Davidson College owns and operates a 94 kW solar PV system (that is tied into the Duke Energy grid). The rest of the electricity is purchased from Duke Energy.
Duke Energy-North Carolina generates electricity with a mix of Nuclear power plants, Coal fired power plants, Natural Gas fired plants, Hydro-electric plants and Renewable Energy (e.g., Solar & Wind) plants.
Average electrical cost based on the sum of three year period 2010-2012 ($4,841,727/ 73,126,612 kWh) cost divided by consumption is $0.066/kWh.
Power companies must have generation capacity equal to the maximum momentary demand of its customer base. At all other times, power companies have excess capacity. Our rates at the College, as a commercial customer, are based on our time of use as well as how much we use. Duke Energy has higher rates during peak times (1 – 9 p.m. in summer months) as an incentive to decrease usage, and lower rates during non-peaks times as an incentive to shift the demand away from peak. Davidson College controls a portion of its energy cost by managing its peak energy consumption and shifting loads by employing a central energy management system; as the campus approaches its peak consumption each day, the energy management system manipulates the settings of a majority of campus thermostats. We have 3 stages of peak demand, raising the set-points by a degree in three stages until the campus kW decreases. This allows the central chilled water plant to slow down its production of air conditioning supply momentarily, conserving electricity during the peak.
In the last three years Davidson College has purchased the following:
Even though we increased our square footage on campus by almost 35,000 ft2, our energy usage has impressively remained pretty even because of Davidson’s focus on energy management.
The Central Steam Plant houses four natural gas fired steam boilers that supply steam to about 70% of the buildings on campus. The steam boilers can also run off #2 low sulfur fuel oil when needed. Steam is used to heat the buildings, generate domestic hot water, humidify buildings, and some for some cooking, steam dryers, and industrial processes.
Most of the campus is cooled by chilled water that is generated by the Central Chiller Plant. The plant houses three electric chillers (800 tons of cooling each: a cooling ton is equal to the amount of heat absorbed by one ton of ice in one hour) and a fourth will be installed by the end of 2013. A variable speed, primary underground pumping loop delivers exactly the chilled water that is needed by the campus at any one moment, without creating surplus.
The buildings have various kinds of Air Handling Units (AHUs) and Fan Coil Units (FCUs) that supply conditioned air to the occupied spaces. The underground steam distribution system and the underground chilled water distribution system were replaced in mass over a five year period from 1999 to 2004. The new piping systems are designed and insulated to lose less than two degrees of temperature from the source to the most distant distribution point.
Davidson College purchases a part of Natural gas volume in advance from Wellhead sources (e.g., brokers for New York Mercantile Exchange (NYMEX), which is regulated by Commodity Future Trading Commission, an independent agency of the United States government) for the Central Steam Plant. The balance is bought monthly from Piedmont Natural Gas which also delivers all of natural gas to the campus.
Despite the coal chimney stack on the Central Steam Plant, Davidson College does not burn coal on campus for heating. Davidson converted from coal fired boilers to natural gas fired boilers in 1962. Natural gas fired boilers produce substantially less, about half, the carbon dioxide that is produced by a coal fired boiler of the same capacity. #2 fuel oil is used only as an emergency backup for periods when natural gas service is curtailed.
Most of the academic and office buildings are controlled by an energy management and control system utilizing Direct Digital Controls (DDC). There are manual thermostats in several residence halls and independent residences. The manual controls are replaced with digital as the systems are upgraded.
The temperature of each occupied space in the buildings with DDC controls is set based on Davidson College’s “Chill Out” Policy established by the College’s past president, Bobby Vagt The energy management system maintains a balance between occupant comfort level and energy efficiency. The unoccupied spaces are maintained at setback/setup temperature and to maintain humidity control. In line with the “Chill Out” Policy, Davidson sets thermostats strictly between 68 and 72 degrees in the winter between 74 and 78 degrees in the summer.
In 2011, Davidson College installed 378 solar PV panels and 64 solar thermal panels on Baker Sports Complex. Utilizing the campus’ best placement for solar energy, the two sets of panels cover 75% of Baker Sports Complex’s southern-oriented flat roof surface and 60% of the pool roof’s surface. Both systems are linked up to a real-time online dashboard.
The 94 kW solar PV array converts sunlight into electricity to power the Baker Sports Complex. In the first year, the PV system generated around 135,000 kWh saving the college about $9,000.
The solar thermal panels heat water in pipes that run through the solar thermal panels, transferring heat to the water in Cannon Pool and in the Knobloch Tennis Center’s showers. The first year energy savings are 390 MMBTU saving the college about $8,000 in energy costs.
As cost of solar power generation becomes more competitive, Davidson College will consider adding more solar power generating projects. Geothermal and small-scale hydro-electricity are also being considered. Charlotte is not a good location to install wind powered electricity generators (wind turbines) due to lack of sustained winds. The College is continually searching for grants and funding for future renewable energy projects to meet our Climate Action Plan goal of 12% energy consumption from renewables by 2020.
Davidson is always engaged in several energy projects. A few of the recently installed and ongoing projects are given ahead:
The simplest way to save energy is energy avoidance, e.g., using natural lighting in the room instead of artificial lighting, shutting off lighting when you leave the room. Use LED or CFL compact fluorescent type light bulbs instead of incandescent. Set your thermostat a few degrees lower in the winter and a few degrees higher in the summer. Turn off computer monitors when you are not going to be there for more than 20 minutes. Enable sleep mode on computers if you away for more than 20 minutes. Unplug all accessories including printers, speakers, and scanners when not in use. And if you don’t need any extra light while you’re working on a computer, switch off desk lamps and overhead lights. Consider plugging appliances into a power strip that can be easily switched off when you’re leaving the office or dorm. Some power strips can detect when appliances are not in use and switch off automatically. Wash only full loads of clothes and air dry your clothes after washing them. Many electrical dryers use more energy during their 45 minute cycle than your room uses in a day. In conditioned rooms keep windows closed, so we can help you better control the temperature and humidity in your room.