Colleges and universities use a substantial amount of energy, hosting numerous well-lit classrooms and residence halls full of students studying well into the night. In the US, higher-education institutions use an average of 19 kilowatt-hours (kWh) of electricity and 17 cubic feet of natural gas per square foot (ft2)—so a 50,000 ft2 building uses, on average, more than $100,000 worth of energy annually. There are many strategies available to help colleges and universities trim their yearly energy bills while still improving the learning environment for their students and staff. We’ve highlighted five of them—ranging from quick no-cost/low-cost efforts to longer-term solutions—each of which are proven energy savers.
1. Replace inefficient fluorescent lamps. Upgrading your existing T12 fluorescent lamps and commodity-grade T8 lamps to high-performance T8 lamps and electronic ballasts may reduce lighting energy consumption by 35 percent or more. Just moving from outdated T12 lamps to high-performance T8s can reduce power consumption by as much as 40 percent. In addition to consuming less energy, upgraded lamps have a higher color rendering index (CRI), which means they can provide lighting quality that more closely resembles natural light while still maintaining similar light levels. And even greater savings can be achieved with the addition of specular reflectors, new lenses, and occupancy sensors or timers. These lighting retrofits typically have payback periods of one to three years.
Alternatively, LEDs can be a more expensive but more effective upgrade. LED prices have been falling quickly, and their advantages over traditional incandescents and CFLs are significant—LEDs last up to 10 times longer and use at least 75 percent less energy while providing higher-quality and more-direct lighting.
For the needs of a college or university, there are very few applications for which the advantages of LEDs don’t at least merit some consideration. In dorm rooms, where lamps are left on for extended periods of time, LEDs will offer a distinct advantage in life span and energy use over halogen lamps or CFLs and will require fewer replacements. For classrooms, LED troffers (2- to 4-foot-long recessed lighting fixtures where the opening is flush with the ceiling and the inner surface serves as a reflector), can compete with typical fluorescent fixtures in quality while providing energy-saving and longevity benefits.
Yet when buying LEDs, caveat emptor (let the buyer beware) remains the key consideration. Not all LED products available on the market are equally effective or offer the savings they describe. Visit the US Department of Energy’s Solid State Lighting website for documentation on the various LED developments in the field.
2. Turn the lights off when they’re not in use. The most obvious strategies are often the most overlooked, and turning off the lights can add up to significant energy savings over time. There are two effective options to be sure this happens. The first is to install occupancy sensors that automatically detect the presence of people and turn lights on and off accordingly; the second is to recruit “energy monitors” from the staff to carry out the task. This strategy can be further encouraged by implementing an energy awareness campaign, which can give students and staff passive reminders in the form of energy conservation posters and stickers placed strategically around the campus.
3. Check the economizer regularly. Many air-conditioning systems in climates with mild outdoor temperatures and humidity have a built-in energy-saving device called an economizer, which draws in outside air to cool the building instead of using mechanically refrigerated air. In many applications, a fully functioning economizer can cut a building’s total energy consumption by as much as 10 percent, or up to 20 percent in mild coastal climates.
It’s important to note that economizer performance can degrade over time, posing the risk that the device will waste more energy than it was originally intended to save. The linkage on the damper can seize up or break, causing the economizer to become stuck in a wide-open position. When this occurs, the economizer will let in hot air during air-conditioning season and cold air during heating season, and the cost of conditioning this outside air can increase a building’s annual energy bill by up to 50 percent. The solution is regularly scheduled maintenance and repair. About once a year, hire a licensed technician to check, clean, and lubricate the linkage, and calibrate the controls of your economizer and repair it if necessary.
4. Commission your building. Commissioning a new building is the process of ensuring that building systems are designed, installed, functionally tested, and capable of being operated and maintained according to the owner’s operational needs. When done well, commissioning can yield energy savings and increased occupant comfort in a building by improving the energy system’s performance. In existing buildings, this process is called recommissioning when it’s been done before, or retrocommissioning when the building has never been commissioned. You can also install monitoring equipment to provide continuous diagnostics that can identify system problems before they have a chance to degrade performance; this is called ongoing commissioning.
Because building energy systems are dynamic and tend to fall out of calibration over time, it’s important to recommission them—typically every three to five years—to maintain optimal performance. For a standard 50,000-ft2 university building, commissioning can often uncover around $17,000 in annual savings and yield a one- to two-year payback period. More information about commissioning is available in the Lawrence Berkeley National Laboratory report Building Commissioning: A Golden Opportunity for Reducing Energy Costs and Greenhouse Gas Emissions.
5. Operate multiple cooling towers to save fan power. For facilities with a central chilled-water plant, running multiple cooling towers at low fan speed is more efficient than running one cooling tower at high fan speed. Energy consumption increases exponentially with higher fan speeds, so running two cooling towers at half speed can often use much less energy than running one cooling tower at full speed. Most chilled-water plants have excess capacity and tend to turn off at least one cooling tower during low-load hours, so running condenser water over as many towers as possible at the lowest possible fan speed can reduce unnecessary energy waste.