Questions about saving electricity in commercial buildings

Your site is mostly geared towards home users. How can we save electricity in our factory?   Crystal Stockton, Glasgow, KY

The main kinds of things that save electricity at home also save money in the factory or office:

1. Use natural lighting where possible (e.g., windows, skylights), and where it's not use T-8 fluorescent lighting.

2. Use ceiling fans where practical so you can raise the AC temperature.

3. Turn off anything that's not being used..

4. Turn off computers and other equipment at night if no shifts are running. If employees can't be counted on to turn off equipment, put them on timers.  This will save not only on the equipment that's turned off, but AC costs will go down because you won't be paying to remove the heat generated by the unused equipment.

5. Don't cool the building too much at night when no shifts are running.  If you thought you needed to keep your computers super-cool, you don't: You'll spend more to keep the equipment cool then it would cost you to replace the equipment a hair sooner than you'd have to replace it otherwise.  The useful life of computers is pretty short, anyway; you'll likely replace your equipment long before it breaks.

For any but the smallest business, it may pay to have an audit performed. You have three choices for audits:

1. Many utility companies provide such audits for free. Call yours to see if they do.
2. Hire a professional. For example, one company in the Dallas area is LPG Energy Consultants.
3. Do it yourself. Check out books like Handbook of Energy Audits and Retrofitting for Energy Conservation.

EnergyStar.gov has calculators which let you compare your business energy use per square foot to other similar businesses, and calculate the savings from installing EnergyStar air conditioning systems. And below is a book review I found which may be helpful.

Update, July & September 2008: I just came across a couple of excellent resources for saving energy in business.

• This massive list of suggestions for reducing energy use of a business on Yahoo Answers.
• This even more comprehensive online book from the Environmental Defense Fund, breathtaking in scope, covering everything from Manufacturing to Fleet Management to Packaging and everything in between.

How many watts does a 480-volt to 208-volt 225KVA transformer use when no load is being pulled (i.e., transformer is powering nothing, just sitting there humming). -- E. Thayer, Wauseon, OH, Dec. 2004

Depends on the transformer. Best bet is to check with the manufacturer.

How much electricity do I save by walking up the stairs vs. taking the elevator up 3 levels? How much extra electricity is used by each additional person in the elevator? -- Philip Maynard, University of California, Berkeley, June 2001

Elevator energy use varies a lot according to many factors:

• The number of people in the elevator (i.e., the weight of the load)
• The capacity of the elevator (regardless of how many people are actually in it)
• Whether the elevator is going up or down
  
• The type of elevator (e.g., hydraulic, regenerative braking, etc.)
  

Then we also have to figure it how much air conditioning energy is used to remove the heat from braking.

One report I found said an elevator in a low-rise building would use 1900 kWh for 100,000 door-openings ("starts").  That would be 19 wH per trip.  Unfortunately we don't know the average number of people in each trip or the number of floors traveled. 

So your question, as you put it, is pretty much unanswerable. It's like asking, "How much gas does my car use?" The answer is going to depend on a lot of factors.

I contacted Otis, the largest elevator manufacturer in the world, to try to get figures for energy use under sample situations (10-person car; 1 floor of travel in each direction; 1, 5, and 10 150-lb people in the car) but they were less then helpful. The person who responded was actually fairly snotty, and insisted that nobody at Otis had information about the electrical use of their products. That's a pretty stupid answer -- you can't design a commercial elevator without figuring how much energy it requires, and obviously Otis engineers made these calculations as part of their design process. But since Otis insists that they're ignorant about their own products, we'll have to look elsewhere.

Search engines aren't much help. I found one page on the National Park Service website which claims that the average office elevator consumes "350 watts" of electricity to travel one floor. But that statement raises more questions than it answers. First of all, is that 350 watts, as they stated, or 350 watt-hours, which is what we expect? I'm guessing watt-hours, but we can't be sure. Their answer also doesn't give the values any of the variables we mentioned above.

Since my initial inquiry to Otis I notice that their New Zealand website has an elevator energy calculator, but it's far from user-friendly. For starters, it assumes that each user takes two trips per day and that each trip equals half of the total number of floors, and you can't change these values. Also, it doesn't give you any clue how many people it assumes are in each car for each trip.

The values I entered were:

• 10-person capacity
• 10 people total in building
• 8 stops
• 1 elevator
• Office building

I couldn't enter in just 1 person in the building because the results given are in kWh per month, and one person alone wouldn't use enough electricity to get any meaningful results.

Based on what I entered, here's what Otis' calculator said:

Unfortunately, without knowing how many people are in the car, we can't know how many trips the elevator took, and we therefore can't calculate the energy used per trip.

I made another inquiry to Otis but not surprisingly I haven't heard back from them. They're not especially helpful.

Update: At long last, Otis finally replied to my second inquiry [Robin Fiala, Senior Manager, New Equipment], but this time all they did was send me a marketing brochure that didn't answer any of the questions I asked. I can't say I'm surprised. I then asked if they would actually read my inquiry and respond to it, to which they demanded to know why I wanted the information I was asking for. (They hadn't bothered to follow the link in my message to this page.) I pointed out the link to this page to explain why I'm looking for the information, but after my previous experience with Otis I'm not holding my breath.