Residential Sector Energy-Efficiency
February 13, 1996
EIA Session Summary
The Energy Information Administration (EIA) has a
new way of doing business ---focusing on the customer, the data users. In this workshop,
there was a consensus that EIA has the database, and from available data, energy
intensity, e.g. energy used per household, can be calculated. But what is energy
efficiency and can energy efficiency be addressed using these measures?
Energy efficiency is an interesting and useful
concept for analyzing energy use. Energy efficiency is analyzed in relative terms; that
is, "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 not only measure
energy efficiency but also measures changes in other entities such as changes in weather
and household income. However, the advantage of considering individual energy intensities
is that you may easily measure and track them over time.
How Should Energy Efficiency be
Defined in the Residential Sector?
The discussions generated many views on how energy
efficiency should be defined. EIA should address or at least consider the different
viewpoints such as the following in the development of future research plans:
- Structural Components to Consider. In any
analysis of energy efficiency in the residential sector, especially for any international
comparisons, energy intensities need to be presented that take into account important
differences between households such as : hot water energy use per capita (some nations
bathe less than others, etc.); household energy use per major appliance; lighting
electricity use per household; energy use per square foot, and energy use by number of
- Changes in Energy Efficiency Should be Converted
to CO2 Emissions Reductions or Increases. Environmental impacts may be considerable.
Congress and the public would be interested in how changes in energy efficiency relate to
changes in CO2 emissions
- One Economist's Perspective of Energy Efficiency.
Energy efficiency is the energy-to- service ratio by which we can transform energy into
household services, e.g., the service is heating the home. Energy-efficiency change
affects the cost of service to the household, and the household responds by changing its
consumption. This is comparable to the impacts of a change in the price of energy.
is EIA's Audience for Energy-Efficiency Indicators?
- EIA Has an Expanded Sense of the Audience.
During the course of the workshop the participants identified at least four different
- Sound-Bite Audience. There have been
surprising media responses to published household energy-use statistics; national and
regional newspapers often like the sound-bite quality macro-level statements about energy
use. "Sound bites," for example, when used by the media or Congressional staff,
may allow EIA to enlarge its audience.
- International Audience. There is an urgency
unlike ever before due to the Rio Accords (international agreement to voluntary reduce
CO2. emissions) and attempts to reach other international agreements. If we know the
components of energy efficiency/intensity change, we could apply analysis to foreign
- Analyst Audience. Energy-efficiency indicators
using highly disaggregated data at the individual household level would satisfy this
audience. Satisfying this audience may be difficult. These types of energy-efficiency
indicators are costly and may not be within the limitations of EIA's available resources.
- Policy Makers May Only Need Simple Aggregates.
Policy makers may not be interested in highly technical energy-efficiency indicators. They
may be more satisfied by the simplest aggregates: for example, reduction in absolute
residential energy consumption relative to a base year.
Should EIA Consider Combining Residential and Commercial
The workshop participants agreed that end uses
within the residential and commercial buildings sectors are so different that they should
- 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 that could be enacted, to influence energy demand
in the residential sector versus the commercial buildings sector.
Considering Cost, Convenience, and Usefulness,
What is Appropriate End-Use Detail?
"More data are always better" seemed to be
an underlying plea from some of the participants of this workshop. Some of their arguments
to support this plea were:
- Need End-Use Data for Modeling Energy Consumption.
In EIA's National Energy Modeling System (NEMS) modeling efforts, energy efficiency is
considered on a technology-specific basis. Modelers account for the difference between a
regular heat pump and a ground-source heat pump, as an example. This starts with the
largest component of household energy-use -- space heating.
- Need Micro-Level Data for Estimation of Policy
Effects. By starting at a micro-level and building up to the aggregate, bottom up, you
have a basis for estimating the kinds of deployment policies or technology policies which
may get you to CO2 stabilization.
Within Budget Limitations, What Should EIA Do to
Provide Aggregated and Disagregated Data?
To satisfy a wide range of customers, workshop
participants suggested that EIA needs to:
- Publish Two Types of Data. EIA needs to
publish data that incorporates losses from the generation, transportation, and
distribution of electricity and data that do not incorporate these losses.
- Investigate Different Approaches. EIA needs to
look at approaches that start at the individual household level, or even at the equipment
level, and build up energy efficiency assessment piece by piece (bottom-up); and look at
approaches that start at the residential-sector level and try to separate energy
efficiency from the effects (top down)
- Separate Sectors. EIA needs to keep
residential and commercial buildings sectors separate.
- Reduce Collection Frequency and Increase Detail.
EIA should cut back on how often the data are collected and present more detailed data.
- Present Data for Different Customers. EIA
should have a variety of information available to satisfy different customers.
- Obtain Input from Customers. EIA needs to hold
more workshops like these to get customer feedback; continue to hold user-needs meetings
before each survey is fielded.
- Know the Issues. It is important, for data
collection and analysis prioritization that EIA considers, for example, where regulators
have been active or where they are likely to regulate in the future.
- Know What is Possible. EIA, as part of this
workshop and other meetings of customers, has had many requests for more data; EIA needs
to explore what data requests are feasible or not feasible to collect within the scope of
availability and budget limitation.
- Search for Other Data Sources. EIA should use
all available data including data collected outside of EIA such as the U.S. Census Bureau
and the Bureau of Labor Statistics.
What are the Important Structural Parameters in the
Changes in energy intensity are effected by
trends in household size, floorspace, occupancy, behavior, and weather. Heating and
cooling energy use are large components of the residential total, and weather trends can
increase or decrease space-conditioning requirements. For example, the base year for the
Rio Accords was 1990; that winter was colder than normal in Europe and warmer than normal
in the U.S. The baseline will have a huge impact on the ability of participating nations
to achieve certain targets if the measurements do not consider the role weather played in
the energy consumed in 1990 by participating nations.
Other important structural parameters that workshop
participants suggested for EIA to consider in any future energy-efficiency analysis are:
- New Home Volume. New homes are not only
getting larger in terms of square footage, but also getting larger volume-wise. In fact,
volume may become more important than only the square footage of a home.
- Type of Ownership. Knowing the type of
ownership also helps an analyst know the saturation, which is necessary for modeling and
forecasting. Saturation data provides the reality check.
- Family Structure. The impacts on household
size of divorce and fractionated families needs to be understood. In the past 25 years,
the shrinking household size and the growth in per capita floorspace have had significant
impact on CO2 levels which needs to be decompose in further analysis.
- Utilization of the Home. The amount of time
household members spend at home and their home activities influence the amount of energy
usage. The utilization of the home for business purposes is a really important new change,
for example. The major impact will be reflected in the commercial buildings sector, where
it will be necessary to add less new floorspace as a result of fewer people needing work
space outside the home.
- Standard for Comfort. The standard for comfort
changes over time and is different for different types of households. In the long term,
this trend may have a very large impact. As an example, in the past, the presence of
air-conditioning was a luxury item. Today most new homes are being built with
air-conditioning. Are we becoming less energy efficient because we are using more air
conditioners or is this a structural change?
Should Energy Efficiency be Measured Using
Primary or Site (Delivered) Energy Consumption?
Primary energy is defined as the amount of energy
delivered to a sector 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. There were diverse opinions among the workshop
participants as to whether primary or site energy should be used in the ratios presented
in this type of report. The following are a few of the comments voiced by the
- Not an Issue in the Residential or Other End-Use
Sectors. The problem with using primary energy versus site energy for the end-use
sectors is that changes in energy efficiency will be reflect what is happening in the
utility sector and not the residential or other end-use sectors. Transmission and
distribution efficiency should improve under competition, but this is an issue for an
analysis of energy-efficiency changes in the utility sector.
- Primary Energy Needs to Be Used in the Analysis of
any Environmental Issue Including Energy Efficiency. From an environmental
perspective, primary energy is useful to show the ultimate resource impact of sectoral
energy demand with respect to CO2, for example.
- Site Energy Used Related to Activities Within A
Home. Site energy is necessary if one wants to know what is going on inside the house.
"Fuel choice" does matter; oil-heated homes may consume more site energy than
electrically-heated homes, for example.
- Expenditure Data Should be Used Instead of Either
Primary or Site Energy. From an economist's perspective, using expenditures instead of
primary or site energy would be preferable. This way it does not matter if there is a
shift from electricity to natural gas or vice versa because when the site energy declines
relative to primary, the expenditures would remain relatively level. Deregulation will
affect the choice of fuels. Households will decide what to consume. But one assumes that
competitive pressures would ultimately equalize prices.
If Primary Energy is the Choice Energy Measure, How and Where
Should Energy Losses be Accounted for in the Residential Sector?
This primary versus site debate centered on
electricity, but losses are associated with other energy sources. For example, one could
take distillate fuel oil all the way back to the refinery, even factoring in energy losses
in the fuel delivery trucks. Most of the participants suggested that only the energy used
in the generation of electricity and electricity transmission and distribution losses
should be considered. According to one participant, if one considers other losses besides
electricity transmission and distribution losses:
- Certain losses may be double-counted when one
considers electricity generation. For example, all of the losses associated with
residential use of distillate or natural gas for heating fuel could be double-counted
since these energy sources are used by utilities as well. Thus, counting primary energy by
just counting electricity losses in the end-use sectors and counting primary energy by
counting losses in all sectors, including the generation sector, would be roughly
What are the Tradeoffs Between Level
of Detail and Frequency of Data Collection and Reporting?
In order to begin to move the Residential Energy
Consumption Survey (RECS) to a computerized system, the EIA may have to cut the scope and
detail of the survey. However, if interviewers are using personal computers, what else
could they be doing while they are already in the housing unit, e.g., measure the size of
the home as in past RECS?
EIA is presently assessing options for reducing
survey costs in the current environment of limited resources. EIA has tried,
unsuccessfully, in a pretest to conduct RECS by telephone using a Random Digitized Dialing
Method of conducting a survey.
If the choice of cost reductions in RECS 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. Note: 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.
The following comments are related to the RECS data
collection and publication than to the measurement of energy efficiency:
- New Home Data Are More Important. If
you know the average Btu per house for existing homes, and you know that newer homes will
consume more energy, the more important demand is to be able to understand
energy-consumption patterns for new homes. This information provides some insight into the
potential energy consumption of the stock of housing in the future.
- The RECS Survey Could be Limited to Every 5 Years
if You Kept the Detail. Canada conducts a large survey of houses every four years but
annually uses flow data, including new construction, sales, etc.
- Need Longitudinal Survey. RECS would be more
useful if it included a longitudinal survey.
- Other Tradeoff. There is a tradeoff between
level of detail and timeliness as well. For example, how soon after we collect data does
it need to be published? The sooner the data are needed, the less data can be presented.
questions on this topic may be directed to:
Modified: October 17, 1999