How the NGBS Can Help You Navigate Green Renovations on Historical Properties
The ICC 700-2020 National Green Building Standard® (NGBS) provides building professionals with a comprehensive, voluntary, above-code approach to design and construct residential and mixed-use properties and for land development. It also provides a flexible roadmap for green renovation projects — including the conversion of existing buildings to residential use, even if that building is subject to historical preservation regulations — in NGBS Chapter 11, 'Certification for Existing Buildings.'
For instance, the process for converting an old factory building to new multifamily lofts includes:
- Determining the number of units for the proposed design.
- Calculating energy and water use for the proposed design with appropriate modeling tools.
- Using the same number of units and configurations (studio, one‐bedrooms, two‐bedrooms, etc.), calculating energy and water use, using 1980 code requirements as a baseline.
- Determining certification level using the difference in energy and water use pre‐ and post‐rehab.
- Buildings with historic designation restrictions are exempt from NGBS mandatory practices for unaltered portions.
- If claiming exemption, building can use Performance Path for compliance or Prescriptive Path and select N/A for mandatory items that are not relevant.
- Verifier must make detailed notes on verification report when exemptions are claimed.
- Buildings with an addition of more than 75% of existing building's above‐grade conditioned area should use new construction path unless there are historic preservation restrictions.
- NGBS Green interpretation allows existing buildings to use NGBS exemptions for mandatory practices that apply to building portions that remain unaltered.