Benchmarking Building Energy Performance

1
Benchmarking Building Energy Performance

• Ron Shelton/Terry Sharp
• Oak Ridge National Lab
• August 7, 2003

2
Value Of Benchmarking

• Identify inefficient buildings
• Identify high performers
• Target buildings
• Estimate energy cost savings potential
• Track progress or degradation
• Marketing
• Establishing performance targets

3
Benchmarking Approaches

• Averages
• Medians
• Simple Distributional Ranking
• Normalized Distributional Ranking

4
Energy Use Intensity (EUI) Is A Common Way Of
Expressing Building Energy Use
Energy use intensity (EUI)
(building total energy use / gross square feet )
5
A Distribution (Histogram) Of Building EUIs Is
Skewed
6
In Skewed Distributions, Averages Exceed Medians
(Hospitals Example)
Median-404 (50)
Average-438 (59)
7
Choose Medians Over Averages And Distributional
Ranking Over Both

• If you prefer one sample statistic, choose median
  value over an average
• A better way is to rank your building relative to
  its location in the population

8
Distributional Ranking
50
75
25
Efficient
Inefficient
90
10
9
Arranging As A Decreasing Cumulative Distribution
Easily Gives Sample Rank
A hospital using 280 kBtu/sqft is efficient and
scores a 70.
o
A hospital using 600 kBtu/sqft is inefficient and
scores a 20.
o
10
ORNLs Benchmarking Website Has These
Distributions And A Tool For Generating Your Own
For

• Office
• Health care
• Food service
• Food sales
• Skilled nursing
• K-12 Schools
• Public assembly

• Educational
• Lodging
• Laboratory
• Parking garage
• Mercantile and service
• Warehouse

http//eber.ed.ornl.gov/benchmark/
11
The Benchmarking Tool in Use Iowa
12
Other Important Drivers Can Strongly Influence
Energy Use And May Need Normalization

• Offices operating hours, occupant density,
  number of computers
• Schools year-round use, number of students,
  swimming pools, climate
• Hospitals service type (acute / tertiary),
  number of beds, number of floors

13
EPAs Energy Star Portfolio Manager Provides
Advanced Benchmarking For
Available Now
Available Soon

• Offices
• Health care
• Hotel/Motel
• Supermarket/Grocery
• K-12 Schools

• Medical Office
• Banks/Financial Centers
• Courthouses
• Dormitory

http//estar3.energystar.gov/pls/portfolio/Pm_Main
.Login
14
Summary

• Beware averages
• Simple ranking by EUI is a good approximation for
  comparisons (ORNLs tools can help)
• Limited and simple data needed
• Distributional scoring is excellent for portfolio
  management
• benchmarking, target setting, targeting
  investments
• tracking progress, degradation, or persistence
• identifying poor or model performers, etc.
• Ranking where important secondary drivers are
  accounted for is best (EPAs tools can help)