The installation and maintenance of HVAC systems in commercial buildings has traditionally been implemented with a focus on building code compliance, statutory requirements for health & safety and providing comfortable conditions for building occupants and visitors. Oftentimes, due to timing pressures and cost constraints, inferior equipment and maintenance agreements are put into place, with little consideration given to the long-term effects on efficiencies, property value and the fluctuating environmental effects on comfort level. When energy efficiency gains are neglected and life cycle costs are not taken into consideration, consequences of higher energy and maintenance spend are not addressed.
In addition to substandard equipment and maintenance agreements, fewer than half of companies perform preventive or predictive maintenance on their building HVAC systems. What property owners and facility managers need to consider, is that studies have shown that good maintenance can cut HVAC energy costs while also extending equipment life, improving occupant comfort, and increasing uptime. Effective maintenance can reduce HVAC energy costs by 5 to 40 percent depending on the system or equipment involved. Proper maintenance is just one important factor for commercial HVAC systems – here are 6 other best practices you need to know:
- Controlling your control system is an integral part of any HVAC system maintenance.
The control system on your HVAC system has a specific purpose and can be as simple as an electronic programmable thermostat or as complex as a robust automation system. Regardless of your system’s level of sophistication, the controls should be used to best optimize the overall HVAC system. Additionally, your controls offer the best opportunity to eliminate energy waste and avoid comfort issues. Working with an efficiency expert can help you substantially decrease energy costs over the lifespan of your equipment.
- Simultaneous heating and cooling occurs in many systems. If it can’t be eliminated, it can be minimized:
Simultaneous heating and cooling can increase operational costs. When the central system delivers cooler air than required, the zone reheat coils must temper the air before it is delivered to the space. At this point the heating and cooling system may be working against each other. This creates additional wear on equipment.
Chillers and boilers may run when none are needed, or a larger chiller or boiler may be sequenced on when a smaller one could have met the load. Electric reheat coils are turned on when they could have been left off. Variable-flow chilled-water and hot-water systems operate at higher flow rates than necessary. Equipment capacity is reduced because the heating and cooling systems are working against each other. This can lead to under-heated or under-cooled areas, discomfort for visitors, and maintenance costs that are sure to be affected.
- Monitoring and improving fan speed controls
Most conventional building HVAC systems are designed to operate fans and pumps at a constant speed. Building needs, however, are anything but constant. In a conventional system, some form of mechanical throttling can be used to reduce water or air flow in the system. While mechanical throttling can provide a good level of control, it is not very efficient. A variable frequency drive (VDF) offers an effective and efficient alternative.
Facility managers and maintenance professionals understand that one of the most successful energy management tools applied to building HVAC systems is the VDF. VFDs are installed on fan and pump motors in a range of variable load applications. When in place, typical energy savings vary from 35 to 50 percent over conventional constant speed applications, resulting in a return on investment in approximately six months to two years.
- Night setback and scheduling
When building systems are properly controlled during unoccupied times, significant cost reductions in commercial buildings can be achieved. Night, weekend and off-hour setback and scheduling is easy to implement, and simple to track and administer. The goal is to shut off systems whenever possible or whenever they are not needed, and refrain from starting up the system for minimal or occasional use. Many times, night-time operations can be the most costly, if roughly only a small percentage of staff are working and all heating, ventilating, and air conditioning equipment is running. A few basic tactics to remember include
-Turn things off when not in use
-Change room set points when spaces are unoccupied
-Close outdoor air dampers when the building is unoccupied
-Disable chillers and cooling equipment during unoccupied hours if possible
- Use Energy (EUI) and Benchmarking
A closer look at a building’s past energy performance and energy-use pattern, and comparing it to typical similar buildings energy use can further identify problem areas.
The energy-use index (EUI) is the amount of energy used by a building per square foot of building floor area. By normalizing energy use to floor area, buildings can be benchmarked and compared for relative energy performance. An EUI can be based on whole-building energy use or on specific end uses such as lighting or heating. A whole-building EUI is a good measure of overall energy-savings potential. While your HVAC contractor or facilities manager is likely your best resource, other tools are available to help with calculating EUI.
- Operation and maintenance:
A few other operation and maintenance tips to consider as best practices for your property(s) include:
– Regularly test refrigerant charge to ensure optimum conditions
– Clean outdoor coils (condenser) by using a pressure sprayer. Be careful not to damage/bend aluminum fins
– Keep filters clean for sufficient air flow and heat transfer. Clean filters require less fan energy to deliver air
Establishing best practices and implementing regularly scheduled maintenance of HVAC systems can increase energy efficiency and longevity of equipment. Obtaining the right equipment for efficiency and researching what is best for your region and climate, is the best thing to do when choosing the best system or product. For the long-term and the overall comfort of your property, take action now to put practices into place for energy efficiencies and cost savings.