seminar 4 – energy performance of active chilled beam installations
TRANSCRIPT
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
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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.
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George Rogers Clark High School
Winchester, Kentucky
18th largest high school in Kentucky
Grades 9 through 12
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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
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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
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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
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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)
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Indoor comfort – Education required
Most schools in the district
operate at 70°F (21.1°C), with
occasional “too warm”
complaints
George Rogers Clark have minimal
complaints even with average
temp of 75°F (23.9°C) due to
dryer building operation
130
120
110
100
90
80
70
60
50
40
30
20
66 68 70 72 74 76 78 80 82
Dry Bulb Temperature (oF)
Hu
mid
ity
Rat
io -
Gra
ins
of
Mo
istu
re P
er P
ou
nd
of
Dry
Air
Relative Humidity
80%
70%
60%
50%
40%
30%
68oF WB
ASHRAE Standard 55 Comfort Zone
Comfort Zone Suggested by Berglund(1)
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Simple System Ductwork Ventilation duct to the beams
Exhaust from classrooms (10% less for pressurization)
6” duct 12” duct
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Four beams typical per classroom
450 cfm (212 l/s) ventilation
15 cfm/person (7 l/s)
Constant volume operation
Active Chilled Beams
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Preliminary Energy Modeling
Electric rate of $0.07/kwh.
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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.
Actual Operational Results
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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
How much was first cost?
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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)
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Cost Savings Construction
Return On Investment - Dollars
No first cost premium
Annual utility dollars saved versus
the replaced and smaller high school
is approximately $65,000
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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
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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
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