Reduced Power Consumption is a Win for Sustainability and Finance

power consumption sustainability

Sustainability has been a hot topic in the AV world over the past few years. Many manufacturers have expanded and touted their sustainability efforts, and customers are pushing for sustainable options. The sustainability of companies involves everything from their policies and practices at their headquarters and offices to the products they sell and end up in our installs. Sustainability has a number of factors to consider, such as how long the product can be serviced, how recyclable it is (what type of hazardous material may be in it), how much recycled material is in it, how it is packed and from where it is shipped. Energy efficiency is also a critical component of sustainability and that is the area that I want to focus on in this blog. Everyone has seen significant increases in the cost of electricity over the past several years. If you have not done anything to reduce power consumption over the past years because the cost did not seem to make it worthwhile, the increased electrical supply costs may give you the chance to rethink.

All AV people are used to math as we use formulas constantly. Figuring out electrical usage and costs is easy enough, it is just another formula. I am going to use the data from a computer to help work through the calculations. A typical desktop computer will use between 30 and 50 watts per hour while it is idle (note that this is NOT sleep — the computer is on, just not being used). For the purpose of this blog, we will use an estimate of 40 watts. If we assume that a computer is not being used from 11 p.m. through 7 a.m. every day, that is 8 hours of idle time. If we take the idle time and multiply it by the watt usage, we get the idle power consumption. In this case, 8 (hours) times 40 (watts) equals 320 watt hours (Wh). Most power companies charge by the kilowatt-hour (kWh). To determine the kWh simply divide the Wh by 1,000. In our case, we get .32 kWh. To determine the cost of running a piece of equipment you would multiply your kWh usage by the cost of your electricity. In Maine, the “standard offer” rate is $.1763 cents per kWh. This is likely more than what a commercial or nonprofit would actually pay, but it gives us a point to do calculations. We would now multiply .32 (kWh) by .1763 to get, .06 cents. So, for every computer we have on campus, we are spending .06 cents to keep it running overnight. If we look at a computer lab that has 30 computers in it, that lab is costing $1.70 each night to keep running, or $612 per year. The math is written as a formula is kWh = watts*(time/1000), and the cost is figured by cost = kWh*electrical supply cost.

If we take into account all of the computers we have on campus, the numbers start to add up. In our environment, we have about 350 public lab computers, 100 research lab computers and about 110 podium computers for a rough total of 560 computers. Multiply that by the .06 cents, and then by 365 days, and the numbers suddenly seem a bit more significant, $12,264. I know that in my case, my finance and facilities offices would pay attention if I told them that I had an idea that would save us over $12,000 per year in our electrical bills. At the start of this blog I was writing about sustainability, so let’s also remind ourselves that in addition to the monetary savings, we are also saving over 65,000 kWh if we were to put these computers to sleep during those eight hours.

These numbers can obviously be applied to an entire AV system, including controllers, touch panels, amplifiers and projectors. It is likely worthwhile for you to take the time to figure out what your standard room is using for electricity when it is not being used. Create a list of the equipment that you have in a “standard” room. Then do a bit of research and find the idle power consumption of each component. Plug that data into the formula above, and you have a decent sense of your electrical consumption and cost per room. Work your programming to put devices into standby mode or sleep mode when the room is not being used. But, also be careful about what devices you choose to use. All devices should have a rating for idle power consumption. A popular brand of amplifiers, for example, currently advertises that all their amps draw no more than 90 watts. If you have 100 amps on your campus that are drawing 90 watts when they are in sleep mode, that is a lot of wasted power (26,280 kWh per year). Start making the idle power usage part of how you specify equipment. A projector may use up to 312 watts when on, and only 2 watts while in sleep mode. A projector that is left on overnight, or even worse for a week or an extended vacation, will waste a tremendous amount of electricity. Using programming to be sure to turn these off every evening is an investment that will pay itself off.

The savings demonstrated here are for a small institution with a limited number of computers and classrooms. Obviously, the larger the institution and the more equipment they have, the monetary and consumption numbers scale. Even more impressive is if we consider the entire community of colleges and universities around the country. What if we all agreed to make these changes and standardized on methods for being sure equipment was going into sleep mode? What if, along with specifying equipment with very low idle power consumption, we let the manufacturers know this was important to us and will be a significant factor in our purchase choices? What type of energy consumption savings would we have in that case?