Upgrading New Zealand's existing office buildings - An assessment of life cycle impacts and its influence on 2050 climate change mitigation target

•Environmental impacts associated with refurbishing New Zealand’s existing office building stock was calculated.•Achievability of New Zealand’s 2050 target with respect to reducing GHG emissions from the office building sector was calculated.•Refurbishing the office building stock can substantially reduce environmental impacts related to energy consumption.•Prioritizing refurbishment in large buildings or major cities reduces can help achieve the 2050 target in office buildings.