Comprehensive Local Actions

Site Planning and Landscape Design

Enhancements to the Building Envelope

Modifications to Existing Buildings

Building Operations

Emerging Technologies

Enhancements to the Building Envelope

OBJECTIVE: Improve upon conventional building envelope design to prevent bird collisions with glazed surfaces, while maintaining transparency for views, daylighting and passive environmental control.

TECHNICAL STRATEGIES
Plan building layout to minimize the likelihood of bird collisions:
Integrate site and landscape features to minimize those hazards that bring birds close to buildings such as vegetation, water and other features attractive to birds. See "Bird-safe Site Planning and Landscape Design."
Where practicable, limit the overall amount of glazing in areas that are in predictable migratory and resident bird collision areas.

Design ground level stories, which are the most hazardous areas of all buildings, to minimize bird collisions:
Wherever possible, limit the amount of glazing used on ground level stories, particularly in areas that are adjacent to landscapes.
In glassy areas, seek to maximize "visual noise", or readily visible differentiations of material, texture, color, opacity, or other features that help to fragment glass reflections and reduce overall transparency. Incorporate "visual noise" at the scale of the building and at the level of the individual glass unit.
Utilize etching, fritting, and opaque patterned glass to reduce transparency.
Utilize low-reflectivity glazing.
Utilize low-e patterning in glass.
Utilize shading devices, screens, and other physical barriers to reduce birds' access to glass.
Consider the use of angled glass, between 20 and 40 degrees from vertical, to reflect the ground instead of adjacent habitat or sky.
Minimize bird habitat near ground level stories.

At the whole building scale, develop strategies to make glazing more apparent to birds:
Avoid monolithic, undistinguished expanses of glazing.
Create building elevations that simulate large scale 'visual noise'.

Utilize bird-legible patterns on individual glass units to make glass more apparent while maintaining its visual acceptability:
Employ patterns in sizes that, according to experiments, discourage birds from attempting through-passage: a maximum space measuring two inches tall by four inches wide, or the equivalent size of a human handprint oriented horizontally.
Consider creative glass patterns that accomplish objectives for shading, views, and bird-safety. Integrate glass patterning with the overall building design.
In locations where bird-collisions are predictable, seek uniform covering of glass with bird-safe patterning.
Consider applying acid etched or sandblasted patterns to glass on the outside surface to "read" in both transparent and reflective conditions.
Use applied ceramic fritting in dot matrix patterns and grids to make glass visible to birds, while achieving solar shading. (Note: Although fritting is useful for creating visual noise, it is less effective at reducing reflectance since it is generally applied on the interior face of the glass.
Use real or applied divided lights to break up large window expanses into smaller subdivisions.
Pay particular attention to treating the ground level stories-which are where most bird collisions occur-as well as any areas that are adjacent to landscapes and other bird habitat.

Develop strategies to minimize the reflection of surrounding habitat or sky in glass facades:
  • Wherever possible, specify reduced- or low-reflectivity glass (0 to 10% reflectivity).
  • In utilizing spectrally selective glass, seek to balance good thermal control and daylight transmittance with reduced or muted reflectivity (less than 10%), or provide exterior devices to reduce reflection.
  • Consider the use of angled glass, between 20 and 40 degrees from vertical, to reflect the ground instead of adjacent habitat or sky.
  • Pay particular attention to treating the ground level stories-which are where most bird collisions occur-as well as any areas that are adjacent to landscapes and other bird habitat.
Employ exterior shading or other architectural devices on glazed facades to enhance bird safety:
Incorporate louvers, awnings, sunshades, light shelves or other exterior shading / shielding devices to reduce reflection and give birds visual indication of a barrier.
Consider other highly patterned shading / shielding devices that will encourage bird safety. Integrate these features with the building's overall design. See examples for details.
Where appropriate, use plastic or metal screens over windows to reduce reflectivity and decrease the damage caused to birds colliding with the glass.
Pay particular attention to treating the ground level stories-which are where most bird collisions occur-as well as any areas that are adjacent to landscapes and other bird habitat.
Coordinate bird-safety efforts with daylighting and passive cooling efforts. See LEED Credit EQ 8.1 Daylight & Views, and LEED Credit EA.1 Optimize Energy Performance for more details.

Design and operate interior window treatments to improve bird safety:
Use light-colored solar reflective blinds or curtains to reduce glass transparency and add visual noise.
Close curtains and blinds if evening illumination is utilized.
Consider photo-sensors, timers, or other automatic controls to regulate shading devices.

Design to eliminate nighttime light trespass from the building's interior:
Integrate automatic lighting controls to extinguish lights in the evening by 11:00pm.
Create smaller zones in lighting layouts to discourage wholesale area illumination.
Incorporate and encourage the use of localized task lighting.
Install light dimmers in lobbies, atria and perimeter corridors for nighttime use.
Install motion detectors to shut-off lights in the evening when no occupants are present.

Design exterior lighting to minimize light trespass at night:
Minimize amount and visual impact of perimeter lighting and fašade up-lighting.
Specify full-cutoff exterior fixtures to reduce light trespass.
Utilize motion-detection as lighting controls wherever possible.
Utilize minimum wattage fixtures to achieve appropriate lighting levels.
Avoid use of floodlighting.
On skyscrapers or other tall structures that must comply with federal aviation or marine safety regulations, install minimum intensity white strobe lighting with a three second flash interval instead of continuous flood lighting, rotating lights, or red lighting.
Ensure that all exterior light fixtures are properly installed to prevent unintended light trespass.

Minimize rooftop obstacles to bird's flight:
  • Minimize the amount of exterior antennas and other tall structures, including cell phone, television and other media equipment. Collocate all necessary antennas and tall equipment, and locate them to minimize conflicts with birds.
  • Utilize self-supporting lattice or monopole towers that do not require the use of guy wire supports.
  • Avoid up-lighting rooftop antennas and tall equipment, as well as decorative architectural spires.
BENEFITS & LIMITATIONS
+ Complements efforts to control interior building climate passively and to create variable climate zones depending on programmatic uses.
+ Encourages innovative aesthetic approaches to fašade treatment in addition to increased bird safety.
- Potentially increases construction costs.
- May compromise daylighting and view objectives.
- Potentially conflicts with desired aesthetic of maximal transparency.
- Untested strategies may not achieve desired outcome.

LEED INTEGRATION
Sustainable Sites (SS) Credit 8: Light Pollution Reduction.
Energy and Atmosphere (EA) Credit 1: Optimize Energy Performance.
Indoor Environmental Quality (EQ) Credit 6.1: Controllability of Systems: Lighting.
Indoor Environmental Quality (EQ) Credit 8.1: Daylight & Views.


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