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Mike Horgan is a PHI Certified Passive House Consultant, zero-net-energy & Passivhaus design-builder, and licensed general contractor in both Massachusetts and California. He lives full-time now on the Central Coast region of California in San Luis Obispo. He founded Horgan Design-Build, Inc. on Cape Cod, MA; now runs Cairn Collaborative, LLC, a design-build firm in San Luis Obispo, CA; and provides education for builders and architects with In Balance Green Consulting as a residential construction specialist. He is on the advisory board of the Tri-County Regional Energy Network on the Central Coast; is Vice-President of Passive House California; co-chairs the Building Decarbonization Task Force in San Luis Obispo; and was named San Luis Obispo’s Climate Champion of 2019 by the SLO Climate Coalition.


Combining an academic background in economics, finance, education, and linguistics from Worcester University and Boston University with over two decades of residential construction experience, his work focuses on designing and constructing homes, not only for his clients but to create real-life teaching moments.  The goal is to transition all builders and architects from baseline practices to designing and building more responsibly with better-performing, healthier, more efficient, and comfortable homes built to zero-net-carbon through Passivhaus. 

Let's see what can achieve together. 


Hannah McKay is a certified Passive House Consultant/Designer with PHIUS and PHI. She graduated with a bachelor’s degree in architecture from Cal Poly San Luis Obispo in 2020 after completing a thesis project centered on resettlement and refugee housing.

Originating from Vermont and now a SLO resident, she connected with Cairn Collaborative through a love of regenerative design and has been designing and building with Mike ever since. She has done build work in Ecuador and Tanzania and is excited to see the growing popularity of Passive House and sustainable materials in California.

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