Optimizing designs for net zero emission buildings – technical and conceptual feasibility in a Norwegian context

Abstract

Abstract This paper investigates how a redesign of five single-family houses can comply with the Norwegian definition of a net zero emission building (ZEB). Central to the ZEB definition used in this study is the assumption that greenhouse gas emissions (GHGe) can be compensated by exporting generated electricity from photovoltaic (PV) systems, thus avoiding emissions from grid-mix. The redesigns were made as part of a master’s level course where five student teams followed an iterative process with three main steps, where 1) the energy efficiency of the building was improved with passive and active measures. Results from this showed how energy demand was reduced, on average, by one-third in the building cases. 2) Selection of materials with low GHGe-intensity was in focus. Results showed how the ZEB designs were 1.5-2.5 times more GHGe-intensive than the base case designs, mainly due to the application of PV systems. 3) remaining life-cycle GHGe were compensated via on-site PV electricity generation and exports. Resulting designs included mounted and integrated PV systems and exported, on average, 14,000 kWh annually. Key learnings from the process were the challenges in adapting an existing design without altering the architectural expression. Hence, ZEB design should preferably begin at the conceptual design level. Additional learnings relate to the sensitivity in parameter setting for the in-use scenarios, specifically the degradation rate of the PV panels and the ZEB-factor for GHGe compensation (132 g CO2eq/kWh used in this study). An outlook from the study relates to the ZEB definition itself, internationally developing towards requirements for active GHGe removals from the atmosphere as a more stringent type of emission compensation.