NREL Passive Solar: Build a 60% More Efficient Home

Produced by the National Renewable Energy Laboratory (NREL), this guidelines package details passive solar techniques for home builders, focusing on specific energy savings examples: 20%, 40%, and 60% reductions. Part One introduces core concepts, emphasizing details in design and construction for effective application. Strategies include added insulation (increasing thermal resistance without solar features), sun-tempering (moderate south-facing glazing), and full passive solar systems. Practical examples specify glazing percentages: sun-tempering uses 5-12% south-facing glass of floor area for modest gains; full systems up to 20-30% with thermal mass. Builders learn to minimize loads via advanced framing, proper insulation installation, and airtight sealing before adding solar elements. The guide provides system-specific info, like direct gain with masonry floors/walls absorbing sunlight, indirect gain via Trombe walls (glazed mass walls venting heat inward), and isolated gain like sunspaces. Actionable advice covers window sizing (vertical glass only to avoid overheating from sloped glazing), overhang calculations for shading, mass thickness (e.g., 6-12 inches concrete for optimal storage), and distribution via open plans or fans. It includes worksheets for load calculations, construction checklists, and cost analyses, enabling builders to select systems matching climate and budget. Ideal for self-sufficiency in regenerative contexts, it offers concrete percentages, diagrams, and step-by-step implementation for resilient, low-energy homes.