REGREENING STRATEGIES & PERFORMANCES
RETROFITTING SUBURBIA PROF. ELLEN DUNHAM-JONES SPRING 2011 NAJIA K ALI
The aim is to analyze underutilized parking lots and create a template to show the possibility of retrofitting a site, and to what degree. A basic strategy to calculate the percentage of regreening that is possible. And To explore some reasons for regreening parking lots and applying greening/regreening options that may be viable. The most intuitive question would be how much land is designated parking and why do we see so many underutilized parking lots? Parking is the largest use of land in both urban and suburban areas.
In most
cases, the reality of parking provided is
very
different
from
the
actual
need. Research shows that business and marketing
policies
establish
parking
ratios needed for peak time, and size parking lots accordingly. These ratios are also set and cross referenced by zoning city
ordinances for
established
different
uses
by
the
(Frielich,
2002). Since municipal codes usually do not enforce maximum parking ratios but concentrate on minimum parking required on
site,
of
parking
is
on
most
overzealous
there
“generous
an
sites
developers parking
overabundance driven
who
by
advertise
provided�
as
part
of their marketing strategy. To pacify developers and investors, municipalities often
grant
variances
to
allow
SACRAMENTO CITY CODES
additional parking to be squeezed on to sites, usually at the expense of green infrastructure such as bioswales, green areas, and planting strips for trees and shrubs. These not only provide shade and aesthetic value, but also alleviate the harmful effect of a parking lot on the environment, to some extent.
Large
cities
such
as
San
Antonio,
Francisco
and
Portland
Seattle,
San
have
established
now
maximum
parking
requirements to curb the oversupply of parking which also leads to less use of public transportation.
As
the
largest
use
of
land,
parking
lots are designed for the convenience of the customers, usually without much regard to aesthetics. These lots are sized to accommodate the need for peak usage which may be as occasional as a couple of weeks a year between Christmas and New Year, and around Thanksgiving.
Parking Requirement Actual Average Parking Ratio Typical Range Parking Demand Single family 2 spaces per 1.11 spaces per 1.5-2.5 homes dwelling unit dwelling unit 5 spaces per 3.97 per 1000 Shopping center 4.0-6.5 1000 ft2 GFA ft2GFA Convenience 3.3 spaces per 2.0-10.0 -store 1000 ft2 GFA 1 space per 1000 1.48 per 1000 Industrial 0.5-2.0 ft2 GFA ft2GFA Medical/ dental 5.7 spaces per 4.11 per 1000 4.5-10.0 office 1000 ft2 GFA ft2GFA GFA = Gross floor area of a building without storage or utility spaces. Land Use
The rest of the year, the parking lots remain criminally underutilized. There are 3 tiers of usage: 1.
Everyday usage;
2.
Weekend usage – 52 weekends/ 104
days a year; and 3.
Occasional usage – 35 -40 days of
holiday shopping.
By conducting a wind-shield survey of different parking lots around the city, it is easy to locate the chronically underutilized parking lots and apply a few basic questions to determine the retrofit-ability
of
the
site.
These
few questions also help to determine which of the three strategies, or which combination of the three strategies (to be discussed) would be appropriate for the site. The questions to ask would be: 1.
What is the parking ratio on the
site? 2.
How much of the parking lot is in
use, on average? 3.
What are the dimensions of the
parking spaces and drive aisles and can these be reduced? 4. Does compact
cars
the as
parking a
incorporate
percentage
of
the
total cars. 5.
What are the uses on site?
6.
Are there any complementary uses
that can share parking?
The next step would be to establish the strategies: STRATEGY 1 [S1]. EVALUATE THE PARKING RATIOS Calculate the area of land available to be retrofitted by calculating the number of cars that the lot can accommodate at present, and the new number it needs to accommodate based on realistic/reduced parking ratios adequate for general needs. (Strom, 2004, p. 154) A sample of the calculations using a hypothetical generic parking lot. Existing ratio for a retail building of 60,000sf @ 5 spaces/1000sf = 300 parking spaces [18’* 9’ = 162’] Area required to accommodate 300 parking spaces = Number of spaces * parking ratio (5/1000 = building SF ) Or Building Square Footage/parking ratio (1000*x) Parking lot area Parking area – cars = 162*300 Parking aisles 24’*414’ [length of aisle] * 6 [# of aisles] = 60,000sf + major circulations = approximately 1500 linear feet*30*2 = 90,000sf Parking lot = 150,000sf for a 60,000sf building -> 70-75% of total site Therefore, Parking is approximately 2.5 times the building area @ parking ratio of 3/1000sf for a building of 60,000sf = 180 90,000 – 54,000 SF (required for the reduced ratio) = 36,000sf of outright regreenable area By these calculations the percentage reduction in parking spaces comes out to be 40% as an optimum solution, but even if we implement about 30-35% realistically, the difference it makes to the environment with respect to the reduced ecological footprint, is pretty significant when we add up the incremental changes that can be made to parking lots all over.
TYPICAL SIZES OF BIG-BOX RETAIL
STRATEGY 2 [S2] – REDUCED PARKING DIMENSIONS By marginally reducing the dimensions of each space provided for parking, there is a significant improvement in the efficiency of land use. This strategy applied in conjunction with strategies 1 and 3 will further reduce the area of land paved for parking. Some parking lots have larger parking spaces than others. For example, Big box store Costco, has a policy for having generous parking spaces of dimensions 10’*20’. Some older developments also use these dimensions. This is a waste of space and the area can be used more efficiently if these wasteful practices are retrofitted to include more green spaces. The Maximum space needed for any car is 9’*18’ ( creating a reduction in paved area by 20%), and a certain percentage (10 – 15%) of those spaces should be for compact cars with a dimensions of 8’*16’, further shrinking the size of the area covered by actual parking. The average space that needed to accommodate a car, which may or may not be paved (gravel parking lots have proved to have a lighter imprint on the ecology), is 8.5’*16’ with a 2’ overhang onto a green space. At the same time, drive aisles at 24’ are also deemed too generous by some studies. These standard practices we’ve established over the years convey over-indulgence and a belief that space for developement is unlimited. We understand this is no longer the case and some of the practices we’ve been taking for granted need careful scrutiny and revision. A 22’ drive aisle is perfectly adequate and will promote speed control in parking lots, and more careful drivers as well. (Strom, 2004, p. 154)
TYPICAL DIMENSIONS OF PARKING SPACES
Strategy 3 [S3] – Calculate parking by actual usage and allow for Shared Spaces for complimentary uses.
Reduce available parking to accommodate average usage of the lot instead of catering to peak usage. Shared parking should be established for companion uses to reduce the load of parking on the land. (CRCOG, 2002, pp. CH-8) Sharing parking spaces is a strategy used more and more in denser areas. Which is not to say that it isn’t something we should employ in places where land is abundant as a way of conserving resources. This strategy depends on the tenants in the development. Some zoning ordinances allow and/or require the sum of parking for complementary uses to be equal to the requirement for one retailer. (Childs, 1999, p. 209) Example of uses would be an office park (with use during daytime) and restaurants (use during evening or on weekends when office use is low to none), or a pharmacy and a grocery store where you would park in one spot and walk to multiple uses within the shopping center. Shared spaces does not reduce the number of parking spaces available to the retailer, in essence reduces the total number of parking spaces, and hence lower total paved area. This is more efficient use of area for parking usage. Another advantage to incentivize shared spaces is by highlighting the fact that by planning for complementary, correlated uses next to each other, these uses generate more business for other uses, boosting sales for all by increased activity. By sharing parking, it is also a cost benefit to have to pay for less land per tenant.
Case study areas for implementation of greening parking lots: 1.
Sage Hill Village, Briarcliff Road and Clifton Road, Atlanta GA
2.
North East Plaza, Buford Highway, Atlanta GA
3.
North Lake Mall, Henderson Mill Road, Atlanta GA
SAGE HILL VILLAGE BRIARCLIFF RD ATLANTA, GA
NORTH EAST PLAZA SHOPPING CENTER BUFORD HIGHWAY ATLANTA, GA
NORTH LAKE MALL HENDERSON MILL RD ATLANTA, GA
Since parking is calculated based on what the marketing analysis from a major retailer or a big box tenant demands, these numbers are generally generous to erring on the side of caution. The tenant, the developer, the designer and often the municipalities have conflicting interests in which numbers are used and it is usually those who are desperate who compromise on the outcome. For the architect, it is usually a balancing act. The oversupply of parking is a common problem today, and plagues all three sites analyzed. It stems from 3 issues. First, from out dated data for parking requirements have not been revised in the last two decades. These are still being used to garner more and more parking spaces even though the recommendations by people who have conducted surveys recently show that the demand for parking spaces has decreased due to increased density and TODs. Second, when parking ratios are established, use is not a major factor and occupancy rates differ than those estimated. For example, for an office building, space per employee has increased but parking per square footage remains the same. If less people are occupying the same amount of space, then the parking provided should be less per square footage. Third, buildings change uses from time to time, but parking numbers don’t change. Parking allowance should be user-specific to be efficient. Fourth, another aspect of the high parking numbers per square footage of building area, is that it is based on isolated single-function suburban development not taking into account the socio-economic factors or the context. (Childs, 1999, p. 203)
Case Study 1. Sage Hill Village The Sage Hill parking lot with the grocery store on Briarcliff Road is the first case study and is an example of the first issue. It is underutilized not because the shopping center is failing, but because of the context. The location is in a dense walkable community serving mostly students with access to public transport. The planning of Sage Hill Village failed to take onto consideration that the site has Emory University just down the road and student housing all around the neighborhood. It’s ideal location between work and home for students with Emory shuttle services making stops right at the intersection along with a Marta stop near by, making the amount of parking provided redundant. The lot remains mostly empty a vast majority of the time, even when the stores themselves are bustling with activity. To compound the problem, the parking ratio implemented is also very high for the type of use it services. The land at a prime location like that could easily be put to better use.
S1
S3
S2
S4
Case Study 2, North East Plaza North East Plaza, the second case study, is a shopping center surrounded by neighborhoods of ethnic minority. The tenants reflect this ethos. There is an ethnic grocery store adjoining an ethnic restaurant and a Dollar store in the center portion, along with a veterinarian’s clinic and an animal hospital on one end with a pool hall and a bowling alley on the other. However, applying standard parking ratios has created a sea of parking not needed or required, as most of the people just walk over from the surrounding areas and are from a low to middle income background. They frequent the ethnic restaurant, grocery store and dollar stores all in the same trip. The possibility of parking in one spot and walking to different destinations calls for a shared parking solution. By consolidating parking and incorporating the leftover space into a park in the center, could potentially generate more activity for the tenants and create a sense of community in an otherwise dismally empty parking lot.
S1
S2
S3
S4
Case Study 3, North Lake Mall The third case study, the Northlake Mall, is a dying mall. The mall tenants cater to middle or low income socio-economic groups. With the economic crisis, people have less disposable income to frequent malls and spend, making this huge facility and its parking unfeasible. To add to the problems, the parking ratio for this mall was unrealistically high to begin with.
S1
S3
S2
S4
GOLD MEDAL PARK, MINNEAPOLIS - used to be an underutilized parking lot
BETTER PRACTICES FOR DESIGNING PARKING LOTS
Even with the most minimum retrofits there is a significant amount of area that can be given over to the greening of the site. By turning a parking lot into a more sustainable parking lot we reduce its considerable ecological footprint. Parking lots, can be phased into being green. Greening or regreening does not mean immediately cutting out the excess parking and growing grass on it. Of course, some lots can be turned to different uses such as playgrounds or parks, but some of the area can be saved and put into greening of the parking lots themselves by introducing green practices (plenty of trees, shrubs, and other vegetation between parking spaces themselves. There are many different and better uses for space that is meant to be occupied by cars, but is not and is not used for anything else either. The fundamental question is why green parking lots? This can also be read a little differently, why smaller parking lots?
CISCO SYSTEMS – SAN JOSE CA
GOOGLEPLEX – MOUNTAIN VIEW
Aesthetic Reason
CA
The obvious reason would be aesthetics. Parking lot is like a desert with no beauty in its desertedness. Visually banal, when located surrounding even the most interesting building, it renders it acontextual, like isolated islands unable to connect to anything around it. Even the most basic buildings designed sensitively can have the most profound effect. The two images show the building for Cisco in San Jose, CA and the Google campus in Mountain View, CA with vastly different ways of dealing with parking. There is a juxtaposition in their design strategies with regard to parking, show with clarity what is possible if we only strive for it.
Environmental Reasons A major part of the environmental impact of parking lots includes: The Heat Island effect Pavements with higher SRI (solar reflective index) or high albedo, reflect sunlight, and absorb and emit less heat than standard pavements, especially compared to asphalt. Therefore, it stands to reason that parking lots have a direct effect on microclimates and city climates.
The vast expanse of dark surfaces of the asphalt increases local
temperature to the extent that the temperature difference between urban and rural areas can be 2 to 8 degrees F because of it. (Childs, 1999, p. 196) Strategies to counter the Heat Island effect: •
Plant canopy trees at close intervals (about every 4 to 6 parking spaces. This
can help the temperature drop by about 9 degrees F in the immediate vicinity of trees. •
Use light colored paving materials to help reduce the temperature by an average
of 5 degrees F in a city during the peak summer season.
Stormwater Runoff. This is a two part issue: •
The quantity of the stormwater runoff
•
The quality of stormwater runoff
INTENSITY OF RAINFALL IN GEORGIA THE ANNUAL AVERAGE PRECIPITATION AT ATLANTA IS 52.22 INCHES. RAINFALL IN IS FAIRLY EVENLY DISTRIBUTED THROUGHOUT THE YEAR. THE WETTEST MONTH OF THE YEAR IS MARCH WITH AN AVG. RAINFALL OF 5.80 INCHES
The water, during a rainfall, travels quickly over the smooth surface of the parking lot to the nearest drain, taking all the pollutants with it if there is no friction (rough surface like grass/ gravel etc) to slow the flow. The impervious surface does not allow any of the water to seep into the ground which would allow it to slow down and filter slowly to the water table. At a point in time, this was the most desirable outcome. The site strategy was to get the water as quickly as possible into the nearest drain. We have learned during recent studies that aside from causing flash floods, these drains have a severely damaging effect on the ecology of creeks, rivers and lakes. The quick routing of the water away from the site also causes the depletion of the water table. The hydrologic cycle teaches us that before the water can go back into lakes and streams, it needs to be absorbed by the ground in order to replenish the earth and also to filter out pollutants that are harmful to marine life. Strategies to mitigate the effects of Stormwater runoff include: •
Minimize paved area - it will reduce the quantity of stormwater runoff;
•
Plant trees and other vegetation generously within the parking lot and also
around it. Planting beds receive water and slowly diffuse into the ground and tree canopy allows for both detention and evaporation of rainfall. •
Introduce systems like rain gardens and bioswales within the parking lot. Swales
and rain gardens slow down the water and allow the ground to filter and soak it up, minimizing pollution of streams and rivers.
Social/Civic Reasons Converting part of a parking lot into green
spaces
may
help
reduce
the
ecological footprint, but that is not the
only
solution.
The
appropriated
space through the analysis may be used to benefit the community. Even with the paving, some solutions can be adopted to minimize the harm or the uselessness of an under-used parking lot. Strategies for the use of appropriated space: Some suggestions would be to transform portions of parking lots into playing fields for the community, accommodating parking
lot
sports
like
basketball,
skate parks, parking lot hockey, or even protected
tot
lots
and
playgrounds.
This can be pitched to developers as a
marketing
or
good
business
model
tool to generate goodwill within the community it serves. People coming to get groceries will bring their children to
the
play
areas
and
spend
quality
time building relationships within the neighborhood.
People
coming
to
spend
time at a playground in the vicinity of a store or a coffee shop are more likely to drop in for some form of purchase or another. It is mutually beneficial. In this way, we introduce a different way of operating
and thinking, rather
than the same old methods that create problems. We can hope to bring about change, one solution at a time. Change is incremental.
ALTERNATE USES FOR PARKING LOTS
Light Imprint is a study in integrated sustainability and community design. Duany Plater-Zyberk & Company (DPZ) has compiled tables with materials and their properties with their application, cost, maintenance, slope, soil, and climate to deal with paving, channeling, storing and filtering situations on the site. These are arranged by transects and are a great tool to gauge and strategize solutions that will have a lighter impact on the ecology. These tables are used in conjunction with the strategies of reducing the area allotted to parking spaces may give us a way to retrofit the problem called parking lots that we have been creating over the last 50 years.
R
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T1
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RURAL pRESERvE
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T2
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NEIGHBORHOOD EDGE
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T3
T
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A
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NEIGHBORHOOD GENERAL
S
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T4
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TOwN CENTER
T5
NEIGHBORHOOD CENTER
U
T6
R
B
A
URBAN CORE
PAVING COMPACTED EARTH WOOD PLANKS
- Low - $
- High - $$$
PLASTIC MESH/GEOMAT CRUSHED STONE/SHELL
- Low - $
- Medium - $
CAST/PRESSED CONCRETE PAVER BLOCK - Low - $$
GRASSED CELLULAR PLASTIC
- Medium - $$$
GRASSED CELLULAR CONCRETE
- Medium - $$$
PERVIOUS ASPHALT
- Low - $$
ASPHALT CONCRETE
- Low - $ - Low - $$
PERVIOUS CONCRETE STAMPED ASPHALT
- Low - $$
- Low - $$$
STAMPED CONCRETE
- Low - $$$
PEA GRAVEL
- Medium - $
STONE/MASONRY PAVING BLOCKS
- Low - $$$
WOOD PAVING BLOCKS ON CONCRETE - Low - $$$
ASPHALT PAVING BLOCKS
CHANNELING NATURAL CREEK -
Low - $
TERRACING -
Medium - $$
VEGETATIVE SWALE DRAINAGE DITCH -
Low - $
Low - $
STONE/RIP RAP CHANNEL -
Low - $$
VEGETATIVE STONE SWALE -
Low - $
- Medium - $$
N
SCULPTED WATERCOURSE CONCRETE TROUGH ARCHIMEDIAN SCREW
- Medium - $$$ Low - $$
- Low - $$$
STORAGE IRRIGATION POND
- Low - $
RETENTION BASIN W/ SLOPING BANK - Low - $$
RETENTION BASIN WITH FENCE
- Low - $$
RETENTION HOLLOW DETENTION POND
- Medium - $ - Low - $
VEGETATIVE PURIFICATION BED
FLOWING PARK
- Medium - $$
- Medium - $$
RETENTION POND
- Medium - $$
LANDSCAPED TREE WELL
- Low - $$
POOL/FOUNTAIN
- High - $$$
UNDERGROUND VAULT - PRECAST CONCRETE
- Low - $$
UNDERGROUND VAULT - CAST-IN-PLACE CONCRETE UNDERGROUND VAULT - PLASTIC
- Low - $$
- Low - $$
GRATED TREE WELL
- Low - $$
UNDRGRD. VAULT - CORRUGATED METAL - Low - $$$
PAVED BASIN
- Medium - $$$
FILTRATION WETLAND/SWAMP FILTRATION PONDS
Low - $
- Low - $
SHALLOW MARSH
- Medium - $$$
SURFACE LANDSCAPE
- Low - $
NATURAL VEGETATION
CONSTRUCTED WETLAND BIO-RETENTION SWALE
- Low - $
- Medium - $$$ - Medium - $$
PURIFICATION BIOTOPE
- High - $$$
GREEN FINGER ROOF GARDEN RAIN GARDEN
- Low - $
- Medium - $$$
- Medium - $$
DETENTION POND
- Low - $
GRASSED CELLULAR PLASTIC
- Medium - $$$
GRASSED CELLULAR CONCRETE -
Medium - $$$
WATERSCAPES
- High - $$$
*note: each cell is laid out as follows: TOOL NAME - Maintenance - Cost ($-$$$) ©2008 Duany Plater-Zyberk & Company
A common argument we hear against reduction of parking spaces or giving them over to green space is that there may be loss of customers because of inconvenience that might be caused by fewer available parking spaces. A a counter argument, however, can be made that consumerism, like many aspects of life, is learned behavior. Studies show that, for example, a grocery store has most customers on weekends between the hours of 10 am and noon, and parking is not so easily available, the person will remember to either visit earlier or later in the day or even change days when they learn that a different schedule might be better suited, and will change their shopping habits accordingly. A little inconvenience isn’t the end of the world. The attitude towards development for the past 50 years has been stilted towards privileging the consumer. This breeds a sense of entitlement. We are now seeing the results of that mindset, where everything is oversized and underpriced to accommodate every wish of the consumer at the expense of many factors, such as, sustainability and economy of means. This kind of lifestyle
cannot be sustained with regard to the environmental and public health impacts that can be felt all over due to our own negligent and self-serving behaviors. With the changes we are making today towards understanding the consequences of our actions with regard to development, the step is towards a more green and sustainable environment becomes the goal of our generation. One issue of serious focus should be different options on how to deal with the monotonous greyfields of parking, and to be able to turn it into a more sustainable entity by reducing the ecological footprint.
Bibliography Arizona State. (n.d.). Arizona State. Retrieved March 27, 2011, from azsustainability.com: http://azsustainability.com/2008/09/21/pervious-concrete-reducing-the-heat-island-effect-oneparking-lot-at-a-time/ Childs, M. (1999). Parking Spaces. New York: McGraw Hill. City of Sacramento. (n.d.). Sacramento City Codes. Retrieved 04 09, 2011, from Development Standards / Parking Regulations: http://qcode.us/codes/sacramento/view.php?topic=17-iii-17_64-17_64_020 CRCOG. (2002, July). www.crcog.org. Retrieved March 02, 2011, from Tools for Towns Chapter 8: http://www.crcog.org/publications/CommDevDocs/TCSP/Ch08_Technical_Part1_Parking.pdf Frielich, L. &. (2002, July 22). Town of Chapel Hill, NC. Retrieved March 10, 2011, from Parking Ratios:
http://townhall.townofchapelhill.org/planning/planning_development/pdfs/Final%20
Parking%20Paper%208-12-02.pdf MAPC. (n.d.). MAPC. Retrieved 03 27, 2011, from http://www.mapc.org/smart-growth/land-use Seamans, G. S. (2009, October 22). localecology.org. Retrieved March 15, 2011, from Local Ecologist: http://localecologist.blogspot.com/2009/10/cooling-parking-lots-trees-face.html Strom, S. (2004). Site Engineering for Landscape Architects. New Jersey: John Wiley & Sons, Inc. Thomas E Low, D. (2008). Light Imprint Handbook. Charlotte: New Urban Press. USA.Gov. (n.d.). National Weather Service. Retrieved Feb 24, 2011, from Advanced Hydrologic Prediction Service: http://water.weather.gov/precip/