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The three levels of home energy audits include:

• Level 1: Review of your energy bills and home for signs of energy inefficiency and areas for improvement. The average cost range is $0.08 to $0.12 per square foot.

• Level 2: A level 2 ASHRAE energy audit costs $0.12 and $0.35 per square foot. In-depth analysis of your energy usage and provides a report of cost-saving changes.

• Level 3: Comprehensive analysis and detailed recommendations for ways to improve your home’s energy efficiency. A level 3 audit costs about $0.36 to $0.50 per square foot.

Window AC units use a fair amount of electricity, but significantly less than central AC systems. Because they are more energy-efficient for cooling individual rooms or small spaces, their usage is comparatively low. On average, a window AC unit consumes between 500 and 1,400 watts, while a central AC system uses over 3,500 watts—meaning a window unit uses about one-third of the energy. This typically translates to a monthly running cost of $15 to $40, although this can vary depending on external factors.

Keep the unit full but not overloaded, ensure door seals are tight, set correct temperatures, and avoid frequent door openings. Position the appliance away from heat sources for optimal performance.

R-value measures an insulation material's thermal resistance, indicating its ability to resist heat transfer. A higher R-value signifies better insulation performance because the material is more effective at slowing heat flow. The R-value depends on the type, thickness, and density of the insulation material, such as fiberglass, foam, or cellulose. Each inch of insulation typically provides an R-value between 3 and 8. There is no single universal R-value; the optimal choice depends on your climate zone. Colder climates require a much higher R-value than warmer ones to maintain energy efficiency, keep the home warm in winter and cool in summer, and manage costs.