The global climate emergency requires existing buildings to modernize and decarbonize using a whole-life carbon approach. The digital-first strategy saves an average of 40% of on-site energy demand and, when paired with electrification, can reduce lifecycle carbon emissions by up to 94%. Building- specific renovation strategies must balance traditional passive strategies with active technology improvements based on the local conditions, including the climate, building characteristics, and utility grid fuel mix. A “one size fits all” approach does not work. Neither does the consideration of each carbon savings measure. Building upgrades must be considered in the larger context to understand the inter-actions between strategies and achieve the most effective road to zero emissions.