Backup energy systems utilizing compressed air storage (CAS) systems and bridging energy systems to supply backup power to a load are provided. During a power failure, the bridging energy system provides backup power to the load at least until the CAS system begins supplying adequate power. In various embodiments, backup power capability is enhanced through the use of one or more exhaustless heaters, which are used to heat compressed air. The compressed air, in turn, drives a turbine which is used to power an electrical generator. In various embodiments, ambient air heat exchangers or other types of heat exchangers are used to heat compressed air prior to the compressed air being routed to the turbine, thereby increasing system efficiency. Backup power and backup HVAC are also provided by utilizing turbine exhaust, heat exchangers and various resistive heating elements.