The Current Landscape
There is currently a very visible focus on the need to reduce energy consumption. The federal government is devoting
billions of dollars toward energy efficiency upgrades to public
buildings. The private sector is also recognizing the financial
benefits of projects that reduce energy costs and improve the
financial bottom line. Furthermore, utilities are subsidizing
sensible efficiency projects all across the country.
Heating, Ventilation, and Air Conditioning (HVAC) typically
accounts for about 30% - 50% of the energy consumed in a commercial
building. A small decrease in energy use by HVAC systems can have a
large impact on the overall energy and greenhouse gas profile of a
building. Increasing a building’s energy efficiency is one of the
most effective ways for organizations to simultaneously meet their
carbon reduction goals and reduce operating costs.
Over 50% of the commercial floor space in the United States is
reportedly served by rooftop-packaged HVAC units. These simple,
constant volume systems are often equipped with airside economizers.
An economizer allows the HVAC equipment to use outside air to satisfy
cooling needs when conditions permit. This free cooling cycle meets
the comfort needs of the space without using electrically powered
compressors. A properly functioning economizer is indispensable to an
efficiently operated HVAC system in most climate zones.
Unfortunately, the vast majority of economizers are not operating
correctly. Most facility operators are not receiving the full benefit
of these energy-saving devices due to common failures. With recent
changes in the energy codes across the country, we are now starting
to see split system HVAC units equipped with economizers. This
increases the total number of economizers nation-wide and creates an
additional opportunity to capture savings in split systems, provided
that they are functional and operated properly.
The HVAC equipment’s role is not just to provide comfort. It is
also responsible for ensuring proper fresh air ventilation rates.
Current practice is to set ventilation levels based upon the maximum
occupancy of the space served. Since a typical space is rarely at
full occupancy, this means that most spaces are over-ventilated the
majority of the time. An energy penalty occurs when the HVAC
equipment unnecessarily conditions large amounts of fresh air.
Current standards allow for the amount of fresh air to vary based
upon actual occupancy levels rather than the maximum anticipated
occupancy rating of the space. However, this practice is rarely
applied to existing equipment as a retrofit strategy due to cost
barriers, especially on constant volume equipment.
In any economy, efficiency makes financial sense. Investing in
energy efficiency reduces operating expenses and can lead to
increased profitability. It is the rare capital improvement to a
facility that will produce a return on investment. In the current
economic climate, it is even more important to focus on strategies
that reduce operating costs, save energy, and lower maintenance
costs. A reduction in energy expenses can help absorb some of the
economic burden of a slow economy and support the profitability of
the overall enterprise.
"Small packaged heating, ventilation, and air-conditioning (HVAC)
systems are among the most common HVAC systems for small commercial
buildings. These systems, however, are notorious for a host of
problems requiring 25 to 35 percent more energy than is necessary to
heat, cool, and ventilate California buildings."
Source: California Energy Commission’s Public Energy Research
Program
