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

“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, 25 2016

Overview Source of data Overview of energy consumption Factors affecting energy consumption Methodology Results Conclusions Behjat Hojjati, Tulsa, Oklahoma October, 25 2016

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, 25 2016

Between 1992 and 2012, total delivered buildings energy consumption increased by more than 30 % total delivered energy consumption in commercial buildings, 1992-2012 quadrillion Btu Source: U.S. Energy Information Administration, CBECS 1992, 1995, 1999, 2003, and 2012 Behjat Hojjati, Tulsa, Oklahoma October, 25 2016

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, 25 2016

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, 25 2016

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, 25 2016

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, 25 2016

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, 25 2016

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, 25 2016

Methodology Behjat Hojjati, Tulsa, Oklahoma October, 25 2016

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

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

Decomposition Results Behjat Hojjati, Tulsa, Oklahoma October, 25 2016

Improvement in energy intensity reduced total energy consumption by 4% decomposition of total delivered commercial building energy consumption changes, 1992-2012 percent change Source: U.S. Energy Information Administration, CBECS 1992 and 2012 Behjat Hojjati, Tulsa, Oklahoma October, 25 2016

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, 1992-2012 percent change Source: U.S. Energy Information Administration, CBECS 1992 and 2012 Behjat Hojjati, Tulsa, Oklahoma October, 25 2016

The impact of electricity intensity per square foot was positive decomposition of total delivered commercial building electricity consumption changes, 1992-2012 percent change Sources: Computed from U.S. Energy Information Administration, CBECS 1992 and 2012 Behjat Hojjati, Tulsa, Oklahoma October, 25 2016

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, 25 2016

During the 1992-2003 sub-period natural gas intensity declined over four times faster than in the 2003-2012 sub-period decomposition of total commercial buildings space heating natural gas consumption changes, 1992-2012 percent change Source: Computed from U.S. Energy Information Administration, CBECS 1992, 2003, and 2012 Behjat Hojjati, Tulsa, Oklahoma October, 25 2016

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, 25 2016

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 1992-2003 sub-period had the largest increasing effect on energy consumption, while an increase in the number of buildings had the largest impact in the 2003-2012 sub-period. Behjat Hojjati, Tulsa, Oklahoma October, 25 2016

Thank You U.S. Energy Information Administration www.eia.gov Behjat Hojjati Behjat.Hojjati@eia.gov 202-586-1068 U.S. Energy Information Administration www.eia.gov Behjat Hojjati, Tulsa, Oklahoma October, 25 2016