The amount of credit for an alteration depends on whether a HERS rater verifies the existing conditions. For example, if you are altering existing metal frame, single-pane windows to vinyl frame, low-e windows, if you do not check “HERS Verification” at the top level of the Building Tree, Residential Tab, the software will not prompt you to input the Existing Conditions. You will only input the efficiency of the new windows and your credit is based on the difference between the new window U-factor/SHGC and 0.40/0.35 (values from Table 150.2-B of the Standards). If you check “HERS Verification” and enter the existing conditions of 1.28 U-factor/0.80 SHGC, the credit you receive is based on the difference between these values and the U-factor/SHGC of the new windows.
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