The new central plant will cut energy use by up to 20 percent.

Based in an area with a rapidly growing pediatric population, Phoenix Children's Hospital is in the midst of a $588 million expansion that includes construction of an 11-story patient tower. Completion of the tower in 2012 will nearly double the number of licensed beds to 634.

To serve the growing 34-acre campus and with an eye on long-term energy savings, the hospital built a new $23 million central energy plant that was up and running in April. Construction was supported in part by a $464,000 incentive payment from the Arizona Public System Solutions for Business program.

Johnson Controls Inc. (JCI) also served as a key partner in the plant's design and operation. The hospital originally agreed to a conventionally designed plant that was more efficient than the prior system.

But JCI, which already had provided the hospital with facilities management services, proposed a different design that utilized the latest building automation systems and advanced heat pump, chiller and boiler technology. The hospital switched to JCI's plan.

The new JCI-designed plant is expected to cut energy use by 20 percent compared to the maximum capacity required by local code. The plant is projected to save the hospital $11 million in energy costs over the next 15 years and 5.6 million gallons of water annually, the hospital says.