[en] At CERN there are currently 200 ventilation air handling units in production, used in many different applications, including building ventilation, pressurization of safe rooms, smoke extraction, pulsion/extraction of experimental areas (tunnel, cavern, etc.), and the ventilation of the computing centre. The PLC applications which operate these installations are currently being revamped to a new framework (UNICOS CPC). This work began 3 years ago, and we are now in a position to standardize the development of these HVAC applications, in order to reduce the cost of initial development (including specification and coding), testing, and long-term maintenance of the code. In this paper we will discuss the various improvements to the process, and show examples, which can thus help the community develop HVAC applications. Improvements include templates for the ^Functional Analysis specification document, standardized HVAC devices and templates for the PLC control logic, and automatically generated test documentation, to help during the Factory Acceptance Test (FAT) and Site Acceptance Test (SAT) processes. (author)