The graph above is the demand curve for the Moody Student Center over the last two weeks. You might notice something different about the middle portion of the graph. That long, flat part in the middle is Thanksgiving break. While our students were gone, we used 14416.7 kWh less than we normally would have. That’s like powering down an average house for an entire year!
I’m sure you’ve wondered to yourself at least once or twice “what’s in that room?” Mechanical rooms house much of the equipment that keeps our campus running smoothly. This can include air handlers, pumps, chillers, switchgears, and often many of the utility lines. Here’s a sneak peek at what you might find in a typical mechanical room.
Building heating and chilled water supply and return lines (Moody)
Chilled water supply and return, air handler in the background (Dana)
Electric panel and feeds (Moody)
Even though I deal with our various utilities and campus infrastructure on a daily basis, for many of you in the campus community these essential items are mysterious (and often uninteresting, which I can appreciate). As long as the lights come on, the water flows, and the heat (or air conditioning) is pumping out of those vents, most people don’t give them a second thought. But I feel that it might be good for the campus community to get a better understanding of how our campus works so they can appreciate the complexity of it all.
This is the first part in a series called How it Works.
Most of our heat on campus comes from the central steam plant. Solid or liquid fuel is fed into what is essentially a giant furnace (called a boiler, E&H coal-fired pictured right). Boilers, like many things these days, have become complex and expensive pieces of equipment. Our boilers are controlled by a large computer that optimizes fuel and oxygen consumption to ensure maximum efficiency. Once the boiler is hot, carefully treated water is boiled until it becomes steam. Once the steam reaches an adequate pressure (here it’s about 30psi), it is fed through a series of underground steam pipes that branch off to various campus buildings. Ideally these pipes are insulated to prevent heat loss, but many of our pipes are older and have yet to be insulated.
Once the steam reaches a building, it’s pressure is reduced and it is usually (though not always) fed into a heat exchanger where the heat is transferred to the building’s heating water loop. By this time, the steam has condensed into water and is returned (hopefully, although leaks are common) to the central plant to be reheated back into steam. Back at the building, the hot water loop circulates through the ducts at various points in a coil that looks fairly similar to the one in your home’s air handler. The air handler in the building and the valve for the heating coils are controlled by a thermostat that is either set locally or controlled at the central plant. This controls the amount of air flowing through the coils and the amount of hot water circulating through the coils. In buildings with internal heating loads (such as computer labs), the space temperature is often warmer than needed and actually has to be cooled down by chilled water (more on chillers and chilled water next week).
Hopefully this gives you a little better picture of what goes on underground and in the walls of our campus. It’s actually more complex than I described above (and would take a team of engineers to explain properly), but that is the basic overview of what a district steam system looks like. Even though it sounds unnecessarily complex, it’s usually an efficient way of heating large spaces (thank you, economies of scale). That being said, there are some highly efficient decentralized systems out there as well. Once the infrastructure is in place, though, it’s often expensive to change over to a different system.
Last month, Hollins recorded its lowest October electricity consumption since 1999. At 906,000 kWh for the month, we were about 50,000 kWh lower than the October average over the past five years. Even if we consume our average amount for November and December, we’ll still be 1.5% lower than last year’s usage. That might not sound like a lot, but it means keeping about 160 tons of carbon out of the atmosphere (or the equivalent of taking 28,000 cars off the road for a year).
Now, I’d love to take full credit for this, but we had a pretty mild October. That being said, we still reduced our consumption quite a bit, and that’s always a step in the right direction.
You might see the image below popping up in classrooms and restrooms soon, so here’s a little bit of explanation. In the next few weeks, we’ll be rolling out a test project at Hollins that will allow you to report facilities-related issues right from your smartphone (or if you’re on campus, from any computer). If you have a smartphone, simply use a barcode scanner app (any one should work, I use Barcode Scanner on my phone) and you’ll be presented with a link that will take you to a form. All you have to do is select which building you’re in, which floor you’re on, and what you’d like to report and you’re all done. It’s quick and easy, and we hope you’ll use it often to help us save water and energy.
mycampusenergy 