point cover jan 13 - Boston Redevelopment Authority

Summary of Key Findings
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Expanded_PNF\04_Environmental_FINAL.do
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Vanasse Hangen Brustlin, Inc.
The Point, Boston
The Project will not result in solar glare impacts on streets (visual impairment vehicle traffic), or on public
open spaces and pedestrian areas (discomfort due to reflective spot glare). The Project will not produce solar
heat buildup on nearby buildings that may receive reflective sunlight from the proposed building. The
proposed building design specifications, such as façade design, glazing systems with specific solar and
optical characteristics as well as streetscape improvements (i.e., street trees) are considered to mitigate the
reflected glare from the viewers’ viewing directions. Additionally, the proposed building design aims to
minimize any negative solar glare effects on passing birds by creating a façade composed of a series of angled
elements that alternate between masonry and glazed panels, thus disconnecting visual reflections.
Solar Glare Analysis Methodology
Glare is the loss in visual performance or visibility, or annoyance or discomfort produced by a luminance in
the visual field greater than the luminance to which the eyes are adapted. There are three types of glare:
veiling or disability glare, discomfort glare, and reflection glare.
A computer simulation combined with spread sheet calculations are used to determine the CIE Glare Index
(CGI) and/or CIE Glare factors/ rating for a given site. The simulation uses hourly weather data based on
average Boston climatic conditions to obtain glare conditions within the critical field of view. The computer
simulation also accounts for actual glass/glazing assumptions in order to determine spectral transmittance
and reflectance data which identifies problem areas near the proposed building.
The subjective scales for the evaluation of these reflections include:
Perceptible - The point at which you would prefer the light not to be present. Imagine that it is a pilot
light on a computer and you are obliged to set the pilot light on/pilot light off. This is the level at which
you would begin to care about such decision.
Annoying - You could live with this glare source present if you were borrowing someone else's computer
for a day. If this glare source were present, you would prefer to remove the glare source if it were
possible, but could live with this annoyance for the next hour or so.
Disturbing - This make you feel uncomfortable. If you had to work like this for any reasonable length of
time (5 minutes or so) you would do something to cover the source. Shield your eyes, etc. In order to
avoid the discomfort.
Intolerable - you could not imagine yourself working with the light source like this. You would certainly
close your eyes or take another avoidance action.
Solar Glare Impact Analysis Findings
The proposed building design specifications, such as façade design, glazing systems with specific solar and
optical characteristics as well as streetscape improvements (i.e., street trees) are considered to mitigate the
4-13 Environmental Protection