ASHRAE Journal - June 2013 - 50

2013 Technology Award Case Studies
patient privacy was maintained. Duct silencers were integrated in
the rooftop air-handling unit curbs to ensure noise from air-handling systems was addressed before the ductwork entered occupied spaces. Fans also were quieter, due to the lower air velocities
used to reduce pressure loss in the system. Additionally, in areas
of concern, heavy (14 gauge) ductwork was used to eliminate potential breakout noise from ductwork within the building.
The HVAC systems were designed to meet thermal comfort
levels as defined by ASHRAE Standard 55-2004. A variety
of rooms, occupant activity levels (met), and clothing levels
(clo), were modeled to ensure occupants would be comfortable and the space would be maintained at 72°F (22°C) and a
minimum of 30% RH year-round.

Maintenance & Operation
While comfortable with the VAV reheat systems used
throughout their network of facilities, the owner also was interested in improving energy efficiency. To address this need
without drastically changing maintenance requirements, energy recovery chillers and other improvements were added to
supplement their typical systems.
The high-efficiency water tube boilers require less maintenance, are easier to operate, and do not require large access
typical of conventional fire-tube systems.
The HVAC, domestic water, and lighting control systems
were commissioned to ensure proper operation, calibration,
and performance prior to the owner taking occupancy. A number of opportunities were addressed to ensure the owner was
provided with a high-performance facility that reduced operating costs and increased occupant productivity.

To System

CWS

Exhaust Air to
Atmosphere

From System

Exhaust Energy
Recovery Units
(110 Tons Total)
(40,000 cfm Total)

CWR

Exhaust Air
From Building

CWS

Chiller Plant
Two 850 Ton
Chillers

CWR

57°F

56°F
42°F

57°F

Energy
Recovery Chiller
280 Tons
140°F
HWS
120°F
HWR

Domestic
Water Service

55°F
CW

To
System
From
System

Domestic Hot
Water Heat
Exchanger

To
120°F
HW System

Figure 3: Exhaust energy recovery unit and energy recovery
chiller optimization.

Environmental Impact
The verified energy performance
of the building compared to the code
baseline indicates an annual greenhouse gas emissions savings of 2,500
tons of carbon dioxide. In addition,
electrical savings could power 200 typical homes in the community. The natural gas, electric, and water savings not
only save substantial facility resources,
but savings also are realized at the offsite natural gas, electric, and water utility plants.

Component

Initial
Cost

Yearly
Savings

Payback
Period

Low Flow Plumbing Fixtures (33% reduction)

$28,000

$8,000

3.5 Years

AHUs and Ductwork Sized to Exceed Standard
90.1-2004 Fan Horsepower Requirements

$500,000

$100,000

5 Years

Chilled Water Cooling

$50,000

$14,000

3.5 Years

Energy Efficient Boilers

$240,000

$60,000

4 Years

Energy Recovery Chillers

$360,000

$120,000

3 Years

Conclusion
High Performance Lighting
$0
$21,000
N/A
By designing and implementing
creative and innovative solutions to
the building’s challenges, the design
Room Occupancy Monitoring
$55,000
$21,000
2.5 Years
team was successful in meeting the
Table 1: Energy-efficiency improvement payback.
goals of the Aurora Medical Center.
The installed energy-efficient equipment can be optimized to provide more than $340,000 in vironmental quality and patient comfort were maximized,
annual savings with a simple payback of less than four allowing the owner to provide a healthy and healing enviyears (Table 1). Also, throughout the process, indoor en- ronment.

ASHRAE Journal

ashrae.org

June 2013

ASHRAE Journal - June 2013

Table of Contents for the Digital Edition of ASHRAE Journal - June 2013