The first use of designed-in, energy efficient German pigments in American paints occurred in the 1970's in collaborations between metal roofing manufacturers and makers of industrial coatings. These coatings contained infrared (IR) and mixed metal oxide (MMO) pigments, were factory applied, and were expensive. Their chemistry was toxic solvent based, and they were exceptionally durable, eventually becoming the standard for commercial and industrial buildings.
Metallic pigments are much more efficient in reflecting away the sun's radiation (infra-red spectrum) than standard organic liquid tints. This trend was brought to the high-end, residential marketplace into the 1980's and hasn’t changed since. The high cost of the metal roof coating system known as Kynar™ (over $100 per gallon) only suited large-capital corporate and industrial jobs and those with unlimited budgets since the lifespan of 20 to 30 years before these coatings failed. Variations of the technology were taken up in military applications as well.
In Australia, there was a huge need for durable, efficient, cool coatings for metal and tile roofs that could be inexpensively field-applied to buildings in the torrid Outback, tropical Queensland and the rest of the vast Australian continent. Thirty years ago, the Australians went with the best acrylic latexes of the day and their own version of the German factory-ground pigments to develop water-based coatings that had the capability to provide the heat reflecting they needed.
While these coatings were slightly more expensive than standard tinted paint formulas (and could not be made at the local store), they still cost much less than the solvent-based roof coatings. Their fully renewable 12 to 15-year lifespans added to their cost-savings benefits with twice the lifespan of standard paints. These paints cooled the buildings dramatically by reflecting away the majority of the sun's radiation (solar reflectance) and by emitting a very high percentage of the heat that did find its way into the underlying substrate materials (thermal emissivity).
Another advantage of reflective paints is that they these required no special procedures to apply, while being substantially more environmentally friendly with low odor. This was in part because the IR reflecting, MMO inorganic pigments were low toxic by their nature, with low-VOCs (Volatile Organic Compounds) unlike the liquid organic-based standard paint tinting systems. They also did not fade, another big plus, and these paints were breathable but waterproof when used on walls (think Gore-Tex™).
These thermally emissive/reflective coatings offer a range of applications such as on roofs and walls of buildings. These coatings will adhere to a variety of materials such as composite roof shingles, metal roofs, and concrete tile roofs as well as stucco, plywood, and concrete block walls. Manufacturers offer a wide assortment of formulations. So be sure to read the spec sheet and get the correct type before application. When considering thermally emissive/reflective cool coatings be sure to look for metal oxide and infra-red emissive pigments. These ingredients are necessary to block ultra violet rays and reflect infrared radiation.
Heat reflective coatings that have met the standards of the Solar Reflectance Index (SRI) can qualify for LEED credit. This credit is available for new construction and existing building LEED projects. The purpose of this credit is to promote the reduction of the heat island effect, which is a known cause of increased temperatures and pollution in urban areas. In addition, for buildings in the state of California, many of these products exceed the state’s Title 24 energy efficiency requirements of 70% solar reflectance for commercial and residential buildings.
It is important to note that a thermally emissive/reflective coating is not meant to insulate. Insulation is used to slow the transfer of heat. Thermally reflective coatings are used to reflect the heat. If the reflective coating is doing its job, the demand on insulation decreases. This assistance is similar to radiant barriers.
A common misconception is that heat reflective coatings, such as cool walls and cool roofs, can only be found in light colors. However, thermally reflective coatings are offered in a variety of colors to suit design specifications. The Lawrence Berkeley National Laboratory offers a Pigment Database for more detailed information. Generally, lighter colors do offer a higher level of thermal reflectance though a quick review of the database reveals many viable options.
Financial Benefits of Cool Paint Technology
Exterior wall paint job life-cycles can be increased by a minimum of 50% percent and as much as 100%. Combined with electrical cost savings of up to 22% (results for Los Angeles residence in U.S.- D.O.E. Cool Wall Paints study, 2007), in locales where air-conditioning is normally used, these solar-reflective paints just on the walls means large and measurable financial paybacks to those who utilize them for repaint and new construction projects. Further combine this with cool roof top coats on the same building(s) and energy needs will be massively reduced with even larger environmental benefits.You can calculate the energy cost savings for cool paint for your location with the US Dept. of Energy's Cool Roof Calculator. (link is external)
Cool Roof Rebates and Environmental Impact
Reflective wall coatings are the last area to be explored by the residential paint manufacturing industry, but the new LEED (Leadership in Energy and Environmental Design) and national Green-Seal standards will recognize them as a significant factor in total building energy efficiency. After all, wall surface areas will equal or exceed that of the roof surface square footage when the buildings are more than one story tall. And with the amount of energy cool paints can save, it’s no wonder rebates are available.Rebates, LEED Credits, and the Green Seal
This means that having the walls coated with solar-reflective paints will ensure added energy cost reductions for air conditioning and this will serve to increase the return on investment for any such paint job. LEED credits for both non-roof and cool roof coatings are available (see LEED Credit 7.1 & 7.2 respectively), which can qualify for energy tax credits, increased property values, and publicity benefits for buildings so coated. Depending upon the zip code, public utilities like PG&E and SMUD (link is external) are already giving residential rebates for Cool Roof Rating Council (CRRC) qualified "cool roof” top coats for both steep slope and low slope roof types.Environmental Impact
Carbon pollution reduction from cooling down roofs and walls in our city environments is a real way to reduce the "Urban Heat Island Effect" caused by buildings absorbing the sun's radiation, then re-radiating that heat after the sun goes down. This "hidden" environmental benefit is one that we must all hope we'll be able to notice. Lawrence Berkeley Labs has quantified that 663 grams of CO2 is the environmental "cost" for every kilowatt hour (KWh) of electricity produced by conventional power plants. The average California house in turn uses 3,000 to 4,000 KWh per year for electricity for cooling from these plants. That equals approximately 2,650 lbs. of CO2 emitted to produce that power per Los Angeles household.Therefore, every reduction in that energy demand has a direct bearing on how much atmospheric, heat-inducing pollution is prevented. When cool paint and cool roof coatings can make an 8% to 60% factored per household reduction in this electricity used, it's easy to see why so energy companies and the government are offering rebates to begin with.
What is a Paint Specification?
A paint specification provides detailed information about preparation for specific substrates, application, color, clean up etc. and specifies what exact products will be used on the repaint: so all contractors will be bidding on the same value line product. This provides the customer a standard to evaluate the painting contractor bids (i.e. so one contractor doesn't include standard paint in the bid while another uses premium). A specification is also a legal document, so the material must be used as directed.The paint specification should include the following:
- Paint Product Line–Determines the performance and longevity of the repaint. Premium lines are products engineered to offer excellent hide, color retention, and resistance to chalking and blistering. A standard line offers good performance when budget constraints are an issue.
- Specific Primers–Includes the primers necessary for all surfaces of the building to be painted, such as wood, ferrous and non-ferrous metal, concrete, and stucco.
- Topcoat Gloss–Indicates the optimum topcoat gloss level for the surfaces and paint product line.
from ECHO-CA.ORG - Michael Biel is the founder of The Ultimate Coatings Company. He has been associated with the trade of both residential and commercial painting for 22 years. He was a high-end house painter/restorer for a majority of that time and was sales consultant, estimator and trainer to a well-known northern California painting contractor for their property management clientele.
