Passive Solar Urban Design
City of Sequim, WA considering a Renewable Energy Ordinance focused on encouraging solar access in
new subdivisions1. Under consideration:



“Solar oriented lots provision” - 65% (increased from 50%) of lots smaller than 15,000 to be
oriented “in a manner that protects solar access for future homeowners”.
o Frontline within 40 degrees of the E/W line
o For corner lot, side of building within 40 degrees
Provisions for solar access. “Physical elements” (eg buildings, circulation, open space,
landscaping) “located and designed to maximum extent feasible” to provide for solar access to
adjacent rooftops (for solar collectors) between 9am & 2pm,
And, to cast no more shadow on structures on adjacent property than a 15 foot fence would,
between 9 and 2 pm on December 21 (winter solstice). This is substantial setback. ~57 feet, by
Dakota County. October 1999. Dakota County 2020 Solar Access Policy Plan.
Minnesota Statutes require that communities address solar access protection in their comprehensive
plans (Minnesota Statutes, Chapter 473.859, Subd. 2)
RMI provides citations of existing LG policies
-
Removing regulatory barriers – (eg covenants, conditions and restricts)
Creating incentives (waive permit fees)
Local
Govt
Fort
Collins
State
Policy
Content
Weblink
Colorado
Oregon
65% solar oriented lots
Solar access during solstice - 25 foot
hypothetical wall
Note: Language of Sequim policy
modeled off this.
Specifies narrow lots on south corners,
north interior, of SF blocks.
Widest lots on EW interior.
Maximizes solar access, but seems to
encourage house shapes that aren’t
passive solar oriented.
http://www.colocode
.com/ftcollins/landus
e/article3.htm#sec3d
2d3
Portland
Land Use
Code: 3.2.3
Solar Access,
Orientation,
Shading
Title 33,
Planning and
Zoning
Chapter
33.639 –
Solar Access
1
http://www.portland
online.com/bps/inde
x.cfm?a=53445&c=34
564
Joseph Irvin, Interim Planning Director. December 10, 2010. Renewable Energy Ordinance, SMC 17.66. Sequim
City Council Meeting.
Teton
County
Wyoming
Ashland
Oregon
Boulder
CO
Solar Access
Resolution
(part of
comprehensi
ve plan) –
adopted
1982.
Municipal
Code
Chapter:
18.70 Solar
Access
Solar Access
Regulations
Defines size of various solar collectors
(structural systems, or active).
9-3, solstice, 10 foot wall on property
line.
Apply for permit for solar right.
Becomes null and void if solar collector
is not “put to beneficial use”
Setback calculations to protect solar
access from buildings. Alternatively,
performance path based off of solar
envelop.
Solar access permit can be taken to
restrict vegetation on adjacent
properties.
18.72.150 – also includes final site
review by Conservation Coordinator –
comment on EE options. Seems like
too late in process.
Provision in new subdivisions for long
axis of home to be with 30 degrees of
EW axis.
2 zones, 12 foot solar fence, 25 ft.
Homes outside zone can apply for solar
access permit, based on solar collection
technology.
New devs . must submit site plan,
showing shadow casting on adjacent
properties.
http://clerk1.state.w
y.us/plan/docs/Comp
rehensivePlan/Resolu
tions/Solar.pdf
http://www.ashland.
or.us/Code.asp?Code
ID=3338
http://www.boulderc
olorado.gov/files/PDS
/codes/solrshad.pdf
http://www.colocode
.com/boulder2/chapt
er99.htm#section9_9_17
Others –
see RMI
report
Discussion with Ralph Knowles2
Ralph Knowles pioneered the concept of solar access zoning, using the solar envelop, in the 1980s. He is
an architect teaching at USC.
His work developing the solar envelop was initiated at the behest of the Social Energy Research Institute
in Golden. SERI’s legal team was looking at how to mandate solar design/access; determined most
legally sound means would be through zoning.
2
Zoning used envelop concept
Ralph Knowles. January 2011. Personal Communication.
-
Federal funding has since dried up for this stuff.
Application of solar envelop is fairly broad
-
CA, AZ, CO,
San Francisco – solar access in public space
New York
Some specify a solar plane, some a solar fence (same as the solar envelop’s shadow fence)
Not all applied, despite what is on the books
Jurisdictions with rigorous application include Davis CA, Boulder CO
o LA began applying solar access zoning, but opposed by developers
Rigorously being implemented in
o China
o Spain (Barcelona)
o Freiburg – Sonnenschiff development
Developers concerns
-
Reduces options for development
Elements of solar access zoning
Temporal and physical components
Solar envelops should be conceived of as variable. Adjust with:
-
land value
land cost
Strategic density
Opportunities to combine passive solar design guidelines with solar access zoning
“Designers aren’t optimizing use of the sun once they have access to it.”
America very hesitant to impede on developers ability to specify orientation; %’s of fenestration.