Throughout this course, you learned how the building envelope influences a home’s comfort, health, and energy use. The building envelope controls how heat, air, and moisture move between the inside and outside of the home, directly affecting how much energy is required for heating and cooling. The key takeaways below summarize the most important ideas to help you make informed, cost-effective decisions about improving your home’s building envelope.

• A well-designed building envelope reduces heating and cooling demand. A tighter, better-insulated home experiences fewer drafts, more consistent indoor temperatures, and lower energy costs.
• Air sealing is one of the most important building envelope improvements. Small gaps and cracks around windows, doors, attic hatches, electrical outlets, plumbing penetrations, and vents can allow conditioned air to escape. Identifying and sealing these leaks can improve comfort and reduce heating and cooling costs.
• Attic insulation is often one of the most cost-effective upgrades for existing homes. Because heat naturally moves upward, underinsulated attics can contribute to significant heat loss in winter and heat gain in summer. Sealing attic air leaks and adding insulation can improve efficiency and comfort.
• Roofing, windows, and doors influence how much heat enters and leaves the home. Choosing reflective roofing materials, maintaining attic ventilation, upgrading inefficient windows, and sealing gaps around doors can reduce heat transfer and drafts.
• If possible, building envelope improvements should be prioritized before replacing heating and cooling systems. Reducing heating and cooling demand first may allow homes to install smaller, more efficient equipment while improving long-term operating costs.

By understanding how the various components of a home’s building envelope work, homes can make targeted improvements that increase indoor comfort and reduce heating and cooling costs.