Commercial Buildings Sector
February 14, 1996
EIA Session Summary
"To achieve efficiency in energy use" is
part of the U.S. Department of Energy's mission. By measuring energy-efficiency changes,
we have a way of knowing if we have achieved our goals.
Energy efficiency is an interesting and useful
concept for analyzing energy use. Energy efficiency is analyzed in relative terms; For
example, "is energy efficiency increasing or decreasing," rather than "what
is the energy efficiency of a particular energy-requiring product or service?"
Considered in relative terms, energy efficiency is a fairly simple concept to describe
theoretically--energy-efficiency improvement occurs when more or enhanced goods or
services are provided with level energy inputs. Energy-efficiency loss occurs when more
energy inputs are required to produce the same or reduced products or services.
In reality, however, efficiency is difficult to
measure. Because energy needs to be assessed relative to the amount of product or service
provided, energy-use rates, commonly called energy intensities, are the measures
ordinarily used to assess efficiency trends. Energy intensities reflect not only energy
efficiency but also changes in other effects such as weather and extent of occupancy.
However, the advantage of considering individual energy intensities is that you may easily
measure and track them over time.
Analysts of energy-efficiency trends in
the commercial building sector are particularly frustrated by the current insufficiency of
energy data for this sector. The Commercial Buildings Energy Consumption Survey (CBECS) is
the only important source of these kinds of data. It seemed natural that much of the
discussion in this session related to CBECS specifically.
How Should Energy Efficiency be Defined in the
Commercial Buildings Sector?
The workshop participants agreed that there was more
than one indicator of energy efficiency. One participant suggested that "Btu per
square foot-hour" is the closest to what an engineer would use to build something.
Other participants thought that energy efficiency was defined in a strictly technical
manner by many experts. In general, the participants agreed that the ultimate use of
energy-efficiency indicators should determine how it is defined.
Who is the Audience for Commercial Buildings Sector
A workshop participant suggested that EIA ask the
questions, "Who is the customer? Who will use the energy-efficiency indicators?"
EIA staff present at the workshop noted that there are two types of uses for the CBECS
- Individual Building Comparisons. Building
managers and owners use the CBECS data to compare their building to the national average
and are not interested in the "big picture...the national aggregates."
- Multiple Building Characteristics Comparisons.
Analysts at the National Laboratories and research institutes are concerned about the
"big picture...the national aggregates." Sometimes manufacturers who want to
sell a new product will make market saturation inquiries. Utilities also use the CBECS
data because they are concerned with the future effects of deregulation and want to plan
for it, such as finding out who are the largest energy consumers.
With respect to the measurement of energy
efficiency, workshop participants felt that there appears to be a need for three different
kinds of energy-efficiency indicators, depending on who uses the indicator:
- Building Owners. Building owners need
energy-efficiency indicators that will serve as a touchstone for comparing their
building's performance to the national average.
- Market and Policy Analysts. Market and policy
analysts need aggregate energy-efficiency indicators for identifying energy-efficiency
opportunities in terms of building characteristics.
- Energy Analysts. Energy analysts need
energy-efficiency indicators to measure how well we are doing on a local and national
Should EIA Consider Combining Residential and Commercial
Most of the workshop participants agreed that end
uses within the residential and commercial buildings sectors are so different that they
should not be combined. Some participant comments were:
- Characteristics of Sectors are Different.
The residential sector is dominated by single-family homes. Single-family households
use energy differently than that of commercial buildings. Also, the mix of commercial
buildings differ so much between themselves, that if single-family homes are added to the
mix, energy-use patterns would be extremely complex and difficult to understand.
- Different Policies for Different Sectors. There
are very different policies in place, or which could be enacted, to influence energy
demand in the residential sector versus the commercial buildings sector.
Other workshop participants were not as negative
about combining the residential and commercial building sectors; This position was due to
the difficulty of analyzing commercial building sector trends in isolation from the other
sectors. These workshop participants argued that:
- Buildings are Difficult to Separate. Energy
efficiency in buildings can get tangled up with energy efficiency in transportation
issues, and perhaps EIA should not get into having to classify between the two.
- Homes are Increasingly Being Used as Businesses. The
fastest growing service sectors may well be in the home and not the commercial building
sector due to more people working at home.
What Are the Important Structural Parameters in the
Commercial Buildings Sector?
In discussion, workshop participants covered many
diverse issues that EIA needs to consider in developing any further research into
energy-efficiency measurement in the commercial building sector. Listed are some of the
- Need Activity Adjustments. EIA needs to make
activity adjustments (whether the building's activity has stayed the same) along with
- Separate Energy Intensive Buildings from Buildings
that are Not Energy Intensive. EIA may need to examine energy intensive and
nonenergy-intensive buildings separately. Details should be reviewed such as specific
configuration of buildings.
- Examine Specific Structural Parameters. EIA
should examine parameters such as the effects of shifts in building space, building mix
changes, and increases in new construction.
- Impact of Computers. In the information
Technology area, computers are having a substantial impact on electricity demand, but what
may be more important is the effect of telecommuting on work space. There may also be a
reduced need to locate offices where business is done. Most work, especially computer
programming, can be done elsewhere such as the home.
- Vacancy or Occupancy Density. If vacancy or
occupancy density is reviewed, it seems that many occupants have relocated to other
low-cost real estate markets to save money. However, there may not be an efficiency
change. Because real estate is cheap, the company may occupy more floorspace and use more
- Location of New Buildings. The use of
electronics for business and transportation substitutes have changed the demographics of
where new buildings/business areas are built. For example, Tysons Corner, VA has more
office space than Memphis, TN. Satellite cities (where costs are lower) are taking the
place of the traditional central city-suburb model.
What is the Appropriate Disaggregation for Analysis of
Efficiency in Commercial Buildings?
Workshop participants suggested the following:
- Suggested End Uses. For policy analysis and
research & development (R&D) planning as well as forecasting, what is needed is a
breakdown to the following components:space cooling, lighting, space heating (electric)
and office computing. For a top-down approach, EIA needs to provide sector-level and
end-use variations (e.g., fuel types and uses). Indicators by specific building activities
are less important.
- Need for Weather Adjustments. Data should also
be normalized for weather differences to be applicable for international comparisons.
- Separate Workplaces from Service Areas. The
commercial stock could be divided into buildings where people come to work (employees as
unit of measure) and buildings where guests or visitors come such as hospitals, schools,
and hotels. The purposes of these buildings are different and the appropriate measure of
activity is, therefore, different.
- Use Representative Buildings. EIA should
consider small sets of representative buildings to arrive at some efficiency measure. The
kind of buildings selected for these small data sets could be based on current issues as
identified by CBECS. Detailed case studies should be performed to allow EIA to say
something about building energy efficiency.
- Need to Use Different Energy-Intensity Indicators.
Calculating energy use per gross domestic product (GDP) by building activity would be
misleading; only at the sector level would service GDP be relevant. EIA needs to look at
other indicators at the building scale. EIA needs to know GDP per square foot to determine
the value produced for a particular building or class of buildings. If commercial building
sector indicators are to be considered in an integrated analysis with other sectors, it
would be necessary to find other denominators: in terms of dollars GDP-- perhaps a revised
service sector split-out of GDP for example.
- Conventional Energy-Efficiency Indicators are Not
Enough. Energy efficiency can be defined in terms of the quantity of energy needed to
provide a warm environment and the quantities of lighting to provide adequate light in a
pleasing and comfortable visual environment. Yet we only assume the space is comfortable,
and we just consider lighting energy used on a per-square-foot basis. Therefore,
conventional indicators of energy intensity do not give the answer to the question of
whether commercial buildings are becoming more energy efficient. For example, we are
interested not in air-conditioning energy consumed by the building stock, or
air-conditioning energy consumed by the air-conditioner stock, but air conditioning energy
consumed by the stock of buildings with air-conditioners.
- EIA Should Publish Snapshots. It may be
appropriate for EIA to consider the sector's leading indicators, by publishing sub-sector
"snapshots...a point in time" as opposed to time trends. Aside from being less
expensive to collect, snapshots are more valuable because EIA and its customers to learn
from one moment in time. EIA needs to study what is happening now, and should not worry
about establishing a baseline 6 years ago or projecting into the future.
- EIA Should Study the Conversion of Buildings. One
of the most rapid employment- growth areas from 1979 to 1992 was the service sector.
Office space has grown much faster than other types of commercial buildings, but much of
the office space boom has finished. Perhaps EIA should look at the conversion of buildings
-- how the stock is being redefined and converted, rather than how energy consumption
changes every year.
Should Energy Efficiency be Measured with Primary or
Primary energy is defined as the amount of energy
delivered to a sector and adjusted to account for the energy sources used to produce the
energy, e.g., energy used to generate electricity. Included also is the energy lost in
delivering the energy to a customer, e.g., the electricity lost in the transmission and
distribution of electricity. Site (delivered) energy is the amount of energy delivered to
a household. Energy generation, transmission, and distribution losses are not included.
EIA used only estimates of site energy in the report Measuring Energy Efficiency in the
United States' Economy: A Beginning, used as the "straw man" for the EIA
The workshop participants were split as to whether
primary or site energy should be used. Some participants think site energy should be used;
many believe that both kinds of data are needed for energy-efficiency analysis. The
participants did raise a few other issues as follows:
- Energy Used at a Multi-Building Facility. For
facilities with cogeneration, how do you account for one building that uses steam for heat
and the other that uses electricity? EIA's response was that it looks at energy and steam
heat in the building but does not handle these issues well.
- Localized Losses. Cogeneration involves a
localized loss versus electric system losses included in primary energy calculations. One
of the EIA staff stated that in the CBECS, EIA combines cogeneration with district heating
without adjusting for localized losses. EIA asked the participants, "How should EIA
handle this issue"? There were no responses.
What are the Tradeoffs Between Level of Detail and
Frequency of Data Collection and Reporting?
EIA is presently assessing options for reducing
survey costs in the current environment of limited resources. If the choice of cost
reductions in CBECS is between conducting the survey less frequently and collecting fewer
data items, overwhelmingly, the workshop participants preferred for EIA to keep the data
items and conduct the survey less frequently. This opinion fortunately coincides with
economic best practice. Since a large proportion of interviewing cost is getting the
interviewer to the house, eliminating data items reduces cost much more slowly than
decreasing interviewer trips--which is what decreased frequency does.
Comments by workshop participants included:
- CBECS Should Be Fielded Less Often and Specialized
Studies Added. Trends analysis for the commercial buildings sector looks like the
residential sector. There was movement from 1975 to 1985, but it has been flat since then.
(However, as noted a recent DOE report, the observed flatness was really caused by two
offsetting trends during that time.) So why should the CBECS be done often? Specialized
studies are more explanatory than the full CBECS and, therefore, data collection could be
at longer intervals.
- EIA Should Field a Core CBECS with Topical
Modules. Without CBECS, there would be no data for the commercial buildings sector. On
the other hand, CBECS could be limited to core questions, and have modules designed to
focus on one area, such as office equipment in alternating surveys. At each CBECS, the
focus could be different.
What is EIA's Role in the Provision of Energy-Efficiency
Indicators for the Commercial Buildings Sector?
The following are some suggested EIA roles from
- Use "Snapshots" as Indicators of Energy
Efficiency. The term "indicator" usually suggests time-series data and
analysis, but, in fact, that would not begin to exhaust the possibilities. For example,
certain kinds of "snapshots" might also serve as indicators of energy
- More Focused Analyses. EIA should undertake
more reports like Lighting in Commercial Buildings, which are more technology-specific and
- Other Shorter Studies. EIA should undertake
case studies and snapshot compilations on hot issues and other important and interesting
- Assistance to State or Municipal Agencies. EIA
should publicize the availability of their data sets as well as the definitions and
methodologies to State or municipal agencies that are closer to the energy users. These
users may be better positioned to analyze efficiency in the commercial building sector or
advance the cause of energy efficiency.
- EIA as a Collector and Consolidator of Data. EIA
could be the collector and consolidator of data sets amassed by diverse organizations.
There is a wealth of data available. Industry is the best source of data like bed-days,
meals served, etc. Utilities, especially, the large utilities and those located in large
urban areas, have historical databases. There are problems, however, with using utility
databases such as different utilities having different data definitions and survey
questions on this topic may be directed to:
Modified: October 17, 1999