A modular heating or cooling system includes a heating andor cooling unit and a plurality of storage modules that may be releasably connected to the heating andor cooling unit by a releasable coupling. In one embodiment, an access control service receives requests to access network beacons from client devices. The meter modules monitor, store, encode and periodically transmit metering data via radio signals in an appropriate RF channel. For example, microwells having a bottom comprising a polar polymeric material and well sidestop comprising a non-polar polymeric material are provided. For each solution in the first set, a driver of the same type as the original driver in the Steiner tree is selected from a driver library and virtually inserted into the solution.