- Beyond Sustainability - The Case for Regenerative Design
- Understanding Place - Climate, Site, and Solar Geometry
- The Six Integrated Systems - An Overview
- Building with the Earth—Natural Materials
- Passive Solar Design - Heating and Cooling Without Machines
- Off-Grid Energy Systems - Power from the Sun
- Water - Catching, Storing, and Cycling
- Liquid Waste Treatment - Botanical Systems
- Food Systems—Buildings That Feed
- Community Design - Scaling Up
- The Integrated Design Process
- Appendix A: Glossary of Key Terms
- Appendix B: The Pangea Textbook Series
- Appendix C: Key Design Principles at a Glance
- The Regenerative Community Vision
- Site Assessment and Land Reading
- Land Use Law and Legal Frameworks
- Master Planning for Regenerative Communities
- Infrastructure Systems Integration
- Housing Typologies and Density Design
- Community Governance Structures
- Economic Models for Community Development
- Phased Development Strategy
- Community Resilience and Long-Term Stewardship
- Appendix A: Legal Entity Comparison Chart
- Appendix B: Community Design Checklist
- Appendix C: Glossary of Community Development Terms
Every passive solar building rests on three interdependent principles. All three must be present and properly balanced for the system to work.
Solar Gain
Solar gain is the capture of solar energy through glazing (windows and glazed panels). South-facing glazing (in the northern hemisphere) receives direct solar radiation during the heating season. The amount of solar gain is determined by the size, orientation, and shading of the glazing; the solar heat gain coefficient (SHGC) of the glass; and the number of heating-degree-days at the building’s location. Sizing south glazing correctly is the central design challenge of passive solar: too little, and the building cannot capture enough solar energy to meet its heating needs; too much, and it overheats on sunny days and loses excessive heat at night through the glass.
Thermal Mass
Thermal mass is the material that absorbs and stores solar energy during the day and releases it at night, smoothing out the temperature fluctuations that would otherwise make a heavily glazed building uncomfortably hot in the daytime and cold at night. Dense, heavy materials — earth, concrete, stone, tile, and water — have high specific heat capacity, meaning they can absorb large amounts of energy with relatively small changes in temperature. In a passive solar building, thermal mass is positioned where it will receive direct sunlight (or at least diffuse solar radiation) during the day: the floor in front of south windows, the interior face of the south wall, and the interior walls that receive reflected sunlight.
Insulation
Insulation is what allows the thermal mass to do its job. A highly insulated building envelope retains the heat stored in thermal mass through the night, while a poorly insulated envelope loses it so quickly that the thermal mass advantage is eliminated. Insulation and thermal mass work together: thermal mass stores energy, insulation retains it. The ratio of thermal mass to glazing to insulation must be carefully balanced for the specific climate; the Heating and Cooling Buildings textbook provides detailed guidance on this calculation for each climate type.
The Passive Solar Rule of Thumb
South glazing area: 7–12% of floor area for most temperate and arid climates.
Thermal mass: 3–6 square meters of mass surface per square meter of south glazing.
Insulation: minimum R-20 walls, R-40 roof for cold climates; adjust downward for mild climates.
Note: These are starting points only. Proper sizing requires climate data and design calculations.