Since 2003, the College has invested approximately $200,000 per year in energy conservation projects, and these projects have had a net simple payback of approximately 2.3 years.Examples of some of these projects are described below.
There are two primary means for the College to reduce its “carbon footprint”: through use of renewable energy sources and through energy conservation projects.While use of renewables is appealing and should be a fundamental aspect of any sound energy strategy, the College has put its initial emphasis on energy conservation projects.The focus on energy conservation projects is driven by the simple fact that we get the highest environmental benefit per dollar spent.That is to say, a dollar spent on an energy conservation project such as a lighting retrofit project that has a simple payback of two years, will reduce our carbon footprint many times more than installing photovoltaic electrical panels.
Energy conservation projects are critical from both an environmental and an institutional financial stewardship perspective.The College views the financial commitment to energy conservation projects not as a cost but rather as an investment.Projects that pay for themselves in a short period of time via the avoided energy costs are analogous to investing money.Specifically, a project that has a simple payback of two years has a guaranteed return on investment (ROI) of approximately 50%, which is far greater than the return on most investment vehicles.
See Also: Weatherization Practices
An ice skating rink’s primary use of power is for cooling the ice: any measure that improves the efficiency of the ice-making equipment will have an big impact on energy use. At Orr Rink we made two important changes:
- Installing a low-emissivity ceiling decreases the radiated heat on the surface of the ice. In a large building such as an ice rink the ceiling can get very warm. In an ice rink this heat comes from the lights, the spectators and the general heating of the building. With a normal ceiling, a significant portion of that heat is radiated to the ice by warm surfaces. With a low-emissivity ceiling, very little heat is radiated down to the ice. The cool air above the ice, trapped behind the boards, acts as an insulating blanket and can reduce by half the energy needed to keep the ice cold.
- Ice temperature also has a significant impact on the energy needed to keep it cold: the warmer the ice, the less energy is needed. Hockey requires very cold (hard) ice, but figure skaters prefer warmer (softer) ice. The control system for the ice refrigeration equipment was upgraded to allow changing the ice temperature at different times of the day.
Kitchens use a lot of heating and cooling by sending heated and cooled air up and out the hoods that ventilate the stoves and other cooking areas. The ventilation is required to keep fumes and heat from entering the kitchen. With a fixed fan speed, the ventilation stays the same whether cooking is going on or not. In June 2007, we installed hood ventilation controls that monitor the amount of heat and smoke going through the hoods. The hood fans are controlled and run only as fast as needed to safely remove the heat and smoke from the stoves. For boiling water and other low-smoke cooking, the fans run at minimum. For grilling, the system senses the extra smoke and the fans run as fast as needed to evacuate it.
Lighting technology has improved recently, and today, new fixtures can use 10% of the energy to deliver the same light as old fixtures. We have aggressively replaced old fixtures with modern ones to take advantage of the electrical and air-conditioning savings. Most recently the Arms Music Building, Alumni Gym, the Steam Plant and Frost Library have had upgrades that improve their efficiency AND light levels.
Vending machines that refrigerate their product typically run all the time whether there is demand for drinks or not. A typical vending machine will use several hundred dollars of electricity each year. The Vending Miser unit senses people near the vending machine and turns it on in anticipation of its being used. When the refrigeration equipment has finished its cycle, the Vending Miser then shuts the machine down. This system has been demonstrated to save about half the energy used by a soda machine. There are about 100 machines on campus, and 42 have been upgraded as of June 2007. Installation of a second wave of Vending Misers is in the works.
This effort will save 27 tons of carbon dioxide per year--the equivalent to taking five cars off the road or planting seven acres of forest.
Big savings can come from turning off lights when they're not needed.
Office and classroom lights are often left on, even when the occupants have left. Occupancy sensors can tell if a room is empty, even for a brief period, and shut the lights off. The sensor also turns the lights on again when the people return. Sensor technology has improved greatly in recent years, and the tendency to shut off the lights in error, because the sensor missed someone reading or working on a computer, has been reduced.
As part of the Athletic Complex renovations in 1999, skylights were re-opened that had previously been covered up. When free daylight is available, the lighting controls in the Athletic Complex are programmed to account for the daylight and shut lights off while keeping on only enough fixtures to maintain adequate brightness for safe play.
Before the 1990’s, when most of the buildings on campus were built, the flow through a pump or a fan was controlled by a throttling valve, if at all (it is difficult to control motors running on alternating current). With recent innovations in electronics, it has become effective to control the speed of an AC motor by using a Variable Frequency Drive (VFD). A motor controlled by a VFD will do only the work it needs to, and the inefficiencies a throttle introduces are eliminated. VFD control of a heating pump also allows the temperature of the water to be optimized, saving heating and cooling energy as well. Today, all large motors serving a variable load get VFDs, saving energy they would otherwise use.
Click image to enlarge
Another big use of electricity is to turn motors. Motors operate fans for ventilation and pumps for heating and cooling. Typically a motor is 75% efficient. Today we use motors that are at least 90% efficient and larger motors that are 95% efficient in all new equipment and when we replace old motors.
One of the most effective tools in controlling energy use is through building automation systems (BAS). The BAS senses many parameters and can adjust energy using equipment to optimize its performance. Since the BAS can be programmed with the schedule of a room or air conditioned area, it can shut down completely equipment that is not being used and turn it on only when it is needed. The BAS can be programmed to turn on a system early enough to warm or cool a space to set-point for when people arrive. The BAS can also be programmed to set-run a system at its most efficient set-points depending on the weather and use.