Frequently Asked Questions

FAQs » MISCELLANEOUS

Question: What is the acrylic coating thickness and % of solids [on 55% Al-Zn Coated Steel]?

Answer:

The thickness is approximately 1 micrometer (0.039 mils) but may vary among suppliers. To put this in perspective, a standard paint system is often about 25 micrometers thick. The percent solids may also vary among coating suppliers but is nominally 25%.

Question: What determines a "Heat Island"? Size"?, Location"?

Answer:

"Urban areas tend to have higher air temperatures than their rural surroundings as a result of gradual surface modifications 4 that include replacing the natural vegetation with buildings and roads. The term ‘Urban Heat Island’ describes this phenomenon." [LBNL –49638] No references can be found that quantified the potential impacts of the changing urban fabric (the relative amounts of buildings, trees, grass, roads, roofs, etc.); the size and climate of the urban area; and the normal, heat-producing activities of a large and dense population (transportation, running domestic and industrial equipment, etc.).

Indeed, it is sometimes difficult to determine whether temperature changes can be attributed to a "Heat Island Effect" at all. One study of the Los Angeles area concluded, "These increases [in yearly temperature maxima] suggest that the daytime warming is becoming more important over time at [three of the eleven stations studied] during the summer months. However, whether this rise in the daily maxima is caused by local-scale heat island effects or simply by changes in microclimate below canopy height is uncertain." The situation was clearer in another city: "Data from stations in the center of Phoenix showed clear and significant nighttime and daytime temperature differences of 1 -- 2OK (3 -- 4OF). These temperature increases may be attributable to a local-scale heat island." [LBNL-41973]

Question: Is the Cool Metal Roofing Coalition available for local CSI or AIA educational presentations?

Answer:

The Cool Metal Roofing Coalition can accommodate most presentation requests.

Question: A quick scan of HDD and CDD for cities in the US shows that the HDD are much higher. What opportunities do you see for addressing this side of the equation especially for metal?

Answer:

Not surprisingly, the greatest benefits to "cool roofs" are to be found in cooling-dominated regions. A study of non-metal roofs with various coatings concluded, "Regardless of surface coating, energy savings were economically significant only in cooling-dominated climates with poorly insulated roofs." [Petri et. al., "Effect of Solar Radiation Control on Energy Costs A Radiation Control Fact Sheet for Low-Slope Roofs", Oak Ridge National Laboratory, no date found] However, the potential benefits of using metal roofs with dark paints that absorb energy in heating-dominated regions have received very little favorable attention.

Question: What literature do you consider to be a

Answer:

Literature on cool roofing and urban heat island effects can be found on the websites of Lawrence Berkeley National Laboratory, Oak Ridge National Laboratory and the Florida Solar Energy Center. Some specific papers are also shown below:

1) Wilkes, Kenneth E., et. al., "Roof Heating and Cooling Loads in Various Climates for the Range of Solar Reflectances and Infrared Emittances Observed for Weathered Coatings," Oak Ridge National Laboratory, no date (available on DOE’s Cool Roof Calculator CD).

2) Konopacki, S., et. al., Cooling Energy Savings Potential of Light-Colored Roofs for Residential and Commercial Buildings in 11 U.S. Metropolitan Areas, Lawrence Berkeley National Laboratory, May 1997 [LBNL-39433].

3) Akbari, H. and Bretz, S., "Cool Systems for Hot Cities," Professional Roofing, October 1998 [Also LBNL-43814].

4) Parker, D.S., et. al., "Comparative Evaluation of the Impact of Roofing Systems on Residential Cooling Energy Demand," Contract Report FSEC-CR-1220-00, Florida Solar Energy Center, Cocoa, FL, November 2000.

Question: Can you provide contact information for speakers and panelists?

Answer:

Requests for speakers and panelists should be forwarded to Mr. Greg Crawford, Executive Director of the Cool Metal Roofing Coalition, at gcrawford@steel.org.