July 31, 2016
Historically, architectural painters have had just one weapon in the battle against heat buildup: Use a light color when painting a building’s exterior.
Light colors reflect a high percentage of infrared radiation, preventing the conduction of heat from the exterior to the interior. Using them is an effective approach, but doing so also limits the color palette for building facades to a relatively narrow range.
However, the introduction of infrared (IR) reflective coatings has given architectural painters a new solution to address the challenge of heat build. As the technology for IR reflective paints has improved, it has expanded the colors for facades to include darker hues of blue, brown, gray and black. These colors can now reflect nearly the same amount of infrared radiation as lighter colors, providing a cool new way to color residential and commercial buildings.
Here’s how this breakthrough impacts architectural coatings on a global scale.
The trouble with heat buildup
Most locations around the world experience warm weather. In the tropics and desert climates, the sun beats down year-round. In temperate climates, while the heat isn’t present year-round, summer is still sunny and hot. That means that structural heat buildup is a potential problem in a majority of the world’s locations, particularly for those who design and build residential, commercial and industrial buildings.
Why is heat buildup such a problem? Imagine driving down a highway in the northern U.S., where you will invariably see streaks of tar and patches of asphalt covering the road. Vast differences in temperature throughout the year cause the road to expand and contract, creating stress points that become cracks and potholes, which must be sealed and patched.
The same thing happens to the exteriors of buildings over time. Buildings with dark exteriors expand in sunlight and contract overnight. In temperate four-season climates, the effect is exacerbated by warm summers and cold winters. In much the same way that a road begins to crumble under stress, walls and facades may begin to warp and crack under the cyclical absorption of heat.
As the heat builds up, it also has to go somewhere – and that is usually the inside of the building. If this heat buildup isn’t managed, the result is higher energy bills to cool the interior at a consistent, tolerable temperature.
How IRR helps
The key ingredient in IR reflective paints is solar reflective colorants. A colorant’s IR reflective effectiveness is measured in terms of total solar reflection, or TSR.
A basic carbon black pigment has a very low TSR factor, reflecting back 10 percent or less of infrared radiation. For this reason, using a colorant with carbon black pigment creates a paint that absorbs a great deal of heat, leading to many of the wear and tear and conductive heat problems outlined above. Replacing carbon black with a higher TSR black pigment can have a profound effect on heat reflection in the infrared light range. For instance, the pigment Brown 29 demonstrates reflectivity of nearly 80 percent in infrared light wavelengths between 1,300 and 1,700 nanometers. Black 33 pigment demonstrates reflectivity approaching 50 percent in the same wavelength range.
Simply put, the higher TSR pigment will help reflect significantly more heat from the building’s exterior while providing a similar aesthetic appeal.
Expanding your palette
Heat buildup has a real cost in terms of both building repairs and energy bills, and it needs to be managed.
Advancements in IR reflective paints now gives your customers new choices to help control heat buildup and give them a greater selection of colors to choose from for their exterior applications.
Keep in mind that not all pigments are ideal for all colorants, just as all paints are not ideal for all applications. So when formulating an IR reflective coating, it’s important to know the end use. Always provide your colorant supplier with details about the environment in which the IR reflective paint will be applied, what conditions it will have to endure and any other critical performance requirements.
Chromaflo Technologies is a leading provider of solar reflective colorant technologies for architectural and industrial coatings. Contact a Chromaflo representative to discuss your colorant requirements.