Current Green Coatings Do Little to Protect the Environment
During the late 1990s many paint manufacturers unsuccessfully sued the South Coast Air Quality Management District (SCAQMD) over new VOC laws that were designed to protect public health. Paint manufacturers claimed that low-VOC coatings would have poor durability and inferior handling. They also claimed prices would significantly increase and existing product lines would be regulated out of existence. The reality is that new compliant coatings did not have a reduction in performance and prices did not dramatically rise, although some products were summarily removed from sale for not complying with new air quality guidelines.
According to the 2005 ARB Architectural Coatings Survey, the VOC emissions from architectural coatings dropped from 113 million tons per day in 1975 to 95.1 million tons in 2004, a 16% drop in emissions (note: this does not include associated emissions from thinning or solvent cleanup). Since 1975, the amount of architectural coatings sold within California has more than doubled, so the actual reduction in VOC emissions is significantly higher. The end result is that air quality has improved and in some cases so has paint durability. So why the lawsuits?
Energy-Efficient Paints Can Reduce Urban Heat Islands, Smog and Greenhouse GasesAccording to a 2007, ABC/Washington Post environmental poll, 94% of American consumers say they are willing to protect the environment by buying green products, while 73% say they will specifically purchase energy-efficient items. With three-quarters of American consumers willing to buy energy-efficient products then why aren’t retail paint manufacturers producing heat-reflective coatings to meet both this commercial and environment demand?
Heat-reflective coatings work on walls and roofs by lowering the surface temperature, which reduces radiant heat transfer. Solar radiation is reflected away from the substrate. Less energy transfer means a lower electrical demand for air-conditioning systems, which mean fewer polluting fossil fuels are being burned by utility companies to run these cooling systems.
Heat-reflective wall coatings can also reduce stress on a home by minimizing the expansion and contraction of the home’s exterior walls, which occurs during intense fluctuations in temperature. It is a well-documented fact that heat-reflective coatings on flat roofs can substantially reduce utility bills depending on insulation, geography, sun orientation and other variables. This is why commercial cool-roof coatings are part of the California Energy Commission’s (CEC) Title 24 energy code. In 2008, the CEC is expected to include heat-reflective residential cool roofs as part of the state energy code. The next step in thermal envelope legislation could be energy-efficient wall coatings.
Promoting the energy-saving benefits of heat-reflective wall coatings is Ferro Corporation Development Manager for Pigment Systems, Ken Loye, and Ferro Corporation, West Coast District Manager, Jim Dunn. “In many instances we see more heat penetrating through walls than through roofs, especially in the downtown areas of big cities,” said Dunn. “We think reflective walls would benefit many industry segments.”
Former Rohm and Haas chemist and Cool Roof Rating Council (CRRC) Technical Chairman, Bill Kirn, wrote a report called, Cool Roof Coatings to Reduce Energy Demand and Temperature in an Urban Environment. In that report, Kirn concluded that once a roof had been coated with a white, reflective membrane then it was no longer the principle source of solar heat gain. Exterior walls were now the leading contributor of heat ingress.
Oakridge National Laboratories, a U.S. Department of Energy (DOE) research facility located in Tennessee, reportedly did a study for the Florida-based coatings manufacturer, Texcote, and found that a cool-wall coating could reduce a home’s cooling cost by as much as 21.9%.
Current Green Coating Standards Need To Go FurtherMost of the current green coatings sold at the retail level promote low VOC and low odor as their principle environmental features. However, in the grand scheme of things, low-VOC coatings only account for a small portion of the overall air pollution problem. According to the ARB Almanac 2006-Chapter 2: Current Emissions and Air Quality Criteria Pollutants, VOCs from architectural coatings in California account for approximately 3.96% of the total statewide VOC gases and 0.40% of total statewide emissions. Reducing VOCs has been a positive step forward in reducing ground-level ozone depletion, however, much more needs to be done to address other serious atmospheric problems.
Green Seal: Disappointing Green Coating StandardsSome coatings companies have products certified through independent, non-profit organizations such as Green Seal. Green Seal’s coating standard, Green Seal 11 (GS-11) was written in good faith, but is easy to meet and does not go far enough to protect the environment especially with respect to global warming. Green Seal’s VOC standards for interior coatings are 150 g/L for non-flat and 50 g/L for flat paints. Exterior coatings are 200 g/L for non-flat and 100 g/L for flat paints. With the latest polymer technology, it is not difficult to manufacture low-VOC coatings to meet these two standards. BASF and Rohm and Haas manufacture a number of polymers that can be formulated into paints that have VOCs of 50 g/L or less. Many elastomeric coatings have VOCs less than 50 g/L.
Removing toxic additives such as heavy metals is another GS-11 standard that is not difficult to accomplish and in many states is mandated.
Green Seal-11 requires a variety of physical property tests such as scrubbability to prove long-term durability. However, most exterior coatings are specified at 350 - 400 square feet per gallon at a DFT of 1.4 - 1.8 mils in two coats, which is too low to prevent electromagnetic radiation being absorbed through the paint film. An easy way to prove this is to film a wall on a hot day with an infrared thermal camera. This will show radiant heat penetrating through the siding, wooden studs and wall cavities. GS-11’s physical property testing means little if the DFT is too low to protect the substrate from heat ingress.
Some paint manufacturers pay a considerable amount of money to be Green Seal certified, but in reality their products are no greener than many regular coatings sold throughout the United States. In fact, some companies, such as Bay Systems North America (BSNA), a division of Bayer Material Sciences, are expected to launch a new exterior wall and roof tile coating that has 50 g/L of VOCs in the base system and zero VOCs in the colorants. This new system is also highly energy-efficient.
The U.S. Green Building Council (USGBC) has adopted GS-11 for Indoor Air Quality 4.2: Low Emitting Materials, under LEED For New Construction Version 2.2. One point is allocated for compliance.
Note: During December 2007 through January 3, 2008, Green Seal accepted submissions for ratifying its current coating standards. An energy-efficient standard was submitted in support of LEED, Urban Heat Island Effect, credit 7.1, non-roof. Green Seal’s final code updates will be released in 2008.
Cool Roof Rating CouncilOne of the current most stringent environmental coating standards in the United States was established by the CEC, EPA and other agencies in the form of the CRRC. The CRRC provides rating numbers for solar reflectance and thermal emittance. The heat-reflective standard for low-pitched roofs is a solar reflectance of 0.70 and a thermal emittance of 0.75. Coatings are tested by third-party laboratories and undergo a 36-month weathering test in three designated areas within the United States. To ensure that coatings meet long-term durability standards, a physical property prerequisite is required under ASTM D 6083, which is referenced in Table 118-C of the state energy code.
Products registered with the CRRC are energy-efficient, durable, sustainable and have low VOCs (many are lower then GS-11 certified coatings). Compliant coatings also help combat global warming, rolling blackouts and Urban Heat Islands. They contribute to energy conservation, better indoor and outdoor air quality and can save considerable amounts of money for property owners.
Rigid coating standards such as those used by the CRRC should be adopted by the USGBC and the EPA for any potential exterior wall standards they may be considering. And since cool walls transfer less energy into buildings, and utility companies are burning fewer polluting fossil fuels to operate air conditioning systems, the EPA can better meet its obligations to regulate CO2 emissions under the Clean Air Act, which they have been required to do by the U.S. Supreme Court.
The USGBC currently offers a one-point credit for cool roofs that meet a solar reflective index (SRI) of 78% for Urban Heat Island Effect, which is referenced under LEED For New Construction Version 2.2.