Efficiency by Design: Haverford University, A Case Study
Philip Bartholomew,
CUH2A, Inc.
Objectives:
The laboratory air system designed for Haverford College responds
to the College's directive to provide a system with the greatest
life cycle benefit. The final design approach not only provided
an extremely efficient system, but also produced an initial cost
savings over a conventional system.
The design incorporates highly efficient makeup air units coupled
with independent room fan coil units. In this scheme, the fan coils
provide individual space sensible cooling and heating with full
return air. The makeup system is controlled to match only the requirements
of the lab exhaust, avoiding using expensive outside air to provide
general space temperature control.
The makeup air units use a dual heat exchanger arrangement to produce
nearly room temperature and humidity neutral air. A total energy
heat wheel is used to provide high levels of energy recovery for
both the sensible and importantly the latent components. Another
sensible wheel is used primarily to eliminate all reheat requirements.
The generation of room neutral air allows for a unique supply plenum
delivery of makeup air. This passive delivery allows for excellent
laboratory pressure control and the elimination of medium pressure
supply duct and expensive laboratory flow tracking control systems.
The cost savings associated with reducing the chiller and heating
plant by 60 percent, along with elimination of medium pressure supply
ducts and laboratory controls, more than offset the additional cost
of the heat exchangers required at the makeup unit.
Findings:
An energy analysis will be presented showing the energy consumed
by five different air handling systems serving the same set of rooms
with the same set of operating conditions. The analysis will show
how a central plant thermal load reduction of two thirds can be
achieved. Systems presented include:
- Conventional once through VAV lab air unit.
- Conventional once through VAV lab air unit with sensible heat
recovery.
- Conventional once through VAV lab air unit with total heat recovery.
- Separate space conditioning and makeup unit with two sensible
heat exchangers.
- Separate space conditioning and makeup unit with sensible and
total energy heat exchangers.
The actual operational characteristics of the passive air delivery
system will be presented including:
- Pressure containment of laboratories.
- Building pressure characteristics.
- Balancing requirements
- Acoustic performance.
Labs21 Connection:
The primary goal of the design was to develop a sustainable, high
performance, and low-energy laboratory. An added benefit of this
approach was that it led to a design that not only provided high
energy efficiency but also provided initial cost savings.
Biography:
Philip C. Bartholomew, P.E.,
a registered engineer since 1982, has been with CUH2A, Inc. for
the past six years. CUH2A is a fully integrated architecture, engineering,
and planning firm dedicated to science and technology. Phil's experience
includes extensive laboratory projects including academic as well
as research and development facilities presenting a variety of functional
requirements and design solutions. Philip is a 1977 graduate of
Pennsylvania State University with a BA in Architectural Engineering.
He is a member of the American Society of Heating Refrigeration
Air Conditioning Engineers.
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