Passive Certified Buildings are residential, commercial and/or industrial buildings that have voluntarily adopted a building design and development that incorporates and implements the highest level of building envelope energy efficiency, comfort and climate-consciousness. Passive House buildings consume up to 90 percent less heating and cooling energy than conventional buildings. Passive houses achieve these high levels of performance by requiring building envelope airtightness of 0.6 air changes per hour (ACH @50Pa) or less, and utilizing renewable energy technologies (ie. Solar Photovoltaic, solar domestic hot water systems, etc.).