Metal vs asphalt roofs and heat gain
Last updated · Energy & ventilation
Short answer: A painted metal roof in a light or cool color usually absorbs less heat than dark asphalt shingles and cools off faster at night. Bare, unpainted metal can reflect sunlight but hold heat because of low emittance. Color, coating, and attic insulation and ventilation matter more than the material alone.[1]
Does a metal roof keep a house cooler than asphalt?
A metal roof can keep a house cooler than asphalt, but only if the finish is reflective and emits heat well. Painted metal panels are often available in cool-pigment finishes that reflect a large share of sunlight, including near-infrared light. Most asphalt shingles absorb more sunlight, especially in dark colors. The DOE's cool roof guide notes that "cool" options exist for both metal and asphalt shingles, so the comparison depends on the specific product.[1]
Why does roof color matter more than material?
Roof color matters more than material because it controls how much sunlight the surface absorbs. A white or light-colored roof of any material reflects more sunlight than a dark one. A dark brown metal roof with a standard finish may absorb about as much heat as dark shingles. Berkeley Lab's Heat Island Group explains how cool pigments let darker colors reflect more invisible infrared light.[3] Compare products using rated values instead of looks.
What is emittance and why does bare metal fall short?
Emittance is how well a surface releases absorbed heat as thermal radiation. Bare or unpainted galvanized and aluminum metal has low emittance, so even when it reflects sunlight well, it holds onto the heat it absorbs. Painted metal has high emittance, like most roofing. That is why painted and coated metal performs better than bare metal for heat. The Cool Roof Rating Council lists both values for rated products.[2]
Does metal cool down faster at night?
Metal does cool down faster at night than heavier roofs because it has little thermal mass. Thin metal panels shed heat quickly after sunset, while heavy tile and multi-layer shingles hold heat longer into the evening. The effect on indoor temperature depends on how much heat reaches the attic, which brings insulation and ventilation back into the picture.
How much do attic insulation and ventilation matter?
Attic insulation and ventilation matter a great deal, often more than the roof surface itself. A well-insulated attic floor limits how much attic heat reaches the rooms below. Balanced ventilation flushes out hot air. Air sealing keeps conditioned air from leaking into the attic. A cool metal roof over a poorly insulated attic may still leave upstairs rooms hot. Our guide on attic insulation and R-value explains the targets.
Is a metal roof louder or hotter in the attic?
A metal roof is not necessarily louder or hotter in the attic when installed over solid decking with underlayment. Rain noise is mostly a concern with metal over open framing. Some metal roofs are installed with an air gap or battens that add a ventilated space under the panels, which can reduce heat moving into the deck. Ask the roofer how the panels will be installed and over what.
How long does each roof last?
How long each roof lasts affects total cost more than energy savings in many cases. InterNACHI's life expectancy chart lists metal roofing at 40 to 80 years and architectural asphalt shingles at about 30 years.[4] Metal usually costs more up front. Over decades, the longer life can offset some of that, depending on how long you plan to stay.
Which roof is better for a hot climate?
For a hot climate, either roof can work well if you choose a reflective color and pair it with good attic insulation and ventilation. Light-colored painted metal and cool-rated shingles are both reasonable choices. Tile is common in desert regions too. Ask for the CRRC-rated reflectance of the exact product and color, and compare full bids. Our metal vs shingles guide covers cost and durability.
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Frequently asked questions
Does a metal roof make a house hotter?
Not if it has a reflective, painted finish. Bare metal with low emittance can hold more heat.
Are dark metal roofs hot?
Dark colors absorb more sunlight on any roof. Cool-pigment dark finishes reduce heat gain compared with standard dark colors.
Will a metal roof lower my electric bill?
It can in hot climates with a reflective finish, but insulation, ventilation, and air sealing usually have a bigger effect.
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Sources
- U.S. Department of Energy: Guidelines for Selecting Cool Roofs (PDF). www.energy.gov/sites/default/files/guide_to_cool_roofs.pdf
- Cool Roof Rating Council: Rated Products Directory. coolroofs.org/directory
- Berkeley Lab Heat Island Group: Cool Roofs. heatisland.lbl.gov/coolscience/cool-roofs
- InterNACHI, Standard Estimated Life Expectancy Chart. www.nachi.org/life-expectancy.htm
Sources checked November 4, 2026. Estimates are not quotes. Roofing, insurance, and legal details vary. Confirm with your contractor, insurer, or attorney.