Assess the learner's ability to apply basic energy-efficiency principles to plan and evaluate a retrofit for a small home, focusing on insulation upgrades, heating system improvements, and lighting replacement. Tasks include: selecting appropriate measures; making simple assumptions about house size, climate zone, and energy prices; performing basic calculations to estimate annual energy savings (kWh/therms), retrofit costs, and simple payback; and justifying prioritization based on cost-effectiveness, comfort, and emissions reduction. Provide clear steps, show calculations, and state assumptions.