Saving energy in the office

Start by figuring out where the energy is going

A few years back I decided saving energy in the office was one way to have a bigger impact than just cutting my home energy use - especially since I share my office with about 2,500 other people! I did an energy assessment for the building where I work. Nobody asked me to do it - I was just curious. How much electricity could 2,500 people working in the IT industry really use in a typical day? And how would understanding that usage help with saving energy in the office?

What I discovered was pretty surprising, at least when compared to how much electricity my family uses at home. A huge amount of energy goes into running computers 24x7, keeping thousands of lights on during business hours (and some of them during off hours), keeping the building cool during warm weather, and keeping people's food cold in kitchenettes and coffee shops.

Figuring out where energy is used is the first step in any successful conservation effort. In the case of saving energy in the office, getting numbers on actual consumption can be tough. I called several people including the building managers, the corporate manager for environmental affairs, the local utility, and others, and nobody could tell me how much electricity the building consumed overall - it was apparently confidential information, although one wonders why anyone would want to keep this information confidential.

But it's not that hard to do a rough calculation for the power consumption of your office. From there, it's easy to sell saving energy in the office as something everyone can get on board with, something that will have a big impact on energy use and greenhouse gas emissions for a team working together. Saving energy in the office can be an empowering experience, if done right. It can be a waste of time, if bureaucracy gets in your way.

Where are the big energy hogs?

I assessed the following areas to understand how saving energy in the office might unfold:

It turns out that lighting was the biggest energy user by far. PC usage added up to a fair bit, and when combined with server use it potentially comes as a close second to lighting. Heat load energy use is pretty hard to assess without getting hard data from the building engineers (again, that's 'confidential' data), but it's worth discussing. And for food refrigeration there were a few obvious improvements we could make, although it didn't amount to nearly as much as the other main energy users.

Why are all these lights on?

I started my office energy use assessment with an investigation of lighting. Most office buildings are lit with fluorescent lighting, which has the advantage of being much more efficient than standard incandescent lighting or halogen lighting. Our office has a reputation for being one of the greenest large office buildings in the area, so it wasn't surprising to find that most of the overhead lighting in corridors consists of compact fluorescent light bulbs. Not only that, shortly after the building was erected, someone must have decided that we didn't need that much light, because each pot light contained two CFL fixtures but only one actual bulb. That's not so bad - these bulbs are 13 watts a piece.

 Our building consists of 14 'pods' seating about 180 people each. In each pod there are roughly of these corridor 80 light bulbs. They are on all the time during business hours. Here's where the first bit of math helps us figure out energy usage for lighting: 13 watts x 80 bulbs x 14 pods = 14.56 kilowatts of electricity draw, which means about 15 kilowatt hours of consumption per hour. The lights are all on from 7am until 7pm; during off-hours half of them go off automatically, which means the building uses (15 x 12) + (7 x 12) kWh per day for these lights alone, or 264 kWh per day. That means those lights alone use as much in a single day as my family uses in an entire month!

There are lots of other corridor lights - 4-foot fluorescent tubes, four to a fixture, in the minor corridors, adding up to an additional 160 watts per fixture times 60 fixtures per pod, or another 130 kilowatt hours. These are turned off overnight, so they consume 1,600 kilowatt hours of electricity per day. Finally, there are meeting room lights (often negligently left on after a meeting ends), and lights at individual cubicles. All these lights are 'energy efficient', but leaving them on when no one is around is not efficient so much of that efficient light is just wasted.

It's not hard to see some serious opportunities for saving energy in the office when you look at all the lights that are needlessly left on. Turning off the second bank of overhead pot lights in just one pod (in other words, turning off 40 lights of 13 watts each) at the start of an 8 hour business day saves about 4 kilowatt hours a day - a full half of what my family uses in a typical day. So here's a first tip for saving energy in the office: look all over the place for light switches, and try them out. It turns out that at the entrance to every pod in our building, there's a switch that turns off one of the two banks of corridor pot lights. In my first years working in that building, I used to make a point of walking through every pod once a day and flicking off the second bank of lights; doing that (and assuming those lights stayed off for 8 hours) winds up saving energy in the office to the tune of 58 kilowatt hours per day. Doing that just one day a week works out to 2800 kilowatt hours of electricity savings per year - not much less than what our household of four consumes in a year. So by one simple action (about 10 minutes of walking from pod to pod, one morning a week) I could save more electricity than my entire home consumes. Not that I save any money doing it, but it does help wipe out my contributions to climate change. (But of course, I already buy green electricity for my home!)

For meeting rooms, I made myself a rule that I would never walk past an empty meeting room with its lights left on, without turning the lights off. Sometimes when you're rushing to a meeting or need to catch the bus home, it's tempting to walk past one of these rooms, but I decided, in a century when climate change will probably be the biggest challenge we face, that I should always make time to turn off lights. In an average day I probably turn off half a dozen individual room lights, which can add up to several hundred watts of consumption.

Finally, when I'm one of the last people leaving the building in the evening, I'll do my bit for saving energy in the office by doing a sweep of the pod I work in, turning off any desk or cubicle lights of people who have gone home for the day, along with PC monitors left on. It amazes me that some people can leave work without thinking to turn off their work lights. But then it amazes many of my co-workers that I care enough to turn a light off when I leave a meeting room!

PC energy usage

You can measure the energy use of a personal computer fairly easily with a simple, inexpensive device called a Kill A Watt meter. Most of my colleagues have laptop computers, and most of these are left plugged in all the time while they're at their desks. I used my Kill A Watt meter to get a wattage reading on several brands and models of laptops, and discovered that the laptops we use typically consume between 15 and 40 watts when plugged in, with some consuming that much even when fully charged. About 10% of my colleagues have desktop computers in place of laptops; these can use up to 200 watts of electricity when the monitor is turned on. Multiply 2,200 workers by an average of 25 watts of plugged in time, times 4 hours a day (I'm assuming they spend two hours unplugged because they're in meetings some of the time, and that for another 2 hours the laptops aren't charging), and you get 220 kilowatt hours a day to run their laptops, and another 400 kilowatt hours for the 250 desktop units.

There's not that much you can do about laptop energy usage, although tips like using a simple, non-animated screen saver, and using the power options on your laptop to reduce energy usage, will help somewhat. The key thing you can do to help saving energy in the office with your computer, is to suspend or hibernate it when it's not in use. We have a laptops-closed policy for meetings in our area (after dealing with years of very inefficient meetings where everyone worked on their laptops through meetings, so no one participated), and as a result, it makes sense to put your laptop in standby during meetings.

For desktops, hibernating or shutting down the computer at the end of the work day makes a big difference. People who leave a computer on from 5pm one evening to 9am the next morning are using 16 hours times 250 watts of electricity, or 4 kilowatt hours, just while the computer is sitting there doing nothing. The 10% of my colleagues who have a desktop computer on are using about 250 x 4 kilowatt hours of electricity per evening, or 1 megawatt hour of electricity per night (in total as a group).

I took a crack at estimating server energy usage, but it turns out that there isn't much the company can do to turn off servers (they're there to serve, after all). In fact, because servers use so much energy, most companies these days tend to factor in "total cost of ownership" when deciding when to upgrade a server and what kind of replacement to buy. That means they factor in both the energy costs and the sticker price, and when they calculate the energy costs, they include not just the energy used by the computer, but the energy used to keep the machine rooms cool (since servers, or any large collection of computers, produce a lot of heat). As a result, there wasn't really that much an individual could do as far as saving energy in the office by cutting down on server consumption, other than not to run unnecessary large jobs on a server, since the more work a computer does, the more heat it produces and the more energy it takes to run it and to cool it.

Heat load energy use

This brings us to the third way I found of saving energy in the office: cutting down on the heat load. There are three things that contribute to heat load in most offices:

  1. Sunlight and radiant heat coming in through windows, at least when the air conditioning is running. (In the winter, sunlight coming through the windows is a good thing.)
  2. Heat from computers, as mentioned above. The more computers are left on, the more heat they produce that needs to be removed from the building.
  3. Heat from lights. Fluorescent lights produce little heat, incandescent lights more so, but even the best fluorescent lights only turn about11% of their energy into visible light, with much of the rest turning into heat.

Lets look at ways of saving energy in the office with each of these heat sources.

To keep sunlight from coming through windows is fairly straightforward if you have window blinds or shades you can close during sunny weather on warm days. On my walks from pod to pod to turn off lights, I discovered I could easily lower the blinds on the south-facing hallway windows, and cut off about 80% of the light coming in from outside. As a result, the hallways don't heat up as much during hot weather, saving energy in the office hallways.

The energy from sunlight at a 40-degree latitude in summer is roughly 600 watts per square meter. I assume the building engineers used low-e glass to reduce the amount of heat radiation entering the building, but conservatively assuming just 10% of it makes it inside, and that each south-facing window results in one square meter of sunlight on the building floors, we get 60 watts X 8 hours = 480 watt hours per window. Round that up to half a kilowatt hour per window per day of added heat to the building, then multiply that by the number of south facing windows: 24 per pod (times 16 pods), 12 per inter-pod corridor (times 12 corridors) and we get 192 kilowatt hours of additional heat from pod windows and 72 kilowatt hours of additional heat from inter-pod corridor windows, for a total of 264 kwh per day.

Now, let's add the wattage from the electrical uses within the building: 264 kwh for pot lights, 1,600 kwh for corridor long-tube fluorescents, 220 kwh for laptops, and 400 kwh for desktops. All that plus the 264 kwh for solar radiation works out to 2,748 kilowatt hours per day of input energy, most of which eventually gets converted to heat inside the building (since energy can't just vanish). 

One BTU is equivalent to about 0.3 watt hours, so 2,748 kilowatt hours is equivalent to 9,160,000 BTUs. That means, to keep the building the same temperature as the out of doors, you'd need to run about a 1,000,000 BTU air conditioner for 9 hours straight (that's like running 200 regular window air conditioners continuously for 9 hours). Assuming a very high efficiency air conditioning unit with an EER of 14, keeping the building cool on a typical warm day (not even counting heat dissipation into the building, only interior load and solar load) would take a 71 kilowatt air conditioner, running for nine hours solid, and consuming an extra 642 kilowatt hours per day. Thus the heat load that needs to be cooled is the second largest power user in or office, which drives home one of the key points of saving energy in the office: every watt of lighting or computer use you save, can save more than a watt overall (because of the cooling load energy use), and cutting back on solar energy input can make a substantial difference in the air conditioning season.

Keeping food and drinks cold and hot

The final issue I considered for saving energy in the office were refrigeration units and water heating units. Refrigeration units included kitchenette refrigerators (2 per pod, for a total of 28), display case refrigerators in coffee shops and cafeteria, and cold water drinking fountains by washrooms (a total of 12). Water heating units consist mainly of the hot water dispensers in the 28 kitchenettes. I didn't do a detailed calculation of these because I quickly realized that with a typical fridge, using 2 kilowatt hours per day, you wouldn't get to more than 100 watts total energy usage for all of these items, and even with 28 kitchenettes we wouldn't be looking at more than about 100 kilowatt hours per day.

However, I did find one obvious area of energy savings: a display case refrigerator with no cover, that was left running continuously day and night, even theough the coffee shop where it operates is only open from 7:30 a.m. to 2:00 p.m. Monday to Friday. Because the display case is wide open, the compressor runs continuously, so my guess is that for the time when it really isn't needed (i.e. all hours except 7:30-2:00 Monday to Friday), that one display case is wasting over 8 kwh per work day, and 12 kwh per weekend day or holiday. An obvious solution? Unplug the unit when the coffee shop closes down at 2pm, or put the plug on a timer that shuts off at 2pm and turns back on at 7am.

With knowledge, saving becomes easy

Saving energy in the office becomes much simpler once you see where the energy is going. I'll grant that the above calculations are overly simplified and each of them may be off by 50% or more, but they are probably in the right order of magnitude. You can do similar calculations yourself if you want to start saving energy in the office: calculate lighting loads, computer loads, solar energy input loads, and from there calculate any additional cooling loads, and you can get a reasonable picture of how much electricity you're using in your office, even if your bosses won't tell you.

You don't actually need to know this to start saving energy in the office. There were some obvious things I started doing as soon as I realized that saving energy in the office gave me much more bang for my effort than trying to turn off the occasional light at home. One light switch at home might turn off one or two 18 watt bulbs. One light switch at work turns off a bank of 40 bulbs at 13 watts each! And there are switches like this all over the building corridors. Also, if I see someone has left their desktop on, I often remind them the next day that it's better to turn it off, both to save energy and to reduce wear and tear on the PC itself.

If you're serious about saving energy in the office you can even get together a group of energy savers to go around looking for savings opportunities. This is especially important on really hot days, when peak electricity demand caused by industrial, commercial, and residential customers all running their air conditioners causes massive spikes in electricity consumption. A handful of dedicated people wandering around a building turning out lights, closing sun-exposed window blinds, and getting people to turn off unneeded computer hardware, can make a noticeable difference in the building's second-by-second demand, and since in many jurisdictions large businesses pay by-the-minute prices for electricity (where peak demand prices can be ten or more times overnight prices), the savings do add up.

Then there's the red tape

Of course, just because you're armed with information and motivated to make a change doesn't mean you'll succeed. I certainly tried. I contacted the manager responsible for environmental affairs for my customer and said I wanted to help out. He suggested I talk to the building management team, which had been subcontracted out to another company. I carefully prepared a presentation showing where I thought the building was using energy and where the savings were, and made several proposals to them about ways in which building management and a group of dedicated employees could find significant savings. The response I got was underwhelming.

I suggested permanently turning off the second set of corridor lights, since in my experience I have never felt it was too dark with just one set on. They quoted vague rules about lighting requirements (which as far as I could tell were not enshrined in law or a code, but were merely the guidelines of lighting engineers). I suggested letting the temperature rise a little more on hot days, since the building is often cold enough that people wear sweaters indoors in summer. They said every time they let the temperature climb even slightly above the guideline temperature, they get a flood of complaints. I suggested putting the coffee shop refrigeration display case on a timer. They said it couldn't be done because the coffee shop is operated by a different company (which, I suspect, doesn't have to pay anything for the electricity they use).

The building managers thanked me for my presentation and recommended that I keep working on saving energy, but they were unwilling to change a single policy or offer any help. My impression was that I was an additional burden on them, or that my proposals wouldn't amount to much savings, or that, since they were a separate company paid to manage the building, and not the company paying the electricity bill, they weren't particularly motivated about saving energy in the office.

I left feeling quite discouraged, but of course turned off several banks of lights on my way back to my desk. I called back the manager for environmental affairs a little later, explaining that I hadn't made much progress with the building management team and would like to speak to him about my ideas. He thanked me for my enthusiasm but said the company is already doing a lot of important work to conserve power, and therefore he did not feel it necessary to go over my ideas.

What this all boils down to, is that if you're serious about saving energy in the office, you have to:

You might think the people responsible for running the building and managing its energy use, or the environmental affairs manager, would be excited about the idea of employees pitching in with saving energy in the office. Sadly they weren't. But I kept on turning off lights and reminding people to shut down their PC's at night, and educated others about the building's energy use and about ways of saving energy in the office, and although I can't say we've had a huge impact, I'm confident that thanks to my efforts and the awareness I tried to raise just among a handful of colleagues, several thousand kilowatt hours of electricity have been saved in my building of 2,500 people - probably more electricity saved there than my house consumed in the same time period.

It's like a big free carbon credit. Not that I'm going to use it to jet off to the Caribbean for a week - but saving energy in the office is a great way to leverage a passion for energy efficiency and achieve more than you could just by tweaking with your home energy use.

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