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

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

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

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

• 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

• 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

• 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

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

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

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

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

• 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?

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

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%

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%

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%

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.

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

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.

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.

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