The medical profession has long since moved from treating pain
to an approach of analyzing the body as a whole to determine
the source of the pain and then treating the source. The Heating,
Ventilation and Air Conditioning (HVAC) industry needs to endorse
the same approach.
Frequently, building
comfort complaints are treated by solutions that address the symptom
and not the source of the problem. These solutions may provide
temporary relief but the real source of the problem may remain
and discomfort will persist. The following actual project describes
such an example.
A building owner contacted Prism Engineering because he had
been advised that his building required additional air conditioning
capacity. The ten-year-old office building had tenant complaints
of being too hot, too cold and having poor air quality. The owner
wanted another opinion before taking on the expense of adding
more air conditioning.
Prism reviewed the building and its equipment, discussed the
nature of the complaints with occupants, and obtained an understanding
of the history of the system. Prism discovered that both hot
and cold complaints were experienced throughout the year.
The review of the HVAC equipment and air distribution system
resulted in the following observations:
- the roof top units were in good condition, however, the economizers
were not responding to the controls;
- the outside air dampers remained open during mechanical cooling
which resulted in the compressors not having the capacity to
meet the additional cooling load;
- on a call for heating, the outside dampers completely closed
resulting in no ventilation air for the occupants;
- the sheet metal distribution ductwork was poorly laid out
with numerous 90° elbows resulting in reduced airflow;
zoning of the air distribution was not appropriate for the
thermal zones and occupant partitioning in the space;
- air diffusers were found with long lengths of round flexible
duct resulting in a further reduction in airflow to their areas.
These conditions not only resulted in poor occupant comfort, they
also caused excessive energy use and the potential for early compressor
failure. After running a computerized calculation of the building
cooling loads, Prism determined that there was adequate air conditioning
capacity. Prism's recommendation was to implement changes to correct
the above situations. Subsequently, Prism revised the roof top
unit controls, redesigned the air distribution zoning and modified
the ductwork to improve air distribution. CAD drawings and specifications
were prepared, the job was tendered, and construction was reviewed
for compliance to the specification.
The changes have had the desired results: improved occupant
comfort, improved air quality, reduced compressor operation,
and reduced energy use and cost.
Prism was able to carry out a redesign of the existing equipment,
correct the problem, and achieve further benefits, without the
expense of adding and operating new equipment.
