Conference article

In this study we analyze the effects of energy efficiency measures on the life cycle primary energy use of a case-study (reference) 4-story wood-frame apartment building using electric resistance heating; bedrock heat pump; or cogeneration-based district heating. The reference building has an annual final heat energy demand of 110 kWh/m2. The energy efficiency measures analyzed are improved windows and doors; increased insulation in attic and exterior walls; installation of improved water taps; and installation of a heat recovery unit in the ventilation system. We follow the buildings’ life cycles and calculate the primary energy use during the production; retrofitting; operation and end-of-life phases; and the energy reduction achieved by the measures. The results show that the measures give significantly greater life cycle primary energy savings when using resistance heating than when using district heating. However; a resistance heated building with the efficiency measures still has greater life cycle primary energy use than a district heated building without the measures. Ventilation heat recovery is the most effective measure when using resistance heating while improved windows and doors is the most effective when using district heating. This study shows the importance of considering the interactions between individual measures and the type of heat supply system when selecting energy efficiency measures.

Life cycle; Primary energy; End-use energy efficiency measures; Retrofitting; Low energy buildings