1. Factors Affecting U.S. Commercial Buildings Energy Consumption, 1992-2012
For
USAEE 2016 Conference
October 25, 2016 | Tulsa, OK By
Behjat Hojjati, PhD

2. “The opinions and conclusions expressed herein are solely those of the author and should not be construed as representing the opinions or policy of any agency of the United States Government.”
Behjat Hojjati, Tulsa, Oklahoma
October,

3. Overview Source of data Overview of energy consumption
Factors affecting energy consumption
Methodology
Results
Conclusions
Behjat Hojjati, Tulsa, Oklahoma
October,

4. Data Source: Commercial Buildings Energy Consumption Survey (CBECS)
The only national-level survey on buildings characteristics and energy use
CBECS includes all buildings >1000 square feet that are not residential, industrial, or agricultural with 50 percent or more commercial activity
Multistage area probability statistical sample
Behjat Hojjati, Tulsa, Oklahoma
October,

5. Between 1992 and 2012, total delivered buildings energy consumption increased by more than 30 %
total delivered energy consumption in commercial buildings,
quadrillion Btu
Source: U.S. Energy Information Administration, CBECS 1992, 1995, 1999, 2003, and 2012
Behjat Hojjati, Tulsa, Oklahoma
October,

6. Electricity continued to be the main energy source in U. S
Electricity continued to be the main energy source in U.S. commercial buildings
Source: U.S. Energy Information Administration, CBECS 1992 and 2012
Behjat Hojjati, Tulsa, Oklahoma
October,

7. Space heating remains the main energy end- use in U. S
Space heating remains the main energy end- use in U.S. commercial buildings
percentage
Source: U.S. Energy Information Administration, CBECS 1992 and 2012
Behjat Hojjati, Tulsa, Oklahoma
October,

8. A wide variety of activities are performed in commercial buildings
Assembly
Education
Food service
Food sales
Health care (inpatient)
Lodging
large offices (>50,000 square feet)
Small offices (<=50,000 square feet)
Mercantile and service
Warehouse
Other
Behjat Hojjati, Tulsa, Oklahoma
October,

9. Mercantile and services account for the largest shares of buildings, energy consumption, and floorspace; Energy consumption per square foot varies by building type
percent
thousand Btu per square foot
Source: U.S. Energy Information Administration, CBECS 1992 and 2012
Behjat Hojjati, Tulsa, Oklahoma
October,

10. The average size of buildings increased between 1992 and 2012
percent
Source: U.S. Energy Information Administration, CBECS 1992 and 2012
Behjat Hojjati, Tulsa, Oklahoma
October,

11. thousand Btu per square foot
The share of buildings and energy consumption per square foot have grown in the Northeast
percentage
thousand Btu per square foot
Source: U.S. Energy Information Administration, CBECS 1992 and 2012
Behjat Hojjati, Tulsa, Oklahoma
October,

12. Methodology
Behjat Hojjati, Tulsa, Oklahoma
October,

13. Decomposition is a means of quantifying an overall change over time into contributions from component factors
This study distinguishes among four main components affecting U.S. commercial building energy consumption:
Activity: defined as the number of buildings
Structural changes: changes in the mix of commercial activities , the regional distribution of buildings, and the average floorspace
Weather: energy impacts from weather variability
Energy intensity: defined as energy consumption per square foot
The analysis is based on a well-known procedure developed by Ang and Choi referred to as the log mean Divisia method (LMDI)
Reasons for selecting LMDI
its wide use in the literature
relative ease of computation
lack of a residual term
Weekly EIA Briefing, Residential Decomposition
April 13, 2016

14. Total change in energy consumption is expressed as the sum of the changes in component factors
E = total energy consumption,
i = represents the 11 types of buildings,
BD = total number of buildings,
BD i = number of building type i,
S i = share of building type i,
F i = average floorspace of building type i,
W i = weather adjusted energy consumption building type i,
Ii= average energy intensity building type i,
Behjat Hojjati, 31st USAEE/IAEE Austin, November 5, 2012

15. Decomposition Results
Behjat Hojjati, Tulsa, Oklahoma
October,

16. Improvement in energy intensity reduced total energy consumption by 4%
decomposition of total delivered commercial building energy consumption changes,
percent change
Source: U.S. Energy Information Administration, CBECS 1992 and 2012
Behjat Hojjati, Tulsa, Oklahoma
October,

17. The decline in natural gas space heating intensity is more than 4 times the decline for total delivered consumption
decomposition of total commercial buildings space heating natural gas consumption changes,
percent change
Source: U.S. Energy Information Administration, CBECS 1992 and 2012
Behjat Hojjati, Tulsa, Oklahoma
October,

18. The impact of electricity intensity per square foot was positive
decomposition of total delivered commercial building electricity consumption changes,
percent change
Sources: Computed from U.S. Energy Information Administration, CBECS 1992 and 2012
Behjat Hojjati, Tulsa, Oklahoma
October,

19. Energy Intensity declined between 2003 and 2012
decomposition of total delivered energy consumption changes
percent change
Source: Computed from U.S. Energy Information Administration, CBECS 1992, 2003, and 2012
Behjat Hojjati, Tulsa, Oklahoma
October,

20. During the sub-period natural gas intensity declined over four times faster than in the sub-period
decomposition of total commercial buildings space heating natural gas consumption changes,
percent change
Source: Computed from U.S. Energy Information Administration, CBECS 1992, 2003, and 2012
Behjat Hojjati, Tulsa, Oklahoma
October,

21. Electricity Intensity declined between 2003 and 2012
decomposition of total delivered energy consumption changes
percent change
Source: U.S. Energy Information Administration, CBECS 1992, 2003, and 2012
Behjat Hojjati, Tulsa, Oklahoma
October,

22. Conclusions
Between 1992 and 2012 energy intensity in commercial buildings declined.
The decline in energy intensity was affected by lighting and space heating efficiency gains.
The decomposed intensity is significantly different from the calculated aggregate intensity.
An increase in the average size of buildings in the sub-period had the largest increasing effect on energy consumption, while an increase in the number of buildings had the largest impact in the sub-period.
Behjat Hojjati, Tulsa, Oklahoma
October,

23. Thank You U.S. Energy Information Administration www.eia.gov
Behjat Hojjati
U.S. Energy Information Administration
Behjat Hojjati, Tulsa, Oklahoma
October,