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System Impacts

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Resources Impact

The HVAC system has a tremendous impact on natural resources, through electricity, gas, and other purchased energy as well as water consumption, materials, and refrigerants. Take steps to optimize the system’s efficiency, implement water conservation measures, and reduce environmental impacts.

Systems Optimization

There is a good chance your building systems are not operating at their peak efficiency. The reasons for this are many, including but not limited to:

  • Changes in the use of the building
  • Different climate conditions than when the building was designed
  • "Temporary" control overrides that were never reset back to normal
  • Piecemeal replacement of equipment due to breakdowns over the years

Ensure your systems are in proper working order and working well together through commissioning. Learn more about commissioning, retrocommissioning, and recommissioning in the O&M Section.

Energy Use

HVAC consumes an average of 30% of a facility’s energy use.1 Much of that use is wasted, at times right through the front door. Other times the energy use is due to poorly operating equipment and controls. When choosing new equipment, more efficient selections nearly pay back the cost differential very quickly. Many other projects that require the replacement of existing equipment can pay for themselves in as little as 2-5 years. Adjustments to controls and temperature setpoints can pay back almost immediately!

Your choice of fuels for heating also has a tremendous impact on energy costs. The most common choices are electricity and natural gas. Examine predicted pricing trends into the future, over the life of your system, rather than just making a decision based on today’s utility rates.

1. The ENERGY STAR Building Upgrade Manual

Conservation Measures

HVAC components, particularly cooling towers, steam systems, and humidifiers, are responsible for large amounts of water consumption in our buildings. Where possible, choose systems that use as little water as possible. Fix any leaks quickly to reduce waste. Adjusting the supply and return temperatures on cooling tower water can affect the amount of water used. Water captured from dehumidification, cooling tower blow-down, and other HVAC processes can be used for toilet flushing and irrigation.

Environmental Impact

One major environmental impact directly related to HVAC systems is the release of refrigerants into the atmosphere. A pound of these chemicals, particularly refrigerants in older systems, contribute to global warming at a much higher rate than a pound of carbon dioxide. Certain types of refrigerants, like CFCs are no longer produced, and others like HCFCs are slowly being phased out. CFCs and HCFCs will likely remain in many of today’s systems for several years, so leaks must be completely sealed to prevent not only greenhouse gas emissions but also the expense of “topping off” your system. For new systems, choose chillers and packaged units that use refrigerants with low global warming potential (GWP) and low ozone depletion potential (ODP). Details on refrigerants and their GWP and ODP values can be found at the US EPA’s website.

Green Tips and Strategies

When selecting new equipment, examine the entire lifecycle cost by comparing first costs, operating costs (energy savings, for example), and disposal costs. Get the most out of your building systems. Learn more about commissioning in the O&M Section.