Selecting a building's comfort system represents a complex
tradeoff between a number of different perspectives. Architects, engineers,
contractors, building owners and developers have many things to consider.
There are issues of first cost and operating costs. What does it take to
operate a system? How is the space to be arranged and used? While the HVAC
system may represent only 10 to 15 percent of the building's total cost,
poor decisions in system design made today can result in significant
problems for building occupants and owners tomorrow. There are the horror
stories of sky high energy bills and almost everyone has heard about the
sick building syndrome – buildings that suffer from inadequate ventilation
or poor air distribution. There are other consequences of poorly designed
HVAC systems. Poorly designed systems in retail space can affect product
sales. HVAC design errors in a manufacturing plant can affect quality and
productivity levels, and in hospitals and high tech operations, even the
placement of the equipment can be critical.
As an illustration, consider an employee making $30,000 per year,
occupying 150 square feet of conditioned space. The cost of that one
individual can be expressed as $200 per square foot per year. This
illustrates why occupant comfort is critical to a company's success. Even a
5 percent improvement in that employee's productivity can justify a
replacement of the HVAC system. And the payback can be less than 2 years.
That makes building owners sit up and take notice. But it's not uncommon for
building owners to run low on money during construction. Budgets almost
always end up being too small to include everything the building owner
desires.
Therefore it's natural to see cuts made as the building nears completion.
Unfortunately some of these well intentioned decisions to reduce HVAC
installed costs come back to haunt the building owner and occupants in the
future. The key to success in the partnership between the designer and the
building owner/developer is to look at the building's overall HVAC system
from a first-cost and an operating-cost perspective. The owner may also be
influenced by a system's flexibility in adapting to changing occupants and
changing use. This evaluation requires the understanding of at least five
different variables. Comparative equipment cost and energy performance,
energy prices today and projections for the future, operation and
maintenance costs, operating characteristics of the system and past
experience with HVAC systems.
The situation is even more complicated today with the phase out of
certain refrigerants, tighter regulations, and heightened concerns over air
emission and global warming gasses. There are a wide range of design
options, trade-offs and considerations.
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