Manual for Refrigeration Servicing Technicians - UNEP - Division of ...

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Environmental Impact
countries which rely heavily on hydro-electricity or other renewable
energy resources (such as solar, wind, geothermal, and biomass),
or nuclear power, there are minimal emissions of CO2 per kWh
of electricity consumed. In countries that use carbon-intensive
electricity production, emissions can be around 1 kg of CO2 per
kWh. In these countries, the energy used is often the dominant
contribution to equipments’ GHG emissions. Therefore, it is
important to also improve and maintain the efficiency of RAC
equipment over its entire lifetime.
Certain concepts are often used to evaluate the overall lifetime GHG
impact of RAC systems. These include a variety of names: Total
Equivalent Warming Impact (TEWI), Life Cycle Climate Performance
(LCCP), and Life Cycle Warming Impact (LCWI), amongst others.
Essentially, all these concepts are the same: they add the total
equivalent GHG emissions from different sources together, over the
lifetime of the equipment. The purpose of doing this is often used to
compare different technologies, and more constructively, to identify
which aspects of the equipment could be most effectively optimised
to help reduce its global warming impact. Lastly, it is of utmost
importance to carry out such evaluations with attention to detail,
since there are myriad assumptions involved, and as such it is easy
to draw erroneous conclusions.
The Earth has a natural temperature control system. Certain
atmospheric gases are vital in this system and are known as
greenhouse gases. The Earth’s surface becomes warm and as a
result of incoming solar radiation and then emits infrared radiation.
The greenhouse gases trap some of the infrared radiation thus
warming the atmosphere. Naturally occurring greenhouse gases
include water vapour, carbon dioxide, ozone, methane and nitrous
oxide: together they create a natural greenhouse effect. Without this
phenomenon the Earth’s average temperature would be more than
30°C (60 °F) lower throughout the year.
Global warming might also slow down the ozone layer’s recovery;
despite the temperature rise in the troposphere, the air might even
cool down in the stratosphere, which is favourable to the depletion
of the ozone layer. The heat budget is dynamic – it is changing.
For example: at the time of the dinosaurs there was more carbon
dioxide in the atmosphere, trapping more heat, creating a higher
planetary temperature. This is an example of a feedback system.
Activity
Affect Increase Earth’s
Temperature
Cutting down forests will: √
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Decrease Earth’s
Temperature
A major volcanic eruption will: √ √
Burning fossil fuels leading to increased
carbon dioxide in the atmosphere will:
The addition of CFCs will: √
The addition of HCFCs will: √
The addition of HFCs will: √
√
(May also offer
some cooling as
particles in the
atmosphere
reflect the sun’s
rays)