Which envelope upgrades pay for themselves over 30 years, by climate, and does advanced framing belong in the answer?

What it found

A degree-day net-present-cost search (not EnergyPlus) over 640 envelope packages of the house-framing house in eight US climates and two heating systems. The advanced 2x6 wall builds for $42 less than a conventional 2x4 and loses 40% less heat through the opaque wall, and is in every cost-optimal package: 13–15% lower 30-year cost than the baseline ($2,100–4,600). Past the wall the optimum is modest (attic R-30–38, 3 ACH50 air sealing, slab-edge insulation from about 3,000 degree-days); R-49 attics and better windows pay back in 23–190 years. At the assumed window prices the optimum picks U 0.50 windows, which a code floor of U 0.35 costs $440–1,270 to avoid; that result does not survive 4× energy prices. Stylised: every price is an assumption, climates are rounded from memory, and there is no solar gain.

A figure from its own output

Paper, code and results

• README and method
• Experiments and results
• Code
• Tests

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Other research topics

Proper scoring & elicitation28Effort & peer prediction9Verification games & slashing19Detection & tolerances14Markets as routers13Prediction-market design9Paying contributors8Decentralised training systems23Digital twins & sim-to-real164LLM chip design loops40Robot manufacturing loops53Ambient AI assistant46Self-replicating manufacturing34Simulation-first design64Engineered clothing45Task-specific AI accelerators40Algorithmic chip-design loops42Open-source purpose-built robots44The software-engineering loop43Adversarial human imitation41Open-source residential construction41Autonomous multi-angle capture34Sensing, imaging and 3D31Energy supply and dense energy storage39Robot societies among people31Agentic co-design of low-cost robots27Laundry-hanging robots25Machine learning on qualitative data23Robots on the building site27Civilizations & group psychology1History & human sciences1

Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.