© Copyright CalCERTS, Inc. 2019
Code Cycle: 2016 & 2019 Standards
Reference: CalCERTS Alterations Training Manual Chapter 3, Section 2
When an entirely new HVAC system is installed in a residential building, the Building Energy Efficiency Standards require that the installer use one of three approved design methodologies to calculate the heating/cooling loads that the new system will service. This requirement applies to both new construction or when an entirely new system is installed in an existing building (ref: §150.2(b)1Ci). Installing oversized equipment leads to reduced efficiency, so the code specifies that the installed equipment shall be properly sized to match the heating and cooling load of the space that it serves.
The methodology used by the installer and the calculated loads shall be recorded in Section A of the CF2R-MCH-01. For HVAC change-outs that are not considered entirely new systems, the installer is not required to perform load calculations and shall indicate “Not Applicable” in the field for methodology. When “N/A” is indicated, the subsequent fields for the calculated loads will auto-populate with “N/A” as well.
Regardless of the project scope, load calculations are always recommended for equipment sizing. Especially if the loads in the house have been changed since the original equipment was installed (reduced via weatherization, other improvements).
150.0(h) - Space-Conditioning Equipment
1. Building Cooling and Heating Loads. Building heating and cooling loads shall be determined using a method based on any one of the following:
A. The ASHRAE Handbook, Equipment Volume, Applications Volume, and Fundamentals Volume;
B. The SMACNA Residential Comfort System Installation Standards Manual; or
C. The ACCA Manual J.
The cooling and heating loads are two of the criteria that shall be used for equipment sizing and selection.
NOTE: Heating systems are required to have a minimum heating capacity adequate to meet the minimum requirements of the CBC. The furnace output capacity and other specifications are published in the Commission's directory of certified equipment or other directories approved by the Commission.
2. Design conditions. For the purpose of sizing the space-conditioning (HVAC) system, the indoor design temperatures shall be 68°F for heating and 75°F for cooling. Outdoor design conditions shall be selected from Reference Joint Appendix JA2, which is based on data from the ASHRAE Climatic Data for Region X. The outdoor design temperatures for heating shall be no lower than the Heating Winter Median of Extremes values. The outdoor design temperatures for cooling shall be no greater than the 1.0 percent Cooling Dry Bulb and Mean Coincident Wet Bulb values.