ASHRAE Journal - September 2012 - 57

2012 ASHRAE Technology Award Case Studies

Air-Handling Unit Water-to-Water Heat Pumps

T North Building Valve Vault Parking Lot Cooling Chilled Water

SC4 North Building Geoexchange Heating and Cooling System
• The HVAC design has converted a vintage 1920s era building with the state-of-the-art geo-exchange heating and cooling systems. • The SC4 North Building renovation is one of the first to use central water-to-water heat pumps to heat Horizontal and cool the building. Underground Geoexchange • The building is located in a dense urban environment. The campus parking lots were used for the Piping installation of the horizontal geoexchange slinky system. • SC4 North Building’s geoexchange system is estimated to save 30% on the building’s energy costs. • SC4 North Building’s geoexchange system has an eight-year simple payback on investment.

Figure 1: The water-to-water heat pump system required only six heat pump units rather than distributed water-to-air heat pumps, avoiding incorporating a compressorized heat pump into each controlled space.

Campus-wide green building initiatives began with several facility efficiency upgrades. Among the green initiative’s many challenging opportunities was an ambitious HVAC replacement project for one of its older buildings on campus, the North Building, formerly known as the Old Main Building. Today, the two-story 58,885 gross ft2 (5470 m2) and 52,574 net ft2 (4884 m2) building houses faculty offices, instructional classrooms, laboratories, a gymnasium, and a fitness area. As a multipurpose facility that had worn many hats throughout its 92-year lifespan, the building was in need of an HVAC system replacement. The existing room unitary heating and cooling system had seen its fair share of use and had begun to deteriorate, providing poor indoor climate and generating excessive noise in each space.

Design Challenge
The design team had their hands full with the challenge of retrofitting a circa 1920 building using the state-of-the-art HVAC technologies.
September 2012

The college had no additional funds to upgrade existing windows or provide additional insulation on the exterior wall of the building, so the existing building shell was to remain as-is and be factored into the new HVAC design. Following weeks of analysis, cost estimating and discussions with the owner, the engineering design team determined the best fit for the college, as far as energy efficiency and creating a demonstration piece for the academic learning community, was to incorporate a central geoexchange water-to-water heat pump system to serve the North Building. Finding a location for a ground source central geoexchange water-to-water heat pump system’s expansive geoexchange field proved difficult in such a tight urban area. Additionally, the design team was faced with applying such a system to a 92-year-old building without affecting the building’s aesthetics and having to complete construction during the summer: May 3 to August 20, in time for the start of the fall semester. The original thought was to use deep vertical bores in the earth around the building to minimize ground surface

area. However, the City of Port Huron denied the vertical bore plan citing the city’s location over a lake bed with large deposits of methane gas. Based on the

Building at a Glance
St. Clair County Community College: North Building
Location: Port Huron, Michigan Owner: St. Clair County Community College Principal Use: Administrative and instructional Includes: Faculty offices and instructional classrooms Employees/Occupants: 1,050 Occupancy: 100% Gross Square Footage: 58,885 Conditioned Space: 52,823 ft2 Substantial Completion/Occupancy: 2010 ASHRAE Journal 57

ASHRAE Journal - September 2012

Table of Contents for the Digital Edition of ASHRAE Journal - September 2012