(e.g., fan static pressure reset, d

(e.g., fan static pressure reset, demand controlled ventilation, use of variable-speed drives, etc.) could reduce or potentially eliminate the fan energy savings for the large hotel building or increase the difference found for the large office building.  For extreme climates, the VRF condenser may not operate due to the outdoor temperature limits imposed by the manufacturers. In this case backup cooling or heating equipment is required to meet the zone loads. For this reason, VRF systems my not be well suited for very cold climates (i.e., other HVAC systems types could be used without the need for backup cooling or heating equipment). These limits are similar to other DX equipment types. Most DX equipment have only a lower outdoor temperature limit, VRF equipment also impose an upper outdoor temperature limit.