Originating in Germany in the late 1980's and building on the earlier Canadian research and experience, the Passive House program is perhaps the most rigorous energy-efficiency standard in the building industry today. Indeed, one of the underlying objectives of the standard is to build enclosures efficiently enough to avoid the need for conventional heating and cooling systems. This is not to say that HVAC contractors and manufacturers need to be worried that they won't get a call to provide goods or services in Passive Houses. It does mean you will have to be respectful of the nature of the loads in a Passive House building (the Passive House concept is of interest to architects in commercial, institutional and residential projects) and be flexible in your approach to meeting the total indoor environmental control and comfort of occupants.