This section is concerned with the impact of mitigation on the construction
industry, rather than with the options for mitigating energy use in buildings,
which are considered in Chapter 3. One of the main products
of the construction sector are buildings which require energy for a number of
services such as lighting, space heating and cooling, and electricity for equipment.
Energy consumption in buildings reaches nearly one-third of total primary energy
consumption in the US, and hence their importance for GHG emission reductions.
Mitigation will lead to changes in the materials used, and in design and heat
control, all tending to increase the quantity (output) and improve the quality
of buildings. Most renewable energy investments, such as hydropower and electricity
from biomass, also require inputs from the construction sector.
Multisectoral modelling suggests that carbon tax and permit policies will have
little impact on construction output and employment; this finding is established
in the literature, but incomplete. Table 9.1 shows
that according to three different macroeconomic models (Garbaccio et al.
1999; Jorgenson et al., 1999; and Barker, 1999) construction will increase
its output by about +1%. Two other models in the same table (Bertram et al.,
1993; Cambridge Econometrics, 1998) find 0% variation in the construction output.
Transport energy use has been growing steadily worldwide, with the largest
increases occurring in Asia, the Middle East and North Africa, and it is projected
to grow more rapidly than energy use in other sectors through at least until
2020 (Michaelis and Davidson, 1996; IEA, 1997b; Schafer, 1998; Nakicenovic et
al., 2000). There are few options available to reduce transport energy use
which do not involve significant economic, social or political costs. Governments
presently find it difficult to implement measures to reduce overall demand for
mobility (IEA, 1997b). Singapore is an exception to this general rule as a result
of a comprehensive set of policies dating from 1975 to limit traffic (Michaelowa,
Almost all transport energy is supplied from oil, and the growing demand for
transport seems inconsistent with macroeconomic studies that project decreased
demand for oil as the result of GHG mitigation policies. Further research is
needed to resolve this apparent inconsistency (Bernstein and Pan, 2000).
Local concerns, traffic congestion and air pollution, are currently the key
drivers for transport policy (Bernstein and Pan, 2000). Measures to reduce traffic
congestion also reduce CO2 emissions, since they involve either reducing
the number of vehicles on the road or increasing the average speed and fuel
efficiency at which vehicles travel through urban areas. Policies to reduce
traffic congestion include: improvements in mass transit, incentives for car
pooling, and fees for entering city centres (Bose, 2000), as well as employer-based
transport management, parking management, park-and-ride programmes, and road
use pricing. One approach has been to assess the external (social) costs of
transport, including contribution to global warming, as a guide to the level
of taxes or user charges by transport modes that would internalize these costs,
and hence improve the efficiency of the system (ECMT, 1998).
: Historical trends in transport and communication volume indices
for France (Source: Gruebler, 1998: Chapter 7).
An information society based on a digital information
network is sometimes projected to replace a substantial proportion of physical
travel. However, historical data show that the telegraph and telephone did not
affect the steady growth of transportation in France (see Figure
9.5). Mokhtarian et al. (1995) conclude that telecommuting, one aspect
of the information society, does reduce transportation energy use. However,
the reductions are smaller than often assumed, because they are partially offset
by increased household energy use, and because some telecommuters do so only
for part of their working day. Care must be taken in extrapolating future reductions
from the limited case studies currently available; the behaviour of early-adapters
may be different from that of later telecommuters. In the medium term, macro
view, information technologies appear to be complementary to transportation
(Gruebler, 1998); but in the longer term an information society
could significantly replace travel and associated impacts, although this remains
In 1999, in response to a request from the International Civil Aviation Organization
(ICAO), the IPCC prepared a Special Report, Aviation and the Global Atmosphere,
which included a comprehensive review of the potential impacts of aviation on
the climate system (Penner et al., 1999). The demand for air travel,
as measured in revenue passenger-kilometres, is projected to grow by 5%/year
for the next 15 years, but improvements in efficiency and operations are projected
to hold the growth in CO2 emissions to 3%/year. Aircraft also emit
water vapour, NOx, SOx and soot, and trigger the formation
of condensation trails (contrails) and may increase cirrus cloudiness
all of which contribute to climate change (Penner et al., 1999).
Penner et al. present several growth scenarios for aviation that provide
a basis for sensitivity analysis for climate modelling. These scenarios, which
assume the scope for switching from air travel to other modes of travel is limited,
show radiative forcing resulting from subsonic aircraft emissions growing from
the 1992 level of 0.05Wm-2 to between 0.13 and 0.56Wm-2
by 2050. The scenario with economic growth equal to the IS92a reference scenario
indicates that aviation may contribute 0.19 Wm-2, or about 5% of
anthropogenic radiative forcing, by 2050. More supersonic aircraft would substantially
increase this contribution, although there is considerable uncertainty whether
any such fleet will be developed. The growth scenarios do not consider air space
and infrastructure limitations; however, recent experience in both Europe and
North America indicates that the air traffic system is reaching saturation.
Penner et al. assume that by 2050 all currently identified improvements
in aircraft efficiency and operations will be implemented. However, turnover
time in the aviation industry is long. Individual aircraft will be operated
by commercial airlines for 25 years or more, and a successful product, including
its derivatives, will be produced for possibly 25 years or longer. Thus, the
overall life of an aircraft type can exceed 50 years.
Penner et al. (1999) conclude:
Although improvements in aircraft and engine technology and in the efficiency
of the air traffic control system will bring environmental benefits, these will
not fully offset the effects of increased emissions from the projected growth
in aviation. Policy options to reduce emissions further include more stringent
aircraft emissions regulations, removal of subsidies and incentives that have
negative environmental consequences, market-based options such as environmental
levies (charges and taxes) and emissions trading, voluntary agreements, research
programmes, and substitution of aviation by rail and coach. Most of these options
would lead to increased airline costs and fares. Some of these approaches have
not been fully investigated or tested in aviation and their outcomes are uncertain
(Penner et al., 1999, p. 11).
The need for further research in this area is explored at the end of the chapter.