Paul Christy
Superintendent
Clark County Public Schools
[email protected]
Seminar 4 – Energy
Performance of Active Chilled
Beam Installations
Successful Application of Chilled
Beams in a High School Building
Font Size 32
Learning Objectives
1.
Distinguish between over designing and opportunities to properly load match a chilled beam
system.
2.
Describe the benefits of a decoupled outside air approach on a chilled beam system using
100% outside air for primary air.
3.
Identify design savings methods to help balance first cost and maximize energy savings to
result in the best return on investment.
4.
Apply chilled beams in a university or K12 classroom to result in a high performance building
design.
ASHRAE is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be
reported to ASHRAE Records for AIA members. Certificates of Completion for non-AIA members are available on request.
This program is registered with the AIA/ASHRAE for continuing professional education. As such, it does not include content that may be deemed or
construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or
dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this
presentation.
Page 2
George Rogers Clark High School

Winchester, Kentucky

18th largest high school in Kentucky

Grades 9 through 12
Page 3
George Rogers Clark High School

Completed August 2013

1,900 student capacity

245,000 SF

Approx. 100 classrooms,
offices, media center,
cafeteria, gymnasium,
auditorium
2015 Center of Excellence Award Winner
George Rogers Clark High School
was built as a replacement high school
Page 4
HVAC System

Multiple Geothermal Water to Water units

Dedicated Outside Air System with integrated WSHP

Active Chilled Beams

Geothermal heat pumps (for high ceiling areas)

Dew point and temperature controls system
Page 5
Still Geothermal – with a twist

Original design 350 heat pumps

Heat pumps still used for
cafeteria, gymnasium and
auditorium

New design 542 active beams

Single Water to water heat
pumps serves 10-15 classrooms
Page 6
Dedicated Outside Air System

Original design was Energy wheel air cooled roof
top units

New design dual wheel dehumidification systems

Ventilation air conditioned to approximately
43°F (6.1°C) dew point

Handles all outdoor load and indoor humidity
using only ventilation air

Recirculation mode for minimum ventilation
during unoccupied times (nights/weekends)
Page 7

130
Most schools in the district
120
ASHRAE Standard 55 Comfort Zone
110
operate at 70°F (21.1°C), with
100
occasional “too warm”
complaints
68oF WB
90
80%
80
70%
70
60%

George Rogers Clark have minimal
complaints even with average
temp of 75°F (23.9°C) due to
50%
50
40%
40
30%
30
Relative Humidity
66
dryer building operation
60
68
(1)
Comfort Zone Suggested by Berglund
70
72
74
76
78
80
20
Humidity Ratio - Grains of Moisture Per Pound of Dry Air
Indoor comfort – Education required
82
o
Dry Bulb Temperature ( F)
Page 8
Simple System Ductwork

Ventilation duct to the beams

Exhaust from classrooms (10% less for pressurization)
12” duct
6” duct
Page 9
Active Chilled Beams

Four beams typical per classroom

450 cfm (212 l/s) ventilation


15 cfm/person (7 l/s)
Constant volume operation
Page 10
Preliminary Energy Modeling
Electric rate of $0.07/kwh.
Page 11
Actual Operational Results

The old high school was 30% smaller and has 35% more expensive utilities

National average high school runs 96 kbtu per ft2 (8.9 kbtu per m2)

George Rogers Clark is running at 31 kbtu per ft2 (2.9 kbtu per m2)

2/3 reduction on energy confirms preliminary energy analysis accuracy

High efficiency lighting and well built envelope contribute to the overall
success of the building, but the HVAC is a large part of the utilities.
Page 12
How much was first cost?

The mechanical system installed for
$19.50 per ft2 ($1.81 per m2)

Cost was equal to the estimates given for
the original geothermal heat pump design
Page 13
Cost Savings Construction

Less geothermal wells required

Less ductwork (water in lieu of air)

Less pipe than traditional geothermal

Less number of geothermal units

1 water to water unit vs 10 heatpumps)
Page 14
Return On Investment - Dollars

No first cost premium

Annual utility dollars saved versus
the replaced and smaller high school
is approximately $65,000
Page 15
Return On Investment - Sense

Fewer teacher complaints

Quieter classroom

More comfortable room conditions

Constant Ventilation to the classrooms

Less absenteeism

Less maintenance

No Filters (vacuum coil once / 5 years)

No Drain Pans
Page 16
Parting thoughts

Condensing beams (raining in classroom) is not a concern
if you design for humidity control first

Educate the occupants that the building will “feel”
different than other buildings, they will adapt

Worry about air comfort, don’t try and do a room with one or
two beams as it will not have good room coverage.

Enjoy the results
Page 17
Questions?
Paul Christy
[email protected]
Page 18