More than half of the total energy consumed by buildings is typically consumed by HVAC systems. According to the U.S. Environmental Protection Agency (EPA), when businesses invest in energy efficiency, it yields 200-300 percent return on investment (ROI). Steps taken to make HVAC systems more efficient are beneficial for both business profitability and sustainable resources.
There are six important, but not expensive, steps to make sure a building’s HVAC system is operating at peak performance and top efficiency.
1. TIGHTEN THE BUILDING ENVELOPE
Whether your climate is hot or cold, tightening the building envelope can reduce energy waste and cost. In a simulation study by the National Institute of Standards and Technology (NIST), annual heating and cooling cost savings as high as 37 percent were modeled when nonresidential buildings were made more airtight.
In “Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC Energy Use,” the NIST estimates that up to 50 percent of the energy for HVAV use is wasted due to air leakage. This costs the commercial sector billions each year.
The goals of the building envelope are to support the comfort of occupants, minimize energy waste, manage moisture, offer separation from the outside environment, and provide fresh air for inhabitants.
2. REDUCE LOAD CAPACITY
Once the building envelope is tight, load capacity (the total amount of HVAC a building uses) will already be reduced significantly. Reducing it further will require you to analyze other building systems that cause the HVAC system to work harder.
For example, assess lighting systems, which often generate a lot of heat. By installing energy-efficient lighting, like improved fluorescents or LEDs, you can significantly reduce the strain on the HVAC system.
The same can be said of other equipment, from office machines to manufacturing equipment. The heat generated by the devices in a building may be costing the building owner double: once to power those systems, and again to cycle the HVAC system more to compensate for the heat they produce.
Of course, optimizing settings of the HVAC system (or the building automation system that controls it) to power down when not in use and maintain a temperature that is comfortable for occupants should go without saying. In some buildings where the temperature is set too low (costing too much), occupants use space heaters (costing even more) to achieve a comfortable temperature.
3. MAKE USE OF AVAILABLE ENVIRONMENTAL RESOURCES TO ENABLE ENERGY EFFICIENCY
As you work to eliminate all unnecessary drains on natural resources, you can also keep in mind that you can enlist Mother Nature to help you protect Mother Nature (not to mention the bottom line).
For example, planting shade trees near the building’s perimeter helps reduce the need for air conditioning. You can also consider natural ventilation techniques to help keep the building breathing properly at no added costs.
4. SEPARATE CONTROLS FOR TEMPERATURE, VENTILATION, AND DEHUMIDIFICATION IN MULTIPLE ZONES
Depending on the size of the building, segmenting the space into zones will allow it to be controlled more efficiently.
According to buildingscience.com:
“Commercial HVAC systems use liquids (such as refrigerants, water, or glycol) to move energy around the building, and only use ducts to move ventilation air through the building while conditioning air temperature within each occupancy (residential unit, office tenancy, etc.). By separating the control of temperature from the control of ventilation and from the control of dehumidification, very robust, simple to control, and energy efficient systems result.”
5. MAINTENANCE OF HVAC
Properly maintaining HVAC systems improves their efficiency and prolongs their life. Arista, a New York City-area commercial HVAC contractor suggests these maintenance tasks:
Spring & Summer Maintenance Tasks
• Replace filters on cooling equipment
• Check condition of belts and pulleys and replace as needed
• Clean condenser and evaporator coils
• Check refrigerant charge and inspect for leaks if charge is low
• Clear drain lines and pans
• Check electrical connections
• Check operation of fan and blower motor and adjust if needed
• Lubricate motors, bearings, and other moving parts
• Check operation of thermostats and other controls
• Check for adequate airflow
Fall & Winter Maintenance Tasks
• Replace filters on heating equipment
• Check condition of belts and pulleys and replace as needed
• Clear drain lines and pans
• Check electrical connections
• Check operation of fan and blower motor and adjust if needed
• Inspect ignition and burner assembly
• Lubricate motors, bearings, and other moving parts
• Check operation of thermostats and other controls
• Inspect heat exchanger
6. EXAMINE USAGE DATA TO UNDERSTAND REQUIRED BEHAVIORAL CHANGES
The final step may be the most important and the most effective to making HVAC systems more efficient: the human element.
By tracking and monitoring HVAC usage data, which can be derived from energy profile information, you can understand if any behavioral change needs to be instilled throughout the organization.
A few years ago, a study conducted on utility data from over 60 million square feet of commercial spaces discovered that behavioral change could “double the potential for energy savings, while simultaneously slashing efficiency implementation costs by a significant margin.”
In the study, 20 percent of the savings potential was a result of corrections to poor scheduling. That is, buildings were completely ready for full occupancy over an hour before they were fully occupied and remained in that state several hours after occupants had left.
The same study also discovered inefficiencies in equipment sequencing, which allowed inefficient equipment to run unnecessarily.
Finally, the study concluded that many buildings are set up to automatically run heating and cooling systems based on temperature. Yet around those threshold transition temperatures, heating and air conditioning would often run concurrently.
This study proves that automation, in and of itself, does not create energy efficiency as it is prone to operator error. But by adding a layer of monitoring to the energy consumption of the devices, you get the oversight and control you need to truly achieve maximum efficiency.
No one of these steps alone will convert a HVAC system into a lean, green energy cost savings machine. But put together, they can make a big difference.
Publication date: 8/8/2016
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