In cases where the user selects 100% sized AWHP, also used for cooling, there's no need for a the backup chiller (or boiler for that matter). However, the user cannot select that as an option. This is relevant for refrigerant leakage considerations, as in cases like these many buildings will be be replacing the existing chiller and there is a potentially substantial refrigerant leakage benefit to doing so.
In cases where the user selects 100% sized AWHP, also used for cooling, there's no need for a the backup chiller (or boiler for that matter). However, the user cannot select that as an option. This is relevant for refrigerant leakage considerations, as in cases like these many buildings will be be replacing the existing chiller and there is a potentially substantial refrigerant leakage benefit to doing so.