Transcript - The University of Iowa Facilities Management
University of Iowa Indoor Practice Facility
Outside-the-box HVAC
Lincoln Pearce
,
PE
– KJWW Engineering
David Hahn
– University of Iowa Chilled Water Plant October 13, 2014
• • • • • OUTLINE AND LEARNING OBJECTIVES: Project scope Design criteria Design concepts and solutions Implementation lessons Performance
PROJECT OVERVIEW
PROJECT SITE
BUILDING LAYOUT
DESIGN CRITERIA • Project is being
built in two phases
• Phase 1 (2012 practice field) is heating only. Phase 2 (2014 operations building) requires heating and cooling.
• Desire to
use campus utilities
- chilled water and steam.
• Desire for
quiet system operation
.
DESIGN CRITERIA • High bay space with a
large volume to heat
. Only about 10% of the volume is occupied.
• Tight site – need to optimize site use to
maximize field area - reduce mechanical space
.
• Chilled water was close and plentiful, but sufficient reliable
steam was about $1 million away
.
HVAC SYSTEM OPTIONS CONSIDERED
1) Campus chilled water
and steam HEX with radiant floor heat for field.
2) Campus chilled water
and water-to-water heat pumps with radiant floor heat for field.
3) Campus chilled water
and water-to-water heat pumps with air rotation units for field.
4) Campus chilled water
and natural gas boilers with radiant floor heat for field.
• HVAC SYSTEM SELECTION
Selected Design Solution – Option 2
Route chilled water mains to facility under Phase 1.
• Use campus chilled water return as heat sink for
water to water heat pumps
to create hot water for Phase 1 and Phase 2.
• Use
in-floor radiant heat
under turf field for practice facility heating.
• Use
natural/displacement ventilation ERV and exhaust fans
.
as primary means of summer conditioning. Supplement with an
HVAC SYSTEM SELECTION
Design Benefits
• Water to water heat pumps have a
COP of 2.6 for heating, 4.6 for simultaneous heating/cooling.
•
System produces chilled water
which is sent back to campus mains or used in the Phase 2 facility.
as a byproduct • Chilled water produced is approximately
180 tons
.
• Utility company Phase 1 & 2)
rebate of $343,394
. Heat pump system accounted for 57% of rebate. (Accounts for
ENERGY ANALYSIS •
Based on Phases 1 & 2 – Comparing to System 1 Annual energy cost savings of $33,855
(11%).
•
Annual EUI reduction of 24%
(54.5 kBtu/SF vs. 71.5 kBtu/SF).
•
$1 million lower life cycle cost
over 25 years.
PRACTICE FIELD PIPING AND ZONING
SYSTEM EQUIPMENT Water-to-Water Heat Pump Units
RADIANT FLOOR SYSTEM Manifold Design Details
RADIANT FLOOR SYSTEM Manifold Installation
RADIANT FLOOR SYSTEM In-Floor Tubing
RADIANT FLOOR SYSTEM Transition to Sub-Floor
RADIANT FLOOR SYSTEM Floor Tubing Arrangement
RADIANT FLOOR SYSTEM Sand Floor Base
NATURAL VENTILATION SYSTEM Air Intake and Relief Path
NATURAL VENTILATION SYSTEM Intake Louvers and Dampers
NATURAL VENTILATION SYSTEM Relief Air Path
HEATING SYSTEM FLOW DIAGRAM
Heating with Chilled Water
HEATING SYSTEM DISCUSSION •
Implementation Challenges First system of this type on campus
.
• Campus plant does not want chilled water over 42°F supplied.
Heat pumps must control both chilled and heating water
.
• Campus chilled water though.
PLC interface and building DDC chilled water system
needed to integrate to operate reliably and seamlessly. Separate controls • What is the
R-value of sport turf?
HEATING SYSTEM DISCUSSION •
Getting it Running– Lesson Learned At start up there should only be one evaporator valve open
to allow flow proof for chiller start up.
• All other
evaporator valves should be closed
if their associated compressor is not operating. • The
PID loops for the evaporator control valves
on the heat pump units needed to be sped up. They were responding far too slowly causing wide control swings and instability.
HEATING SYSTEM DISCUSSION •
Getting it Running– Lesson Learned Required manufacturer design staff to physically visit site
to observe issues of chilled water control. The slow responding evaporator valves were main cause of instability.
•
Chilled water system failures in other campus buildings can affect the heat pumps
.
•
Differential pressure set point
system return temperature.
for the chilled water pumps should be reset based on varying campus
HEATING SYSTEM DISCUSSION •
Getting it Running– Lesson Learned Chilled water pumps
flow.
should be enabled to run for 60 seconds prior to enabling the heat pumps to stabilize •
Building heating water loop bypass
heating load reduction.
valve needs to be engaged to maintain system flow in the case of rapid • The PLC for the
U of Iowa chilled water interface was limited in programming capability
. Needed to find rudimentary ways to control the bypass valve.
SYSTEM PERFORMANCE REVIEW • The heating water system has operated in the Indoor Practice Facility for two years.
• Specific knowledge of the system is needed to operate and trouble shoot when required.
• Energy consumption over the past 24 months to heat, ventilate, and light Phase 1 was ….
21 kBtu/SF/year
QUESTIONS? THANK YOU!
Lincoln Pearce
KJWW Engineering 515.334.7937 [email protected]
David Hahn
Thank You!
319.335.8625 [email protected]