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Shaded Parking Lots

Parking lots are large contributors to urban heat islands and polluted stormwater runoff. As climate change continues to warm our town, parking lots are exacerbating the problem, trapping heat that affects human health and energy use. One relatively easy and inexpensive way to mitigate these environmental issues is to design green parking lots with canopy tree cover that provides shade along with stormwater interception and infiltration.

A More Livable Town

  • Greener Streets
  • Cooler and more Pleasant
  • Better for Local Business

Climate Change Resilience

  • Reduced Heat Islands
  • Reduced Flooding
  • Improved Air Quality

Advances Community Goals

  • Sustainable Action Plan
  • Hazard Mitigation Plan
  • Net Zero Action Plan

Right Here & Right Now

Climate Change is driving global temperatures higher

Unshaded “Heat Islands” contribute to Arlington’s warming

We can think globally & act locally,

 > Right Here & Right Now <

(click to enlarge)

Global Average Temperature

(click to enlarge)

Arlington Heat Map

Shaded Parking Lot Bylaw Amendment

Existing bylaw language:

6.1.11.D. (6) Parking areas providing more than 25 spaces shall include:

  • Landscaped areas at least 8% of the total paved parking area
  • Individual strips of landscaping at least four feet wide

Article 30 would add the following language:

In addition, pavement shade shall be provided by one or both of the following methods:

a. Install one shade tree for every eight parking spaces, with some part of each space within 32 feet of a tree

  • Tree planting areas at least six feet in diameter
  • New trees at least three inches in diameter
  • New trees selected from an approved Tree List
  • New trees to be watered for three years
  • Where practicable, existing healthy trees retained
  • Option to include shade from healthy off-property trees not planned for removal

b. Install solar panels over parking spaces allowing cars to park underneath to a minimum of 50% of the parking lot surface

Click for the full text of the proposed Amendment

Example: Whole Foods parking lot

Frequently Asked Questions (with answers)

What would trigger the new requirements if an existing lot is changed? Would this apply to an existing parking lot if it’s repaved? The new parking lot requirements would be triggered only when building a new parking lot of over 25 spaces or expanding an existing lot to over 25 spaces. Existing parking lot owners would not be required to use the new shaded parking lot requirements when repaving, yet we hope town officials will encourage them to do so.

How many parking lots are there in Arlington that have > 25 spaces? Green Streets Arlington counts nearly 70 parking lots, both private and publicly owned in Arlngton which have greater than 25 spaces and WOULD HAVE been subject to the changes proposed by Article 30 if they were developed today. Future parking lot developments, over 25 spaces, including any parking lots that will be created with new building development within the new MBTA-Communities overlay districts will need to adhere to the new shaded parking lot requirements.

What other towns have similar shaded parking lot requirements? Lexington, MA has similar shaded parking lot requirements with their zoning bylaws and was used by Green Streets Arlington as a template in designing the requirements within Article 30 for Arlington. A handful of towns in Massachusetts require some of the components of Article 30, for example, Amesbury, MA requires a shade tree every 8 parking spaces. Outside of Massachusetts a few municipalities have shaded parking lot requirements. For example, Los Angeles requires a tree planted for every 4 parking spaces in municipal parking lots.

Does the Arlington’s Redevelopment Board endorse the Article 30 Shaded Parking Lot Amendment? Yes, the Arlington Redevelopment Board voted to endorse Article 30, an important endorsement of the Amendment. Some concerns were raised during hearings that the measure was too onerous or too prescriptive,  Green Streets Arlington disagrees and notes that the costs of tree shade are a small fraction of landscaping costs, and smaller still of total project costs. History shows that developers need guidelines –  virtually all of Arlington’s parking lots over 25 parking spaces developed with the current 8% landscape requirement zoning law are highly inadequate in providing shade.

Gibbs School
CVS 833 Mass Ave
Thompson School

Arlington’s current zoning for parking lots over 25 spaces requires a minimum 8% landscaped area. How much more landscape area will be required with the zoning changes within Article 30? Article 30 does not target a certain percentage of landscape area. Article 30 requires that parking lots with 25 or more spaces continue the minimum 8% landscaped requirement plus minimum required landscaped setbacks and buffers at the perimeter of the parking area, yet, parking lots would now need landscaping layout to include 1 shade tree planted per 8 parking spaces, and make sure that every parking space is within at least 32 feet of a shade tree. Noting that every parking lot configuration and area is differently shaped and that neighboring healthy shade trees can be used for shading a parking lot, the percent of additional landscape area with the requirements of Article 30 may or, may not change. What will change is that shade tree planting will be more evenly distributed throughout the parking area to create shade.

What if there are existing street trees or neighbor trees that will provide shade to a new parking lot, can they be considered in the requirements within Article 30? Yes, healthy neighbor or street trees that are of shade tree size can be used toward shading a new parking lot.

How many parking spaces would be lost? The number of parking spaces that would be taken up by adding trees depends on the parking lot layout, and the area of the surface area. Using examples of Arlington’s existing parking lots, Green Streets Arlington has found minimal reductions in the number of parking spaces when applying Article 30 requirements.

Would this impose an undue financial burden on developers or discourage new housing or commercial development? No. Arlington zoning already requires 8% area within parking lots with 25 spaces or more to be landscaped plus minimum required landscaped setbacks and buffers at the perimeter of the parking area.  Traffic experts advised that the additional trees and/or solar panels would add only a small fraction of the total construction cost.  In addition, the beauty and shade of the added trees will likely return the investment by attracting in hot weather more customers for the businesses served by the parking lot than otherwise, and the electricity cost savings from the solar panels will benefit the parking lot owner.

Who would be responsible for keeping the trees healthy after planting? The parking lot owner would be responsible for watering and maintaining the care of the parking lot trees. The Amendment specifically requires new trees to be watered for no less than thirty-six months after planting.


References – Urban Forestry & Green Parking

Arlington MA Zoning Bylaw

Trees and Parking Lots (Arbor Day Foundation)

Green Parking Lots: Mitigation Climate Change and the Urban Heat Island (Penn State Extension)

EPA’s Green Parking Lot Resource Guide

Healthy Forest -> Healthy City (City of Cambridge)