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The building sector is a major driver of climate change, and the increased focus on significantly reducing greenhouse gas (GHG) emissions in recent years calls for major initiatives in the way we plan, build and operate buildings and neighbourhoods. Life-cycle assessment (LCA) is a commonly used and well-established tool to estimate the total emissions caused by buildings throughout their entire life cycle. Yet, LCAs of more complex systems such as neighbourhoods are scarce.

We have developed an LCA model for neighbourhoods with a focus on GHG emissions based on a modular structure with five physical elements: buildings, mobility, open spaces, networks and on-site energy infrastructure. We applied it on the Zero Village Bergen pilot project in Norway.

The results give total GHG emissions of 117 ktons CO2-eq over 60 years, equivalent to 1.5 tons CO2-eq/ capita/year or 21.2 kg CO2-eq/m(2)/year on average over the period. The buildings constitute the largest share of emissions among the elements with 52%, then mobility with 40%, and only 2.3% from networks and open spaces. Emissions embodied in the materials consumed in all the elements of the neighbourhood account for as much as 56% of total emissions, with a large share coming from materials consumed in mobility vehicles. Critical parameters are emission intensities for electricity and heat production by waste incineration, as well as the daily distance travelled by the inhabitants.