 October - December 1997 
Dealing With Global Warming: [e-lab Home Page] [Energy Lab Home Page] [MIT Home Page] .
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[e-lab Home Page] Copyright © Massachusetts Institute of Technology 1997. Material in this bulletin may be reproduced if credited to e-lab. |
recent years, intense international negotiations have focused on how much
each of the developed nations should limit their emissions of carbon dioxide
(CO2). Now researchers in MIT's Joint Program
on the Science and Policy of Global Change warn that setting such limits
will not by itself be a sufficient response if the threat of global warming
proves real. Analyses using their "Integrated Global System Model"
suggest that even the toughest current proposal for limiting emissions
from developed nations will reduce projected warming in 2100 by only about
20%. Further, the analyses show that developed countries alone cannot reduce
emissions enough to stabilize atmospheric CO2
concentrations at levels now proposed as "safe." The rapidly
growing emissions from developing nations must also be curbed. There are
even more challenging tasks for the long-term future. First, we should
develop "greenhouse-friendly" technologies that permit emissions
reductions without threatening economic health. Second, we should design
broad international climate agreements that can evolve over time and that
address all issues, from sources and sinks of all greenhouse gases to emissions
monitoring and enforcement. Finally, we should develop an international
system that can, if necessary, transfer substantial funds to developing
countries to support their emissions-control efforts. These long-term undertakings
should be tackled with the same fervor that characterizes current negotiations
on near-term emissions limits.
esearchers in MIT's Building Technology Program and the Energy Laboratory
are studying an approach to ventilation that is radically different from
that now used in the United States and could both improve indoor air quality
and save energy. While conventional ventilation systems mix large quantities
of newly conditioned air into the air in a room, "displacement ventilation"
systems prevent mixing by injecting limited amounts of air, slowly and
near the floor. Pollutants and heat that are produced by people and equipment
rise naturally to ceiling exhaust vents, and the fresh air rises into the
breathing space. The difficulty is that the precise system specifications--air
temperature, velocity, and so on--must be tailored to the space being ventilated
or occupants may be uncomfortable. The MIT researchers are developing tools
that can help. They have formulated a computer model that calculates how
different system specifications affect airflows and heat and pollutant
dispersion in a well-defined room. And they have built a full-size experimental
room in which they can test the effects of different ventilation strategies
in various situations (an office with two "people" in front of
computers, a classroom with "students" behind desks). The model
predictions and experimental results agree quite well, and both confirm
that a well-designed displacement ventilation system can provide clean
air and comfort and also reduce the amount of ventilation air that must
be heated or cooled--now a major consumer of energy in commercial buildings.