The roof receives more direct sunlight than any other part of the home, making it one of the largest sources of heat gain during warm weather. The type of roofing material, roof color, attic ventilation, and air sealing all influence how much heat enters the home and how much heating and cooling energy is required throughout the year.

Roofing materials

Roofing materials differ in how much solar radiation they absorb and reflect. Traditional dark asphalt shingles absorb a large portion of the sun's energy, causing roof surfaces and attics to become much hotter during sunny weather.

Metal roofs with reflective finishes absorb less solar heat and can reduce cooling energy use by approximately 10-40% compared with conventional asphalt roofs, depending on the climate, roof color, and building design. Homes in hot, sunny climates typically experience the greatest energy savings.

When replacing a roof, consider materials with higher solar reflectance and look for products that are certified as cool roofs in your region. Cool roofs are designed to reflect more sunlight and absorb less heat than conventional roofing materials. Choosing lighter-colored or reflective roofing materials can help reduce heat gain, especially in warm climates.

Attic ventilation

Proper attic ventilation helps remove heat during the summer and moisture during the winter, improving comfort and protecting the roof from moisture damage.

To improve attic ventilation:

• Check that soffit vents are open and unobstructed so fresh air can enter the attic. Insulation or debris blocking these vents can reduce airflow.
• Install ridge vents along the roof peak when appropriate to allow hot air to escape naturally.
• Add gable vents or an attic fan when needed to improve airflow, especially in homes where natural ventilation is insufficient.

Attic ventilation works best when combined with proper insulation and air sealing. Increasing ventilation alone will not prevent conditioned air from escaping into the attic.

Air leakage through the roof and attic

The attic is one of the most common locations for air leakage. Warm conditioned air naturally rises and can escape into the attic through small gaps and openings, increasing heating and cooling costs.

Common sources of attic air leakage include attic access hatches, recessed lighting fixtures, plumbing penetrations, electrical penetrations, chimneys, and duct penetrations. Before adding attic insulation, seal these air leaks using appropriate materials such as caulk, spray foam, or weatherstripping. For example, adding weatherstripping around an attic hatch and sealing gaps around plumbing and electrical penetrations can prevent conditioned air from escaping into the attic.