It is the purpose of this article
to develop minimum standards for use in the design and installation
of outdoor lighting that enhance visibility and public safety by preventing
uncontrolled intrusion into adjacent properties and the natural environment
and to promote energy conservation and preserve the Town's night sky,
which is a valuable natural resource important to the Town's character.
It is the intent to conserve energy without decreasing safety, utility,
security, and productivity, while enhancing nighttime enjoyment of
property within the Town and surrounding area. It is assumed that
appropriate lighting is safer and more efficient than inappropriate
lighting; therefore, use of lamp technologies with high efficacy is
encouraged.
This article shall apply to all outdoor
lighting within the Town of Denton unless otherwise exempted herein.
A.
Applicability:
(1)
All commercial site plans shall demonstrate that the proposed development shall comply with the requirements set forth in Subsection B below with respect to exterior lighting.
(2)
This article does not apply to emergency
lighting.
(3)
This article does not apply to temporary
lighting.
(4)
This article does not apply to vehicular
lighting.
(5)
This article does not apply to lighting
on wheeled farm machines.
B.
Requirements:
(1)
Motion sensors shall be utilized
to control flood and spot lights.
(2)
High-pressure sodium (HPS) lights
shall be used to minimize energy consumption, maintenance costs, and
sky glow where color recognition is not needed.
(3)
Nonsecurity parking lot lights shall
be turned off after business hours to save energy and protect the
night sky.
(4)
The minimum amount of light needed
shall be used to achieve safe uniform lighting with lights that consume
the lowest amount of power possible.
(5)
Fully shielded or horizontally flush
mounts shall be used for all lights.
(6)
Signs and flags shall be lighted
from above.
(7)
All sports lighting shall be shielded.
(8)
All lights greater than 1,800 lumens
shall be shielded to direct all light toward the ground so that the
lighting elements are not exposed to normal view by or do not create
or constitute a hazard or nuisance (e.g., glare) to motorists, pedestrians
or neighboring residents.
(9)
Lighting shall be designed so as
not to throw glare onto surrounding properties.
For purposes of this article, the
following definitions apply:
Property abutting the lot being developed as well as properties
that are separated by a street, road or right-of-way.
The unit that describes the intensity of a light source in
a specified direction, and is equal to one lumen per steradian (lm/sr).
A luminaire light distribution where the candela per 1,000
lamp lumens does not numerically exceed 25 (2.5%) at an angle of 90°
above nadir, and 100 (10%) at a vertical angle of 80° above nadir.
Any light fixture that emits its light below 45° when
measured from 0° to 180° vertical. Dark sky cutoff fixtures
keep most of their light from reaching the night sky (i.e., emit no
more than 2% of light above the horizontal plane) and also minimize
ground reflection and reduce light scatter beyond the property line.
Any light fixture that emits its light below 90° when
measured from 0° to 180° vertical. Dark sky fixtures keep
most of their light from reaching the night sky (i.e., emit no more
than 2% of light above the horizontal plane).
Anything that is used to shade a light fixture so that it
behaves as a dark sky fixture. These include, but are not limited
to, fixtures outfitted with caps or housings or installed under canopies,
building overhangs, and roof eaves or shaded by other structures,
objects or devices.
Anything that is used to shield a light fixture so that it
behaves as a dark sky cutoff fixture. These include, but are not limited
to, fixtures outfitted with caps or housings or installed under canopies,
building overhangs, and roof eaves or shielded by other structures,
objects or devices
Light emitted directly for the lamp, off the reflector or
diffuser of a luminaire.
Glare which reduces visual performance due to light scattered
in the eye reducing the contrast of the image.
A measurement of the ratio of light produced by a light source
to the electrical power used to produce that light, expressed in lumens
per watt.
Illumination as required by civil officers, agents and officials
to perform their duties to maintain the public health, safety and
welfare.
The assembly that holds the lamp (bulb) in a lighting system.
It includes the elements designed to give light output control, such
as a reflector (mirror) or refractor (lens), the ballast, housing,
and the attachment parts.
A light designed to flood a well-defined area with light,
with a reflector or optical assembly that concentrates the light output
in a particular direction or spot.
A lamp used for indoor retail and office uses and occasionally
in outdoor area lighting. Fluorescent lamps are also available in
the so-called "compact" styles. Advantages include low initial costs
for lamps and fixtures compared with the lamp types below, low life
cycle costs and high efficiency compared to incandescent, no warm-up
period, good color rendition, and long lifetimes. Disadvantages include
higher initial costs compared to incandescent lamps, large lamp size,
low efficiency (compared to HID lamps) and poor output maintenance,
attraction of insects, and potentially hazardous mercury waste.
The basic unit of luminance (the amount of light falling
on a surface). Footcandle measurement is taken with a light meter.
One footcandle is equivalent to the luminance produced on one square
foot of surface area by a source of one standard candle at a distance
of one foot. Horizontal footcandles measure the illumination striking
a horizontal plane. Vertical footcandles measure the illumination
striking a vertical plane.
A shielded fixture that directs all light towards the ground
by preventing all transmission of light above a horizontal line as
specified by the Illumination Engineering Society, i.e., distribution
where zero candela intensity occurs at an angle of 90° above nadir
and at all greater angles from nadir, and prevents the direct image
of a bright source. Additionally, the candela per 1,000 lamp lumens
does not numerically exceed 100 (10%) at a vertical angle of 80°
above nadir.
A bright source which causes the eye to be drawn continually
toward the bright image or when the brightness of the source prevents
the viewer from adequately viewing the intended target.
High-intensity discharge lighting, a family of bulb type,
including mercury vapor, metal halide, or high-pressure or low-pressure
sodium, which glows when an electric current is passed through a gas
mixture inside the bulb.
Most widely used HID lamps for roadway and parking lot lighting.
Advantages include a long lifetime, a wide variety of moderate to
high luminous output lamps, high efficiency and good maintenance,
moderate color rendition, and wide availability and moderate cost
of lamps and luminaires. Disadvantages include poorer color rendition
than metal halide, fluorescent and incandescent, poorer output efficiency
than low-pressure sodium, and potentially hazardous mercury waste.
Festoon-type lights, limited to small, individual low-wattage
bulbs on a string.
Lamp commonly used for the majority of residential lighting,
both indoor and outdoor. Incandescent lamps are widely available in
a huge variety of lamp styles of low to moderate luminous output.
They are commonly used in applications where such low outputs are
needed and where the lighting is often switched off and on. Advantages
include low capital cost for lamps and luminaires, wide availability,
wide variety of both lamp and fixture types, lack of a warm-up period,
and lack of hazardous wastes. Disadvantages include short lifetimes,
low efficiency with resultant high per-lumen energy use and life cycle
cost, attraction of insects, and high heat production.
Direct light that has been reflected or scattered.
The attachment or assembly of any outdoor lighting fixture,
and its fixing in place, whether or not connected to a power source.
The upward emitting of stray light which may illuminate clouds,
dust, and other airborne matter, and may obscure the night sky.
The lamp or enclosing bulb or reflective enclosure.
Any artificial light greater than 0.10 footcandle falling
outside the boundaries of the property upon which the outdoor luminaire
is installed. Light trespass occurs when neighbors of an illuminated
space are affected by the lighting system's inability to contain its
light within the area intended.
A HID lamp popular in some American cities, the light produced
by LPS lamps is nearly monochromatic at a wavelength near 589 nanometers.
Though the eye is very sensitive to this wavelength (leading to the
high efficiency of LPS), the eye cannot distinguish colors when LPS
light is the only source available. Low-pressure sodium lighting is
favored where energy consumption and costs are a major concern and
where color discrimination is either not needed or is supplied by
other lighting. Advantages include the highest luminous efficiency
and lowest energy use, low glare associated with the large lamps,
good visibility and low scattering, minimal effects on insects and
other wildlife, and lack of hazardous mercury wastes. Disadvantages
include the lack of color rendition, shorter lamp lifetime, higher
lamp replacement costs compared to HPS, and large lamp size in the
higher output lamps.
The unit of measurement of the quantity of light produced
by a lamp or emitted from a luminaire. The lumen quantifies the amount
of light energy produced by a lamp at the lamp, not by the energy
input, which is indicated by the wattage. For example, a one-hundred-watt
incandescent light produces 1,800 lumens, while a seventy-watt high-pressure
sodium lamp produces 6,000 lumens. Lumen output is listed by the manufacturer
on the packaging.
A complete lighting unit often referred to as a "light fixture."
A luminaire consists of the lamp or light source, optical reflector
and housing, and electrical components for safely starting and operating
the lamp or light source.
The first widely used HID lamps. Though highly efficient
and long lived compared to the incandescent lighting technology they
displaced, they have many disadvantages compared to other lighting
sources available today, including low luminous efficiency, poor color
rendition, and high ultraviolet output. Mercury vapor lamps have now
been almost completely replaced in new applications by the more efficient
metal halide and high-pressure sodium lamps.
A HID lamp, similar to mercury vapor lamps, but with the
addition of small amounts of various metallic halides, such as scandium,
sodium, dysprosium, holmium and thulium iodide. The many different
varieties of metal halide lamps give a wide variety of slightly different
color characteristics, though generally they are white or blue/white
sources. Besides a relatively steep fall-off in intensity with time
(compared to high-pressure sodium; see below), many metal halide lamps
also change their color as they age. Metal halide lamps are very commonly
used in commercial outdoor lighting where white light with good color
rendition is required or simply desired, such as car dealer display
lots, sports lighting, and service station canopies. Advantages include
a wide variety of moderate to high luminous output lamps, high efficiency
compared to incandescent and mercury vapor and good color rendition.
Disadvantages include lower efficiency and output maintenance compared
to high- and low-pressure sodium, shorter lamp lifetime compared to
high-pressure sodium, color changes, ultraviolet output if not adequately
filtered, and potentially hazardous mercury waste.
Any device that turns a light fixture on when it detects
motion and off when motion stops.
The point directly below the luminaire.
A luminaire light distribution where there is no candela
limitation in the zone above maximum candela.
The nighttime illumination of an outside area or object by
a device that produces light by any means.
Any outdoor electrically powered luminaire, permanently installed
or portable, used for illumination, decoration, or advertisement.
Such devices shall include general ambient lighting, street and area
luminaires, decorative lighting, accent or feature lighting, as well
as searchlights, spotlights, and floodlights, any of which being for
use at or on:
Buildings and structures, including
church steeples.
Recreational areas.
Parking lot and area lighting.
Landscape lighting.
Outdoor signage, both internally
and externally lit (advertising or other).
Streetlighting.
Product display area lighting.
Building overhangs, eaves, and open
and closed canopies.
Farms, dairies, or feedlots.
Gas canopy lighting.
Outdoor walkways.
Flag poles.
Monuments or sculptures.
Luminaire light distribution where the candela per 1,000
lamp lumens does not numerically exceed 50 (5%) at an angle of 90°
above nadir, and 200 (20%) at a vertical angle of 80° above nadir.
The result of scattered light in the atmosphere, means the
haze or glow of light that reduces the ability to view the nighttime
sky.
The basic international system unit of measurement of a solid
angle in a sphere. One steradian is the solid angle made at the center
of a sphere by an area on the surface of the sphere equal to the square
of the sphere's radius.
Any device that can be manually controlled by a person to
turn a light fixture on and off. For the purpose of this article,
switches include motion sensors but switches do not include light
sensors or timers.
Illumination as required by citizens to carry out legally
approved activities for durations as specified in the permits for
those activities. These include, but are not limited to, activities
such as nighttime agricultural operations, construction work lighting,
and seasonal decorations, but in no case shall such temporary lighting
continue for more than a period of three months without an exemption
granted by the Town of Denton.
A.
Non-dark sky fixtures are prohibited in
the Town of Denton unless otherwise permitted by this chapter.
B.
In addition to Subsection A, the following light fixtures are prohibited:
(1)
Lights which shine directly into
neighboring residential districts or buildings and adjacent properties.
(b)
No line of sight to a light source
is permitted five feet or more beyond the edge of the public right-of-way
or property line in a residential district by an observer viewing
from a position that is level with or higher than the ground below
the fixture.
(c)
Compliance is achieved with fixture
shielding, directional control designed into the fixture, fixture
location, fixture height, fixture aim, or a combination of these factors.
(2)
Excessive lighting: lighting which
directs attention away from existing business and community lighting.
New lighting shall not cause existing lighting to appear noticeably
dimmer or reduce the sense of security it provides.
(a)
Areas under structural canopies shall
be illuminated so that the uniformity ratio (ratio of average to minimum
luminance) shall be no greater than 5:1 with an average illumination
level of not more than 30 footcandles.
(b)
Light fixtures located on structural
canopies shall be mounted so that the lens cover is recessed or flush
with the ceiling of the canopy.
(3)
Glare: high-intensity discharge (HID)
light sources which cause disability glare directly visible to drivers.
Full cutoff fixtures shall be used so as to ensure lighting elements
are not exposed to normal view by or do not create or constitute a
hazard or nuisance to motorists, pedestrians or neighboring residents.
(4)
Flashing lights.
The following light fixtures and
lighting are permitted:
A.
All light fixtures that were installed
prior to the effective date of this article.
B.
All light fixtures that are dark sky fixtures
and dark sky cutoff fixtures.
C.
All light fixtures that have a dark sky
shade or a dark sky shield.
D.
All light fixtures that are dark sky fixtures
and dark sky cutoff fixtures providing uniform and appropriate lighting
in parking lots.
E.
All light fixtures that use quality prismatic
or translucent lens materials to spread the bright image over a larger
area and reduce the brightness of the source.
F.
Lighting designed for historic or residential
streets with special product aesthetics or vertical luminance criteria
to limit the lamp lumens or wattage and thereby control glare and
light trespass.
G.
Appropriate lighting used solely to enhance
the beauty of an object.
H.
Necessary floodlights mounted at the appropriate
height, so as to reduce glare in an unintended field of view and with
a total effect that conforms to reasonable ambient lighting levels,
based on the environment of the proposed installation. The light sources
in flood and spot lights shall not be directly visible from adjacent
properties.
I.
All temporary light fixtures for special
public events.
J.
All temporary holiday lighting.
K.
All emergency lighting.
L.
All lighting less than 1,800 lumens.
M.
Lighting of churches and flags, as well
as sports fields in nonresidential areas.
N.
Waterfront lighting: All lighting in and
around the ponds, lakes and other waters of the Town shall not be
installed or maintained so as to create a hazard to or nuisance to
other property owners, navigation or boaters and shall comply with
the following:
(1)
Lights on docks or piers shall be
no more than three feet above the docks or piers, shall be downward
directed, and shall be no more than 550 lumens or less.
(2)
Lights illuminating paths, decks,
etc., shall not be directed toward the waters and shall be no more
than 1,800 lumens or less.
(3)
All exterior lighting shall be located,
mounted and shielded so that direct illumination is not directed on
the water surface more than 20 feet from the shore.
O.
Appropriate sign lighting as referenced in Article XV, Signs, of this chapter.
(1)
Illumination. The illumination of
all signs shall comply in all respects with the provisions of this
article.
(2)
All illuminated signs shall be lighted
by top-mounted lights pointed downward. No sign may be illuminated
with fixtures not shielded from upward transmission of light.
(3)
Nonflashing illumination. Signs may
be illuminated only by conflating lights. Lights that flash, pulse,
rotate, move, or simulate motion are not permitted.
(4)
All lights shall be shielded to ensure
that light sources are not directly visible to drivers or from neighboring
properties.
When a non-dark sky fixture is replaced,
it shall be replaced with one of the following:
A.
When a new light fixture is installed,
it shall be installed with a switch to allow lighting to be manually
turned on and off, with a motion sensor to automatically turn it on
when motion is detected and turn it off when motion ends, or with
timers or photocells when lighting is not needed.
B.
Noncritical lighting after business hours
and at other times shall be turned off when it is not required.
A.
Light fixtures with motion sensors are
encouraged to minimize the duration of nighttime lighting.
B.
Light fixtures with soft yellow or orange
lights (e.g., high-pressure sodium) instead of harsh white lights
(e.g., metal halide) are encouraged to protect the view of the night
sky.
C.
Dark sky shades and dark sky shields are
encouraged for old existing fixtures to protect the view of the night
sky, minimize ground reflection and reduce light scatter beyond the
property line.
D.
Dark sky cutoff fixtures are encouraged
where light fixtures are mounted on structures or poles higher than
the first level above ground level to protect the view of the night
sky, minimize ground reflection and reduce light scatter beyond the
property line.
A.
The Planning Commission may allow exemptions
from this article, as needed, to relieve any unusual circumstances
or difficulties or costs that would be encountered if an attempt were
made to comply with this chapter.
B.
The Town Council may allow exemptions from
this article to recognize that a good faith attempt has been made
to comply with this chapter but compliance is still not possible due
to unusual circumstances or difficulties or costs encountered.
The Building Official and the Department
of Planning are authorized to enforce the provisions of this article.
The Town of Denton does not, by approving
or disapproving a lighting fixture, warranty or make assurance of
any kind whatsoever, specifically as to whether the subject of the
approval or disapproval is safe, suitable for its intended purpose,
merchantable, or in compliance with any applicable codes or regulations.
