Duluth UDC (unnumbered, p.404: Definitions — O)

Off-Site Facility. A stormwater management facility located outside the boundaries of the site. On-Site Facility. A stormwater management facility located within the boundaries of the site. Open soil surface area. The minimum area around a planted tree that shall remain in a permeable condition as specified in the City of Duluth Tree Species List. Open Space. See “Greenspace or Open Space.” Operator. The party or parties who have: (A) operational control of construction project plans and specifications, including the ability to make modifications to those plans and specifications; or (B) day-to-day operational control of those activities that are necessary to ensure compliance with an erosion, sedimentation, and pollution control plan for the site or other permit conditions, such as a person authorized to direct workers at a site to carry out activities required by the erosion, sedimentation and pollution control plan or to comply with other permit conditions. Outdoor Lighting. 1. Candela. A measure of luminous intensity in a certain direction. Useful in determining how much light is shining out of a fixture and in what direction. One candela is one lumen per steradian (lm/sr). 2. Candela Diagram. Diagram of light power produced by a source and the value of luminous intensity is given directions. A picture of how much light is shining out of a fixture and in what direction. 3. Candlepower. Luminous intensity expressed in candelas. 4. Color Rendering Index (CRI). A measurement of the amount of color shift that objects undergo when lighted by a light source as compared with the color of those same objects when seen under a reference light source of comparable color temperature. CRI values generally range from 0 to 100. 5. Contrast. The ratio of the luminance of an object to that of its immediate background. 6. Cut-off Angle. The angle, measured up from nadir, between the vertical axis and the first line of sight at which the bare source is not visible. 7. Efficacy. A measurement of the ratio of light produced by a light source to the electrical power used to produce that quality of light, expressed in lumens per wall. Efficacy is an important determinant of energy efficiency in lighting equipment. 8. Footcandle. A unit of illuminance. One foot footcandle is one lumen per square foot (lm/ft2). 9. Floodlight. A light fixture designed to light an object to a luminance greater than its surroundings. The beam spread of floodlights may range from narrow field angles of 10 degrees to wide angles (more than 100 degrees). 10. Fluorescent Lamp. A lamp that produces light by means of electric arc that excites a phosphor coating deposited on the inside of a glass bulb. 11. Glare. The sensation produced by luminance within the visual field that is sufficiently greater than the luminance to which the eyes are adapted to cause annoyance, discomfort, or loss in visual performance or visibility. 12. Glare, Blinding. Glare that is so intense that for an appreciable length of time after it has been removed, no object can be seen. 13. Glare, Direct. Glare resulting from insufficiently shielded light sources or areas of excessive luminance within the field of view. 403 | P a g e Article Fourteen. Interpretation and Definitions 14. Glare, Disability. The effect of stray light in the eye whereby visibility and visual performance are reduced. 15. Glare, Discomfort. A Glare that produces discomfort. It does not necessarily interfere with visual performance or visibility. 16. Glare, Reflected. A Glare resulting from reflections of high luminance in polished or glossy surfaces in the field of view. 17. High Intensity Discharge (HID) Lamp. A lamp that generates large quantities of light with electric arches through small tubes. The tubes also contain phosphors that generate additional light output and color. 18. Illuminance. The amount of light falling on a surface measured in lux (lx) or foot-candles (fc). 19. Illumination. An alternative term for illuminance. Commonly used in qualitative or general sense to designate the act of illuminating or the state of being illuminated. 20. Lamp. A generic term for a man-made source of light (e.g. bulb). 21. Light. Radiant energy that is capable of exciting the retina and producing a visual sensation. The visible portion of the electromagnetic spectrum extends from about 380 to 770 nanometers. 22. Luminaire. A complete lighting unit, consisting of lamps, reflector, refractor, or lens, wiring, and sockets. Often referred as “fixture.” 23. Light Loss Factor (LLF). The ratio of illuminance for a given area to the value that would occur if lamps operated at their initial rated lumen output and if no system variation or depreciation occurred. 24. Light Trespass. A subjective perception of undesirable illumination including the following examples: a. The classic “light shining in a window” b. Unwanted light on an adjacent property c. Excessive brightness in the normal field of vision (nuisance glare) 25. Lumens. In physics, the SI unit of luminous flux. Photometrically, it is the luminous flux emitted per second within a unit solid angle (one steradian) by a point source having a uniform luminous intensity of one candela. 26. Luminaire. A complete lighting unit consisting of one or more lamps (light sources) together with the parts designed to control the light distribution and other mechanical and electrical components. 27. Luminaire, Cutoff. A luminaire light distribution is designated as cut off when candlepower per 1000 lamp lumens does not numerically exceed 25 (2.5%) at an angle of 90 above nadir (horizontal), and 100 (10%) at a vertical angle of 80 above nadir. 28. Luminance. The emitted or reflected light from a surface; related directly to perceived “brightness.” The unit of luminance is the candela per square meter (cd/m2). 29. Luminous Flux. Radiant flux (radiant power); the time rate of flow of radiant energy evaluated in terms of a standardized visual response. 30. Luminous Intensity. The luminous flux per unit solid angle in the direction in question. May be expressed in candelas or lumens per steradian (lm/sr). 31. Lux. The SI unit of illuminance. One lux is one lumen per square meter (lm/m2). 32. Nighttime. The hours between the end of evening civil twilight and the beginning of morning civil twilight. Civil twilight ends in the evening when the center of sun’s disk is 6 degrees below the horizon and begins in the morning when the center of the sun’s disk is 6 degrees below the horizon. 33. Spill Light. Light shining beyond a facility that may annoy occupants of the adjacent property. 34. Watt. A unit used to measure electric power. One watt equals one joule/second. Outfall. The location where storm water in a discernible, confined, and discrete conveyance, leaves a facility or site or, if there is a receiving water on site, becomes a point source discharging into that receiving water. Overbank Flood Protection. Measures taken to prevent an increase in the frequency and magnitude of out-of- bank flooding (i.e. flow events that exceed the capacity of the channel and enter the floodplain), and that are intended to protect downstream properties from flooding for the 2-year through 25-year frequency storm events. 404 | P a g e Article Fourteen. Interpretation and Definitions Overstory Tree. Those trees that compose the top layer or canopy of vegetation and will generally reach a mature height of greater than 40 feet. Also see Canopy Tree. Owner. The legal or beneficial owner of a site, including but not limited to, a mortgagee or vendee in possession, receiver, executor, trustee, lessee or other person, firm, or corporation in control of the site.