Passive House
A Passive House is a building that meets a specific high-performance standard for envelope quality, airtightness, and energy use. The two main certification bodies are PHIUS (Passive House Institute US) and PHI (Passive House Institute, Germany). Both require very low heating and cooling demand (4.7 kBTU/sq ft·yr or less), very low source energy use (38 kBTU/sq ft·yr), exceptional airtightness (0.6 ACH50), and balanced mechanical ventilation with heat recovery. A Passive House uses 70-90% less heating energy than a code-built home.