6 Energy-Saving Tips for Your Commercial HVAC System

Your HVAC system can play a significant role in the quality of your business environment over time. Comfortable employees are more productive, and customers are likely to stay longer. Energy-efficient systems cost less to operate and require fewer repairs and maintenance.

Below are a few general things you can keep in mind to get the most out of your system.

Determine the Age of Your System

Most commercial or mixed-use buildings have rooftop units that heat and cool conditioned spaces, while HVAC systems in smaller buildings may more closely resemble residential setups. Either way, the life expectancy of your HVAC unit will be around 15 years. Larger commercial systems that use chillers or boilers last longer, between 20 and 25 years.

To determine when your building’s HVAC system was manufactured, contact your HVAC contractor, or locate the unit’s serial number, usually found on a metal plate on the external portion of the system. The Building Intelligence Center maintains a database of HVAC system manufacturing dates, based on serial numbers, for most common HVAC systems. You can also check ASHRAE’s HVAC Service Life Database to confirm the specific life expectancy of your system.

If your system still has some life left in it, it may not make sense to replace it for energy savings alone. But as you get closer to the end of its life expectancy, put an upgrade in the budget and be ready to swap out your system in the event of a failure. It’s a good idea to contact your contractor ahead of time to get a quote and make sure that there is a more energy-efficient replacement available. We can help you review your quotes, determine how much you can save, and let you know how much of a rebate you can receive for making the upgrade.

Keep Up on Maintenance

Keeping up with maintenance will help keep your system running as efficiently as possible. Most commercial HVAC contractors offer service contracts to help you maintain your system. If you choose to maintain the system yourself, make sure that you change your filters on a regular basis. A dirty filter increases the pressure on your fans and duct work, putting stress on the entire system. You should also have any dents or indentations combed out in the condensing unit fins that may have occurred as a result of hail or wear and tear.

If you have access to an HVAC control system, you may be able to check on additional metrics, such as refrigerant pressure (and differential pressure), which could indicate issues with refrigerant levels, compressors, or expansion valves.
In general, if you are noticing leaks, scheduling frequent maintenance, or experiencing frequent complaints about room temperatures or noise, it’s time to have a technician evaluate your system.

Take Control of Your Controls

When the building is unoccupied, you can let your thermostat float about four degrees lower in the winter, and up to four degrees higher in the summer until about two hours before people will be in the building. The exception to the rule is if you have a heat pump HVAC system. In this case, it’s almost always more efficient to set the thermostat to a comfortable temperature and forget it.

If you only have one thermostat, consider investing in a smart thermostat to reduce the chances of forgetting to turn the temperature up or down. Multi-zone systems are more complicated, though you may still be able to program them using a technical manual or with assistance from your contractor or HVAC manufacturer.

If you have a building automation system (BAS), you can set limits on temperature changes remotely, further reducing human errors to maximize your energy efficiency and savings.

Finally, if your facility has a unit serving a single space with variable occupancy or a makeup air system with 100 percent outside air, consider a Variable Frequency Drive (VFD) on your unit’s fan. The VFD will reduce the speed of the fan when there is less load in the space. Reducing a fan’s speed by just 20 percent can result in a nearly 50 percent reduction in energy use.
Use your economizer.

It is almost always more expensive to heat or cool outside air than to reuse the conditioned air that is already in your building. If your HVAC system has the option, run it in economizer mode—also known as “free cooling”. When conditions are correct, more outdoor air can be pulled in at a lower temperature and humidity than recycled air to reduce or eliminate the cooling load.

For instance, rooftop units usually include an outdoor air damper that pulls in the necessary amount of ventilation to meet local building code requirements. Opening the damper five percent may be enough to satisfy the code—anything higher means you are unnecessarily conditioning outside air that you don’t need under non-economizing conditions.

Make sure that all your economizer’s linkages and dampers are operating correctly. If these linkages fail to open or close, they may be pulling in too much outside air when it isn’t necessary, or not pulling in any air which can lead to stuffy conditions. This leads to wasted energy and higher electric bills. To fully optimize for humidity as well as temperature, contact your contractor.

Don’t Neglect Unused Spaces

Most commercial offices have spaces that see heavy use, and a few that don’t, such as a board room that is only used for a monthly meeting, or a utility room to store files or supplies. Be conscientious of how you heat and cool these spaces. Consider setting the thermostat in a rarely used space up to four degrees higher or lower than normal, except when it is being used.

There are two ways to ensure these rarely used spaces aren’t wasting energy. First, use a smart thermostat or building automation system to establish settings that return the room to the appropriate temperature when not in use. If setting a control for the space isn’t an option, consider asking employees to make it part of their daily routine to check that the space is at the correct temperature.

Get Advice That’s Customized to Your Workspace

HVAC systems vary widely depending on the age, size, and application of your building. For the best advice on your specific setup, reach out to Efficiency Smart. Our engineering consultants are available to help you prioritize projects, review proposals from vendors, or answer your energy-efficiency questions.