Insulation, Air Sealing, and Smart Thermostats
Space heating and cooling represent 42–47% of home energy use — the single largest residential energy category. Three interventions target this directly. Attic insulation: heat rises, and an under-insulated attic can account for 25% of home heating loss. The DOE recommends R-38 to R-60 for most US climate zones (2 and above). Adding insulation where R-values are below spec has a 2–5 year payback period. The federal 25C tax credit (2023–2032) covers 30% of insulation costs up to $1,200. Air sealing: cracks and gaps in the building envelope (around windows, doors, outlets, plumbing penetrations) account for 25–40% of heating/cooling loss — often more than the insulation itself. Caulk and weatherstripping are among the highest ROI home improvements: $30–$100 in materials can save $150–$300/year. A blower door test performed by an energy auditor identifies all air leakage points. Most utilities offer free or subsidized energy audits. Programmable and smart thermostats: the DOE estimates that setting the thermostat back 7–10°F for 8 hours per day (during sleeping and work hours) saves about 10% on heating and cooling annually. Smart thermostats (Nest, Ecobee, Honeywell) learn occupancy patterns and automate setbacks; Ecobee's published data shows average household savings of $177/year. Nest payback period: under 2 years.