Every few years, the U.S. Department of Energy (DOE) updates its guidelines regarding energy efficiency for a wide variety of products. If you work in commercial HVAC, you’re probably following the standards related to commercial HVAC efficiency requirements. Although there are a variety of standards, the most relevant ones in the commercial and industrial sector govern rooftop units (RTUs). These standards comprise at least half of all commercial heating and cooling systems and have the most impact on design and manufacturing improvements.
However, these requirements can be hard to navigate without the right knowledge.
Measuring Commercial HVAC Equipment Efficiency
On January 1, 2018, the DOE introduced updated efficiency requirements for rooftop HVAC units. As of January 1, 2023, the DOE will begin enforcing higher efficiency standards. Based on the DOE’s new requirements, RTUs made after 2023 must be 15 percent more energy-efficient than older models.
However, the new efficiency goals aren’t the most significant challenge manufacturers face. The fundamental challenge is how to measure that efficiency.
Until recently, the DOE measured split-system commercial HVAC energy solely by energy efficiency ratio, or EER. Put simply, EER measures the efficiency of a piece of HVAC equipment when it is operating at full load—during the hottest days of summer and coldest days of winter. The higher the EER rating, the more efficient a unit is considered during peak demand hours. This information may be useful, but it doesn’t accurately represent the energy efficiency of larger units for buildings with many occupants with different HVAC needs. The vast majority of operating hours of commercial HVAC equipment is spent running at less than full capacity. So a rating system that more accurately represents the real world of cooling operation is coming into place: IEER, or integrated energy efficiency rating.
Today, these larger pieces of HVAC equipment are also evaluated in terms of the integrated energy efficiency ratio, or IEER. As with EER ratings, the higher the IEER rating, the more efficient the unit.
However, IEER requires a different approach to measuring energy efficiency. Instead of judging a system solely by its performance at peak demand, IEER measures a system’s efficiency at various loads on a weighted basis. Essentially, it evaluates how well a system performs at different temperatures across wide-ranging conditions to provide a more accurate picture of overall system performance.
Making the Grade: HVAC’s Evolving Efficiency
To meet these standards, HVAC manufacturers have responded in many innovative ways, including:
Although these features have been implemented in many other industries for years, HVAC manufacturers must incorporate them while still meeting existing size requirements for units. Moving forward, smaller AC and heating RTUs (units that require >65,000 to <135,000 Btus per hour to function, respectively) must maintain IEERs of at least 14.5 and 13.9, depending on their energy source. On the other end of the scale, very large AC and heat pump RTUs must maintain an IEER of at least 13 and 12.3, respectively. For a more detailed breakdown of these air conditioning and heat pump unit standards, see the table below.
Find RTUs That Meet DOE Commercial HVAC Efficiency Standards
Windy City Representatives works with leading manufacturers of rooftop units and other systems that are both efficient and durable. We look forward to working with you to find units that meet current DOE commercial HVAC efficiency standards and will help future-proof your project through 2023 and beyond. Contact us today to discuss the right units for your building.