zoning for sustainability: green area ratio for sustainability: green area ratio september 27, 2011...

Zoning for Sustainability: Green Area Ratio

September 27, 2011

Laine Cidlowski, AICP, LEED AP

District of Columbia Office of Planning

Zoning Review Process

OP Goals for Zoning Review:

Clarity

Relevance

Ease of use

Zoning Review Process: Subject Areas

Policy Procedural

• Low/Mod Density – Res.

• Industrial

• Campus/Institutional

• Downtown

• Parks/Open Space

• Med/High Density

• Commercial Corridors

Mixed/Other (Waterfronts)

• Planned Unit Development (PUD)

• Design Review

• Administration/ Enforcement

• ZC & BZA Procedures

Land UseLand Use

• Floodplain• Height• Parking• Loading• Arts & Culture• Retail• Historic Structures• Sustainability

Sustainability RecommendationsA. Integrating Land Use and Mobility

B. Energy Conservation and Renewable Energy

C. Water and Sensitive Resource Protection

D. Food Security

E. Green Jobs

F. Large Area Development

Water and Sensitive Resources

5 Major Topics

Promote Water Conservation Protect and Enhance Tree Cover Reduce Runoff and Soil Erosion Provide Buffers for

Environmentally Sensitive Areas Protect Floodplains

Water ConservationRain Harvesting Devices Explicitly permit Allow in yard setbacks,

underground and on rooftops

Vegetated roofs Exempt from rooftop

setbacks Encourage through site

design requirements Updated building code

likely to require “cool” roofs

Tree Cover Protection

Expand tree cover protection

Study applying TSP overlay to residential zones citywide

Potential Guides Lower trigger to 25”

circumference (or equivalent dbh)

Allow tree removal subject to replacement of equivalent carbon absorption

Consult with Urban Forestry Administration (UFA)

10

Water ConservationLow-Water Use

Landscaping Specify native and low-

water demand species and encourage their use

Encourage through site design requirements

11

Reducing Runoff/ErosionParking Lot

Landscaping Require design and

distribution of landscaped areas to reduce/filter runoff (e.g., minimum planting bed size)

Encourage pervious pavement through site design requirements

Encouraging Green Site Design Water Recommendations Encouraged: Green/cool roofs Pervious surfaces Native/water conserving landscaping Tree planting/preservation

These can be addressed comprehensively through site design requirements

Green Area Ratio provides flexible, consistent regulation of environmental site design

Best Practices: Other Cities Berlin, Germany: Biotope Area Factor Seattle, WA: Green Factor Required for all new development in neighborhood business

districts with more than four dwelling units, more than 4,000 square feet of commercial uses, or more than 20 new parking spaces

Goal: Increase the amount, quality of urban landscaping in dense areas while allowing flexibility for developers and designers to use property efficiently

Fife, WA: Fife Green Factor

Seattle’s Green Factor

A landscape requirement that values both the aesthetic and ecological functions of planted areas.

Raises the bar for total landscaped area, but awards credit to new types of features.

Adopted for Commercial zones as part of the Neighborhood Business District Strategy in 2006, implemented Jan 20, 2007

DC’s Green Area RatioWhat is it? A flexible green site design

requirement that varies by building type

How Achieve? Choose from a range of

environmental landscaping practices each of which have been assigned an environmental performance ranking

Examples may include… Turf grass

Un-vegetated permeable pavement

Vegetated permeable pavement

Green roofs

Natural ground cover

Rain gardens

Trees & shrubs

Vegetated walls

GAR: How Does it Work?How to calculate: Add up landscape elements

by number or size # trees Size of green roof Size of rain garden # of plants Soil depths

Divide by lot area

= GAR score

Green Area Ratio Benefits• Increase the amount and quality of urban landscaping in

dense urban areas while allowing increased flexibility for developers and designers to efficiently use their properties:

Builds on DDOE stormwater requirements Applicable to low & moderate density zones Flexible Consistent Higher environmental value Provides targets based on relative level of urbanism

GAR: Recommendations to Reality Sample sites for proof of

concept testing by zone and building type

Costing estimates for proof of concept testing

Discussions with DCRA, DDOE, DDOT

Many decisions on program details

Detailed Decisions Where will it apply What will the

environmental multipliers be

What landscape elements will be included

By whom will the projects be certified

GAR Sample Scoresheet Landscape elements Allowed to double count

plant and soil depth Different values for

different size plants Includes permeable paving Includes green roofs Includes bonus for native

plants Bonuses for food

cultivation

1300. Introduction to GAR regulation Explains what the GAR is “Green Area Ratio (GAR) is the ratio of the weighted value of

landscape elements to land area. The GAR score relates to an increase in the quantity and quality of environmental performance of the urban landscape. “

Explains why the GAR is being implemented Achieve environmental performance Meet city-wide environmental goals

1302. Applicability of GAR Standards Applies to all new buildings requiring a C of O i.e. no single family homes

Does not apply to R-1 to R-4 zones Applies to all renovations over 100%

assessed value Will not apply in public space

Will apply different GAR scores in different zones

1303. Calculation of GAR Info used to calculate GAR Landscape element options, and GAR values How to measure landscape elements Sf equivalencies for plants & trees Technical calculation of GAR

GREEN AREA RATIO LANDSCAPE ELEMENTS MULTIPLIERLandscaped area (select one of the following for each area)Landscaped areas with a soil depth of less than 24 in. 0.3Landscaped areas with a soil depth of 24 in. or more 0.6Bioretention facilities 0.4PlantingsGround covers, or other plants less than 2 ft tall at maturity 0.2Plants at least 2 ft tall at maturity 0.3Tree canopy for all trees 2.5 in. to 6 in. in diameter 0.5Tree canopy for new trees 6 in. in diameter or larger 0.6

Tree canopy for preservation of existing trees 6 in. to 24 in. in diameter 0.7

Tree canopy for preservation of existing trees 24 in. diameter or larger 0.8Vegetated wall, plantings on a vertical surface 0.6Vegetated roofsExtensive vegetated roof over at least 2 in. but less than 8 in. of growth

medium 0.6

Intensive vegetated roof over at least 8 in. of growth medium 0.8Water features (using at least 50% recycled water) 0.2Permeable pavingPermeable paving over at least 6 in. and less than 2 ft of soil or gravel 0.4Permeable paving over at least 2 ft of soil or gravel 0.5Enhanced tree growth systems 0.4Renewable energy generation (area of) 0.5BonusesNative plant species 0.1Landscaping in food cultivation 0.1

1304. Landscape element eligibility conditions for GAR Bioretention = rain gardens, includes Baysavers Trees Vegetated walls – further specifics on how to

measure Vegetated roofs

1304. Landscape element eligibility conditions for GAR Water features Enhanced tree growth Native plant species Food cultivation Stormwater irrigation

1305. Submittal Requirements for GAR 1305.2 Requires certified landscape experts Submit landscape plan with typical elements Flexibility for weather, seasons, reasonable changes 1305.2 Certified landscape experts rely on MD and VA programs

1306. Special Exception for GAR Allow flexibility for our historic sustainable fabric Recommendation – Calibrate by zone

1307. Maintenance Requirements for GAR To ensure that environmental performance is achieved

Case Study : High Density Multi-family Residential: 900 G Street NE

Zone: R-5-D

Existing GAR = 0.18

Paved areas to permeable paving + trees = 0.36

Above + ½ green roof =0.488

All of Above + raingarden = ≥ 0.5

G ST NE

9TH

ST

NE

PIC

KFO

RD

PL

NE

Lot 08030650 10TH ST NE

Lot 08310656 9TH ST NE


Lot 08290813 G ST NELot 0827

0651 8TH ST NE

Lot 00570900 G ST NE

Lot 00550901 H ST NE





Lot 00700718 10TH ST NE

Lot 00720714 10TH ST NE

Lot 00760706 10TH ST NE

Lot 00740710 10TH ST NE

Lot 00780702 10TH ST NE

Lot 00710716 10TH ST NE

Lot 00790700 10TH ST NE

Lot 00730712 10TH ST NE

Lot 00770704 10TH ST NE

Lot 00750708 10TH ST NE











Case Study: 100% Lot Occupancy Downtown 800 17th Street NW

Zone: C-4

Existing GAR = 0.30

Low green roof = 0.30

Thicker green roof instead = 0.40

Low green roof + renewable energy generation = 0.56 max

Case Study: Small scale Commercial: 1443 Howard Road SE Zone: C-1 Existing GAR = 0.0 ½ roof with thick green roof

= 0.1 ≤ 1/2 the paving to

permeable = 0.1 All pavement permeable+

plants and trees = 0.26 Permeable paving +

raingarden + plants + green roof = 0.37

Green Area Ratio: Where is it in Process? Developed from

Sustainability Working group

Preliminary text approval from Zoning Commission

Administrative process & responsibilities

Finalize city-wide research to determine GAR for all zones

Next Steps Interagency Admin group Set GAR for all zones Implement!

GAR: Long Term Steps Training of Program administrators, inspectors Develop educational materials and training for developers

and the public Step by Step instructions Webinars Sample implementation Etc.

Establish tracking system for projects Obtain funding for interactive online weighting tools or

‘find a BMP’ databases

Contact Questions?

Laine Cidlowski, District of Columbia Office of Planning Urban Sustainability Planner AICP, LEED AP [email protected]

zoning for sustainability: green area ratio for sustainability: green area ratio september 27, 2011...

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