Good afternoon,

We’re working with a Multifamily building that’s pursuing compliance with LEED V4.1. According to LI 10500 a project may apply ASHRAE 90.1-2019 Appendix G in lieu of ASHRAE 90.1-2016 Appendix G. There are some key differences we identified between both ASHRAE versions. Will these be the correct assumptions to consider within our 2019 model (which is pursuing 2018 Seattle Energy Code compliance):

  • DHW demand: Baseline values shall not follow EPACT 1992 water demand. The baseline hot water demand should be based on the maximum allowed by the applicable code. In our case, the project is in Seattle and code maximum flow rates are 1.8gpm for showerheads and 1.2gmp for sinks. Should these values be the ones modeled in the Baseline (1.8gpm and 1.2gpm)?
  • Envelope air leakage: Baseline design shall be modeled using 1.0 cfm/ft2. Meanwhile proposed design shall be modeled with 0.60cfm/ft2 if prescriptive barrier requirements are met.
  • In-unit LPD: Proposed design 0.60W/ft2 or as designed, whichever is greater. Baseline: 1.07W/ft2.

Thanks!