A new roof can help lower energy costs, but the roofing material alone does not determine how much a home or commercial building will save. Reflective roofing can reduce the amount of solar heat absorbed at the surface, while insulation and ventilation affect how heat moves through the rest of the roof assembly.
For most roofing projects, three factors are especially worth evaluating: solar reflectance, insulation, and ventilation. A highly reflective shingle or membrane may help reduce heat gain, but its impact depends on what is happening underneath the roof as well. Understanding how these components work together gives homeowners and building owners a more realistic picture of what an energy-efficient roof can actually accomplish.
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Key Factors in Roof Energy Performance
Three factors are especially important when evaluating how a roof affects energy use: solar reflectance, insulation, and ventilation. Solar reflectance affects how much sunlight the roof absorbs as heat, while insulation helps limit how much heat moves between the roof and the conditioned space below. Ventilation can also help manage heat and moisture within certain attic and roof assemblies.
These factors work together, and the impact of any one improvement depends on the rest of the building. A reflective roofing material may reduce heat absorption at the surface, for example, but the overall energy benefit will also depend on insulation, climate, HVAC efficiency, and the design of the roof assembly.
For Homeowners: How a New Roof Lowers Energy Bills
How a new roof lowers energy bills for a typical house depends heavily on three specific components, each addressing a different part of the heat transfer problem. For homeowners already considering a new roof installation, replacement is also an opportunity to evaluate materials, ventilation, and the condition of the attic assembly together rather than treating each one separately.
Shingle Color and Solar Reflectance
Shingle color and solar reflectance affect how much solar energy a roof absorbs during the day. More reflective roofing materials absorb less heat, which can help keep the roof surface cooler and reduce the amount of heat transferred into the home. According to the Lawrence Berkeley National Laboratory Heat Island Group, a clean white roof reflecting 80 percent of sunlight can stay about 55 degrees cooler on a typical summer afternoon than a gray roof reflecting only 20 percent.
One distinction is worth knowing when comparing roofing products. EPA discontinued ENERGY STAR certification for roof products in 2022, so homeowners should not rely on an ENERGY STAR roofing label when comparing current products. Solar reflectance and thermal emittance provide more useful information about how a roofing material handles solar heat, and the Cool Roof Rating Council maintains ratings for roofing products based on these performance characteristics.
Attic Ventilation and Energy Savings
Proper roof ventilation affects more than attic temperature. It also plays a role in how efficiently the roof and attic assembly manage heat throughout the year. Building codes generally call for one square foot of net free vent area for every 150 square feet of attic floor space, split roughly evenly between intake at the soffit and exhaust near the ridge.
Adding a ridge vent without matching soffit intake does not improve ventilation. It can make things worse. Without enough intake, an exhaust vent can draw air through gaps and penetrations in the ceiling rather than creating the intended airflow from the soffits to the ridge. The result is an unbalanced ventilation system that may pull conditioned air into the attic instead of improving overall roof performance.
Underlayment and Insulation Beneath the Surface
What sits beneath the shingles matters as much as the shingles themselves. Research from Oak Ridge National Laboratory found that combining a radiant barrier under the roof deck with cool-colored shingles reduced simulated energy consumption by 28.2 percent, a combination the researchers noted was roughly as effective as doubling ceiling insulation from R-19 to R-38. The finding reinforces the larger point: a reflective shingle installed over inadequate attic insulation can only address one part of the home’s energy performance.
For Commercial Buildings: Membrane Reflectivity and Insulation
Flat and low-slope commercial roofs follow the same underlying physics, but the materials and scale change the math considerably. The membrane, insulation, drainage, rooftop equipment, and overall roof assembly all affect performance, which is why commercial roofing services have to account for more than the condition of the surface alone.
TPO vs EPDM: Reflectivity Numbers That Matter
The choice between roofing materials for energy efficiency on a commercial building often comes down to TPO versus EPDM membranes. White TPO typically achieves a solar reflectance value between 0.80 and 0.88. Standard black EPDM measures between 0.06 and 0.12, a gap large enough that the membrane choice alone can swing cooling costs by a wide margin on a large flat roof. White EPDM formulations exist and close much of that gap, though they have not gained the same market share as TPO.
For commercial buildings in Greenville, where long stretches of summer heat can put substantial demand on rooftop HVAC systems, membrane reflectivity is one factor worth considering when a roof is repaired or replaced.
R-Value and Cooling Load Over Large Flat Roof Areas
Membrane color gets most of the attention, but insulation R-value underneath can have just as much influence on overall energy performance. A highly reflective membrane can reduce heat absorption at the roof surface, but it cannot compensate for an inadequately insulated roof assembly. The right insulation level depends on the building, existing roof system, and applicable energy code, making it important to evaluate the membrane and insulation together.
For Anderson commercial properties, looking at the entire roof assembly gives building owners a better picture of potential energy performance than choosing a roofing material based on reflectivity alone.
Routine commercial roof inspections can also help facility managers track membrane condition, drainage, penetrations, and other changes that can affect the roof’s performance over time.
Separating Marketing Claims From Real Energy Performance
Not every roofing product marketed as “energy efficient” will have the same effect on a home’s energy use. Shingle color, solar reflectance, attic insulation, and ventilation all influence how much heat reaches the conditioned space below, so choosing a reflective roofing material is only one part of improving overall performance.
The same principle applies to commercial roofing. Reflective membranes can help reduce heat absorption at the roof surface, but their performance also depends on the insulation and other components of the roof assembly. Building owners should consider how those components work together rather than evaluating a roofing material based on a single efficiency claim.
Material selection is only part of the decision. Knowing how to choose a roofing contractor who evaluates the entire roof assembly is just as important when energy performance is one of the goals of the project.
Inspections and Maintenance Help Protect Roof Performance
Understanding which part of a roof system may be underperforming takes an inspection, not a guess based on age or appearance. Ongoing residential roof maintenance provides opportunities to catch changes in ventilation, roofing materials, flashing, and moisture conditions before they develop into larger problems.
Commercial properties benefit from the same approach. Routine commercial roof inspections allow facility managers to track membrane condition, drainage, penetrations, and other changes that can affect roof performance and service life.
Cox Bros. Roofing works with homeowners and commercial property owners throughout the Upstate, including those looking for a roofing company in Greenville or an experienced Spartanburg roofing contractor, to evaluate all factors before recommending changes.
