Email   Password


ASHRAE Membership

ASHRAE membership is open to any person associated with heating, ventilation, air conditioning or refrigeration. ASHRAE is unique because its membership is drawn from a wide range of disciplines relating to the HVAC&R field. Over 56,000 individuals from more than 100 nations belong to the Society.

Discounts on Publications

ASHRAE members earn 15% off publications. Hundreds of titles are available including the complete collection of ASHRAE Standards including 90.1, 62.1 and 189.1.

Develop Leadership Skills

When you join ASHRAE, you are making an investment in yourself. When you become active in the Society by giving your time and sharing your knowledge, you get even more out of that investment.

Network with Industry Professionals

Each month, all over the world, ASHRAE chapters convene for an informational program featuring a speaker or topic that is key to professionals in the industry. Meet with your peers and share ideas.
Need technical info? Search ASHRAE's Bookstore >
Resources & Publications


©2014 This excerpt taken from the article of the same name which appeared in ASHRAE Journal, vol. 56, no. 10, October 2014.

Steve Kavanaugh, Ph.D., Fellow ASHRAE

About the Author
Steve Kavanaugh, Ph.D., is a professor emeritus of mechanical engineering at the University of Alabama, Tuscaloosa, Ala.

The Leander Independent School District (LISD) is located in one of the fastest growing suburbs of Austin, Texas. The district maintains 36 buildings that use ground source heat pump (GSHP) technology and garnered an average 2010 ENERGY STAR rating of 97. LISD has fostered a team of local design engineers, ground loop contractors, general contractors, and architects who interact closely with their construction, maintenance and energy management staff. Teamwork is essential because new elementary schools are added at a rate of one per year with very tight construction schedules. The fast-paced construction of LISD schools has not negatively affected energy consumption since the average ENERGY STAR rating for newer schools is over 99.

Figure 1 provides the annual electrical energy consumption for the all-electric buildings. The turnkey construction costs of recently completed GSHP systems (HVAC, outdoor air, controls and ground loop) are in the range of $20/ft2 to $24/ft2 ($215/m2 to $260/m2) of floor area. Given the significant quantity and cost of outdoor air systems with energy recovery, these systems are comparable in cost to non-GSHP systems and provide savings in both energy and maintenance costs.


Owner's Perspective

With more than 21,000 vertical bores and 2,100+ miles of U-tube heat exchanger piping, the area surrounding Austin has perhaps the largest concentration of GSHP institutional and commercial buildings in the U.S. In 1994 LISD adopted many local practices, but also did a few things differently to reduce installation and maintenance costs. The GSHP system is a simple unitary approach with each classroom heat pump connected to an individual ground loop with an on-off circulator pump.

LISD brought together its primary engineering firm, general contractor, several architects and their staffs to evaluate the program in 1997–98. The school board and superintendent supported additional upfront spending on quality, but they wanted proven life-cycle costs based on measured data rather than simulated performance. The team chose to apply a few things from the LEED rating system but ultimately decided on ENERGY STAR as the evaluation tool since it is based on actual measured data. Specific outcomes of the evaluation included longer ground heat exchangers, improved specifications for backfill material, and greater vertical bore separation compared to the practices in the 1980s. Specifics are discussed later.

The system evaluation was repeated by LISD in 2002–03 and again in 2012. A major result of the 2002–03 process was to implement a program of start-up and commissioning. The primary technical improvement was to abandon the custom classroom console units and place vertical upflow heat pumps and ventilation air equipment on mezzanines that were created over the hallways. Maintaining the console units located in the classrooms was difficult and the vertical mezzanine mounted units are inherently more accessible to maintenance personnel.

The major finding of the 2012 evaluation was the amount of after-hours use that happens in only certain portions of the facilities with typically very light occupancy. This finding provided additional support for the original design choice of individual units that do not require central equipment to be turned on to condition a limited number of zones and occupancy loads.


Read the Full Article


Return to Featured Article Excerpts