Environmental Assessment of Air-conditioning Systems. Design Considerations for Swedish Conditions.
Doctoral thesis, 2007
There is an increased awareness about global environmental changes, and a need for
products and systems with the lowest possible impacts on the environment, without
trade-offs on the original function or quality. The need for air-conditioning and
comfort cooling in commercial buildings has increased and an appropriate design of
the air-conditioning system is thus important in order to reduce the environmental
impact related to air-conditioning of buildings.
The aim is to describe how the environmental performance of air-conditioning
systems can be assessed at the design stage. The focus is on the application of existing
methods. The life cycle assessment (LCA) based weighting methods are used for the
environmental assessment of these systems. This approach is exemplified in five case
studies. The case studies form a basis for identification of the major sources of the
environmental impacts and enables recommendations on how to improve the
environmental performance of the systems. Furthermore, environmental consequences
of various requirements on the indoor thermal climate are analyzed.
It is shown that life cycle assessment (LCA) based weighting methods can be used for
environmental assessment of air-conditioning systems. The required effort to use
these methods is reasonable in relation to design practice, but the interpreters of the
results and decision-makers have to be aware of the limitations and trade offs of these
methods in order to draw appropriate conclusions. It is also shown that the major
contributor to the environmental impact of air-conditioning systems is the electricity
used for the operation of fans. A design with a low specific fan power is thus an
advantage from an environmental point of view. The environmental impact from the
production of the components is comparably low, especially if recycling of used
materials is considered. The influence of thermal comfort criteria is also comparably
low, especially, if the system is designed with a low specific fan power. It should
further be noted that the environmental performance is strongly affected by
assumptions about the electricity mix used.
life cycle assessment (LCA)