The impact of roofing systems on energy costs is often overlooked but can be significant. Insufficient roof insulation allows heat to easily escape. In the winter, this means higher heating costs; the same is true for summer months. Heat is gained easily through the roof, which in turn increases electrical demand to cool the building. A flat or low-slope roof allows for maximum exposure to the sun’s heat.
When a roof is black, the materials absorb more solar energy, meaning roof temperatures can be between 60 degrees and 100 degrees higher than the air temperature. Some of that heat will be radiated away from the building but most of it will be absorbed.
Overall, the correlation between the roof and energy use depends on five key factors:
• The climate
• Orientation of the roof
• Thickness and quality of insulation
• Reflectivity of the roof
• How well the roof is maintained
When it comes to insulation, it is important that the materials are of high quality. Also, some might think that more is better, but that’s not always the case. Installing too much installation can stress the roof membrane by increasing the thermal shock. However, insulation is vital to limiting heat transfer from or to the building through the roof. Following manufacturer’s guidelines is essential to determining the correct amount of insulation to install.
In order to get the most out of an energy-efficient roof, a reflective coating is highly recommended. An uncoated black roof absorbs about 80% of the solar energy that hits it. That percentage drops to about 30% when a white or light-colored coating is applied. A coating will usually decrease the heat gained through the roof by 50% for buildings in warmer climates. The coatings can also extend the life of the roof by shielding roofing materials from the sun’s harmful ultraviolet rays.
Roof maintenance is important in keeping the effects on energy minimal. Leaks in the roof will allow the insulation to become saturated and dramatically decrease its thermal resistance, as well as the roof’s lifespan. This is one of the man reasons that roofs with higher sustainability are becoming more attractive to homeowners and facility executives. Roofs built with sustainability in mind leads to higher energy savings, therefore completely offsetting the initial difference in costs of installation within a few years. A sustainable roof will also decrease the effect of waste products on the environment. When it comes time to replace or renew the roof, the resulted waste will be minimized because of the decrease in the number of times the roof will have to be replaced or repaired.