ASHRAE Journal - December 2012 - 47

2012 ASHRAE Technology Award Case Studies
DB WB Summer 77.7 67.7 Winter 62 –
DP

DB WB Summer 95 74 Winter 10 61.8

Geothermal Heat Pump
FZ

800 cfm (Max.)

Filter
M

Heat Recovery Ventilator
T RH

1,550 cfm

1,550 cfm MERV 13 Filters Water from Geothermal Field
DB WB Summer 76 63.3 Winter 70 52.2

1,550 cfm Humidiﬁer
T RH C

800 cfm 800 cfm Filter

T M

Water to Geothermal Field 1,550 cfm

Learning Center 100

800 cfm (Max.)

800 cfm to Storage 108

Figure 1: Energy recovery ventilator, geothermal heat pump for learning center.

The ﬁnal design target was LEED Platinum certiﬁcation and to use solar energy to power building systems. The project was somewhat delayed to acquire additional funds, and to obtain renewable energy grants. The design engineers focused on maximizing LEED points for water efﬁciency, energy and atmosphere, and indoor environment. The architectural ﬁrm used exterior spaces for exhibits. This decision helped reduce the building’s overall size, which created a smaller internal volume and helped contain costs and minimize the energy footprint.

Geothermal Heat Pumps
Two geothermal heat-pumps are used for air-conditioning of the entire building. A typical heat pump system (Figure 1) has a cooling efﬁciency rating of 15.39 EER or 0.78 kW/ton and heating efﬁciency rating of 4.45 COP. The geothermal heat pumps were sized to meet the winter heating load to ensure that supplemental heating is not required during the winter. In the Chicago metropolitan area, heating requirements govern the size of heat pumps. Therefore, the project uses energy recovery ventilators (ERVs) to reduce the size of the heat pumps. ERVs recover heat from exhaust air to preheat outside air during winter and precool outside air during summer before introducing the air to the heat pumps for mixing with return air. This helped reduce the size of the heat pumps, eliminated reheating requirements, and reduced the size of the geothermal loop. The heat recovery units are rated at 60% efﬁciency. Value engineering was an ongoing process during the design phase to stay within budget.

tors can see through the display and into the building. The lighting in the learning center consists of indirect light with metal halide lamps. The metal halide lamps have twostep controls that use solar light sensors. The rest of the areas are provided with T8 lamps and electronic ballasts controlled by occupancy sensors. Outdoor spotlights are used to illuminate the exhibits to prevent direct proliferation of light to the dark sky. Solar bollards powered by solar light are used to illuminate the walkway to the building from the roadside.

Orientation & Natural Ventilation
The building has an east/west orientation, and the solar gain was offset using large overhanging eaves on the southfacing façade and minimal eaves to the north. The 20 ft (6 m) high windows provide visitors incredible views of the prairie and allows for daylighting, saving energy. Operable windows in every space allow prevailing breezes to ameliorate temperatures without using energy. Careful attention to cross ventilation design means that the building is comfortable in the summer without mechanical systems running, despite being completely exposed on the prairie. Two-thirds of the roof is vegetated with the other one-third used for photovoltaic panels. The roof has an Rvalue of 38. The walls are designed with a U-value of 0.039. A window shading coefﬁcient of 0.25 is used.
December 2012

Building at a Glance Evelyn Pease Tyner Interpretive Center at Air Station Prairie
Location: Glenview, Ill. Owner: Glenview Park District, Illinois Principal Use: Interpretive center Includes: Museum and learning center Visitors: More than 2,550 visitors annually Gross Square Footage: 6,466 Conditioned Space: 3,000 ft2 Substantial Completion/Occupancy: Oct. 2006/April 2007

Lighting and Daylighting
Every space within the building is lit with natural daylight and has a view to the prairie. Because of the amount of natural daylight in the building, electricity consumption for the lighting system is minimized. The display cases and shelves embedded within the façade are transparent, allowing sunlight to penetrate. Also, visi-

ASHRAE Journal

ASHRAE Journal - December 2012

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