Today's HVAC systems
are intended to meet the stricter indoor air quality, environmental, and user
requirements. Most of the improvements in the efficiency of the HVAC systems
have resulted from the advancements in the operating efficiency of system
components. Other advancements are the result of using newer technologies.
Even though
there are several individual developments that have been a catalyst in improving
the operating efficiency of HVAC systems, much of the overall improvement can
be credited to the factors mentioned below:
Chiller
design changes
Higher energy efficiency is not
the only advantage of the new generation of chillers. They also provide better
refrigerant containment. While standard chillers lose ten to fifteen percent of
the refrigerant charge routinely per year, newer chillers can keep the losses
to 0.5 percent. Better purge systems and lower leak rates decrease the amount
of non-condensable gases that are found in the new chiller system – an
important factor in maintaining better performance of the system over time.
Another important development
is in the operation of the boiler system: the replacement of manual and pneumatic
controls with microprocessor systems. This has helped the systems to achieve 5%
to 7% energy savings over traditional pneumatic-based boiler systems.
Energy-efficient
motors
The HVAC systems today use
energy-efficient motors. These motors provide a moderate but substantial
increase in the operating efficiency over traditional motor designs. For instance,
a ten horse power energy-efficient motor functions at about 90% efficiency; a traditional
motor of a similar size is rated at 85%.
Chiller
loads
Chillers inside the HVAC are sized
for highest cooling loads. Standard control systems close vanes on the chiller
inlet, dropping the efficiency of the system at the time of part-load
operation. When VFD or variable frequency drives are applied, chillers regulate
the operation by decreasing the compressor speed. The end result is full-load
operating efficiency over an extensive array of cooling loads.
Conservation of energy is not
the only benefit of VFD variable frequency drives. The electric motor along
with the mechanical system is strained every time a fan, a pump or chiller is initiated
at full-line voltage: Belts slip, high-pressure is developed and drive chains
stretch. VFD helps in decreasing these stresses by starting systems at low
frequencies and voltages in a soft start, leading to increased equipment and motor
life.
At last, the most significant
element in a modern HVAC system is the way it’s used. No matter how energy
efficient or sophisticated the system is, its performance depends on the way
it's maintained and operated. It is important to be properly trained before
using the features of the system. Also, it is advised to get the system
maintained by professional contractors. The personnel should be equipped and
trained with the proper knowledge and tools to keep the HVAC operating in the
way it was intended. Maintenance should never be taken lightly.
