Buildings are responsible for 40% of energy consumption and 36% of EU CO2 emissions. Improving energy performance of buildings is key to achieving EU climate and energy objectives. The "Passive House Standard" is an ultra-low energy building standard that requires annual heating/cooling demands of less than 15 kWh/m2 and total primary energy consumption of less than 120 kWh/m2. It results in buildings that require little energy for heating, cooling, and hot water. The Passive House Standard is the closest standard to a zero energy building.