- 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
Direct gain is the simplest and most common passive solar heating strategy. Sunlight enters directly through south-facing windows or glazed panels and strikes the thermal mass of the floor and interior walls, where it is absorbed and stored. The building interior is the solar collector. Because the occupants are in direct contact with the solar-charged thermal mass, direct gain systems provide excellent radiant comfort — warm floors and walls — in addition to air temperature control.
The most important design considerations for direct gain systems are the placement and area of south glazing, the depth and surface color of the thermal mass that the sunlight strikes (darker colors absorb more energy), and the control of summer overheating through appropriately sized roof overhangs and operable windows for night flushing. The Earthship model uses direct gain as its primary passive heating strategy, with the massive tire walls providing the thermal mass that absorbs and stores the solar energy.