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Single-Duct Constant Air Volume System Supply Air Temperature Reset: Using Return Air Temperature or Outside Air Temperature?
Abstract
The supply air temperature set point for a singleduct
constant air volume air handling unit (AHU)
system is often reset based on either return air
temperature or outside air temperature in order to
reduce simultaneous cooling and heating energy
consumption. Both reset strategies make engineering
sense as long as the reset schedules are reasonable.
Quite often the decision to use one over the other is
made with the assumption that they will all achieve
some sorts of energy savings. However, the impact of
these two strategies on AHU energy consumption
could be very different. A comparison of these two
commonly used supply air temperature reset
strategies for a single-duct constant air volume
system is presented in this paper. It is shown that
from either the building energy consumption or
building comfort point of view, the reset strategy
based on outside air temperature is inherently better
than that based on return air temperature. Significant
amount of heating energy savings can be achieved by
switching from return air temperature based reset to
outside air temperature based reset. The reset strategy
can also benefit variable air volume (VAV) AHUs.
An improved supply air temperature set point reset
control strategy is proposed by combining and
staging the outside air and return air temperature
based resets.
Citation
Wei, G.; Turner, W. D.; Claridge, D.; Liu, M. (2002). Single-Duct Constant Air Volume System Supply Air Temperature Reset: Using Return Air Temperature or Outside Air Temperature?. Energy Systems Laboratory (http://esl.tamu.edu); Texas A&M University (http://www.tamu.edu). Available electronically from https : / /hdl .handle .net /1969 .1 /5165.