per year or about 1.36 trips per day. Many different rates of fuel consumption are given for a car idling, but 1/4 gallon per hour seems to be in the ball park. This means that a little over 4 gallons of gasoline are will be burned waiting for the driver to open or close the door. Convert the gasoline to kwh gives 137.5, or a little more than Curt Kindler's phantom load. With this, I have not counted the little tap on the accelerator to get the car moving again to pull into the garage or get it back up to speed coming out.
This tells me that getting an energy efficient door operator has a real payoff, but eliminating the door operator won't save energy, it may actually cost energy, but certainly will sour your mood when you get out in the pouring rain to open the door.
That's an excellent point about external costs
However, the "we-can-only-save-the-planet-by-collectively-shivering-naked-dirty-hungry-and-in-the-dark" crowd will insist we all need to forgo the garage altogether, as well as the car.
Response to Kurt Hanushek
Kurt,
I loved your calculation of the amount of gasoline required to keep a car idling while the driver steps out of the car to open the garage door. You make an excellent point.
Small quibble: I bet the average driver could open a garage door in less than a minute. But we'd have to run some tests to see.
Thanks!
How about .03
A few years ago at the NAHB Green Building Conference, I came across an opener that at the time seemed the best yet in terms of energy efficiency. The Marantec Eco Series claims a power consumption of .03 watts in standby mode. That so far is the best I have seen.
Response to Daimon Doyle
Daimon,
Thanks for the information. That is a great spec.
Automatic Garage Door Opener
Is that Garage Door opener can be operated using smartphone application . Can I know the facilities are there?
Calculations way, way off?
Hi all,
I know this is an ancient post and I sincerely apologize for bringing it back from the dead, but I am currently researching this very topic for a building I'm building and am interested in getting accurate information.
In the body of the article, Martin describes GBA reader Curt Kinder calculating the phantom draw of his 3 garage door openers at 5 kWh/day, which is an eye-poppingly huge amount.
He then, however, describes the measured phantom draw of those three units at 14.5W apiece.
I'm no mathematician, but 14.5W per unit x 3 units x 24 hours per day is 1044 Wh... or 1 kWh. Not 5 kWh.
What's wrong here?
Response to Chris Conti
Chris,
The table in this article accurately reports that one of Curt Kinder's garage door openers uses 127 kWh per year. That amounts to 348 watt-hours per day (if you divide 127 kWh by 365 days per year). So three such garage door openers use 1,044 watt-hours per day. Your numbers and my numbers agree.
The 5 kWh per day is Curt Kinder's report of the total electricity used at his house for phantom (standby) electrical loads. His garage door openers only account for about 20% of these phantom loads -- the rest of the loads are from doorbell transformers, cable boxes, security system electronics, wall cubes for electrical gadgets, and other standby loads.
Log in or become a member to post a comment.
Sign up Log in