Skin Cancer xxix, 2011 : Page 66

INTERNATIONAL • whether vegetation is evergreen or deciduous (drops leaves in winter); the latter can be used in tandem with appropriate translucent roofi ng to maintain comfort through “warm shade” in cooler seasons. Remem-ber, UV levels can remain high even when temperatures are cool. When you analyze your property, carefully note activity areas without shade, or where shade fails to pro-vide adequate UV protection. Before committing to new shade, consider if there are existing shade areas not in use — you may be able to relocate some activities. DESIGNING SHADE Once you have determined where new shade is required, you need to design effective solutions, meaning shade that: • falls in the right place, at the right time. • provides effective blockout of direct UV radiation. • protects against indirect UV radiation (scattered by clouds and/or atmo-spheric particles, or which reaches an area after being bounced off of UV-refl ective surfaces like sand, snow, ice, and concrete). • will be comfortable to use in both summer and winter. 3 BUILT AND NATURAL PROTECTION roofs, translucent and solid roofs, gazebos and verandas. Structures can be fi xed, providing permanent shade, or adjustable, allowing the amount of shade to vary seasonally. Materials such as polycarbonate and solar glass (glass specially treated with UVA-protective window fi lm – see sidebar, p.67.) effectively block up to 99 percent of UVR while still transmitting heat and light. Natural shade solutions such as trees, shrubs, vines and ground cover can provide effective and aesthetically appealing sun protection. Used along with translucent man-made UV-blocking materials, species that drop leaves in winter can provide safe UVR levels throughout the year — thicker coverage and shade during summer, with less shade allowing more heat in less sun-intensive months. Talk to a horticultural specialist or local nursery for advice on suitable shade vegetation for your area. SHADE IN THE RIGHT PLACE, AT THE RIGHT TIME or trees with high canopies may cast shade well away from the desired shade area at various times of day. EFFECTIVE BLOCKOUT OF DIRECT UV RADIATION Built shade can include fabric shade sails and awnings, pergolas, louvered We all know that the sun moves throughout the day, and is at differ-ent heights in the sky throughout the year, but this is often neglected when designing shade. Shade structures and trees are often too small to be effective in early morning and late afternoon, when the sun is lower and hits the earth at a different angle than at high noon. Similarly, high structures When building shade structures, be sure your materials provide at least 94 percent UV radiation blockout. Materi-als can vary widely in effectiveness. Most often, the denser the material, the better; a tightly woven shade cloth will generally offer more protection. Also, fabrics used for shading are rated by approved labs; these ratings should be part of the manufacturers’ specs. The ideal translucent sheeting or roofi ng is polycarbonate. It is cheap, light, easy to support, and can be tinted to reduce glare as well as treated to exclude heat. If you’re using natural shade, the protection provided depends on canopy density, since different trees and plants provide varying UV protec-tion. One method is to look at the sky through the tree canopy or at the shade on the ground and match the density to one of the diagrams below 4 [Figure 5] . BLOCKING INDIRECT UV RADIATION Indirect UV radiation can come from any direction, so it is diffi cult to exclude completely. Since it can sig-nifi cantly increase overall exposure, it is important to limit indirect UV by: • making shade structures of adequate size. Extending the shade 1 2 3 Shade sails over terrace Optimum shade locations and confi gura-tions can easily be determined with shade planning software. Folding arm awning Well-designed shade enhances the home environment, resulting in spaces that are visually appealing and comfortable to use. 66 N E W S F R O M T H E I N T E R N AT ION A L A D V I S O R Y C O U N C I L

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