Micro publishings of building science research findings.
Typically, when people think of campus building energy use, they think of lighting. Lights are very visible, are often left on when no one is using the space, and are a sizeable portion of commercial building energy use.
There is also a lot of energy in the light we don’t see – long-wave radiation in the infrared, which we perceive heat. We wanted to see that energy use as well, so last week, members of BSG and the Student Sustainability Committee traveled around campus at night to see the campus through an IR camera.
Taking pictures with a digital camera is called photography, taking them with an IR camera is called thermography. IR cameras convert the long-wave radiation they perceive into a visible image so that we narrow-spectrum people can “see” in the infrared range. We went did our thermography several hours after sunset to avoid seeing the residual impact of solar radiation on the building walls.
Here’s what we found.
At UMD, we heat most of our buildings with steam, produced using natural gas at the campus combined heat and power plant (CHP).
The steam is sent underground through buried pipes to campus buildings. It condenses, releasing the latent heat to a building’s hot water system or a radiator, then the condensate travels back to plant. Steam lines are typically insulated, but they still lose a lot of heat. Condensate lines are also very hot, and at UMD they are directly buried in the ground without insulation. The result is a lot of heat loss to the ground, which we can see using an IR camera. Somewhere between 10-20% of the heat produced at the plant is lost to the ground in the distribution system.
Once the heat is delivered to the building, hot water flows through heating coils in air handling units, providing warm ventilation air. The heat is lost through conduction through the windows, walls, and roof, or from air that leaves through small gaps in the building enclosure. Air leaks show up as hot spots around the edges of windows, doors, and the roof line. Conduction losses show the building as warmer than the surroundings, and the better insulated a building is, the more “invisible” it will be on the IR camera. Metal framing around windows or other structural members show up very clearly in the pictures. These thermal bridges compromise the insulating value of the wall and windows. Designing more insulating framing systems is a big industry focus.
Over 1/3 of UMD’s carbon emissions and energy costs go towards heating buildings. It’s very expensive to retrofit buildings with insulation, and most of UMD’s older buildings have load-bearing masonry walls, which require particular care to prevent moisture from eroding the wall if exterior insulation is excluded as an option. This means most buildings on campus won’t be IR-invisible anytime soon. But there is a lot that can still be done in sealing air leaks and making sure new buildings avoid the mistakes of lots of thermal bridging or inadequate insulation.