4.3   Cooling Equipment

This section addresses the requirements for space cooling equipment.

4.3.1    Mandatory Measures for Cooling Equipment    

A.   Equipment Efficiency

The efficiency of most cooling equipment is regulated by NAECA (the federal appliance standard) and the California Appliance Efficiency Regulations. These regulations are not contained in the Building Energy Efficiency Standards but rather in separate documents. These regulations are referenced in §110.1. The Appliance Efficiency Regulations include definitions for all types of equipment. The energy efficiency of larger equipment is regulated by §110.2(a). See the Nonresidential Compliance Manual for information on larger equipment.

1    Central, Single Phase Air Conditioners and Air Source Heat Pumps (under 65,000 Btu/h)

The central, single phase air conditioners and air source heat pumps that are most commonly installed in residences have a smaller capacity than 65,000 Btu/h. The Appliance Efficiency Regulations for this equipment require minimum Seasonal Energy Efficiency Ratios (SEER).

The Seasonal Energy Efficiency Ratio of all new central, single phase air conditioners and air source heat pumps with output less than 65,000 Btu/h shall be certified to the Energy Commission to have values no less than  the values 'listed below in Table 4-6.

Table 4-6 – Minimum Cooling Efficiencies for Central Air Conditioners and Heat Pumps

Source: California Appliance Efficiency Regulations Table C-2 Title-20

NR = No Requirement

2    Other Air Conditioners and Heat Pumps

The current Appliance Efficiency Regulations for larger central air conditioners and heat pumps, and for all room air conditioners and room air conditioner heat pumps shall be certified to the Energy Commission by the manufacturer to have values no less than the values 'listed in Table 4-7 and Table 4–8.

Table 4-7 – Minimum Cooling Efficiency for Larger Central Air Conditioners and Heat Pumps

Source: California Appliance Efficiency Regulations Table C-3, C-5

 Table 4-8 – Minimum Cooling Efficiency for Non-Central Space Cooling Equipment

Including Room Air Conditioners; and Room Air Conditioner Heat Pumps; Package Terminal Air Conditioners (PTAC); Package Terminal Heat Pumps (PTHP), Single Package Vertical Air Conditioners (SPVAC) and Heat Pumps (SPVHP)

Source: California Appliance Efficiency Regulations the Energy Efficiency Standards Title -20

B.   Insulation for Refrigerant Lines in Split System Air Conditioners

§150.0(j)2 and 3, §150.0(m)9 Two refrigerant lines connect the indoor and outdoor units of split system air conditioners and heat pumps: the liquid line (the smaller diameter line) and the suction line (the larger diameter line). The liquid line is at an elevated temperature relative to outdoor and indoor temperatures, in those areas, heat escaping from it is helpful; therefore, it should not be insulated. When the liquid line runs through the attic, its surrounding temperature is higher than the liquid line temperature. It would be advantageous to insulate liquid lines running through attics. The suction line carries refrigerant vapor that is cooler than ambient in the summer and (with heat pumps) warmer than ambient in the winter. This line must be insulated to the required thickness (in inches) as specified in the table below.

Table 4-9 – Insulation Requirements for Split System Refrigerant Piping

Insulation used for the suction line must be protected from physical damage or from UV deterioration when it is located in outside conditioned space. Pipe insulation is typically protected by an aluminum or sheet metal jacket, painted canvas, plastic cover, or coating that is water retardant and UV resistant.  Additionally, the insulation used for the refrigerant suction line of a heat pump must be Class I or Class II vapor retarding.  If the insulation is not Class I or Class II, then the insulation must be installed at the required thickness that would qualify it as a Class I or Class II vapor retarder.  See §150.0(j) 3, and Figure 4-1.

Figure 4-1 – Refrigerant Line Insulation

C.   Outdoor Condensing Unit Clearance

Any obstruction of the airflow through the outdoor unit of an air conditioner or heat pump lowers its efficiency. Dryer vents are prime sources for substances that clog outdoor coils and sometimes discharge substances that can cause corrosion. Therefore, condensing units shall not be placed within 5 feet of a dryer vent. Regardless of location, condenser coils should be cleaned regularly in all homes.

Figure 4-2 – Non-compliant Condensing Unit Clearance from Dryer Vents
Source: California Energy Commission

D.   Equipment Sizing

Similar to heating equipment, the Standards do not set limits on the size of cooling equipment, but they do require that cooling loads be calculated for new cooling systems. Avoiding oversizing is especially important for cooling equipment because ducts must be sized large enough to carry the mandatory airflow and oversized air conditioners make this difficult.

The outdoor design conditions for load calculations must be selected from Reference Joint Appendix JA2, Table 2-3, using values no greater than the “1.0 percent Cooling Dry Bulb” and “Mean Coincident Wet Bulb” values listed. The indoor design temperature for cooling load calculations must be 75°F.  Acceptable load calculation procedures include methods described in

1.   The ASHRAE Handbook – Equipment,

2.   The ASHRAE Handbook – Applications,

3.   The ASHRAE Handbook – Fundamentals,

4.   The SMACNA Residential Comfort System Installation 'Manual, or

5.   ACCA Manual J

Cooling load calculations must be submitted with compliance documentation when requested by the building department. The load calculations may be prepared by 1) a mechanical engineer, 2) the mechanical contractor who is installing the equipment or 3) someone who is qualified to do so in the State of California according to Division 3 of the Business and Professions Code.:

E.   Hole for Static Pressure Probe (HSPP) or Permanently Installed Static Pressure Probe (PSPP)

Space conditioning systems that utilize forced air ducts to supply cooling to occupiable space shall have a hole for the placement of a static pressure probe (HSPP) or permanently installed static pressure probe (PSPP) installed downstream from the evaporator coil.

The HSPP or PSPP must be installed in the required location, in accordance with the specifications detailed in Reference Residential Appendix RA3.3. The HSPP or PSPP is required in order to facilitate system airflow measurement when using devices/procedures that depend on supply plenum pressure measurements. The HSPP or PSPP allows HERS raters to perform the required diagnostic airflow testing in a non-intrusive manner, by eliminating the necessity for the rater to drill holes in the supply plenum for placement of pressure measurement probes.

The size and placement of the HSPP/PSPP shall be in accordance with RA3.3.1.1 and shall be verified by a HERS rater.  In the event that the HSPP/PSPP cannot be installed as shown in Figure RA3.3-1, due to the configuration of the system or that the location is not accessible, an alternative location may be provided that can accurately measure the average static pressure in the supply plenum.  If an alternative location cannot be provide then the HSPP/PSPP is not required to be installed.  The HERS rater will verify this.  Note that not installing an HSPP/PSPP will limit the airflow measurement method to either a powered flowhood or passive (traditional) flow hood.

When the mandatory measure for minimum system airflow rate is in effect (entirely new systems), there must be a hole in the supply plenum, provided by the installing contractor, for the placement of a static pressure probe (HSPP).  Alternatively a permanently installed static pressure probe (PSPP) must be installed in the same location. 

This requirement also applies when the plenum pressure matching method or the flow grid method of airflow measurement is used by either the installer or the rater to verify airflow in an altered system.  Note that the HSPP/PSPP must be installed by the installer, not the rater.

See Air Distribution Ducts, Plenums, and Fans Section 4.4 for discussion regarding mandatory sizing/airflow requirements for ducted systems with cooling.

4.3.2    Prescriptive Requirements for Cooling Equipment    

The Prescriptive Component Packages do not require that a cooling system be installed. However if one is to be installed, the cooling equipment efficiency requirements are specified by the mandatory measures (see above).

Using the prescriptive compliance approach, no additional credit is given for selecting equipment that is higher than what is required by the prescriptive component package. 

Prescriptive Component Package A, for split system equipment in climate zones 2 and 8 through 15, requires refrigerant charge verification (RCV) and the installation of a measurement access hole (MAH). The RCV must be performed by the installer and/or HERS rater.  The MAH provides a non-intrusive means of measuring return air temperature, which is a parameter important to the RCV process. The alternative to RCV is the installation of a refrigerant charge indicator display (§151(f)7Aia).

A.   Refrigerant Charge Verification (RCV)

The prescriptive standards require that a HERS rater verify that air-cooled air conditioners and air-source heat pumps have the correct refrigerant charge. The RCV procedures are documented in Reference Residential Appendix RA3.2, and RA1.2.

Refrigerant charge refers to the actual amount of refrigerant present in the system. Excessive refrigerant charge (overcharge) reduces system efficiency and can lead to premature compressor failure. Insufficient refrigerant charge (undercharge) also reduces system efficiency and can cause compressors to overheat.  Ensuring correct refrigerant charge can significantly improve the performance of air conditioning equipment. Refrigerants are the working fluids in air conditioning and heat pump systems that absorb heat energy from one area (the evaporator),transfer and reject it to another (the condenser).

B.   Note: The Refrigerant Charge Verification process is discussed in greater detail later in Section 4.9.Measurement Access Hole (MAH)

MAH provide a non-intrusive means for refrigerant charge verification by HERS raters and other third party inspectors, since they eliminate the need for the raters/inspectors to drill holes into the installed air conditioning equipment enclosures for placement of the temperature sensors that are required by the refrigerant charge verification test procedures described in the Reference Residential Appendix RA3.2.

Installation of MAH must be performed by the installer of the air conditioner or heat pump equipment according to the specifications given in Reference Residential Appendix RA3.2.

The MAH feature consists of one 5/8 inch (16 mm) diameter hole in the return plenum, upstream from the evaporator coil (see figure RA3.2-1 in Reference Residential Appendix RA3.2).

C.   Charge Indicator Display

The installation of a charge indicator display (CID) may be used as an alternative to the prescriptive requirement for HERS diagnostic testing of the refrigerant charge in split system air conditioners and heat pumps. The purpose of the CID is to provide real-time information to the building occupant about the status of the system refrigerant charge, metering device, and system airflow. The CID will monitor and determine the operating performance of split system air conditioners and heat pumps, and provide visual indication to the system owner or operator if the system’s refrigerant charge, airflow, or metering device performance does not conform to approved target parameters for minimally efficient operation. Thus, if the CID signals the owner/occupant that the system requires service or repair, the occupant can immediately call for a service technician to make the necessary adjustments or repairs. A CID can provide significant benefit to the owner/occupant by alerting the owner/occupant to the presence of inefficient operation that could result in excessive energy use/costs over extended periods of time. A CID can also indicate system performance faults that could result in system component damage or failure if not corrected, thus helping the owner/occupant to avoid unnecessary repair costs.

The CID procedures are documented in Reference Residential Appendix RA4.3.2.

Charge indicator display technologies shall be factory installed or field installed according to manufacturer's specifications. Reference Joint Appendix JA6 contains more information about CID technologies.

The presence of a CID on a system must be field verified by a HERS rater. See Reference Residential Appendix RA3.4.2 for the HERS verification procedure, which consists of a visual verification of the presence of the installed CID technology. The rater must inspect to see that the visual indication display component of the installed CID technology is mounted adjacent to the split system's thermostat. When the outdoor temperature is greater than 65°F, the rater must also observe that the system reports no system faults when the system is operated continuously for at least 15 minutes when the indoor air temperature returning to the air conditioner is at or above 70°F.  When the outdoor temperature is below 65°F the Rater must observe that the CID does a self diagnosis and indicates that the sensors and internal processes are operating properly.

Though not specifically mentioned in the CID protocols of Residential Appendix RA3.4.2, the Winter Set Up Method detailed in RA 1.2 may be used when normally allowed.  For purposes of CID verification the Winter Setup Method will be treated the same as the Subcooling Method.

4.3.3    Performance Compliance Options for Cooling Equipment    

There are several options for receiving compliance credit related to the cooling system. These credits are available through the performance compliance method.

A.   High Efficiency Air Conditioner

Air conditioner efficiencies are determined according to federal test procedures. The efficiencies are reported in terms of Seasonal Energy Efficiency Rating (SEER) and Energy Efficiency Rating (EER). Savings can be achieved by choosing an air conditioner that exceeds the minimum efficiency requirements.

The EER is the full load efficiency at specific operating conditions. It is possible that two units with the same SEER can have different EERs. In cooling climate zones of California, for two units with a given SEER, the unit with the higher EER is more effective in saving energy. Using the performance compliance method, credit is available for specifying an air conditioner with an EER greater than 10 (see the compliance program vendor’s compliance supplement). When credit is taken for a high EER or SEER, field verification by a HERS rater is required (see Reference Residential Appendix RA3.4).

B.   Air Handler Watt Draw and System Airflow

It is mandatory that central forced air systems produce fan watt draws less than or equal to 0.58 watts/CFM and flow at least 350 CFM per nominal cooling ton. Performance compliance credits are available for demonstrating the installation of a high efficiency system with a lower fan wattage and/or higher airflow than the mandatory requirements. These credits can be achieved by selecting good duct design and can be assisted by a high efficiency fan. There are two possible performance compliance credits:

1.   The performance compliance method allows the user’s proposed fan watt draw to be entered and credit earned if it is lower than the default of 0.58 watts per CFM of system airflow. To obtain this credit, the system airflow must meet the mandatory requirement of at least 350 CFM/ton of nominal cooling capacity.

2.   The performance compliance method allows the user’s proposed airflow to be entered and credit earned if it is higher than the default of 350 CFM/ton of nominal cooling capacity. To obtain this credit, the fan watt draw must meet the mandatory requirement of no more than 0.58 Watts per CFM of nominal cooling capacity.

After installation, the contractor must test the actual fan power and airflow of the system using the procedure in Reference Residential Appendix RA3.3, and show that it is equal or better than what was proposed in the compliance software analysis.

Field verification by a HERS rater is required (see Reference Residential Appendix RA3.3).