The important part of the program for mechanical professionals is to get comfortable with the Passive House performance metrics or requirements. There is, of course, a comprehensive list of the enclosure and mechanical requirements for a Passive House building, but the primary requirements of interest to mechanical contractors are as follows:
Let's consider an example, using my own 2,100 ft2 Net Zero Energy home. The definition of usable floor space within Passive Houses has its own nuances, but for the purpose of this example, let's assume all 2100 ft2 or 195 m2 is usable. That would mean, the heat loss for the building could be no more than 1950 watts. That's just a heat loss of approximately 6150 BTUs/hr in imperial units. Moreover, in the Passive House program, there is no allowance for climate zones, so this heat loss compliance would be the same for Vancouver to Edmonton to Windsor to Quebec City to Halifax.
The alternate compliance metric would be the annual space heating demand. In the example house, that metric would allow a maximum of 15 x 195 = 2925 kWh of energy used for space heating. Fortunately, the Passive House software considers solar gain and, to some extent, thermal mass, such that it encourages large expanses of south-facing glass to get as much "free heat" as possible. The table below shows the results from the Passive House software for that 2100 sq.ft. houses under 2 scenarios; as it was designed to meet Net Zero specifications and what Passive House ultimately recommended to meet their requirements.