Energy Efficient Server Rooms at the University of Cambridge
Achieving ASHRAE 90 plus 30
1. B Y M A R I A R A M O S , P E , L E E D A P , C X A
ACHIEVING ASHRAE 90
PLUS 30
2. ABOUT ME
• Employed at Fosdick and Hilmer in Cincinnati
• First LEED project in 2007
• Performed energy modeling on about 10 LEED
projects
• Have achieved platinum, gold and silver status
• Use primarily Trace 700 for energy modeling. I have
also used Equest.
4. RESOURCES AVAILABLE FOR
GUIDANCE
• ASHRAE Advanced Energy Guidelines
• http://aedg.ashrae.org/
• Has guides for a variety of buildings, achieving plus
30 and plus 50% savings
5. SAMPLE MODEL ASSUMPTIONS
• Midrise Medical Office building, 5 floors, 150,000 SF
• Space types: enclosed office, open plan office,
corridor, conference area, exam rooms, operating
rooms
• Started out with baseline and proposed both 100%
ASHRAE compliant (so nothing in the proposed did
not meet ASHRAE 90)
• 32% glass
• System 7s with 95% filtration, ducted return
• Hot water boiler, screw chillers
6. ECM #1
• Increase roof insulation to R-30 and wall insulation to
R-15.6 ci
• Cumulative savings: 0.2%
7.
8. ECM #2
• Fenestration improvements, U value of 0.29,
SHGC=0.34
• Resulted in cumulative savings of 0.61%
• Added in sunshades for south facades, but took
them back out because they caused a slight
increase in energy usage
• Glass ECMs may have a bigger impact on a
different building
• What happens when there is an unexpected result?
9.
10.
11.
12. ECM #3
• Improve lighting W/SF
• Exam rooms, 1.2 (1.66 allowed)
• Laboratory, 1.2 (1.8 allowed)
• Office, 0.9 (1.1 allowed)
• Did not change patient rooms (0.62 allowed), operating
rooms (1.89 allowed), or corridor (0.89 allowed)
• Did not include any savings for occ sensors in non-required
areas
• Cumulative savings 1.35%
15. ECM #5
• Improve chiller efficiency to 0.57 kw/T (need a VFD
chiller to accomplish this)
• Cumulative savings: 5.4%
• A lot more can be done here if your building has
centrifugal chillers
16. ECM #6
• HVAC—Increase motor efficiency on fans (to 95%)
• Calculate kw-cfm/in-wg for each fan
• Cumulative savings: 12.5%
17. ECM #7
• Bring miscellaneous equipment down to around
25% of baseline (by energy usage, not cost at this
stage)
• Not strictly an ECM, but helps other ECMs have
more impact
• Will impact the baseline
• Cumulative savings: 14.5%
18.
19. ECM #8
• Add daylighting with continuous dimming, all
exterior rooms in proposed
• Cumulative savings: 17%
20. WHAT TO DO NEXT?
• We’ve exhausted our list from the plus 30 guide
• Go to the plus 50 Hospital. Also browse the other
guides
• Some other resources:
• http://www.i2sl.org/resources/toolkit.html
• http://energy.gov/eere/efficiency/buildings
• I’m going to add a few ECMs I’ve used previously
21. ECM #9
• Reduce airflow in O.R.s at night
• Reduce from 20 ACH daytime to 50% at night
• Will require tracking boxes on supply, return for pressurization
control
• Can be used in labs or other spaces where a high
airchange rate is required by ASHRAE 170
• Cumulative savings: 22.8%
22. ECM#10
• Add heat recovery chiller to proposed
• 250 T heat recovery chiller, rejects heat to the heating plant
• Cost
Cumulative savings: 26.0%
23. OTHER POTENTIAL ECMS
• Separate OA treatment
• Energy recovery
• Use energy star rated computers, etc and take
credit for it in the W/SF receptacle density
• More efficient elevators (trackless), take credit for it
in the miscellaneous loads
24. MINOR REFINEMENTS
• Custom unloading curves
• Raise chilled water temps if you can (and use
improved chiller kw/T)
• Calculate out actual u value of window assy
• Consider exterior lighting savings
• Increase supply air reset by 1 degree
25. LEED/HIGH ENERGY SAVINGS PROCESS
Development
of Schematic
Energy Model
•Identify and evaluate major cost impact items,
i.e. Daylighting sensors, LED lights, Heat
recovery chiller, improved glass or insulation.
Contractor input very helpful for pricing.
DD/CD
•May have to create an energy model before rooms are
known. This model will be “throw away”
Major cost
impact items
Construction •Energy model assumptions
are documented in submittals
• Refine equipment
selections, make sure any
model assumptions are
reflected in bid docs
