Zone 5 Walipini: R-30 Greenhouse, 10K Lbs/Yr Harvest

John Sviokla's 2025 Permies.com build log documents a 20x40 ft walipini greenhouse in Zone 5, using 4-ft earth-bermed walls, 500-gallon black-painted water barrels for thermal mass, and RMH exhaust for 6-month seasons yielding 10,000 lbs produce/year. Design calcs: R-30 via polycarbonate panels + mass (barrels store 1.2 million BTU via phase change), bermed north wall (80% earth contact) stabilizes at 55°F. RMH routes hot gases (982°F riser) through barrel surrounds and cob bench before vertical exhaust, extending viability to -20°F outsides. Regenerative techniques: hugelkultur beds, compost heating, and aquaponics (200 sq ft fish tanks). Step-by-step: excavate 8-ft deep pit, berm walls with clay cap, install barrels on gravel (phase-change optimized), plumb RMH (6-inch pipe, perlite riser). Insulation: 2-inch foam board edges, door airlocks. Vetted by Paul Wheaton: photos show failures like barrel leaks (fixed with epoxy), over-insulation drafts (added vents), and tweaks boosting efficiency 15%. Yields breakdown: tomatoes (3000 lbs), greens (5000 lbs) via mass-released CO2. Soil building: worm bins + cover crops regenerate 2 inches/year. Cost: $8k DIY, ROI in 2 years via food savings. Forum depth: airflow sims (chimney effect), mass calcs (1 gal water = 8.3 lbs, 1°F rise = 8.3 BTU), and integrations like rocket cookstoves. Scalable for earthships/passive houses, with regenerative focus on biodiversity (pollinator walls). Hands-on metrics empower replication in variable climates.