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The Wasteful Door Unlocker Analysis

| Monday March 20th, 2006 | 1 Comment


This post is partly for the sake of amusement, but may have some useful points. Last night at an event, my collegue Pablo noticed that the locking mechanisms on the door were hot to the touch. Quite Hot. It turns out that the lock had a constant stream of electricity flowing through it in order to keep it engaged. In the event of a fire (or presumably a power outage) the door would lose its charge and unlock. But for the most part it just sits there heating up and wasting electricity. So we sat down and decided to figure out just how wasteful it was (I’ll withold the brand name). Here’s Pablo’s analysis:
The unit uses 8W 24hours day. kWh/year = .008kWh/h x 8760h =70.8kWh
Which, at $0.13/kWh: 70.8kWh x $0.13/kWh = $9.204/year per door

Nine bucks a year is pretty trivial, and surprisingly low given the heat coming off this thing, but it was a useful little exercise in noticing and analysing inefficiencies! Find enough 9 dollar items and you’ll eventually save a fortune.

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  • Simon

    An Australian inventor has developed a system that uses compressed air for security windows and doors that does the same thing but once the air pressure to lock the door is established the compressor switches off saving power.