lessons learned on causes of high energy performance from epa e nergy s tar buildings ashrae 2002...
TRANSCRIPT
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Lessons Learned on Causes of High Energy Performance from EPA ENERGY
STAR Buildings
ASHRAE 2002 Winter MeetingSeminar 41
Thomas W. HicksU.S. Environmental Protection Agency
Washington, DC
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Answer: Common Knowledge
Why Get Involved?
Is 10 MPG high or low for an automobile?
Is 100 kBtu/ft2-year high or low for a typical office building?
Answer: ??
Missing Comparative Metric
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Num
ber
of
Build
ings
Large Variation in Energy Performance
Worst PerformersBest Performers
Site Energy Intensity(kBtu/ft2-year)
National data sets show large variations in energy performance exist even after significant drivers of energy intensity are normalized.
121.129.9 165.786.0 339.4
Basis: Office Buildings, 1995 CBECS
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1 to 100 scale was overlayed - creating a national energy performance rating.
Energy Performance Rating
1
Worst PerformersBest Performers
Num
ber
of
Build
ings
255075100
Rating &Site Energy Intensity
(kBtu/ft2-year)
121.129.9 165.786.0 339.4
Basis: Office Buildings, 1995 CBECS
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• In January 1999, EPA released an energy performance rating system which was intended to be:• Objective• Reasonably accurate• Assess performance relative to peers• Originally just for office buildings
• Recognition is offered (via the ENERGY STAR Label) for:• Buildings whose energy performance is among nation’s top 25%
while• Meeting current standards for indoor environment as verified by a
PE.
History
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• Based on actual annual energy performance
• Not as-designed performance
• Source energy not site energy
• Commonly understood 1 to 100 rating scale
• Rating of 75 or greater = ENERGY STAR
• Accounts for building’s business activity• Operating & physical characteristics, climate (HDD & CDD)
• Adjusts for year to year weather variations• El Niños, La Niñas, colder/warmer than normal, etc.
Details...Inside the Box
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• Benchmarking Tool Database (171 buildings)• Operating characteristics (i.e. hours, occupants, & PCs)
• Physical characteristics (i.e. size, location, & climate)
• Annual energy consumption & expenditures (by fuel type)
• Exit Interviews• 15 minutes, CBECS-like
• 91 of 171 buildings participated
• HVAC equipment and systems
• Energy management equipment and systems
• Building management
• Amenities
• Architectural characteristics
• Self-Selection Bias
Note: 25 of the 171 buildings that earned recognition were removed from the dataset since their size was less than 50,000 ft2.
Data Collection
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Compared buildings earning the ENERGY STAR label in 2000 to buildings found in:
• CBECS 1995• Top 25%, Average, & Bottom 25%
• 1,228 office building records
• 530 records remained after applying screens
• Sampling weights were applied
• BOMA Energy Exchange Report 1997
• 3,364 office building records
• 92 cities in the U.S.
• Data access limited
Note: 1999 CBECS micro data is not publicly available as of presentation date.
Approach
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Filters applied to 1995 CBECS data set involved:
1) ENERGY STAR eligibility requirements• Weekly hours ≥ 35
• Months in use ≥ 11
2) Removal of unreasonable records• Electricity consumption > 0
• # of workers > 0
3) More physically and operationally comparable data
• Building area ≥50,000 ft2
Screening Criteria
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Basic Comparison
Size(ft2)
Hoursper
Week
OccupantDensity
(Occ/1,000 ft2)PC Density
(PCs/1,000 ft2)
YearBuilt
(Median)
ENERGY STAR 274, 917 65 2.65 2.73 1976
CBECS Top 25% 123,051 79 2.72 3.54* 1978
CBECS Average 129,677 75 2.65 3.31* 1978
CBECS Bottom 25% 119,482 79 2.43 2.73* 1974
BOMA EER 209,262 -- 3.31 -- --
* - estimated
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Energy & Cost Comparison
On average…
• buildings in the top 25% have annual energy cost nearly $1/ft2 less to operate
Note: Cost in 2000 U.S. Dollars.
Site EnergyIntensity
(kBtu/ft2-year)
Energy CostIntensity
($/ft2-year)
2000 ENERGY STAR 48.9 1.16
1995 CBECS Top 25% 48.2 1.02
1995 CBECS Average 101.1 2.03
1995 CBECS Bottom 25% 217.0 3.52
1997 BOMA EER -- 2.11
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• Codes and/or original design• Application of:
• energy efficient technologies• renewable energy technologies
• Regular Operations & Maintenance• High level to commitment to performance• Dedicated on-site energy manager• Occupant behavior • Some or All of the above
Does a Single Path to EE Exist?
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Tendencies in Building Characteristics
ENERGY STAR
CBECS Top 25%
CBECS Average
CBECS Bottom 25%
HVAC
Boiler 62% 32% 46% 49%
Chiller 69% 26% 43% 65%
VAV 69% 36% 50% 67%
Energy Efficiency
EMS 85% 23% 43% 56%
Economizer 71% 29% 55% 73%
VSDs 57% 19% 33% 45%
Motion Sensors 47% 8% 16% 21%
Management
Energy Audit 57% 23% 24% 36%
Regular O&M 99% 92% 96% 98%
Equip. Upgrade 76% -- -- --
Percentage of Buildings in Data Set
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Amenities
Percentage of Buildings
Notes:
• Data on Class A, Elevators, Escalators, Atriums, and Balconies was not available for CBECS and BOMA EER data sets.
• CBECS data on glass as the predominant exterior wall material is as follows: Top 25% (12%), Average (15%), Bottom 25% (20%). Data was not available from BOMA EER data set.
Class AGlass
Construction Elevators Escalators Atriums Balconies
57% 21% 82% 2% 30% 21%
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Who’s Running the Building?
Title of Person with Daily Responsibility
BuildingEngineer Custodian
Maint.Contractor
Owner /Manager
EnergyManager No One Other
52% 20% 7% 5% 3% 1% 11%
Noteworthy: rarely have on-site energy managers, building engineers and custodians account for nearly 75%
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Glass Characteristics
0 to 25% 26 to 50% 51 to 75% 76 to 100%
23% 32% 24% 21%
Single PaneDoublePane Triple Pane
45% 55% 0%
Window Types
Percentage of Glass on Exterior Wall
# of Panes for Each Window
Noteworthy: Low-e glass rare, no triple pane windows, single pane as likely as double pane, and no bias toward % of glass.
Tinted ReflectiveLow
Emissivity Operable Storm
43% 20% 10% 8% 21%
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What did They Upgrade?
Lighting Cooling Heating ControlsLoad
Shifting RenewablesOccupantBehavior
65% 51% 39% 49% 22% 4% 1%
76% had completed an energy upgrade within the last 3 years, here’s what they did...
Energy Upgrade Areas
Noteworthy: majority of upgrades involves Lighting, HVAC, or controls, only 4% upgraded with renewables, and just 1% attempted to modify occupant behavior.
Renewables included installations of PV electric generation, solar DHW, and geothermal.
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Operations & Maintenance
HVAC Lighting Windows
98% 58% 28%
What building systems are being actively covered in the building’s O&M plan?
O&M Areas
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Why is Building Efficient?
OriginalDesign
Renovation/ Upgrade
OccupantBehavior
13% 57% 27%
In the opinion of the building manager or representative, why did the building qualify? (only 3 choices)
Reason Building is Energy Efficient
Noteworthy: Original design is the least cited reason for building being energy efficient.
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Systems Covered by EMCS?
Heating Cooling Lighting Hot Water
87% 90% 29% 16%
85% have an EMCS, here’s what systems they are controlling...
Building Systems Controlled by EMCS
Noteworthy: nothing, no surprises here.
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Conclusions
Sample size is relatively small and is subject to self-selection bias, but there appears to be...
• No single path to achieving energy-efficiency• High level commitment to energy-efficiency
Coupled with the• Application of good practice technologies
And• Good operating practices
• Little support that any of the following has an impact:
• Renewables• Percentage of exterior glass • Original design