achieving ashrae 90 plus 30

BY M A R I A RA M O S , P E , L E E D A P , C X A

ACHIEVING ASHRAE 90 PLUS 30

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.

AUDIENCE

• What is your experience with LEED?

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

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

ECM #1

• Increase roof insulation to R-30 and wall insulation to R-15.6 ci• Cumulative savings: 0.2%

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?

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%

ECM #4

• Improve HVAC plants• VFD on tower fans• Reduce cooling, heating pumping energy (22 W/GPM

allowed, 19 W/GPM allowed)• HW boiler 90% efficient

Cumulative savings: 3.2%

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

ECM #6

• HVAC—Increase motor efficiency on fans (to 95%)• Calculate kw-cfm/in-wg for each fan• Cumulative savings: 12.5%

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%

ECM #8

• Add daylighting with continuous dimming, all exterior rooms in proposed• Cumulative savings: 17%

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

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%

ECM#10

• Add heat recovery chiller to proposed• 250 T heat recovery chiller, rejects heat to the heating

plant• Cost

Cumulative savings: 26.0%

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

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

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

QUESTIONS?