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93 <br />Design Elements of Spill Light and Glare Control <br />I. Introduction <br />H. Why are aiming angles important? <br />III. Why is photometry of the fature important? <br />IV. Summary of Light - Structure Green'm features that control spill light <br />and glare <br />1. Introduction <br /># T130015 <br />Purpose: Spill light and glare are a nuisance for nearby neighbors and the community. This <br />bulletin discusses ways to limit spill light and glare. <br />Scope: The scope of this bulletin is limited to lighting design. There are other things a property <br />owner can do to limit spill and glare. For example: build fences or plant bushes or trees. <br />Spill light illuminates areas off the field of play, which can be a nuisance for nearby neighbors. <br />Glare is the discomfort experienced when looking directly at a light source. The design elements <br />that affect of -site spill light and glare are basically the same, so this discussion is relevant for both. <br />The two primary design elements that control spill light and glare are the fixture aiming angle and <br />fixture photometry. Both elements need to be coordinated within the design to properly control <br />offsite spill light and glare. <br />In addition to preventing light trespass on neighboring properties, another benefit of controlling spill <br />light is that fewer fixtures and less electrical power may be required to light a field, since less light <br />is wasted. <br />See Technical Bulletin # TB0005 for a more detailed explanation of spill light and glare. <br />H. Why are aiming angles important? <br />The vertical aiming angle is a key element in controlling the amount of light that is directed onto <br />the field, with steeper aiming angles generally directing more light onto the field resulting in less <br />spill and glare off -site. The two factors that determine the vertical aiming angle are fixture <br />mounting height and pole setback, assuming a fixed aiming point. Below are examples showing <br />how mounting height and setback affect aiming angles. <br />A. Mature Mounting Height <br />Mounting height is typically the factor that is most easily adjusted in a lighting design, since <br />pole locations are frequently subject to various constraints. The higher the mounting height, the <br />800 825 6030 <br />m WWW.musco.com <br />email: lighting @musco.com <br />0 2001, 2003 Musco Lighting Page 1 of 3 <br />