Session · Climate and carbon · Designers and consultants

Passive House + Foundation Reuse

Anika Linde; Dawson Linde, Lime Tree Carpentry; Greg Fisher, Greg D. Fisher, Architect; Ed May, bldgtyp · June 18, 2026 · Chapter · PHRM (Passive House Rocky Mountains)

A Passive House home in Fort Collins, Colorado, built on an existing foundation to cut embodied carbon. The owner-builders, architect, and consultant on the design, designPH modeling, certification choices, and lessons learned.

Key points

• Strategies for reusing a foundation in a high-performance rebuild.
• The role and limits of design tools such as designPH.
• PHI certification pathways, including Low Energy Building and Classic, and how they shape design.
• Common challenges in hybrid retrofit and new-build projects.

Learning objectives

• Identify strategies for reusing a foundation in a high performance rebuild.
• Compare the role and limitations of design tools and modeling workflows, including DesignPH and evolving Passive House analysis methods.
• Distinguish between Passive House certification approaches, including PHI Low Energy and Classic pathways, and their influence on design decisions.
• Recognize common technical and construction challenges encountered during high-performance retrofit/new-build hybrid projects and strategies used to address them.

Topics: Embodied carbon