Cool Roof Economics
Roof cost should be evaluated using a lifecycle approach. This means taking into account the upfront costs as well as the ongoing savings and expenses incurred throughout the roof’s service lifetime. Other non-cost considerations are shown in Table 3. Roof lifetime, expected maintenance (regular roof inspections, repairs, and recoatings), disposal, and replacement costs should be evaluated for each viable roof option. Table 4 shows the range of benefits and costs you can expect to encounter for cool roofs.
How Much More Will It Cost
A cool roof need not cost more than a non-cool roof. Major roof costs include upfront installation (materials & labor) and ongoing maintenance (repair, recoating, and cleaning).
Materials & Labor
The installed costs of a roof can vary depending on several factors, including its type, size, complexity, method of attachment, and building location. Nevertheless, in cases where new roof surfaces need to be installed, cool roof options are usually similar in cost or slightly more expensive than similar non-cool alternatives (see Table 5). Slightly higher upfront costs occur mostly in colored roofs that require specialty reflective pigments. Manufacturers must research, develop, and test cool products, and this can also lead to higher prices. The labor required to install or coat cool roofs is about the same as for non-cool roofs.
On the other hand, converting a roof that is in good condition into a cool roof can cost more (see Table 6). For instance, if you want to coat your new dark roof just to make it a cool roof, the additional cost can be significant. More often, roofs are coated to extend their lifetimes. If you are already planning to coat your roof, then using a cool coating instead of a dark one will probably cost about the same. Notice that the cost of coating a roof cool depends on the existing roof’s surface. Rough surfaced roofs, like those covered in granules, have more surface area, and require more coating material to achieve the desired thickness. If the existing roof is not already cool, it may require one extra coating to ensure full coverage.
Typical, approximate installed roof cost premiums for different cool roof options are given in Tables 5 and 6. The premiums equal the additional cost you can expect to pay for a cool product. For example, if you are planning to install a mineral-surfaced modified bitumen roof, the table indicates you might expect to pay $0.50/ft2 more for a cool roof with the same kind of surface. Since costs vary widely by location, check with your roofing contractor or estimator for more accurate cost comparisons.
How Much Will You Save
Cool roofs can save money in several ways, including energy savings, rebates and incentives, HVAC equipment downsizing, and extended roof lifetime.
Energy Savings from reducing cooling loads are achieved each year, reducing building operating costs. Climate, roof reflectance, insulation levels, utility rates, and HVAC equipment efficiency all affect the expected savings. Web-based calculation tools make it easier for building owners predict the yearly energy and cost savings associated with cool roofs. Later, we will show you where to find and how to use one such tool to predict savings.
Rebates and Incentives for cool roofs are offered by some utilities and agencies. To find out if there are any programs in your location, visit the CRRC website and check with your roofing contractor. Currently, certain kinds of residential cool roof projects are eligible for a Federal Tax Credit of 30% of materials, up to $1,5005. Nonresidential building rebate programs can be more complicated, and may also include other efficiency measures besides cool roofs. Contact the rebate program agencies to determine the probable savings associated with a cool roof rebate.
HVAC Equipment Savings may be achieved when a cool roof reduces peak cooling loads significantly enough to reduce the air conditioning capacity needed. At best, the associated savings are modest ($0.03-0.07/ft2 of cool roof area), and can only be realized when HVAC equipment is being replaced at the same time as the roof. Be aware that downsizing HVAC equipment could lead to insufficient cooling capacity if the cool roof becomes excessively dirty or is later replaced with a dark roof.
Extended Roof Lifetime is one possible advantage of using cool roofs. Roofs wear out and fail for many reasons, and some are linked to temperature. For example, higher temperatures can speed up material degradation. Cool roofs maintain a lower average temperature, so, in principle, this could slow heat-related degradation. Furthermore, several metal roof manufacturers believe that cooler roof temperatures slow color fading. In cases where heat-related degradation is the main reason for roof failure, it is plausible that a cool roof could be more durable and outlast a similar dark roof. More study is required to quantify these effects. Damage caused by other sources, like mechanical impacts, will not be avoided by using a cool roof. Today, manufacturers offer similar warranties for both cool and non-cool roofs.