There are a number of interesting elements to this comparison. Notice that the design cooling load for the Passive House went up. In order to meet the annual space heating load, the Passive House software recommended increasing the amount of south-facing glass by over 160 sq.ft - triple what was originally in the design. Then, Passive House software, in my opinion, underestimates cooling loads significantly. First, it assumes a set point temperature of 25 0C (77 0F), rather than the Canadian norm of 23 0C or 24 0C (74 0F to 75 0F). Second, for those readers who do heat gain calculations, you will recognize that the base 4,000 BTUs/hr cooling load would just barely match the appliance and people loads in a CSA F280 calculation. Passive House makes different assumptions about people, appliance and hot water loads than we traditional use in Canada. However, Passive House software does calculate the percentage of summer hours that a house or building will be above the set point temperature of 25 0C (77 0F) and limits that percentage to less than 10%. In the example above, those calculations indicate the house will be above this temperature 27% of the time. Rather than recommending additional cooling, however, the Passive House consultant recommended extra southern face shading and a night-time by-pass of the energy recovery core or whole house fan. This may not be practical in the parts of Canada that have high night-time humidity levels.