The Impacts of SEER2 and HSPF2

What is SEER and HSPF?

The Seasonal Energy Efficiency Ratio (SEER) relates to how much energy an air conditioning unit will use over the course of 1 year. More specifically, it is the cooling output (measured in British Thermal Units (BTUs)) during a typical cooling-season (in a specific testing environment) divided by the total electric energy consumed (measured in watt-hours) during the same period. The higher the unit's SEER rating the more energy efficient it is. In the U.S. the SEER is the ratio of cooling in (BTUs) to the energy consumed in watt-hours.

The Heating Seasonal Performance Factor (HSPF) applies to heating operation efficiency. It is the measure of a heat pump’s efficiency during the heating season. HSPF ratings are calculated by dividing the total heating output during the heating season (measured in BTUs) by the total watt-hours of energy consumed during these months (measured in kWh). The higher the unit’s HSPF rating the more energy efficient it is.

In a nutshell, HSPF ratings apply to measuring the efficiency of heating units and SEER ratings apply to measuring the efficiency of cooling systems.

Both SEER and HSPF are defined by the Air Conditioning, Heating, and Refrigeration Institute in its 2008 standard AHRI 210/240. The Department of Energy (DOE) requires that all AC units meet minimum efficiency requirements (dictated by region) identified by the SEER and HSPF ratings.

What are the differences between SEER / HSPF and SEER2 / HSPF2?

The main difference between the SEER2/HSPF2 and SEER/HSPF ratings is the testing conditions for each rating system. The new testing conditions will produce different data values and warrant a new rating system. For SEER2 and HSPF2 ratings, the testing procedure increases the pressure conditions to make them more like those a typical ducted system would see in the field. As a result, SEER2 ratings for cooling equipment will be a bit lower (approx. 5%) than SEER ratings in most cases and similarly, for heat pumps, HSPF2 ratings will also be lower (approx. 15%) than HSPF ratings. For example, a heat pump with a SEER rating of 14 and HSPF rating of 10 would likely get a SEER2 rating of about 13 and HSPF2 rating of about 8.5. It is important to note that this does not mean that the equipment is less efficient. The difference between SEER2/HSPF2 ratings from SEER/HSPF ratings will vary from one equipment to another, but it mainly depends on the system type (such as split system, single package, etc.).

At the start of 2022, it was announced that by January 1, 2023, SEER2 and HSPF2 will be the new efficiency metric standards for product regulation going into 2023. The products affected by the new regulations include different types of air conditioners and heat pumps (such as split systems, single packaged units, small ducts with high velocity and space constrained units).

The DOE periodically evaluates energy efficiency levels, available technology and the economic impact of changing standards. In the case of SEER2 and HSPF2, they determined that changes to the test procedure to better represent the average use cycle were warranted. They also determined that higher efficiency levels were technologically feasible and economically justified.

What are the main components of the SEER2/HSPF2 changes?

There are 3 main components to the SEER2/HSPF2 changes that you’ll need to be aware of to prepare for 2023.

1. Testing Procedure Updates

The testing procedures for new efficiency ratings will be more stringent and will result in a lower numerical rating value, however the actual performance will be unchanged. The new M1 Testing Procedure will increase systems' external static pressure by a factor of 5.

The current testing procedure for SEER/HSPF does not accurately reflect the influence of ductwork and external static pressure on HVAC products. It’s typically not representative of real-world applications. By increasing systems’ external static pressure from current level (0.1 in. of water) to a bit higher level (0.5 in. of water), new M1 testing procedures more accurately reflect current field conditions.

2. Regional Minimum Efficiency Requirements

For the manufacturing and installation of split system air conditioners, the country has been split into 3 climate regions: North, Southwest, and Southeast (see map below).

Source: Air Conditioning, Heating and Refrigeration Institute

Each region has specific SEER minimums based on the new testing procedures. For split system heat pumps, packaged systems, small-duct with high-velocity systems, and space-constrained systems, national minimum efficiency standards are applied. These new requirements are tabulated as below:

In the North, air conditioner efficiencies will increase by 1 SEER point, from 13 to 14 SEER.

In the South (including Southeast and Southwest) region, minimum efficiencies for air conditioners with a capacity less than 3.75 tons will increase 1 SEER point, from 14 to 15 SEER. For air conditioners with a capacity of 3.75 tons or more, the minimum requirement will increase from 14 to 14.5 SEER.

For split system heat pumps, the new national minimum efficiency standard will increase by 1.0 SEER to 15.0 SEER for cooling and the HSPF requirement will also increase from 8.2 to 8.8 for heating.

For single packaged systems (heat pumps and air conditioners), minimum efficiency will remain the same.

3. Install Dates vs. Manufactured Dates

In both climate regions in the South, AC units need to meet the new requirements in order to be installed, based on the energy guide label and system certificate rating. Any system manufactured before 2023 is not grandfathered into this requirement and will not be allowed to be installed.

However, in the North, SEER compliance is determined by the manufacture date, allowing inventory on hand to be installed indefinitely.

Because heat pump efficiency levels fall under a national standard, heat pumps manufactured in 2022 can still be installed beyond January 1, 2023 in all regions.

For split system AC equipment manufactured prior to December 31, 2022, and installed in the South or Southwest Regions after January 1, 2023, there are specific stipulations. If the model is discontinued by the OEM, the least efficiency* SEER rating, as listed on the Energy Guide label, must be greater than the new efficiency minimums as mentioned above.

How will modeling in Ekotrope RATER change?

1. Modeling equipment with SEER2/HSPF2 ratings in Ekotrope RATER

To support modeling of equipment rated in SEER2 and HSPF2 in Ekotrope RATER, Air Conditioner, Air Source Heat Pump and Custom mechanical equipment will include options to specify efficiency in SEER2 and HSPF2 as well as a new dropdown field to specify the system type (split system, single package, small duct high velocity, space constrained or unspecified).

“Under the hood” Ekotrope will use the conversion factors in the table below to convert SEER2 and HSPF2 to SEER and HSPF respectively. These conversion factors are updated in accordance with the guideline finalized in MINHERS Addendum 71f. Note that ANSI/RESNET Standard 301 previously proposed conversion factors which are still used in Ekotrope versions before version 4.2.0 and can be found on freshdesk here.

These conversion factors will be used to convert SEER2/HSPF2 ratings into SEER/HSPF. For example, if a ducted split system heat pump is rated with 14 SEER2 and 10 HSPF2, it will be modeled with a SEER and HSPF of:

Cooling efficiency = 14 SEER2 = 14/0.95 SEER = 14.74 SEER

Heating efficiency = 10 HSPF2 = 10/0.85 HSPF = 11.76 HSPF

2. Reference Homes with Federal Minimum Efficiencies

There are a handful of reference homes in Ekotrope that use federal minimum efficiency equipment. Some utility programs use these reference homes as the baseline against which they calculate the energy savings achieved by their program. We will be updating these reference homes to use the new SEER2 and HSPF2 minimums specified above in Algorithm Version 4.1.0 which we plan to release around January 1, 2023.

As a result, in programs that use these reference homes, moving to version 4.1.0 will cause most projects to see a reduction in energy savings.We will also be working with utility programs that have custom reference homes to update those reference homes as necessary.

If you have any questions about SEER2, HSPF2, or other updated requirements on the horizon, please reach out to us at info@ekotrope.com.

* If the Energy Guide label includes a range for the least efficient SEER rating, the lower SEER rating should be used. And in that case, DOE Guidance requires the least efficient SEER rating (coil-only rating) to be used in determining if the equipment meets the efficiency standard. Blower-coil combinations cannot be used to meet the minimum efficiency requirement. Source.

Blower-coil combinations cannot be used to meet the minimum efficiency requirement. Source.

Note: This article was updated in September of 2023 to reflect the guidelines finalized in the MINHERS Addendum 71f.