Table 2 Prescriptive path to PHIUS certified passive buildings

Compactness

To prevent non-compact designs, by restricting enclosure area based on geometry of the buildings

Solar protection

To achieve optimal solar heat gain through appropriate fenestration orientations and overhangs

To limit high peaks in cooling load in summers, and to limit net heat loss in winters

Different limits set for different climate zones, using regression

Thermal enclosure

To set maximum U-value for fenestration and minimum R-value for walls and roofs, using climate-dependent regression formulae

Mechanical ventilation

To set climate-specific limits on ventilation to obtain continuous fresh air supply while achieving required thermal enclosure

Mechanical systems

To use energy efficient air source and ground source heat pumps, depending on climate zone of the site

Lighting, appliances and water heating

To use energy efficient electrical appliances, usually in compliance with ENERGY STAR or ENERGY STAR Most Efficient 2020 appliance ratings