The 2015 Washington State Energy Code, which is actually a combination of the 2015 International Energy Conservation Code (IECC) and the 2012
Washington State Energy Code (WSEC), has now been divided into commercial and residential provisions - both are available to download below:
Based on the 2015 IECC; "Residential" includes one- and two-family dwellings, townhouses and group R-2 and R-3 buildings three stories or less. "Commercial" includes
all buildings not covered under "residential."
Below are highlights of the revisions and significant changes to the WSEC:
- Additional Energy Efficiency Requirements, Chapter R406
This section was expanded to include all low-rise residential dwelling and sleeping units, not just IRC buildings. The updated requirements
increase the number of credits required for each dwelling and size to the following:
- .5 credits for an addition less than 500 s/f
- 1.5 credits for additions over 500 s/f and a house under 1500 s/f
- 2.5 credits for dwelling units serving R-2 occupancies
- 3.5 credits for house 1500 to 5000 s/f
- 4.5 credits for a house over 5000 s/f
- The list of options for compliance has to be reorganized and expanded. There is also an adjustment of the credit allowances for some of the options
- Energy Compliance
Performance-based compliance includes changes to simulated energy performance required per square foot of condition floor area.
- Mini-split Heat Pumps
All detached one- and two-family dwellings and multiple single-family dwellings (townhouses) up to three stories using electrical zonal heating as the
primary heat source, must now install an inverter-driven ductless mini-split heat pump in the largest zone in the unit.