In 1990, the residential, commercial, and institutional buildings sector was responsible for roughly one-third of global energy use and associated carbon emissions both in the Annex I countries and globally. In that year, buildings in Annex I countries used 86 EJ of primary energy and emitted 1.4 Gt C, accounting for about 75% of global buildings energy use (112 EJ, with associated emissions of 1.9 Gt C). 6 However, the share of primary energy use and associated emissions attributable to Annex I countries is projected to drop; the IS92a scenario projects that global buildings-related emissions from Annex I countries will be about 70% in 2020 and slightly over 50% in 2050.
Greater use of available, cost-effective technologies to increase energy efficiency in buildings can lead to sharp reductions in emissions of CO2 and other GHGs resulting from the production, distribution, and use of fossil fuels and electricity needed for all energy-using activities that take place within residential, commercial, and institutional buildings. The buildings sector is characterized by a diverse array of energy end uses and varying sizes and types of building shells that are constructed in all climatic regimes. Numerous technologies and measures have been developed and implemented to reduce energy use in buildings, especially during the past 2 decades in Annex I countries.
Table 1 outlines measures and technical options to mitigate GHG emissions in the buildings sector, and provides a brief description of the climate and environmental benefits as well as economic and social effects (including costs associated with implementation of measures), and administrative, institutional, and political issues associated with each measure. Tables 2 and 3 provide estimates of global and Annex I, respectively, emissions reductions associated with both energy-efficient technologies and the energy-efficiency measures.7 The estimates for the reductions from energy-efficient technologies are based on studies described in the SAR, using expert judgment to extrapolate to the global situation and to estimate reductions in 2020 and 2050, because most of the studies in the SAR estimate energy savings only for 2010. The estimates for the reductions from energy- efficient technologies captured through measures are based on expert judgment regarding policy effectiveness. These two categories of reductions-"potential reductions from energy-efficient technologies" and "potential reductions from energy-efficient technologies captured through measures"-are not additive; rather, the second category represents an estimate of that portion of the first that can be captured by the listed measures.
2.2. Technologies for Reducing GHG Emissions in the Residential,
Commercial, and Institutional Buildings Sector
A significant means of reducing GHG emissions in the buildings sector
involves more rapid deployment of technologies aimed at reducing
energy use in building equipment (appliances, heating and cooling
systems, lighting, and all plug loads, including office equipment) and
reducing heating and cooling energy losses through improvements in
building thermal integrity (SAR II, 22.4.1, 22.4.2). Other effective
methods to reduce emissions include urban design and land-use
planning that facilitate lower energy-use patterns and reduce urban
heat islands (SAR II, 22.4.3); fuel switching (SAR II, 22.4.1.1, Table
22-1); improving the efficiency of district heating and cooling
systems (SAR II, 22.4.1.1.2, 22.4.2.1.2); using more sustainable
building techniques (SAR II, 22.4.1.1); ensuring correct installation,
operation, and equipment sizing; and using building energy
management systems (SAR II, 22.4.2.1.2). Improving the combustion
of solid biofuels or replacing them with a liquid or gaseous fuel are
important means for reducing non-CO2 GHG emissions.
The use of biomass is estimated (with considerable uncertainty) to
produce emissions of 100 Mt C/yr in CO2-equivalent,
mainly from products of incomplete combustion that have
greenhouse warming potential (SAR II, Executive Summary).
The potential for cost-effective improvement in energy efficiency in
the buildings sector is high in all regions and for all major end uses.
Projected energy demand growth is generally considerably higher in
non-Annex I countries than in Annex I countries due to higher
population growth and expected greater increases in energy services
per capita (SAR II, 22.3.2.2). Although development
patterns vary significantly among countries and regions, general
trends in Annex I countries with economies in transition and non-
Annex I countries include increasing urbanization (SAR II, 22.3.2.2),
increased housing area and per capita energy use (SAR II,
22.3.2.2, 22.3.2.3), increasing electrification (SAR II, 22.3.2.2),
transition from biomass fuels to fossil fuels for cooking (SAR II,
22.4.1.4), increased penetration of appliances (SAR II, 22.3.2.3), and
rising use of air conditioning (SAR II, 22.4.1.1). For simplification, the
authors assume that by 2020 urban areas in non-Annex I countries
will have end-use distributions similar to those now found in Annex
I countries, so that energy-saving options and measures for most
appliances, lighting, air conditioning, and office equipment will be
similar for urban areas in both sets of countries. The exception is
heating which is likely to be a large energy user only in a few of the
non-Annex I countries, such as China (SAR II, 22.2.1, 22.4.1.1.1). In
addition, it is assumed that the range of cost-effective energy-
savings options will be similar for Annex I and non-Annex I
countries by 2020.
2.2.1. Building Equipment
The largest potential energy savings are for building equipment.
Cost-effective energy savings for these end uses vary by product and
energy prices, but savings in the range of 10-70% (most typically 30-
40%) are available by replacing existing technology with such
energy-efficient technologies as condensing furnaces, electric air-
source heat pumps, ground-source heat pumps, efficient air
conditioners, air-source or exhaust air heat pump water heaters,
efficient refrigerators, horizontal axis clothes washers, heat pump
clothes dryers, kerosene stoves, compact fluorescent lamps, efficient
fluorescent lamps, electronic ballasts, lighting control systems,
efficient computers, variable speed drives, and efficient motors (SAR
II, 22.4)
(see Table 1).
Residential buildings are expected to account for about 60% of global
buildings energy use in 2010, falling to 55% by 2050. Based on this
ratio, IS92a scenarios indicate that residential buildings will use
energy that produces 1.5 Gt C in 2010, 1.6 Gt C in 2020, and 2.1 Gt C
in 2050, while commercial buildings will be responsible for emissions
of 1.0 Gt C in 2010, 1.1 Gt C in 2020, and 1.7 Gt C in 2050. Based on
information presented in the SAR, the authors estimate that
efficiency measures with paybacks to the consumer of 5 years or less
have the potential to reduce global residential and commercial
buildings carbon emissions on the order of 20% by 2010, 25% by
2020, and up to 40% by 2050, relative to a baseline in which energy
efficiency improves (see section of
Table 2)
entitled "Potential Reductions from Energy-Efficient Technologies").
2.2.2. Building Thermal Integrity
Heating and cooling of residential buildings is largely needed to make
up for heat transfer through the building envelope (walls, roofs, and
windows). Energy savings of 30-35% between 1990 and 2010 have
been estimated for retrofits to U.S. buildings built before 1975, but
only half of these are cost-effective. Adoption of Swedish-type
building practices in western Europe and North America could reduce
space heating requirements by an estimated 25% in new buildings
relative to those built in the late 1980s (SAR II, 22.4.1.1.1). Although
large commercial buildings tend to be internal load-dominated,
important energy savings opportunities also exist in the design of the
building envelope (SAR II, 22.4.2.1.1). Considerably larger cost-
effective savings are possible for new buildings than for existing
ones (SAR II, 22.5.1). Since most of the growth in building energy
demand is expected to be in non-Annex I countries and a large
percentage of this will be new buildings, there are significant
opportunities to capture these larger savings if buildings are
designed and built to be energy-efficient in these countries (SAR II,
22.4.1).
Overall, based on information presented in the SAR and on expert
judgment, the authors estimate that improvements in the building
envelope (through reducing heat transfer and using proper building
orientation, energy-efficient windows, and climate-appropriate
building albedo) have the potential to reduce carbon emissions from
heating and cooling energy use in residential buildings with a 5-year
payback (or less) by about 25% in 2010, 30% in 2020, and up to 40%
in 2050, relative to a baseline in which the thermal integrity of
buildings improves. Heating and cooling are about 40% of global
residential energy use and are expected to decline somewhat as a
proportion of total residential energy. For commercial buildings,
improvement in the thermal integrity of windows and walls with
paybacks of 5 years or less have lower potential to reduce global
carbon emissions, because only about 25% of energy use is due to
heating and cooling, and reductions in these loads are more difficult
in commercial than residential buildings (see section of Table 2 entitled "Potential
Reductions from Energy-Efficient Technologies"). Most of these
reductions will occur only in new commercial buildings, as retrofits
to the walls and windows of existing buildings are costly.
A myriad of measures have been implemented over the past 2
decades with the goal of increasing energy efficiency in the buildings
sector. This discussion focuses on four general policy areas: (i)
Market-based programs in which customers or manufacturers are
provided technical support and/or incentives; (ii) mandatory energy-
efficiency standards, applied at the point of manufacture or at the
time of construction; (iii) voluntary energy-efficiency standards; and
(iv) increased emphasis of private or public research, development,
and demonstration programs for the development of more efficient
products. Information and training programs are a necessary
prerequisite for most of these measures, but it is difficult to directly
estimate savings attributable to such programs (SAR II, 22.5.1.6).
Direct government subsidies and loans will not be covered as a
separate policy category but rather treated in the context of other
measures as a means to reduce private investment costs.
8
The measures discussed herein often work best in combination.
Mutually reinforcing regulatory, information, incentive, and other
programs offer the best means for achieving significant portions of
the cost-effective energy-efficiency potential (SAR II, 22.5.1.8).
Demand-side projects can be "bundled" in order to provide a larger
energy "resource" and attract capital, especially in non-Annex I
countries (SAR II, 22.5.1.7). Measures need to be carefully tailored to
address specific issues and barriers associated with various building
characteristics, including commercial versus residential buildings,
new construction versus existing retrofits, and owner- versus renter-
occupied buildings (SAR II, 22.5.1).
For all of the measures, environmental benefits associated with the
use of more energy-efficient equipment and buildings include
reduction of other power plant emissions (especially sulfur oxides,
nitrogen oxides, and particulates), reduced impacts on land and
water resulting from coal mining, reduction of air toxics from fossil
fuel combustion, and the whole range of environmental benefits
resulting from reduced extraction, transport and transmission,
conversion, and use of energy (Levine et al., 1994).
2.3.1. Market-Based Programs
Market-based programs, which provide some sort of incentive to
promote increased use of energy-efficient technologies and practices,
can be divided into the following five types:
Importantly, market-based programs can be directed toward
building systems (as opposed to individual pieces of equipment) to
reduce energy consumption resulting from inadequate design,
installation, maintenance, and operation of heating and cooling
systems. There are numerous examples of systems problems, such as
mismatches between air-handling systems and chillers, absence or
inadequate performance of building control systems, simultaneous
heating and cooling of different parts of the same building, and so on.
Based on expert judgment, the authors estimate that market-based
programs will result in global carbon emission reductions of about 5%
of projected (IS92 scenarios) buildings-related emissions by 2010,
about 5-10% by 2020, and about 10-20% by 2050 (see section of Table 2 entitled "Potential
Reductions from Energy-Efficient Technologies Captured through
Measures"), after allowing for an estimate of the portion of savings
that is "taken back" in increased services (usage).
Surveys of the costs and benefits of these programs as they have
been applied in the United States generally indicate that they are
cost-effective (SAR II, 22.5.1.4). However, it is not possible to
generalize, since there have been limited analyses and the costs and
savings depend both on the specific technologies that are promoted
and the method of implementation of the program.
The major administrative, institutional, and political issues in
implementing market-based programs for residential and
commercial building equipment follow:
Mandatory energy-efficiency standards-through which the
government enacts specific requirements that all products (or an
average of all products) manufactured and buildings constructed
meet defined energy use criteria-are an important regulatory option
for residential and commercial buildings; such standards have the
potential to yield the largest savings in this sector (SAR II, 22.5.1.2,
22.5.1.3). Appliances typically have lifetimes of 10-20 years (SAR II,
22.4.1.5), while heating and cooling equipment is replaced over a
slightly longer time period. These rapid turnover rates mean that
inefficient stock can be relatively rapidly replaced with more
efficient stock that meets established standards. Residential and
commercial buildings, however, more typically last between 50 and
100 years.
Depending on the stringency of the standard levels, the authors
estimate (based on expert judgment) that mandatory standards
applied to appliances, other energy-using equipment in the building,
and the building envelope could result in global carbon emission
reductions of about 5-10% of projected (IS92 scenarios) buildings-
related emissions by 2010, about 10-15% by 2020, and about 10-
30% by 2050 (see section of Table 2 entitled "Potential
Reductions from Energy-Efficient Technologies Captured through
Measures"), after allowing for an estimate of the portion of savings
that is "taken back" in increased services (usage).
Mandatory energy-efficiency standards are typically set at levels
that are cost-effective such that the benefits in terms of energy
savings outweigh any additional costs associated with the more
efficient product or building. Thus, such standards yield reductions in
carbon emissions at a net negative cost on average. Using the impact
of U.S. National Appliance Energy and Conservation Act (NAECA)
residential appliance standards during the period 1990-2015 as an
example, the cumulative net present costs of appliance standards
that have already been implemented in the United States are
projected to be $32,000 million and the net present savings are
estimated to be $78,000 million (in $US 1987) (Levine et
al., 1994).
Project-level costs associated with mandatory standards include
program costs for analysis, testing, and rating of the products.
Testing laboratories and equipment to certify the performance of the
appliances will be needed for a country or group of countries without
such facilities but with a growing demand for appliances. Other major
costs are the investment costs for initial production of the more
efficient products, the need for trained personnel, and the need for
new institutional structures.
Administrative, institutional, and political issues associated with
implementing mandatory energy-efficiency standards include the
following:
There also are administrative, institutional, and political benefits
associated with mandatory energy-efficiency standards, including
responding to consumer and environmental concerns, reducing
future generating capacity requirements, and providing credibility to
manufacturers that take the lead in introducing energy-efficient
products through uniform test procedures. Harmonization of test
procedures and standards could reduce manufacturing costs
associated with meeting various requirements.
2.3.3. Voluntary Standards
Voluntary energy-efficiency standards, where manufacturers and
builders agree (without government-mandated legislation) to
generate products or construct buildings that meet defined energy
use criteria, can serve as a precursor or alternative to mandatory
standards (SAR II, 22.5.1.2). For products covered by these
standards, there must be agreement on test procedures, adequate
testing equipment and laboratories to certify equipment, and product
labeling-thus satisfying the prerequisites of mandatory standards.
Voluntary standards have been more successful in the commercial
sector than in the residential sector, presumably because commercial
customers are more knowledgeable about energy use and efficiency
of equipment than residential consumers.
Energy use and carbon emissions reductions for voluntary standards
vary greatly, depending upon the way in which they are carried out
and the participation by manufacturers. Based on expert judgment,
the authors estimate that global carbon emissions reductions from
these standards could range from 10-50% (or even more if combined
with strong incentives) of the reductions from mandatory standards.
Project-level costs associated with voluntary standards (costs of
testing equipment and laboratories, and the initial investment costs)
are the same as those for mandatory standards. The increased
investment for more efficient products, however, will be lower than
that for mandatory standards, as voluntary standards are expected
to affect the market less.
The administrative, institutional, and political issues surrounding the
achievement of voluntary standards are similar to those for
mandatory standards but of smaller magnitude, proportionate to
their ability to affect energy efficiency gains in appliances, other
equipment, and buildings.
2.3.4. Research, Development, and Demonstration
RD&D programs foster the creation of new technologies that enable
measures to have impacts over the longer term. In general, only
large industries and governments have the resources and interest to
conduct RD&D. The building industry, in contrast, is highly
fragmented, which makes it difficult for the industry to pool its
resources to conduct RD&D. Government-supported RD&D has played
a key role in developing and commercializing a number of energy-
efficient technologies, such as low-emissivity windows, electronic
ballasts, and high-efficiency refrigerator compressors. While Annex I
RD&D results can often be transferred to non-Annex I countries,
there are conditions specific to these countries that require special
attention, such as building design and construction for hot, humid
climates. For this reason, it is essential to develop a collaborative
RD&D infrastructure between researchers based in non-Annex I
countries and both Annex I and non-Annex I country RD&D
specialists (SAR II, 22.5.1.5).
A specific carbon emissions reduction estimate is not assigned to
RD&D in Table 2; rather,
it is noted that vigorous RD&D on measures to use energy more
efficiently in buildings-encompassing improvements in equipment,
insulation, windows, exterior surfaces, and especially building
systems-is essential if substantial energy savings are to be achieved
in the period after 2010. It is essential to note that the emissions
reductions potentials for the residential, commercial, and
institutional buildings sector will not be realized without significant
RD&D activities.
A range of total achievable emissions reductions for global
residential, commercial, and institutional buildings is provided in Tables 1 and 2. These reductions are estimated
to be about 10-15% of projected emissions in 2010, 15-20% in 2020,
and 20-50% in 2050, based on IS92 scenarios. Thus, total achievable
carbon emissions reductions for the buildings sector are estimated to
range (based on IS92 scenarios) from about 0.175-0.45 Gt C/yr by
2010, 0.25-0.70 Gt C/yr by 2020, and 0.35-2.5 Gt C/yr by 2050.
The measures described can be differentiated based on their
potential for carbon emissions reductions, cost-effectiveness, and
difficulty of implementation. All of the measures will have favorable
impacts on an overall economy, to the extent that the energy savings
are cost-effective. Environmental benefits are approximately
proportional to the reductions in energy demand, thus to carbon
savings. The administrative and transaction costs of the different
measures can vary markedly. While building codes and standards
can be difficult to administer, many countries now require some
minimum level of energy efficiency in new construction. Many of the
market programs introduce some complexity, but they often can be
designed to obtain savings that are otherwise very difficult to
capture. The appliance standards programs are, in principle, the least
difficult to administer, but political consensus on these programs can
be difficult to achieve.
Go to Introduction
Market-based programs can be used in place of, or in addition to,
standards. In combination with standards, market-based programs
can be designed to induce the acceptance of new and innovative
technologies in the marketplace in advance of when they would
otherwise be adopted. When combined with active, ongoing RD&D
programs, such efforts are likely to have significant long-term
impacts on the availability and performance of advanced, more
efficient technologies. For appliances, lighting, and office equipment,
such programs can influence a very large number of purchasers,
many of whom have little knowledge of or interest in the energy
efficiency of the product. Combining market-based programs and
mandatory standards can help overcome some of the difficulties of
imposing standards, and could have an impact greater than
standards alone.
2.3.2. Regulatory Measures
Overcoming these difficulties will require substantial effort. Because
many appliances are designed, licensed, manufactured, and sold in
different countries with varying energy costs and consumer use
patterns, regional initiatives coupled with financing to set up
standards and testing laboratories, especially in Annex I countries
with economies in transition and non-Annex I countries, may be
needed to overcome many institutional barriers.
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