Washington state moves to require heat pumps in new residential construction

S&P Global Market Intelligence ($):

Washington state will require heat pumps in its residential building code, a move that will prompt most new homes to opt for electric space and water heating.

The Washington State Building Code Council, or SBCC, on Nov. 4 voted to include the heat pump mandates in an update to the state's residential energy code. The SBCC required heat pumps in the commercial code earlier in 2022, meaning nearly all new commercial and residential buildings will rely on electric power for primary space and water heating once the codes go into effect in July 2023.

The residential code update is a victory for local governments and climate activists seeking to phase out natural gas use. Currently, cities only have authority to amend Washington state's commercial code, which covers large apartment complexes. Several cities have exercised that authority, but local governments have been waiting for the state to provide a path to mandating heat pumps in single-family houses, townhomes and low-rise apartment buildings.

The heat pump requirements in both codes generated substantial debate. Opponents attempted to strip the requirements from the residential code, but the motion, introduced by Republican State Sen. Lynda Wilson, failed in an 8-5 vote.

Proponents said the mandates would help the SBCC meet a directive from the state legislature to improve energy efficiency in each three-year code cycle. Washington state law requires the council to adopt energy code updates that reduce annual net energy consumption in new buildings by 70% from 2006 levels by 2031.

Heat pumps, which condition outdoor or underground thermal energy to heat and cool indoor spaces, are more energy efficient than standard gas heating equipment, though air-source heat pump performance decreases in extreme cold. The code update allowed gas use for backup heating and includes exceptions for certain homes with very little heating load, including residences that follow passive building design.

The space heating proposal initially mandated electric heat pumps, but proponents revised it to allow gas heat pumps for primary heating. The gas industry often promotes gas heat pumps as solutions for reducing building emissions, but the technology is not in wide commercial use. Partly for that reason, opponents said the heat pump requirement amounted to a de facto gas ban. Critics and supporters also clashed over the proposal's costs and benefits, rehashing the debate over whether to mandate heat pumps in commercial buildings, which took place in April 2022.

[Tom DiChristopher]

More ($): Washington state to require heat pumps in new homes, boosting electrification