Q: Tell us a little about Marin County’s experience with the FlexPath approach, Mark.
A: Sure, the County adopted its first FlexPath reach code in 2022 and began implementation and compliance efforts in 2023. The triggering threshold was any addition or alteration project for a single family home that exceeded 750 ft2. We had worked very closely with a wide range of stakeholders in the policy development process, including developers, residents, building departments both at the county level and at jurisdictions within the county, and local staff from other jurisdictions as well. Consistency across the county was a very important factor for builders so they could rely on similar approaches for projects located in different jurisdictions.
In 2025, the County team looked at the experience to date since the first FlexPath measure adoption to assess how this approach could be more impactful. We realized that the 500-750 ft2 footprint for additions and alterations was where the most activity was and by updating the triggering threshold to 500 ft2, we could extend the benefits of the FlexPath approach to as many as 50% more projects. This would also improve consistency across the county as several cities and towns have adopted a similar threshold in their FlexPath ordinances.
Q: What are the biggest benefits to the FlexPath approach?
A: The flexibility, of course, is primary. Homeowners can choose from a menu of energy efficiency (e.g. insulation, PV), electric readiness, and/or electrification (e.g. heat pump, induction stove) measures that have been developed and proven by the statewide program to be cost-effective. So it’s easier for homeowners to work within their budgets. For instance, a homeowner doing a smaller addition with a smaller budget may look more closely at the energy measures and select options such as attic or wall insulation, lighting or air sealing. Likewise, homeowners with larger projects and more substantial budgets could determine that the fuel substitution measures involving replacing appliances with heat pumps or induction cooktops would be appropriate for their needs.
Another benefit is the opportunity for county-wide collaboration, again going back to the consistency factor. By actively working with other jurisdictions, we are able to develop and implement very harmonious reach codes that simplify compliance for builders. While every measure might not be exactly the same the framework is so consistent that builders and remodelers can proceed with greater certainty and understanding of the overall compliance process.
Q: Have there been any challenges with the implementation and compliance process?
A: Well, there are always challenges but the team has worked hard to develop, maintain and update support materials for homeowners and builders. For instance, we realized that some of the earlier checklists could be improved for clarity. We have a robust resource area online for both education and compliance materials. We also offer a Green Building Decision Tool to help homeowners identify the forms and checklists they will need for their project.
Q: What are other aspects of the approach that would be helpful for other jurisdictions to know?
A: One of the most important aspects for us is to maintain ongoing and open lines of communication and collaboration with other jurisdictions across the County. We invest time and effort in coordinating with cities and towns across the county to ensure the highest level of consistency possible. For instance, our Marin Climate and Energy Partnership’s Reach Code Committee meets monthly and sustainability staff from cities and the county join to collaborate on implementation materials. Similarly, we participate in the Marin County Codes Advisory Board, a group of building department staff from across the county who meet monthly. This commitment maintains trust in the important stakeholder relationships that help ensure the reach code is ultimately successful.
Finally, there are so many resources available for other jurisdictions and regions who are interested in exploring FlexPath approaches. Some of these resources are available at the statewide level, but many are resources we’ve developed for Marin County that could serve as useful models for other regions. For more information, visit the Marin County sustainability webpages or email me at energy@marincounty.gov.
