Inner Loop Urbanism: Phoenix Edition

INNER LOOP URBANISM: PHOENIX EDITION

Spring 2023

Alan M. Berger

Rafi Segal

INNER LOOP URBANISM: PHOENIX EDITION

Spring 2023

Alan M. Berger

Rafi Segal

Studio Instructors

Alan M. Berger

Rafi Segal

Teaching Assistant

Sarine Vosgueritchian

Chenhao Zhu

Students

Maria Castillo

Wladyslawa Kijewska (GSD)

Sarah Lohmar

Elyse Oliver

Hazel O’Neil

Mikaela Strech

Workshop: An Analytical Framework to Read the City

Chenhao Zhu

Alan M. Berger

Lecture: Fundamentals of Heat in the Built Environment

Edu Gascón

Nada Tarkhan

Sarah Mokhtar

Final Review Critics

Kenoff Jeffrey

Mohamad Nahleh

Lizzie Yarina

External Collaborators

City of Phoenix, Office of Heat Response and Mitigation

Arizona State University, Landscape Architecture

Department

Cover Image 1: Bird’s-eye view of Phoenix central city village;

Source: New York Times

Cover Image 2: Bird’s-eye view of Phoenix;

Source: Matt Mawson/Getty Images

Temperatures in Phoenix are becoming deadly

Source: Ralph Freso/Getty Images

“Cooler” Living in America’s Hottest City

In the US, population continues to relocate to sunbelt states and Phoenix is one of the fastest growing metros in the country. This influx of new people during recent extreme droughts has pushed water resources and heat impacts to their limits. Phoenix is now the hottest city in the US with months of average temperatures exceeding 100 degrees Fahrenheit. For those who still live in the urban core, the lack of shaded landscape and abundance of heat absorptive building materials has produced dangerous living conditions. Our studio will examine the inner loop core neighborhoods of Phoenix to re-imagine how new (theoretical and practical) landscapes, infrastructures and housing typologies can be combined for “a cooler,” safer, and healthier living environment in the future and how these solutions can be applied to other city cores as the world heats up.

This joint urban studio presents a new pedagogical model that brings together planners (DUSP students) and designers (ARCH) around a shared urban challenge. The studio will be offered as 2 study modules. The first module, which takes place over 7 weeks and includes a spring break trip, will focus on research - ‘reading’ the metro landscape through analytical representation and mapping, and then further programming and writing a design brief which will inform design projects goals and parameters. The second module, which takes place over the following 6-7 weeks, will advance the learnings and briefs created in the first module to work on the design projects.

The Inner Loop: Phoenix Central City Village

What we term Phoenix’s “inner loop” will be the studio site. It is a 9.3 square miles rectangle site enclosed by I-10 and I-17, located inside the central city village, one of fifteen villages in Phoenix, AZ. The central city village had 63020 population (20440 households) in 2015, which is estimated to grow to 104250 by 2030. More than 50% of the central city village population (roughly 35000) live in 26 neighborhoods/districts of the inner loop.

The 26 neighborhoods/districts of the inner loop can be further categorized into three types: 1) underserved low-income residential neighborhoods, including Central City South (CCS), Garfield, Eastlake Park, Montezuma Heights, East Van Buren, residential inside Capitol Mall district; 2) mixeduse residential neighborhoods, including Roosevelt, Evans Churchill, F.Q.Story, Grand, Booker T. Washington; and 3) office, commercial and industrial district, including Downtown Core (traditional office and commercial), Warehouse (startup, industrial business, creative business, co-work space), Capitol Mall (governmental office), and Sky Harbor Center (airport industry park).

Geographic location of the Inner Loop area

Source: Hazel O’Neil

Bird’s-eye view of the site (Phoenix central city village)

Source: New York Times

Layers of site analysis

Source: Hazel O’Neil

The Site Analysis: Reading the Metro Landscape

Module I Exercise 1: Research and Analytical Mapping of Phoenix’s Inner Loop

In this module, interdisciplinary teams are assigned one of the topics listed below to map, analyze, and reveal the current state of Infrastructure, Typological, Socio-Demographic, Environment and Landscape conditions within Phoenix’s Inner Loop. This exercise is intended to expose students to both the general issues and trends facing our site’s neighborhoods today, as well as to ground later design proposals in quantitative data and mapping.

The Infrastructural: Transportation networks, transit lines and stops, rail lines, networks of particular land use types (such as warehouse districts, etc.), water and drainage lines or systems, hierarchy of roads, energy, green infrastructures, shading and cooling projects underway, neighborhoods scale changes taking place (such as gentrification or large change over time), etc.

The Formal-Typological: Typologies (housing, office, retail, etc.), real-estate values, new construction permits and applications, number of bedrooms, big-box development, malls, storage and logistics, foreclosure numbers, architectural styles and typical floor plans, elevations, materials, building / development process over time, etc.

The Social-Demographic: Location of Administrative / Jurisdictional Boundaries, Population Densities, Historical Redlining, Developments and Land Use Change projections, Real Estate Values, FEMA Flood Insurance Maps, Age groups shifts and trends, Aging and millennial concentrations, household incomes, race and ethnicity, immigration, health-indices, per capita measurements, etc.

The Environmental and Landscape: Heat and Shade measurements, percentages of previous / impervious surfaces, air pollution, soil quality, tree plantings and other landscape surfaces, park distribution, trails, topography, watersheds, prevailing winds, atmospherics, air pollution, noise pollution, weather patterns, etc.

Many insights about the condition of our site and its various networks and infrastructures, and how they came to be over time, emerged from this exercise, which laid the groundwork for design brief formulation and design development.

The Site Analysis: Key Neighborhoods

The Central City South (CCS) usually refers to eight or more neighborhoods at the southwest corner of the central city village, or more generally, 13 neighborhoods with a roughly 10,000 population located on the south side of Union Pacific Railroads.2 Historically, 10 out of these 13 neighborhoods were inside the historical redlining area. According to the U.S. census bureau, by 2018 more than 70% of the population from these communities are under the poverty line, while more than 85% of the population are not white non-Hispanic.2 The average tree canopy of these neighborhoods is around 3%, which is significantly lower than the current average tree canopy coverage of Phoenix (12.4%) and even further away from the 2030 tree canopy target of the city (25%). Due to the lack of tree canopy and the number of paved surfaces, the CCS tends to be 1.85.4 degrees hotter than surrounding areas.

The Eastlake and Garfield neighborhoods are located in the northeast part of the central city village with a population of roughly 8000.2 They have very similar but slightly better conditions when compared to the CCS. A sustainable green systems strategy plan was enacted to cultivate equity, engagement, economic development, and design excellence for these two neighborhoods through transit-oriented development. It aims to increase permeable surfaces from 44% to 70.3%, reduce the percentage of surfaces with a temperature above 130 F from 31.4% to <1%, and meet the citywide tree coverage target (25%) by 2040.

The Roosevelt, Evans Churchill, F.Q.Story, and Grand Neighborhoods are located on the north side of the downtown core with a population of roughly 8000.2 These areas are becoming increasingly popular and desirable. Increasing development and improvements throughout downtown Phoenix provide a perfect clientele and the support uses on which a district such as Roosevelt Row can develop and ultimately thrive. Their challenges are usually caused by the disparity between increasing new developments, outmoded infrastructures (parking/ curb/pedestrian connectivity), and lack of amenities.

Neighborhood map

Source: Chenhao Zhu

The Site Analysis: History + Demographics

The Inner Loop Area was first inhabited by the Hohokam people between AD 700-1400. Pueblo Grande, an important Hohokam archaeological site, is located roughly 3.5 miles to the east of the Inner Loop’s eastern border. The Hohokam were welladapted to the desert climate and lived along the Salt River. Before the creation of modern-day dams in the 1930s, the Salt River ran year-round and provided a lush, vegetated riparian habitat from which the Hohokam lived off. They created an expansive system of irrigation canals (copies of which are used to move water around Phoenix today), hunted fish, mollusks, and waterbirds; wove fibers from cat-tails; and found shade and fuel from willow and cottonwood trees along the riverbanks. The Hohokam people abandoned the Phoenix area presumably due to drought before white settlers arrived and laid claim to the modern city, so-called Phoenix because it arose from the ashes of a previous civilization.

For the last decade, population growth in Phoenix has focused in and around its downtown core, with the downtown area growing on average 5.8% between 2011-2019. Roughly 134,000 regional residents enter this “Inner Loop” each day for work. Conversely, approximately 16,000 Inner Loop residents exit their neighborhoods as part of their commute.

Our analysis reveals that specific areas within the Phoenix central city village exhibit a heightened vulnerability compared to other regions, primarily due to a higher concentration of aging and impoverished populations. Significantly, these vulnerable areas coincide with the historically red-lined districts in Phoenix.

Aging + Poverty (2020)

Top left: Population map; Bottom left: Aging and impoverished population map; Right: Source: Top/Bottom Left: made by Chenhao Zhu based on ASC 2020 1-year estimates

Right: Historical relining map

Right: made available by the University of Richmond

The Site Analysis: Heat

Phoenix is a BWh subtropical desert KöppenGeiger Climate Zone. It receives substantial solar radiation throughout the day, and there is not much moisture in the atmosphere to hold the temperature steady, therefore the region experiences dramatic diurnal swings over the course of the day. Temperatures are pleasant in the shoulder seasons, and summer nights and early mornings. However, thermal stress is extremely high between the hours of 8AM and 8PM during the summer months

Phoenix is America’s hottest city. In 2022 alone, there were 378 heat-related deaths in Maricopa County. Most of these deaths occurred outdoors (89%), suggesting a lack of cooling outdoor infrastructure, and most of the victims were older adults (62%), indicating that cooling infrastructure is most critical in areas where there are higher concentrations of vulnerable older residents. Phoenix has made efforts to address the public health impacts of heat by offering and advertising cooling centers where residents can access air conditioning and water on hot days. The City also recently created a designated Office of Heat Response and Mitigation. The office has set a number of goals to mitigate heat through interventions in the built environment, including planting trees along streetscapes and within parks and replacing dark pavement and roofs with more reflective materials.

According to a growing body of literature and the City of Phoenix’s Climate Action Plan, one of the most efficient and high impact solution to provide cooling and other quality of life improvements is to invest in Phoenix’s urban forest. Trees provide cooling effects not only through shade, but also through a process called evapotranspiration, through which they add moisture to the air. Trees can improve air quality, reduce stormwater runoff, increase mental and physical health by improving the quality of outdoor spaces, and raise property values. Per the City’s Tree and Shade Master Plan, the State of Arizona sees a 2.23 to 1 return on investment for every tree planted. Notably, the Inner Loop has some of the lowest tree canopy coverage in the City of Phoenix, ranging from just one to nine percent. Canopy coverage is much lower in the southern half of the Loop than the north, where the Grand Arts District, Capitol Mall, and Garfield and Roosevelt neighborhoods are.

Heat island distribution and tree canopy coverage map Source: Hazel O’Neil, Mikaela Strech

The Site Analysis: Landscape

The Inner Loop is almost entirely urbanized, and experiences some of the highest concentrations of urban heat island effect (places where the ground temperature is hotter than average typically due to dark-colored paving that absorbs and emits radiant heat) in the Phoenix region. There are a handful of parks throughout the Loop that have cooler temperatures and are often co-located with indoor cooling centers. Parks are critical cooling infrastructure because they are free public places where people without air conditioning can go during hot days to experience reduced temperatures. The parks create micro-climates of reduced heat and better air quality; the quality of parks (determined by size, landscaping, and tree canopy coverage) varies throughout the Loop in regard to usage, amenities, and cooling benefits. Cooler parks extend their benefits to the surrounding neighborhood as well.

Presently, most parks within the Loop are not wellconnected to their surrounding neighborhoods by foot. Most parks are designed for people to drive to them, with large, paved parking lots that produce urban heat island effect. Many surrounding streetscapes that nearby neighbors would use to walk to the parks do not have shaded features such as trees, canvas covers, or tall buildings. The mapping shows parks, tree canopy coverage, and the street network in the Inner Loop, highlighting areas where cooled streetscapes are most needed to expand pedestrian access to parks. Planting trees and providing built shade along these corridors would help the city meet its Climate Action Plan Goal H-1, “Create a network of 100 cool corridors in vulnerable communities by 2030 to facilitate movement of people walking, biking and using transit, particularly within and connecting to Transit Oriented Development Districts, Village Cores, and Centers.”

Under-shaded street map

Source: Hazel O’Neil

The Site Analysis: Drosscape*

The Loop is also home to many “drosscapes,” or underutilized or vacant land produced by the city’s horizontal expansion. The largest of these areas is the railroad right of way that bisects the Loop from east to west. When the highways were built, the rail yard lost its significance as a regional transportation and economic asset. Although it is still used for freight shipping today, its appearance is blighted. Throughout the Loop, including along the rail yard, there are parcels large and small of vacant or underutilized land, or waste, that have resulted from Phoenix’s horizontal expansion and changing economy. In the last decade, a Warehouse District has begun to emerge along the rail yard, which makes use of some of this existing building stock to provide new commercial and entertainment space. Some of these parcels are Brown field sites, and have been listed by the US Environmental Protection Agency as having toxic material underground leaking storage tanks, or USTs. Given federal tax incentives that help finance the remediation of Brown field sites, these areas provide opportunities for phased redevelopment without displacement.

* Berger, Alan. Drosscape: wasting land urban America. Princeton Architectural Press, 2007.

Drosscape is an urban design framework that looks at urbanized regions as the waste product of defunct economic and industrial processes. The concept was realized by Alan Berger, Professor of Landscape and Urban Design at MIT, and is part of a new vocabulary and aesthetic that could be useful for the redesign and adaptive reuse of ‘waste landscapes’ within urbanized regions.

Drosscapes + flood risk map

Source: Hazel O’Neil

The Site Analysis: Building Typology + Housing

Although Phoenix’s population grew by approximately 820,000 people between 2000 and 2018, housing production was significantly slower, particularly following the 2008 mortgage crisis. The City’s 2018 Housing Plan identifies this housing shortage as cause for rising housing costs. Over one third of the City’s population is housing burdened (pays more than one third of their income on housing), and low-income households are most impacted as there are extremely limited affordable options available to them. Prices have continued to rise rapidly during the COVID-19 pandemic, and the fear of gentrification feels real to longtime Central City residents, particularly those who have been impacted by disinvestment, urban renewal, and gentrification in the past. As affordable housing accessibility dwindles, Phoenix has seen a subsequent rise in homelessness in the Inner Loop, where multiple service providers and shelters are concentrated. Homelessness is a complex issue and these residents are particularly vulnerable to extreme heat. Until homelessness can be solved, public realm designs should plan for comfortable coexistence between housed and unhoused residents. Strategies include zoned lighting, private pockets, programming that connects homeless. Users with social work services and/or fosters empathy between housed and unhoused park goers, and basic amenities like public restrooms, water fountains, and benches.

Building typology map

Source: Sarah Lohmar, Wladyslawa Kijewska

housing typology

single family - horizontal grid

single family - vertical grid

single family - row, attached mid rise - 3-4 floors

mid rise - 5-10 floors

housing towers other

The Site Analysis: Housing

The City’s 2018 Housing Plan estimates that 163,067 new units are needed, of which 99,581 are to be designated affordable or subsidized. The City calls for new developments to be designed on vacant land in a sustainable fashion, meaning a variety of multifamily housing types including townhomes, duplexes, triplexes, condominiums, and courtyard. Units should be affordable by design to a variety of potential residents, including maintenance workers, families, young couples, single parents, and retirees living on a fixed income. Members of the Greater Phoenix Urban League suggested that community members in the South Central area, Phoenix’s historically Black neighborhood (now predominantly Latinx) that has seen both disinvestment in the 1960s-80s and rising costs in recent years, suggested that the community is interested in smaller infill development such a granny flats or additional dwelling units (ADUs) that stabilize multi-generational families and builds wealth for low-income home-owners.

Percentage of cost burdened households map

Source: U.S. Department of Housing and Urban Development

1. Housing needs assessment; Source: City of Phoenix, “Housing Phoenix Plan,” 2018. Housing Needs Assessment, p. 8. Site: https://www.phoenix.gov/housing/plan

https://www.rentcafe.com/average-rent-market-trends/ us/az/phoenix/

2. A 2022 rank of rental in various neighborhood of Phoenix; Source:

3. A photo of Phoenix residents in the central city south area; Source: Urban Design Studio 11.S942

The Site Analysis: Mobility + Pollutions

Though a hub for economic flow, the 9.3 square mile Inner Loop remains difficult to access for elderly and low-income residents due to the downtown’s car-centric design. The Inner Loop is surrounded by two interstate highway systems and includes a road network of primarily bidirectional arterial lanes. This presents a challenging landscape to traverse for residents who do not own vehicles.

Furthermore, the American Lung Association classified Maricopa County—inclusive of Phoenix and the surrounding cities of Chandler, Glendale, Mesa, Scottsdale, and Tempe—within its lowest ranking for environmental quality in part due to the dangerous confluence of road noise, air pollutants, and heat at the Inner Loop’s interstate entry and exit points toward the center of downtown. Pollution places those with respiratory challenges, such as the elderly, at greater risk. Rice University reports that poverty and the proportion of older and younger residents are growing fastest in Sun Belt Cities and Arizona State University found evidence that Hispanic and poor communities in Phoenix experience more extreme heat compared to their White and wealthy counterparts.

The Inner Loop has wide public transportation coverage, which should reduce traffic volume and improve air quality. However, the service has experienced limited ridership, with roughly 75% of commuters traveling to work by car historically and currently. Stations with high ridership (i.e., bus stops with greater than 71 riders per day are co-located with areas of high automobile traffic, exposing riders to higher noise and air pollution levels. The City of Phoenix thus seeks to reduce use of singleoccupancy vehicles to improve residents’ health and quality of life.

Regional air pollution map

Source: AZDOT

The Site Analysis: Mobility Challenges

Implementing new mobility solutions represents a unique challenge in Phoenix given the strategy’s departure from past transportation planning priorities. Barriers to consider during design are threefold:

Regional-scale transportation has been a priority: First, regional—rather than local or hyper-local— mobility has historically been a priority for Phoenix given the metropolitan area’s sprawl. A prime example of the regional focus of public investment in transportation is Valley Metro’s light rail expansion. The original light rail system consisted of one, 20mile line and has since been expanded to a 28-mile length. Three additional expansions are planned through 2030 to extend the light rail to the south and west of the Inner Loop. In contrast, the bus system has not shifted its network in the last five years, despite population growth in the area and new development.

Transit stations not considered destinations:

Second, investment in transit stations has been relatively nonexistent given the predominance of private vehicle ownership. Over 60% of Inner Loop households own at least one vehicle, resulting in a lack of public attention and demand for quality transit stations. Yet to increase public transportation ridership, it is important to think about the full ridership experience, both at the station and within the vehicle. The public transit system must become a set of destinations in and of itself; a first for Phoenix.

Cost of transportation:

Finally, a shift from a car-centric cityscape to one that prioritizes alternative modes of transportation requires significant economic behavior change. Phoenix residents spend on average 20.5% of their income on transportation related expenses, which is three percentage points higher than the next comparable metro area. The sunk costs of car purchase and maintenance account for this disparity and may dissuade individuals from selecting an alternative mode despite daily cost savings. It may also make traditional mechanisms for financing transit—i.e., sales tax increases—unpopular. An alternative approach must be shown to be a better value for residents, whether through cost or time savings.

Traffic volume map

Source: Hazel O’Neil

The Site Analysis: Mobility Needs

The Valley Metro Regional Transportation Authority (Valley Metro) operates public transit throughout the Phoenix metropolitan area. Valley Metro services include regional bus and light rail systems, as well as on-demand para-transit and a local streetcar service in Tempe. Despite this wide coverage, ridership remains low due to challenges in efficiency and comfort.

Efficiency: First, many residential areas cannot access Valley Metro’s most reliable bus lines. These “frequent” routes have headways of 15 minutes or less, but only run along the central axes of downtown Phoenix, dividing the geography into roughly comparable quadrants, each with centers farther than a 5-minute.

Amenities and Comfort: Second, Valley Metro transit stops have few features that make waiting for public transportation bearable in extreme heat. Only 55% of bus stops have shelters that provide shade; only 9% within the light rail system. Valley Metro reports that ridership increases at stations with seating and shade, but to date, these features have not been implemented widely across the entire system.

Active Transportation and Micromobility: The Inner Loop includes roughly 30 miles of “quickbuild,” dedicated bike lanes. Private micromobility companies Spin and Lime operate their own networks within the Inner Loop, which allow residents to rent e-scooters, bicycles, and e-bikes for short trips charged by the minute. Though a useful alternative for those living in areas without access to public transit, equitable distribution and adequate safety measures for these vehicles have not been achieved. Eighty-eight percent of the Inner Loop’s dedicated bike lanes are located within a five-minute walk of a bus stop, providing an incentive for ridership in areas already well served by multiple transportation modes.

Transit infrastructure map Source: Maria Castillo, Elyse Oliver

The cover image of the report titled: Economic Assessment of Heat in the Phoenix Metro Area

Source: The Nature Conservancy and AECOM

Precedent Research: Heat and Built Environment

In conjunction with the exercise - reading the metro landscape through research and analytical mapping, an extensive precedent research endeavor was undertaken to scrutinize, ongoing developments, prevailing planning documents, studies, and design guidelines pertaining to the central city area. Moreover, a lecture on the fundamental knowledge of heat and built environment was given by three PhD students from MIT building technology group. Additionally, several recently proposed heat mitigation plans were also studied. By various inputs, students acquired a methodical comprehension of the site and urban heat issues, enabling them to formulate pertinent design ideas and questions that would be further investigated during the site visit.

Precedent Research: Existing Development Plans, Action Plans, Research, Design Guidelines, and More

Students are tasked with engaging in an extensive review of diverse planning documents, which can be classified into four genres:

A. Master Plan:

1. Phoenix 2015 General Plan

2. Central City Village Character Plan

3. Phoenix 2018 Housing Plan

4. South Central TOD Community Plan

B. Environmental Plan & Studies:

1. Phoenix Climate Action Plan

2. Tree and Shade Master Plan

3. Economic Assessment of Heat in the Phoenix Metro Area

C. Transportation Plan & Design Guidelines:

1. Phoenix Transportation 2050

2. Comprehensive Bicycle Master Plan

3. Phoenix Comprehensive Downtown Transportation Study. (Wilson & Company, 2014)

4. Walkable Urban Code

D. Neighborhood Specific Plan & Design Guidelines:

1. Central City South General Plan

2. Central City South at a Glance

3. Nuestro Barrio Background Information and Community Issues

4. Downtown Urban Form Project

5. Roosevelt Row Design Guidelines

6. Story Neighborhood Conservation Plan

7. Reinvent Phoenix: Sustainable Green Systems Strategy for the District of Eastlake-Garfield

8. Garfield Redevelopment Plan

9. Capito Mall Redevelopment Plan

10. Eastlake Park Neighborhood Plan

A set of existing development plans, research, action plans, design guidelines, etc.

Source: The City of Phoenix, The Nature Conservancy/AECOM, Phoenix Revitalization

Precedent Research: Fundamentals of Heat in the Built Environment

A group of MIT PhD students, who held a course on urban heat related issues, were invited to offer a lecture to equip students with fundamental knowledge covers the following topics:

1. Introduction of urban heat

2.Decoding the impacts of urban heat on human and environment

3. Optimizing urban heat mitigation performance through spatial design elements

4. Advanced research and practices related to urban heat mitigation

Top: How environmental heat affect human; Source: Adapted by Edu Gascón, Nada Tarkhan, “CityComfort+: A Simulation-based Method for Predicting Mean Radiant Temperature

Bottom: Urban elements with strong impacts on the environmental heat; Source: Edu

Tarkhan, Sarah Mokhtar from: Fiala et al. (2011) “UTCI-Fiala Multi-node Model of Human Heat Transfer and Temperature Regulation” Huang et al. (2014) Temperature in Dense Urban Areas”

Gascón, Nada Tarkhan, Sarah Mokhtar

Precedent Research: Existing Heat Mitigation Plans

Two recently completed heat response and mitigation plans have been examined. One plan, titled “Turing the Heat,” was developed by the New York Urban Design Forum. It presents a comprehensive set of design guidelines aimed at tackling extreme heat challenges in densely populated urban areas. The other plan was conducted by the City of Boston and encompasses a detailed research on heat analysis and measurement. It also focuses on community engagement in developing a heat response plan and offers specific proposals for five neighborhoods in Boston. This comprehensive report provides a holistic approach to heat response and mitigation strategies.

Left: The cover of the report titled Turning the Heat; Source: Urban design forum

Right: The cover of the report titled Heat Resilience Solutions for Boston; Source: the City

Precedent Research: Ongoing Housing Developments in Phoenix

Two ongoing multi-family housing development under the similar context are studied. One is Soluna Apartments development in the central city area of Phoenix, another one is Culdesac neighborhood in Tempe.

Soluna, the first phase of a five-phased undertaking, features 177 modern, energy-efficient units ranging from one to five bedrooms. The community is designed to provide quality living at an affordable cost, with 80 percent of units offered as affordable housing and 20 percent of units available at market rate.

Located just 2.5 miles from downtown Tempe, Culdesac neighborhood features zero residential parking on a 16-acre infill site next to a light rail station. The car-free neighborhood is largely driven by innovative mobility technology that makes it easier for people to give up their car. The neighborhood will be 100% rental, thus providing a different approach to multifamily development.

Left: Soluna Aparments; Source: https://www.yourvalley.net/stories/mixed-income-apartment-community-opens-in-phoenix,339187

Right: Culdesac Tempe; Source: https://opticosdesign.com/work/culdesac-tempe/

https://www.yourvalley.net/stories/mixed-income-apartment-community-opens-in-phoenix,339187

MIT team at Taliesin West

Source: Kelly Kubicki (Taliesin Institute Coordinator)

The Site Visit: Learning from the Locals

During the spring break, students, companied by Professors and TAs, embarked on an in-person site visit to fulfill two main objectives. Firstly, despite the students’ current grasp of the site through analysis and research, it remained vital to verify whether their imagination of the site aligns with its actual conditions as perceived through their own eyes. If discrepancies are discovered between the site’s conditions and their initial analysis, they were encouraged to delve into the underlying reasons causing such disparities.

The second purpose of the site visit was to glean insights from local experts in Phoenix who have been investigating similar issues. The itinerary included a visit to the Heat Response and Mitigation Office in the City of Phoenix, where students had the opportunity to familiarize themselves with the city’s approach to addressing heat-related challenges. Additionally, the students engaged in discussions with Prof. Chingwen Chen regarding her prior teaching and studio work, which specifically focused on the Phoenix South Central Corridor. By leveraging the expertise of these local professionals, the students gained valuable knowledge and perspectives on tackling heat-related issues in the region.

The Site Visit A Day in the Life in Phoenix

Students endeavored to investigate the impact of heat and the built environment on the everyday lives of typical Phoenix residents by immersing themselves in the role of local workers who commute to their jobs. This experiential approach allowed them to gain a deeper understanding of the challenges faced by individuals living in Phoenix and how their daily experiences are influenced by the interplay between heat and the surrounding urban infrastructure.

Through their investigation, the students discovered a significant contrast in thermal comfort between shaded and under-shaded streets. This observation emphasized the critical role that tree shade plays in mitigating the effects of heat and enhancing the comfort of pedestrians. Furthermore, the students noted a substantial disparity in tree shade coverage between the central city’s southern and northern areas, which corroborated their previous mapping and analysis findings. This discrepancy in tree shade distribution highlighted the need for targeted interventions and strategies to address the unequal distribution of thermal comfort resources within the city.

Photos of the site

Source: All students in the studio

Left: Shaded streets

Right: Under-shaded streets

Left: Streets in the central city north

Right: Streets in the central city south

The Site Visit Discussion with Officials and Experts From the City of Phoenix

The MIT team engaged in extensive discussions with several city officials, primarily from the Office of Heat Response and Mitigation. The individuals involved in this discussion included the director of the Heat Response & Mitigation Office, David Hondula, as well as other key personnel such as Lora Martens, the Tree Program Manager; Joel Carrasco, the City Village Planner; and Mary Wright, a PhD student from ASU, among others. This collaborative discussion allowed the team to benefit from the diverse perspectives and expertise of these individuals, fostering a comprehensive understanding of the heat-related challenges in the city and facilitating the exchange of innovative ideas and strategies.

MIT team is having a discussion with officials from the city

Source: Chenhao Zhu

The Site Visit Discussion with Prof. Chingwen Cheng (Then Head of ASU Landscape Architecture Department/CELA

After visiting city, MIT team went to Arizona State University Tempe to meet with Prof. Chingwen Cheng, who was then head of ASU Landscape Architecture Department and president of Council of Educators in Landscape Architecture (CELA). She delivered a brief presentation on their past efforts concerning the Phoenix South Central Corridor Study and Community Design. The report showcased the diligent work carried out by ASU students, encompassing preliminary site analysis and meticulous landscape design, which tackles the prevalent challenges posed by extreme heat in a comparable context. Through the presentation and discussion, the students acquired a profound comprehension of the structural dynamics within the central city area and its communities.

MIT team is having a discussion with Prof. Chingwen Cheng Source: Chenhao Zhu

Department/CELA President)

An early sketch of cooling corridor planning

Source: Mikaela Strech

The Design Brief: Connecting the Loop through Cooling Corridors

Module I Exercise 2: Envisioning the Project and Drafting of a Schematic Design Brief

In this module, each team will choose one design intervention after consultation with the professors and develop a detailed design brief that analyzes and frames the challenges your mapping phase discovered, and moves towards projective design recommendations.

A design brief is the written document that a business client (private or public entity or developer) uses to communicate with its design team about what is necessary for a successful built project. It should include the following components: 1) a summary of needs and challenges; 2) design objectives; and 3) design recommendations.

The Design Brief

The Design Challenges, Objectives, and Recommendations

Built upon all previous efforts, students have identify the main thesis of the design brief:

Design a heat-responsive, multi-modal, and mixed-income neighborhood district that can serve as a model for adapting across Phoenix. This design thesis comes with the following design objectives and recommendations:

Equity: Ensure that regional investments in transit and landscape are accessible to residents in underinvested neighborhoods.

Recommendation A: Creating heat-mitigating street connections to increase accessibility to regional transit investments in Southwest Central City Phoenix.

Recommendation B: Re-connecting Phoenix residents to natural landscapes like the Rio Salado.

Mitigation: Improve Phoenix’s climate resilience through adaptable, modular heat-reduction strategies.

Recommendation A: Promoting new block types that maximize wind and minimize sun exposure.

Recommendation B: Strategically locating the tree canopy for high-impact and high-efficiency investments.

Adaptation: Transition Phoenix toward its climate vision by increasing ridership of lower-emission public transportation modes.

Recommendation A: Restoring brownfields into people-centric, multi-modal transportation hubs.

Recommendation B: Increasing TOD with meaningful affordable housing components appropriate for the neighborhood character and with heat-responsive TOD block design techniques.

Proposed cooling corridor framework

Source: Mikaela Strech

The Design Brief Integrating Cooling Corridor and Mobility System

The design brief also requires a integrated consideration between cooling corridor planning and existing/future mobility system, which include the following design components:

1. multi-modal anchors

2. high-capacity transit corridor

3. secondary transit corridors

4. modular cooling corridors

5. modular housing and development block strategy

Through synthesizing these components, the S. Central Ave is proposed to be a central and connecting axis for both cooling corridor and mobility system.

Source:

An integrated framework that connects cooling corridors and mobility

Maria Castillo

A rendering envisions a built environment with improved outdoor thermal comfort

Source: Hazel O’Neil

Featured Projects: Multi-Scale “Cooler” Livings

Working both individually and in groups, the students developed urban design proposals encompassing three distinct scales: district, block, and street. The primary goal was to envision a living environment with higher thermal comfort for Phoenix and its residents. Following the design brief, each project imaginatively leverage the site’s unique elements and innovative design solutions to enhance shade, ventilation, walkability, thermal comfort, and other performance factors of the area. By integrating design solutions across all three scales, a systematic approach to addressing urban heat and creating a “cooler” living environment was formulated.

Cooler Districts: Cooling Mixed-use Districts through Waving Nature and Built Environment

Hazel O’Neil

At this scale, innovative planning and design strategies have been employed to create a mixed-use district that effectively addresses the challenges and recommendations outlined in the design brief. The following solutions have been implemented to tackle specific issues:

Heat Mitigation: To combat extreme heat and establish a more enjoyable outdoor environment, this proposal incorporates three primary design techniques. Firstly, the architectural design is tailored specifically for desert environments, incorporating contiguous gray spaces. Secondly, public spaces are strategically covered by a combination of tree canopies and building shades. Thirdly, wind corridors are evenly distributed throughout the site to facilitate natural ventilation. Additionally, shade structures and water cooling spots are installed at regular intervals of every 5-10 minutes of walking distance.

Mobility: The design aims to foster a car-free environment by leveraging an extended light rail line, shared micro-mobility infrastructure, and an enhanced walkable design. Furthermore, designated pickup and dropoff zones for ride-hailing services are conveniently located near building entrances, enhancing accessibility for residents and visitors.

Landscape and Resilient: The district integrates landscape resources primarily along the Salt River, both visually and functionally. The inclusion of visually appealing design elements and various programs enhances the overall landscape experience. Additionally, flood walls and relevant infrastructure are installed to safeguard the district from potential flooding events.

Concept diagram: District is organized by well-shaded cooling

cooling corridors and plazas

Top: Site conditions; Bottom: Site operation (planar diagram)

Top: Site Operation (sketch); Bottom: Site operation (section)

Cooler Blocks: Cooling Residential Blocks through Optimized Block Configurations

Mikaela Strech

When it comes to residential blocks, the design proposals aim to optimize their heat mitigation capabilities through two distinct strategies related to the block configuration.

For multi-family residential blocks, a fully shaded and continuous green space is created within the courtyard. Additionally, parking spaces are thoughtfully integrated into the building design and adequately shaded to reduce heat impact.

For single-family residential blocks, the front setback is significantly reduced, and the original backyards of adjacent parcels are combined to form a larger inner-block green space. Simultaneously, parking spaces are fully shaded to mitigate heat.

A series of post-design analyses have been conducted to validate that the proposed configurations outperform the existing conditions in terms of shade provision and ventilation. These analyses serve as evidence of the improved performance and effectiveness of the design in addressing heat-related challenges.

Concept diagram: Well-shaded courtyard provides viable living

living spaces for residents

Sketches

Multi-family residential block: Existing block configuration

Multi-family residential block: Proposed block configuration

Multi-family residential block: Sun light analysis of the proposed block configuration

Multi-family residential block: Wind corridor analysis of the proposed block configuration

Single family residential block: Existing block configuration

Single family residential block: Proposed block configuration

Single family residential block: Sun light analysis of existing block configuration

Single family residential block: Sun light analysis of the proposed block configuration

Cooler Streets: Cooling Streets through Shade-Oriented Streetscapes

Maria Castillo, Sarah Lohmar, Elyse Oliver

At this scale, the design proposals strive to establish a new paradigm for street design, focusing on enhancing outdoor thermal comfort, promoting walkability, and integrating micro-mobility options. Three crucial spatial elements are utilized to optimize shade performance: architectural design (including building height and façade characteristics), strategically placed street trees, and the incorporation of artificial structures.

To illustrate the transformative potential of this new design paradigm, Pima Street serves as an example. Given the varying land uses along Pima Street, three distinct sections are delineated to demonstrate how street design should adapt to different land use configurations.

By incorporating these design principles and tailoring them to specific land use contexts, the proposed street designs aim to create an environment that maximizes shade provision, improves outdoor comfort, seamlessly integrates with the surrounding urban fabric, and provides multi-modal mobility options.

Concept diagram: Cooling streets through shade-oriented streetscapes

streetscapes

Existing site conditions

Proposed site design

Proposed site design with section lines

A series of sectional perspectives show how to leverage various spatial design elements, such as buildings, trees, and structures, to maximize the street shade

A set of before/after sections show how to integrate multi-modal mobility into the proposed streetscapes

The first ‘cool corridor’ in Phoenix Source: Brandon Loomis/The Republic

Future Research: Enhancing Heat Mitigation through Innovative Methods

After an extensive semester of research, analysis, discussions, planning, and design iterations, a set of four research ideas has emerged, all of which are closely tied to improving the analysis, measurement, and mitigation of urban heat. These ideas serve as a foundation for further exploration. Some of them will be the focal point of an upcoming urban design studio scheduled for Fall 2023. The studio will provide an opportunity to delve deeper into these concepts and develop practical solutions to address urban heat challenges.

Future Research 01

A New Method to Quantify Tree Shade Coverage

The extant methods primarily center on the computation of tree canopy coverage. Nonetheless, it is imperative to acknowledge that the extent of tree canopy coverage does not equate to the provision of tree shade coverage. This is due to the fact that the latter is contingent not only upon the size and extent of the tree canopy, but also on the tree’s height, geographic location, and the passage of time. It should be noted that the amount of shade provided by a tree with an identical canopy coverage may vary significantly across different seasons. Hence, a novel metric or method must be formulated to capture the subtleties of the disparity between tree canopy coverage and tree shade coverage. Furthermore, this new metric or method ought to take into consideration the changes in shade levels over varying time frames within a day or a year.

Top: Three existing methods of measuring tree canopy/shade coverage; Source: Left: the City of Decatur; Middle: Li, X., Ratti, C., & Seiferling, I. (2018). Quantifying the shade provision of street trees in urban landscape: A case study in Boston, USA, using Google Street View. Landscape and Urban Planning, 169, 81-91. ; Right: 2010 SMA Conference

Bottom: A simulation shows the differences between Tree Canopy and Tree Shade and how Tree Shade changes in different times

Tree Canopy (no sunlight)

Tree Shade (0101 - 12:00pm-Phoenix)

Tree Shade (0701 - 12:00pm-Phoenix)

Tree Shade (1001 - 12:00pm-Phoenix)

Tree Shade (1001 - 04:00pm-Phoenix)

Future Research 02

An Integrated Approach to Optimizing Building/Tree Shade Simultaneously

Concerning the provision of shade by trees and buildings, there are six distinct relationships that merit attention: 1) tree shade on the ground;

2) building shade on the ground; 3) building shade on the building

4) building shade on the tree; 5) tree shade on the tree; and 6) tree shade on the building. It is noteworthy that previous research has predominantly focused on one or two of these relationships. Therefore, a holistic approach that can negotiate trade-offs between all six relationships need to be developed to optimize the tree/building shade performance. This objective can be achieved through the utilization of computational tools built upon open-source software applications.

Top: A proposed configuration of tree and building from student’s work; Source: Hazel O’Neil

Bottom: A simulation shows how tree shade impacts on the surrounding buildings; Source: Zhao, Q., Wentz, E. A., & Murray, A. T. (2017). Tree shade coverage optimization in an urban residential environment. Building and Environment, 115, 269-280

Future Research 03

A Shade-Oriented Tree Database for Desert Environment

Based on the newly proposed tree shade metric and other planting/ maintenance related data, a shade-oriented tree database can be created. It is important to acknowledge that the shade performance of a tree can significantly vary during its different life stages. Therefore, this database should contains a set of selected tree species that not only are suitable for local (desert) environments (e.g., requiring minimal water and nutrients) but also have a higher life-cycle performance in providing shade.

Life-Cycle Shade Performance? +

Left: A diagram shows a life-cycle of a tree; Source: Ilyakalinin

Right: A page of Arizona urban tree map; Source: https://dffm.az.gov/sites/default/files/files/forestry/ucf/azutm/AZUTM_tree_guide_ southwest_desert_2015_04_28.pdf

Future Research 04

Optimizing for A More Equitable Cool Corridor Planning

The current methods of identifying priority areas for tree planting within underserved communities require a degree of refinement. For instance, certain analytical frameworks (e.g., the tree equity score by American Forests) need a more explicit definition of how the tree canopy target is computed for designated areas. Furthermore, in certain locations such as Phoenix’s central city south, existing tree equity analysis holds little value since the entire region is almost equally deficient in terms of tree shade coverage. Instead, the real question is how to leverage limited resources in order to equally distribute and maximize the benefits derived from government-led initiatives like the cool corridor program.

In light of this, the City of Phoenix is formulating its own unique method for analyzing cool corridor prioritization, as depicted in the left image. The upcoming urban design studio can facilitate the city in carrying out a more thorough analysis, optimization, and evaluation of cool corridor planning for underserved communities.

Top: Cool corridor prioritization analysis framework developed by the City of Phoenix;Source: Phoenix Cool Corridors Program: https://www. phoenix.gov/streets/coolcorridors

Bottom: Identifying under-shaded street through tree canopy dataset; Source: Hazel O’Neil

The final review

Source: Chenhao Zhu

The Next Studio: Fall 2023

• Multi-generational Housing

• Heat Mitigation

• Autonomous Universal Access

Hazel O’Neil is delivering an analysis that maps the heat conditions of the central city during the final review

Source: Chenhao Zhu

Contributors

This studio would like to acknowledge the following people, organizations, and institutions for their generous support and feedback throughout the course of the semester.

David M Hondula

Lora Martens

Joel Carrasco

Alicia Arauz-Orozco

Mary Wright

Chingwen Cheng

Kenoff Jeffrey

Mohamad Nahleh

Lizzie Yarina

Edu Gascón

Nada Tarkhan

Sarah Mokhtar

Jennifer Gray

Kelly Kubicki

The City of Phoenix Office of Heat Response and Mitigation, Phoenix Arizona State University Taliesin Institute

MIT Norman B. Leventhal Center for Advanced Urbanism