Compactness of building form makes it easier to achieve Passivhaus standards, because the heat loss area (envelope) is minimised in relation to the building’s volume. In general the larger the building the easier it is to achieve the standard, including airtightness.
However, for Passivhaus we are interested in heat loss per m2 of Treated Floor Area (TFA) – therefore high ceilings and double height spaces all contribute to the volume but not the habitable floor area. As a rule, terraced housing will need less insulation than detached houses, and a block of flats less still. Integral garages, ornate dormer windows, bay windows, or an intricate building footprint, all worsen the ratio between a building’s envelope and it’s volume, and make it more difficult to achieve Passivhaus.