Computational fluid dynamics packages are now being widely
used in industry and research alike to simulate phenomena like
fluid flow, heat transfer and diffusion. They may be used to simulate
physical processes where physical measurements are not possible
or are very difficult or expensive. Currently only experimental
methods are being used to measure leakage from ducts. Very little
insight has been offered into the actual physics of the flow inside
residential HVAC ducts. This study is part of a larger experimental
study funded by the National Center of Energy Management and
Building Technologies (NCEMBT) to develop an alternative method
of trying to determine local as well as global air leakage flow rates
in a residential duct system and hopefully reduce the costs of fixing
the leaks. This is all part of the overall aim of increasing overall
energy efficiency in residential structures in the US. In [1] the paper
describes the results of a field investigation of duct systems in California
for light commercial buildings and the finding that some of
these duct systems can have an unusually large leakage rates that
can reach up to 40% ratio of their total supply air flow. Researchers
in [2] discuss the effects of duct leakage and heat transfer on residential
space-cooling energy use. It was found through simulations
in this study that duct leakage and it ensuing heat transfer efficiency
loss is highly time dependent and hence can generate larger
electrical demand on systems that are leaky in nature. It was also
found that the air leakage phenomenon is not only reserved for the
supply air side but is found in varying degrees on the return side.