energy use in commercial buildings

Energy Use in Commercial Buildings

Annie Smith, EI, CEM, LEED AP BD+CMechanical Engineer

OverviewLearning Objectives• Explain how energy usage in buildings is measured.• Discuss the data found in the Commercial Building Energy

Consumption Survey.• Explore trends in commercial building energy use.• Illustrate the importance of proper energy benchmarking.

Energy Use in Buildings• Fuels

• Electric • kWh, kW

• Natural Gas• CCF (therms)

• Steam• kLBS

• Fuel Oil• Gal (therms)

Energy Use in Buildings• Fuels

• Electric • kWh, kW

• Natural Gas• CCF (therms)

• Steam• kLBS

End‐Use Breakdown

End-Use Breakdown

Convert all energy units

to kBtu!

CBECS Database• Commercial Building Energy Consumption Survey (CBECS)

• Database of energy usage• Statistics related to construction, building technologies,

energy consumption, and building characteristics• Updated every couple of years• Available in PDF and spreadsheet formats

Access It • Query Tool:

http://buildingsdatabook.eren.doe.gov/CBECS.aspx

CBECS Database• Various topics to

explore• Most familiar

with commercial sector

http://buildingsdatabook.eren.doe.gov/

CBECS Database

Acknowledgement: Terry Townsend, PE

National Trends• Which facility types are impacting the overall trend?• Where are they located?

CBECS Database


CBECS Database

St. Louis (Zone 3)

CBECS Database


CBECS DatabaseExample• Office• St. Louis• 100,000sf

Interpreting Results• Sample Size• Energy Use Intensity

(kBtu/sf)• Energy Cost Index

($/sf)• End-Use Distribution

End‐Use BreakdownEnd-Use Breakdown

Heating25%

Cooling9%

Ventilation8%

Water Heating1%

Lighting29%

Cooking0%

Refrigeration3%

Office Equipment

4%

Computer Use8% Misc

13%

Deeper Dive: Weather RegressionPlot energy use and temperature

Information SourcesCorroborate information sources for each facility

You can’t determine potential savings without knowing where it’s being spent!

Ways to Use the DataGoal - Setting• Pick a goal for your facility(ies)• Focus on end uses that use the most energy

Benchmarking• Compare your facility EUI and ECI to other similar facilities.

Reality Check on LEED Energy Models• Can help verify results.

Energy Auditing Tool• Provides clues as to biggest energy users.

Ways to Use the DataPick a goal based on facility type and national median

www.energystar.gov

Ways to Use the DataOngoing benchmarking and energy management

www.energystar.gov

Ways to Use the Data

• BD+C 2009• EAp2: Minimum Energy

Performance• EAc1: Optimize Energy

Performance• EAc2: On-Site Renewable Energy

• BD+C version 4• Integrated Process• Minimum Energy Performance• Optimize Energy Performance• Advanced Energy Metering• Renewable Energy Production

Proposed ModelBaseline

Verify LEED energy model savings

Ways to Use the DataEnergy auditors use it for the end uses

ConclusionsThings to Remember When Using the Database• At a minimum, filter by climate zone, building type, and square

footage.• More input is better BUT you may run into sample size issues.

Uses for the Database• Goal-setting• Benchmarking (initial and ongoing)• Verify energy model results• Energy auditing tool

You can’t manage what you don’t measure!• Database can give you an idea of the major end uses without

even stepping foot in the building.

ResourcesWhat is EUI?• https://www.energystar.gov/buildings/facility-owners-and-

managers/existing-buildings/use-portfolio-manager/understand-metrics/what-energy

Ways everyone can benchmark performance• https://www.energystar.gov/buildings/facility-owners-and-

managers/existing-buildings/use-portfolio-manager/interpret-your-results/ways

CBECS Query Tool• http://buildingsdatabook.eren.doe.gov/CBECS.aspx

Questions?| Thank you!

Annie Smith, EI, CEM, LEED AP BD+CMechanical Engineer

energy use in commercial buildings

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