Retrofit or Rebuild? Overview Sustainable, or ‘green’, buildings are becoming the norm when we talk about new construction projects. With a range of certifications available, it’s hard to find a new development that doesn’t boast a LEED, BuiltGreen, PassiveHaus, or EnergyStar rating. This is particularly apparent in cities like Vancouver where building bylaws require energy reductions of 20% below 2007 levels by 2020, and to be “carbon neutral” by 2030, for some project types