Questions: Energy Efficiency Assessment and Improvement Priorities

Question 1

A homeowner wants to improve energy efficiency and has a limited budget. Which improvement should they prioritize first?

• A. Replace old single-pane windows with double-pane windows
• B. Install a new high-efficiency furnace
• C. Seal air leaks around electrical outlets, attic hatches, and plumbing penetrations
• D. Add solar panels to offset electricity consumption

Answer: (C)

Air sealing is the highest-ROI improvement: it costs $50–$200 in materials and can reduce heating and cooling costs by 10–20%. Window replacement (option A) is typically last to pencil out, costing $300–$1,000 per window with a 20–30 year payback. Furnace replacement and solar are significant investments that assume you've already minimized losses through the building envelope.

Question 2

Why is window replacement typically recommended last in an energy efficiency upgrade sequence, even though windows are often what homeowners think of first?

• A. Windows don't significantly affect energy use because glass is a good insulator
• B. Building codes prohibit window replacement before other improvements
• C. The payback period for window replacement is often 20–30 years, making it a poor financial return compared to cheaper envelope improvements
• D. New windows reduce natural light, increasing artificial lighting costs

Answer: (C)

New double-pane windows cost $300–$1,000 per window installed and the energy savings rarely justify this cost quickly — payback periods of 20–30 years are common. Meanwhile, window film, interior storm inserts, or heavy curtains provide 70–80% of the thermal benefit at 5–10% of the cost. Air sealing and insulation deliver far more savings per dollar spent.

Question 3

Adding window film to existing windows provides almost no thermal benefit compared to full window replacement.

• T. True
• F. False

Answer: False

Window film and interior storm inserts actually provide approximately 70–80% of the thermal benefit of full window replacement at just 5–10% of the cost. The marginal gain from replacing the entire window unit is relatively small compared to the large additional cost — which is why window replacement has such long payback periods.

Question 4

Air sealing is typically the highest-ROI energy efficiency improvement because air convection accounts for a surprisingly large share of heating and cooling loss, and the materials cost is very low.

• T. True
• F. False

Answer: True

Air leakage (convection) is responsible for a large portion of energy loss in many homes, and sealing gaps with caulk, spray foam, and weatherstripping costs only $50–$200 in materials. This combination — high impact, low cost — produces a payback period measured in months rather than years or decades, making it the best starting point before investing in more expensive improvements.

Question 5

Explain why the correct order of energy efficiency improvements (audit → air sealing → insulation → HVAC → appliances/windows) maximizes the return on investment.

Model answer: Each improvement in the sequence has a shorter payback period and lower upfront cost than the ones that follow. Air sealing is cheap and directly addresses one of the largest sources of energy loss; insulation follows because it's next most impactful per dollar; HVAC improvements only deliver full value once the envelope is tight; windows and appliances cost the most per unit of savings achieved. Doing the sequence out of order wastes money — improving your furnace in a leaky house means conditioning air that immediately escapes.

ROI-driven sequencing works because the interventions are interdependent: a tight envelope (air sealing + insulation) reduces the load on HVAC systems, making HVAC upgrades more effective and less expensive. Jumping to expensive improvements before foundational ones means spending more for less gain. The energy audit first ensures you're targeting actual problem areas rather than guessing.