Life Cycle Primary Energy Use in Buildings of High Energy Standards

In this study, we examine the life cycle primary energy use of buildings. Our analysis starts with a conventional timber-frame building. We maintain the architectural design, but alter the thermal properties of the envelope components and include heat recovery of ventilation air to achieve buildings with similar thermal properties as three existing passive house in Sweden. We also vary the building frame material from timber to concrete, and the heat supply system between district heating and electric resistance heating. We then follow the life cycle of the buildings, analyze and compare their life cycle primary energy use, including the production, operation and end-of-life energy uses. The results show that the life cycle primary energy use of a passive house building is substantially lower when it is constructed with a timber instead of a concrete frame and heated with district heating instead of electricity. A passive house with electric heating does not achieve lower primary energy use than a conventional house with district heating. Material production accounts for a relatively large share of the life cycle primary energy use in passive standard buildings, and is proportionally more significant if the heat supply is from district heating. Material choice is thus relatively more important as buildings become more energy efficient and energy-efficient heat supply systems are used.