Roofing Renovation: 3 Energy Efficient Strategies

Roofing projects are an opportunity to bring this building envelope item up to current building codes, including energy performance aspects.

By Tom M. Hanzely

There are nearly 5.6 million commercial buildings across the United States, which generate approximately 16% of greenhouse gas emissions. In order to reduce the environmental impact of these commercial facilities, even the smallest eco-friendly renovation shouldn’t be overlooked, as it can create positive change. In fact, according to the U.S. EPA’s ENERGY STAR program, if energy efficiency among commercial buildings improved by just 10%, there could be a total cost savings of about $40 billion, not to mention the amount of greenhouse gas emissions that would be prevented. Following are three renovations may not only reduce a commercial building’s carbon footprint, but even help save money over the long-term:

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Daylighting systems are an option to reduce the need for artificial lighting in a building.

Re-roof and optimize insulation level. The opportunity to re-roof presents itself every few decades. This delivers the chance to bring your roofing assembly — a critical part of the building envelope — up to current standards. When it comes to re-roofing, the International Code Council (ICC) makes a distinction between a roof recover and a roof replacement. A roof can be recovered once, but if you’re re-roofing due to a roof system failure, it’s likely time to look at a true roof replacement. You can remove old materials and build a new roofing assembly that meets today’s standards. In most cases, old roofs will typically only have 1-2″ of insulation, and a complete roof replacement would require additional inches of insulation to be installed. The industry now has more data on the appropriate levels of insulation to maximize the efficiency of the thermal barrier. When you re-roof, you can increase thermal performance by following the latest prescriptive guidelines found in the International Energy Conservation Code (IECC) and ASHRAE tables, which prescribe minimum R-values to ensure you’re effectively keeping heat in during the winter and out during the summer.

When it comes to re-roofing, the International Code Council (ICC) makes a distinction between a roof recover and a roof replacement. A roof can be recovered once, but if you’re re-roofing due to a roof system failure, it’s likely time to look at a true roof replacement. Facility managers can have old materials removed and a new roofing assembly built that meets today’s standards.

In most cases, old roofs will typically only have 1-2″ of insulation, and a complete roof replacement would require additional inches of insulation to be installed. The industry now has more data on the appropriate levels of insulation to maximize the efficiency of the thermal barrier. When re-roofing, thermal performance can be increased by following the latest prescriptive guidelines found in the International Energy Conservation Code (IECC) and ASHRAE tables, which prescribe minimum R-values to ensure the roof is effectively keeping heat in during the winter and out during the summer.

Insulation works to consistently regulate energy flow throughout a roofing assembly and minimize energy leakage. If re-roofing, facility management may want to consider a more energy efficient insulation such as polyiso, which can be recycled and reused on roofing applications.

Change existing skylights to daylighting units. When looking at the breakdown of energy consumption by building category, lighting is usually at the top of the list as a main consumer of energy. Utilizing daylighting systems, however, can save energy because the availability of sunlight matches the time we spend in commercial and industrial buildings daily. Furthermore, the sunlight matches the electrical demand put on the energy infrastructure.

Daylighting units provide the highest visible light transmittance with superior light distribution, compared to sunlight domes. This technology keeps facility interiors bright enough to decrease the use of indoor electrical lighting up to 70% during daylight hours. Daylighting units can catch up to 20% more light at low angles than standard shapes and transmit more light to the workplace area without producing glare, hot spots, or UV damage to interior furnishings, equipment, and other items.

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When designed properly for the building site, vegetative roofs improve energy efficiency inside a facility.

Install vegetated roofing. Vegetated roofs offer a host of environmental and functional benefits to facility management staff, ranging from stormwater management and creation of new usable space to air quality improvements and, of course, significant energy savings. Vegetated roof systems provide shade and aid in cooling the air around the building through evapotranspiration. This reduces the pressure put on a facility’s mechanical heating and cooling systems for the floor directly below the vegetated roof, resulting in significant energy savings.

However, the actual thermal performance varies widely and is dependent upon factors including building design, time of year, depth of media, vegetation type and coverage, and amount of water held within the system. Nonetheless, these energy savings are real; they’re a dividend on the initial investment in a vegetated roof. Vegetated roofs also help protect the underlying roof system from extreme temperatures and ultraviolet rays, extending its service life and saving money from a roof replacement or restoration.

In addition to energy savings, installing a vegetated roof offers ample stormwater management benefits. A vegetated roof system reduces the volume of stormwater runoff, which helps alleviate the stress put on infrastructure. This is of importance in urban areas because excess stormwater runoff is the major contributor to non-point source pollution, stream bank erosion, and the cost to treat the water. Vegetated roofing mimics the role that soil and vegetation play in a natural setting by absorbing the water and eliminating impervious surfaces.

Maximizing R-value of roofing insulation, staying up-to-date on codes and standards, implementing daylighting units, and installing vegetated roofs are all renovations that can offer commercial buildings significant energy savings while also working to decrease greenhouse gas emissions.

roof replacementHanzely is a national sales manager for Firestone Building Products SkyScape™ Vegetative Roof System. He has 17 years of experience designing and installing vegetative roof systems throughout North America and is an accredited Green Roof Professional and a LEED professional. Hanzely holds a bachelor’s degree from Northern Illinois University, DeKalb, and a master’s degree from Lake Forest Graduate School of Management, Schaumburg, IL.