Passivhaus is an integrated design system that defines parameters for ultra-low energy buildings. It requires annual heating/cooling demands of ≤15 kWh/m2a and air leakage of ≤0.6 air changes per hour at 50 pascals of pressure. Passivhaus provides advantages like high indoor air quality, thermal comfort, and elimination of thermal bridges and mold. It achieves a quantum leap in energy efficiency through rigorous quality control and verification to achieve zero energy use with minimal expense.