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Cornell University

Energy Conservation Initiative

Fan and pump variable speed drives

From 1985 through the present, nearly 20,000 horsepower of building variable speed drives were installed on fans and pumps in heating, ventilating, and air conditioning (HVAC) systems. Before these devices, equipment energy use was either constant or varied slightly due to throttling devices. After drives were installed, energy use is only what is necessary to provide the air or water movement required to heat/cool the space. Practically invisible to the layperson, the alternating current drive technology on campus saves approximately 30,000,000 kWh/yr. This technology alone saves nearly 10% on the campus electricity consumption.

Campus lighting upgrades

Over multiple years (1994-1996 and present), the entire campus was inventoried and all light fixtures that could be economically converted, were changed to high efficiency fluorescent sources. Over 83,000 two-lamp fixtures were modified or replaced. This project reduced lighting energy use on average by 30 percent, and in many places improved light levels in work areas. Although not required to do so, Cornell recycled the removed lamps to ensure safe disposal of the pollutants in these products. Applicable guidelines, such as those presented in the Greenlights program, were exceeded, saving 6,000,000 kWh/yr, enough lighting energy for 700 homes.

In 2005, an additional phase of lighting retrofit work was completed. This project tackled another 1 million square feet across 20 buildings, saving an additional 1 million kWh/yr.

All new lighting on campus utilizes T8 and T5 fluorescent technology inside buildings.

Occupancy sensors and daylight controls for lighting and HVAC

New sensor technology allowed the installation of occupancy sensors for lighting and for heating/cooling/ventilation in spaces where they could be cost effective. The sensors are installed throughout many parts of the campus to turn off or set back systems when people are not moving in the spaces.  Daylight level based controls are used whenever cost effective in new construction.

Building digital energy systems controls and central EMCS

In 1984 the university started up its first all digitally controlled building, Snee Hall. Since that time hundreds of direct digital control systems have been installed in over 150 campus buildings. These systems allow accurate, reliable, variable capacity, and networked control of building HVAC equipment. Together with variable speed drives, digital controls allowed the first variable flow laboratory spaces to be installed successfully on campus.

All of the building automation and control systems (BACS)are networked to a master energy management system (EMCS - Energy Management Control System) that supervises and records system data. This system was first developed in the 1960's and is now in its fourth generation of computer technology. Together with building and central plant metering data, energy use is supervised and analyzed to minimize how much is used in providing heating, cooling and lighting to campus spaces.

Heat recovery from exhaust air

There are a number of building systems on campus that require 100% outside air and full exhaust from the space, totaling over 3 million cubic feet of air per minute!  In some of these cases, it has been possible to utilize heat recovery to preheat the incoming outside air with some of the heat in the leaving exhaust air.

Chilled water building temperature rise improvement project

Seventeen major campus buildings were retrofit from 1988 to 1992 with new control valves, digital controls, and variable speed drives to minimize the amount of cooling used and to maximize the return temperature of the chilled water (minimize flow for any given cooling load). This effort not only reduced energy use by building equipment, it reduced central plant pumping and chiller energy use.

Chilled water building differential pressure project 

The building differential pressure (dP) project team completed a survey of 32 buildings in the year 2000 that were identified by KY Pipe modeling to have a high chilled water dP as a result of LSC coming on line. The survey included a condition assessment of the building chilled water pump station and recommendations for system modifications to assure reliable building operation after the commissioning of LSC (Lake Source Cooling).

The building dP project objectives were to evaluate the extent of the hydraulic situation in the buildings as a result of LSC, make recommendations for building system modifications, and follow through with design and construction management. This was accomplished with a survey of the buildings with high dP conditions and an evaluation of whether the existing re-circulation loop control valves were adequate for the new chilled water service condition as summarized in the report. The goal of the project was to support start-up of LSC with minimal disruption to the building occupants and assure the efficient operation of the distribution system following LSC commissioning.

As a result of this project, no adverse conditions were reported in building operations due to changed distribution hydraulics from LSC.