• EarthWise™ HVAC System
• Significant Energy Savings: 40 Percent HVAC Energy Savings; 20 Percent Overall Building Energy Savings
• Improved Comfort for Students and Staff
In the spring of 2006 Birdville Independent School District (BISD) decided to replace the two 400-ton chillers that had been serving Haltom High School for 17 years. The chillers
were no longer reliable or very efficient. The major challenge was that all of the replacement work needed to be completed that summer in time for the start of the 2006-2007 school year.
BISD worked with Image Engineering Group, Ltd., consulting engineers of Grapevine, Texas, and the account managers at Trane in Fort Worth and Dallas to develop a chiller replacement plan. In addition
to replacing the old chillers, Trane recommended implementing its EarthWise™ chiller system design strategy to maximize comfort and system efficiency throughout the high school building. The EarthWise system strategy takes advantage of the high efficiency and high performance available with
Trane direct-drive centrifugal chillers and employs a design philosophy that reduces first cost, lowers operating costs, and is substantially quieter than traditional HVAC systems. Central to the EarthWise system design are low flow rate, low temperature, and high efficiency for both the airside and waterside systems, along with optimized control algorithms for sustainable performance.
By slowing the chilled water flow rate and producing colder than traditional chilled water temperatures, significantly less pumping energy is required. Similarly, supplying less airflow at colder temperatures reduces fan power requirements, reduces relative humidity in the building and results in
quieter operation and improved indoor air quality. In addition, the Trane Free Cooling feature allows the chillers to produce cold water without operating the compressor motors when outdoor temperatures are cool enough.
Robert Frick, a LEED accredited professional with Image Engineering Group Ltd. consulting engineers, was the senior project manager for the project. Frick commented that the EarthWise system upgrade was the result of a collaborative effort with Trane and BISD and was the right choice as evidenced by
the significant energy savings.
Don Penn, P.E., a principal with Image Engineering Group, said that Birdville ISD is a "very forward thinking school district that continuously looks to optimize their facility’s performance with solutions like the Trane EarthWise system and the numerous geothermal ground source heat pump systems
that they have installed.
EarthWise™ systems are less expensive to install and operate than conventional designs. With smaller equipment and ductwork, the EarthWise concept reduces design time by simplifying the
HVAC layout. Trane Integrated Comfort System (ICS) control technology and the Tracer Summit™ building automation system help assure that the EarthWise System delivers optimal, reliable performance. Compared to conventional designs, an EarthWise chilled water system
reduces total cost of ownership by decreasing installation and operational costs.
To keep the chillers operating with like-new performance, Trane and Image Engineering also recommended installing an automatic tube cleaning system on the new chillers to continuously
and automatically clean the condenser tubes daily.
Haltom High School has seen a 20 percent decrease in the school’s overall energy use thanks to a 40 percent reduction in HVAC energy use (HVAC typically represents 50 percent of a building’s
overall energy use). Haltom High School is also realizing significant savings in reduced maintenance costs.
Bill Barrow, BISD Systems Administrator, said, "The results of this project are awesome. We are seeing a noticeable, tremendous improvement in comfort throughout Haltom High School."
Barrow added, "Previously, we had to run the chillers every day no matter how cool it was outdoors. Now, we can often operate the system in Free Cooling mode throughout the entire day
in cooler weather. The Free Cooling system and Tracer Summit™ building automation system make it very easy to efficiently run the school."
With roots in the 1850s, Birdville ISD is now the third largest school district in Northeast Tarrant County, with 32 campuses serving more than 22,400
students. The district spans 40 miles and is located at the "hub" of the Fort Worth-Dallas Metroplex. The entire community of Richland Hills and
parts of Haltom City, Hurst, North Richland Hills, Watauga, Colleyville and Fort Worth are within its boundaries.