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ENERGY STAR HVAC Design Report: 3. Room-by-Room Heating & Cooling Loads

 

When certifying a home to ENERGY STAR Certified Homes, Version 3.0/3.1 (Rev. 08), the HVAC Designer completes the HVAC Design Report Checklist and provides it to the Rater to document the types of mechanical ventilation, heating, and cooling equipment specified for the home, and the heating and cooling calculation inputs and loads.

This page shows the checklist requirement for Section 3. Room-by-Room Heating and Cooling Loads and applicable footnotes.

For information on installing HVAC equipment, see installation guides linked to the HVAC section of the Rater Field Checklist.

For information on determining heating and cooling loads, see the Air Conditioning Contractors of America’s ANSI/ACCA 5 QI - 2015 HVAC Quality Installation Specification and ACCA Manual J - Residential Load Calculation (unabridged) or the 2013 ASHRAE Handbook – Fundamentals.

Information guide describing section 3 requirements in Version 3.0/3.1 Rev. 08 ENERGY STAR HVAC Design Report Checklist.
Checklist revised 09/15/2015.  Required for homes permitted starting 07/01/2016.18

Footnotes

1. This report is designed to meet ASHRAE 62.2-2010 / 2013 and ANSI / ACCA’s 5 QI-2015 protocol, thereby improving the performance of HVAC equipment in new homes when compared to homes built to minimum code. However, these features alone cannot prevent all ventilation, indoor air quality, and HVAC problems (e.g., those caused by a lack of maintenance by occupants). Therefore, system designs documented through the use of this report are not a guarantee of proper ventilation, indoor air quality, or HVAC performance.

2. The report shall represent a single system design for a house plan. Check the box for “site-specific design” if the design was created for the specific plan configuration (i.e., elevation, option, orientation, and county) of the home to be certified. Check the box for “group design” if the design was created for a plan that is intended to be built with potentially different configurations (i.e., different elevations, options, and/or orientations). Regardless of the box checked, the system design as documented on this HVAC Design Report must fall within the following tolerances for the home to be certified:

    • Item 3.3: The outdoor design temperature used in loads are within the limits defined at energystar.gov/hvacdesigntemps.
    • Item 3.4: The number of occupants used in loads is within ± 2 of the home to be certified.
    • Item 3.5: The conditioned floor area used in loads is between zero and 300 sq. ft. larger than the home to be certified.
    • Item 3.6: The window area used in loads is between zero and 60 sq. ft. larger than the home to be certified.
    • Item 3.7: The predominant window SHGC is within 0.1 of the predominant value in the home to be certified.
    • Items 3.10 - 3.12: The sensible, latent, & total heat gain are documented for the orientation of the home to be certified.
    • Item 3.13: The variation in total heat gain across orientations is ≤ 6 kBtuh.
    • Item 4.16: The cooling sizing % is within the cooling sizing limit selected.

Provide the HVAC Design Report to the party you are providing these design services to (i.e., a builder or credentialed HVAC contractor) and to the Home Energy Rater. The report is only required to be provided once per system design, even if multiple homes are built using this design (e.g., in a production environment where the same plan is built multiple times, only one report is required). As long as a report has been provided that falls within these tolerances for the home to be certified, no additional work is required. However, if no report falls within these tolerances or if any aspect of the system design changes, then an additional report will need to be generated prior to certification.

Visit energystar.gov/newhomeshvacdesign for a tool to assist with group designs and for more information.

11. Select “2013 ASHRAE Fundamentals” if using Chapter 17 of the 2013 ASHRAE Handbook of Fundamentals. Select “Other per AHJ” if the Authority Having Jurisdiction where the home will be certified mandates the use of a load calculation methodology other than Unabridged ACCA Manual J v8 or 2013 ASHRAE Fundamentals.

12. Visit energystar.gov/hvacdesigntemps for the maximum cooling season design temperature and minimum heating season design temperature permitted for ENERGY STAR certified homes. For “County & State selected”, select the County and State where the home is to be certified. The same design report is permitted to be used in other counties, as long as the design temperature limits in those other counties meet or exceed the cooling and heating season temperature limits for the county selected. For example, if Fauquier County, VA, is used for the load calculations, with a 1% cooling temperature limit of 93 F, then the same report could be used in Fairfax County (which has a higher limit of 94 F) but not in Arlington County (which has a lower limit of 92 F).

13. To determine the number of occupants among all HVAC systems in the home, calculate the number of bedrooms, as defined below, and add one. This number of occupants must be within ± 2 of the home to be certified, unless Item 1.5 indicates that the system is a cooling system for temporary occupant loads. A bedroom is defined by RESNET as a room or space 70 sq. ft. or greater size, with egress window and closet, used or intended to be used for sleeping. A “den”, “library”, or “home office” with a closet, egress window, and 70 sq. ft. or greater size or other similar rooms shall count as a bedroom, but living rooms and foyers shall not. An egress window, as defined in 2009 IRC section R310, shall refer to any operable window that provides for a means of escape and access for rescue in the event of an emergency. The egress window definition has been summarized for convenience. The egress window shall:

    • have a sill height of not more than 44 inches above the floor; AND
    • have a minimum net clear opening of 5.7 sq. ft.; AND
    • have a minimum net clear opening height of 24 in.; AND
    • have a minimum net clear opening width of 20 in.; AND
    • be operational from the inside of the room without the use of keys, tools or special knowledge.

14. “Predominant” is defined as the SHGC value used in the greatest amount of window area in the home.

15. Infiltration rate shall reflect the value used in the confirmed or projected HERS rating for home to be certified. Alternatively, use “Average” or “Semi-loose” values for the cooling season infiltration rate and “Semi-tight” or “Average” values for the heating season infiltration rate, as defined by ACCA Manual J, Eighth Edition, Version Two.

16. Orientation represents the direction that the front door of the house is facing. The designer is only required to document the loads for the orientation(s) that the house might be built in. For example, if a house plan will only be built one time in a specific orientation (e.g., a sitespecific design), then the designer only needs to document the loads for this one orientation.

17. Determine the orientation with the largest and smallest Total Heat Gain. Verify that the difference in Total Heat Gain between the orientation with the largest and smallest value is ≤ 6 kBtuh. If not, then assign the orientations into one or more groups until the difference is ≤ 6 kBtuh and then complete a separate HVAC Design Report for each group.

18. This Revision of the HVAC Design Report is required to certify all homes permitted after 07/01/2016, but is allowed to be used for any home permitted or completed prior to this date. The Home Energy Rater certifying the home may define the ‘permit date’ as either the date that the permit was issued or the date of the contract on the home. In cases where permit or contract dates are not available, Providers have discretion to estimate permit dates based on other construction schedule factors.

Contributors to this Guide: ENERGY STAR Certified Homes, Pacific Northwest National Laboratory

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Last Updated: Wednesday, January 27, 2016