Greenhouse Gas Contributions in California 

Source: CA Air Resources Board 2021 report, California Greenhouse Gas Emissions 2000-2019

Residential Above Retail is Coming to LA

The core housing typology of a 15 minute street is residential over small retail — usually 3-5 stories of housing above shops, and without driveways and parking.  

The Livable Communities Initiative is a program to create 15 minute neighborhoods along commercial corridors in LA. Thanks to years of work by the LA City Council, LA’s Planning Department and a broad group of experts and stakeholders, the Los Angeles Planning Department is initiating a 10-15 street pilot project, along with a step-by-step plan to implement the LCI, addressing affordability and home ownership; smaller lots; family-sized homes; high quality homes; with the cornerstone feature being residential over small neighborhood-serving retail. The plan provides the clearest  blueprint for a zero-carbon housing with zero-carbon mobility. 

This strategy can revitalize vacant and dying retail blocks because having customers upstairs for the businesses creates vibrancy and means there are stores for the residents conducive to convenience and quality of life – creating a virtuous cycle. This combination is the backbone of a 15 minute city: a walkable street with small retail so residents can meet their daily and weekly needs without a car. Constructing residential units above retail spaces maximizes land efficiency, especially in urban areas where space is limited. This vertical integration supports higher density without expanding the urban footprint, preserving open spaces and mitigating urban sprawl.

This typology is naturally low carbon because the design requires a “zero lot line” between the buildings, and therefore an interior courtyard for light and air which allows cross breezes to self-cool units. With clean technology (solar, heat pumps etc), buildings can be net-zero carbon.

If the street is inviting to walk or bike, and accessible to transit and jobs, residents can have high quality zero carbon mobility – creating neighborhoods with zero carbon housing and zero carbon mobility.

The Livable Communities Initiative provides for a three-pronged approach: (1) Identify Pilot Streets with the bones to be a 15 minute neighborhood (walkable, existing small shops, near transit, etc); (2) Make it feasible and inviting to build zero carbon housing along the Pilot Street; (3) Utilize effective street design to create a high quality street with high quality mobility options so it is pleasant to walk, safe to bike, and easy to get to great transit and jobs – creating a 15 minute neighborhood.

Here is an overview of the three building blocks to create 15 minute climate solution:

(1) Identify the Street

The backbone of a sustainable neighborhood is a walkable street of small shops with residential housing over retail. The housing typology of residential over retail dates back hundreds and even thousands of years: Roman towns were laid out with a market street: shops on the ground floor and housing above (and the standard town was one kilometer long – a 10-15 minute walk.) Southern California already has the bones for this model: historically, LA was a city of neighborhoods with local main streets and shops (Larchmont, Abbot Kinney, Westwood, etc), and these neighborhoods were connected by the world’s largest trolley system, allowing people to live car-free.

We can revive this combination by identifying underutilized commercial corridors with the following characteristics:

• small retail

• directly touch LA’s Metro (or other robust public transit)

• located near jobs and great public amenities (parks, schools and universities, etc)

• a narrow street with minimal traffic that can be slowed for livability

For example, Beverly Blvd (6-7 lanes with small shops) has the bones that Olympic or Wilshire (9-11 lane arteries with big box stores) do not.

LCI has identified potential streets from among the 400 of LA’s Historic Main

Streets and Villages, many of which still support small, locally-owned retail and touch LA’s high quality Metro. These Legacy Family Businesses are an important component because they create an existing fabric and community. This is less possible with newly-constructed mixed-use developments where banks often require a big box store or national chains such as Subway, Verizon, etc., that do not lend themselves to livability and daily or weekly needs. 

(2) Building Zero Carbon Residential over Retail Quickly and at Scale

(2) Building Zero Carbon Residential over Retail Quickly and at Scale

The classic building typology of a 15 minute neighborhood is residential over small retail— a 3-5 story building with zero-lot-lines, a courtyard, and retail on the ground floor. This typology is found across the world, perhaps most recognizably in the U.S. in neighborhoods around Greenwich Village. It is an efficient use of land, and places residents in direct proximity to neighborhood serving retail, creating a virtuous cycle of customers for the stores, and stores for the residents to live a walkable life without a car. 

The LCI offers a clear plan for cities to allow and incentivize them using Standard Plans and Streamlining:

Standard Plans: Residential over small retail lends itself to an efficient simplification called a Standard Plan. Standard Plans are pre-entitled architectural plans that can be created for typologies like an ADU, multi-family infill, or in this case, commercial parcels, and then can often be re-used on other parcels on the block (because commercial corridors are made up of identical parcel sizes, with some small variations). The city can designate any architectural plan as a pre-entitled Standard Plan (using various stakeholder processes to decide which) and create a database of off-the-shelf, hassle-free, low-cost options for parcel owners to develop their own land. Architects get paid for every use of their plan (justifying the time and expense of creating exceptional design), while builders can replicate the design on multiple lots, building “cookie cutter” to achieve economies of scale.

Streamlining for Feasibility:  Cities can guarantee Standard Plans (and conforming plans) approval in under 90 days. They can also address the hundreds of friction points with city agencies that cause delays and incur expenses by using a system like

Standard Plans can also revolutionize sustainable housing by baking in zero carbon features: 

Design: 

• Courtyards for cross-breezes so units can self-cool

• High ceilings to lower indoor temperatures (by up to 8°)

• Colonnades over the sidewalk to lower indoor temperatures (by up to 10°)

• No parking

Clean Technology: 

• Solar panels

• Electrification

• Heat pumps

• Energy-efficient appliances 

• Grey water/water recycling

Standard Plans can take advantage of prefab and modular construction, further bringing down costs and improving quality.

Mayor’s Housing Innovation Advisory (an estimated  40% of construction cost can be attributed to delays and red tape for zoning – soft costs and carrying costs, not land, labor or construction materials.) A few technical things also need to change in the code to allow 3-5 story zero lot line courtyard buildings: eliminating side yard setbacks and parking minimums (where applicable); increased density allowance for small lots; and single staircase reform to allow courtyard buildings to 4 or 5 stories (the current rule is 3 stories). 

Cities can also waive or reduce fees (there have been recent calls for a window for free permits, and Governor Newsom recently waived permitting and review requirements under CEQA to allow for faster rebuilding after the fires). Waivers could apply to zero carbon communities outside of fire zones. Cities can also upgrade infrastructure (sewers, electric, etc) for the entire Pilot Street, which is a far more efficient use of public resources.

(3) Effective Design for High Quality Mobility 

Once streets are identified and building can proceed, the city can transform the road to ensure livability and high quality mobility. It’s essential to use proven design and engineering, otherwise bike lanes and buses are simply not used.  

There are effective street designs that create high quality mobility options to make it pleasant to walk and safe to bike directly to high quality transit and jobs (without a detour under a freeway overpass, for instance).  The broad strategies include: 

Walking: Slowing cars and adding trees, al fresco etc to make it pleasant to walk. 

Biking: Creating child-safe Dutch protected bike lanes can expand micro-mobility options, including cargo bikes and adaptive bikes. The LCI has collected design guidelines based on best practices from Dutch engineers and experts around the world. For bikes and micro-mobility in particular, child-safe design and engineering is essential to attract users. 

Transit: Safe and pleasant walking and biking creates the first mile/last mile connection to high quality transit – creating a high quality Transit Oriented Development (TOD). But transit only scales if it is high quality – which in LA means Metro (light rail (LRT( and subways/heavy rail (HRT)) and buses in dedicated bus lanes (BRT). 

Putting it Together

The LCI has identified around 20 opportunity streets that have the bones to be transformed into a 15 minute neighborhood: existing fine grain retail (small shops); touches a Metro or BRT stop; and a street that can be slowed for livability without impacting traffic nearby (dead end streets, low volume streets, underutilized streets, etc). Here is a map of a some of the most promising options: 

Clockwise from top: Hollywood, Vermont, Pico, Beverly/Larchmont/Fairfax/Melrose/Robertson/6th; Crenshaw/Leimert Park, Market Street (Inglewood), Washington/Culver Blvd (Culver City), Abbot Kinney/Main Street/Third Street Promenade/Montana (Santa Monica and LA), Westwood, Beverly Drive (Beverly Hills).

Once streets are identified and designated an LCI Pilot Street, cities can adopt a streamlined approval process for zero carbon conforming plans (using something similar to the Mayor’s Advisory model) and an optional Standard Plan program. This combination will allow high quality, sustainable and affordable housing to be built quickly and efficiently. Finally, using Dutch design and global best practices, streets can be redesigned for walkability and micro-mobility which also creates access to transit and jobs. The result is a zero carbon 15 minute neighborhood. 

Case study: Westwood

Westwood Blvd is 1.5 miles of mostly small retail that touches two Metro stops (E line and incoming D line), as well as having a massive job center – the U.S.’s premier public university, UCLA, and a major medical center where 63,000 people drive in for work every day.

Case study: Culver City

Washington Blvd in Culver City is 1.2 miles of 30’ x 90’ parcels of mostly one-story retail and touches the Metro (E Line). 32,000 commuters drive into Culver City for work, and 97.5% of jobs in Culver City are fulfilled by people who live outside the city. Almost 7,000 travel over an hour to get to work.

VMT and Commutes

LCIs and 15 minute cities have the potential to significantly reduce commutes across the region. Currently, 586,000 people commute to the Westside and Central LA for work, some lasting 1-2 hours each way. By creating housing closer to jobs and transit, 15 minute communities can enable residents to shed their cars and save the substantial $7,000–$10,000 per year associated with vehicle ownership, while significantly reducing Vehicle Miles Traveled or VMT.

For necessary trips, car ownership can be replaced with services like Waymo, Uber, onsite car sharing, and peer-to-peer car sharing platforms like Turo.

This shift away from intensive and daily car use is essential because climate scientists warn that EVs (electric vehicles) alone cannot scale quickly enough to meet CA’s climate goals. Current carbon capture and storage (CCS) technologies face significant challenges in scalability, energy consumption, and cost-effectiveness, making them presently unfeasible for offsetting emissions on a meaningful scale. Cutting VMT is currently the only viable path to achieving these critical goals in time. A recent report by California’s Legislative Analyst’s Office (LAO) highlighted that the state lacks a plan to achieve the necessary 25–30% reduction in VMT. Current strategies fall far short, targeting only a 4% reduction.

With passenger vehicles and VMT accounting for 28% of California’s greenhouse gas emissions, addressing car dependency is a cornerstone of any climate solution.

Green Space

Biodiversity and urban cooling to combat climate change are key benefits of 15-minute communities. Tree-lined, pedestrian-friendly streets create a lush canopy that mitigates the heat island effect. Fewer cars means more room for parks, playgrounds, and bioswales, creating healthy and highly valued public amenities and shared spaces:

• Linear Parks: Inspired by Las Ramblas in Barcelona, these pedestrianized streets can stretch for miles, incorporating a lush tree canopy, bioswales and native plants to manage stormwater and enhance biodiversity, and creating a shaded path for stolling, walking and running for exercise. 

• Pocket Parks: Unused side streets can be repurposed as green spaces or small playgrounds.

Underground Parking Replacement: Converting surface parking lots into underground parking allows for housing and parks above, creating opportunities for hundreds of new parks and recreational areas, as well as housing.

Car Share

Car sharing can enable car-free living and contribute to a virtuous cycle of reduced car dependency:

1. Cost Efficiency: For those who drive infrequently, car sharing costs $30/day, while walking, biking, and transit are virtually free – aligning financial incentives towards green mobility.

2. Parking Efficiency: Cars sit idle 95% of the time. Shared cars reduce the need for parking spaces while maximizing vehicle usage. Fewer parked cars creates space for bike lanes, bus lanes and al fresco dining.

3. EV Integration: Requiring car-sharing fleets to be 100% electric can immediately increase the number of EV trips, accelerating the transition from internal combustion engine (ICE) vehicles. Each car share is estimated to replace 9-13 cars, 9-13X the use of an EV.

4. Car Shedding: Car sharing allows households to shed vehicles, freeing up street space, and nudging drivers to walk, bike or take transit.

The Big Picture

According to researchers at UC Berkeley, building housing near jobs in walkable, bikeable 15-minute communities is the most impactful action Los Angeles can take to combat climate change. The Livable Communities Initiative combines two essential strategies:

• Reducing VMT (less driving)

• Urban Infill (building housing near jobs and transit)

What about other housing typologies? Other housing typologies can be affordable and built to be zero carbon - such as adaptive reuse, garden courtyards, mass timber mid-rises and high-rises, Tiny Home Villages, communal living and single family home boarding houses; and for a mid-range price point, townhomes. But every green building typology relies on proximity to a 15 minute street to have zero carbon mobility (a far bigger issue for climate – 28% of emissions are from passenger vehicles vs 6% from residential housing). If housing is to be clustered around a 15 minute street, residential over retail is the most efficient use of land, and having customers in such close proximity helps the stores thrive – creating the backbone of a 15 minute neighborhood. Thriving local retail that offers a diverse range of shops can significantly reduce car usage by enabling nearby residents to complete more errands within walking or biking distance, and/or shortening car trips, further lowering emissions. It’s called a “walk shed” or “bike shed” – the ¾ miles around a vibrant retail destination that draws people in. 

Building housing above retail creates the backbone of a thriving local 15 minute street and opens up the opportunity for car-light living, which is why 15 minute city advocates start with residential over small retail as the essential building typology. 

Why do residential over retail (ROR) buildings have zero lot line and courtyards? ROR housing is zero lot line because small retail streets are zero lot line (the shops directly touch each other), so housing above it touches as well. Therefore windows are in the front and back of the apartment with an interior courtyard (instead of windows on side yard setbacks that can be as narrow as 3 feet). 

Courtyard buildings are how we have built for 100s and even 1000s of years around the world in warm climates – before the invention of AC, the design of the building was the only way to self-cool a space. The courtyard allows for cross-breezes and ample air and light. With solar panels, heat pumps, and other sustainable technologies, this building typology can easily be zero carbon.

The typology of a zero lot line single staircase courtyard building is classically low-carbon/zero-carbon because the courtyard creates cross breezes that self-cool units, which is especially important in warm climates like LA. These buildings have been built all over the world for thousands of years, and were designed to work in warm climates before AC. To this day, 25% of LA apartments do not have AC because of the passive design features.

What is Single Staircase design? Zero lot line courtyard buildings are designed around a “single staircase” model, which makes the floor plan more efficient and allows for the elimination of side yard setbacks, replaced with an interior courtyard which creates cross-ventilation so the building can easily be zero carbon. Single Staircase buildings are legal to 5-6 stories around the world, but in CA the limit is 3 stories. The height limit hurts the feasibility of projects (upper floors are less expensive to build than lower floors). Because this typology is easily zero carbon and is the backbone of a 15 minute street, this reform allows more buildings to “pencil” in more neighborhoods and therefore get built. As a city and state, we want as many people as possible to live in walkable neighborhoods in zero carbon housing. 

Why not use big parking lots instead of building over small shops?

Big parking lots (especially next to Metro stops) offer huge parcels for housing, but there are several drawbacks:

(1) Banks and financiers often require the ground floor retail to be a big box store; even if it’s broken into small retail spaces – they require national chains like Verizon or Subway or Pizza Hut. Building on top of commercial corridors with small retail have neighborhood serving retail and legacy family businesses, which already has vibrancy and customers, and creates the bones for a 15 minute walkable neighborhood.

(2) The courtyards are child-friendly for children to run and play on grass rather than cement where a fall can result in an injury. 

(3) Tall buildings are usually high carbon (embodied and the need for mechanical cooling). They often have expensive amenities and luxury prices (while some buildings set aside a few units for affordability): for instance, a 1BR in the ARQ rents for $3850.  

An alternative for a big parking lot is a Courtyard Building known as Perimeter Block Apartments or PBAs. This typology was recently made famous in the tv show Only Murders in the Building – the Arconia (which is a fictional name; it’s called the Belnord in real life). PBA’s can also have small retail on the ground floor.

Why not taller buildings? While tall buildings can achieve zero carbon but in CA and much of the US they are required to have a single-loaded or double-loaded corridor design (the apartments are all off one corridor), with windows typically on only one side of a unit. This requires a side yard setback for any air and light. Critically important to climate, this design limits air circulation and cross-ventilation so buildings rely heavily on mechanical cooling and heating. 

The corridor also makes the floor plan less efficient. Tall buildings also need more carbon-intensive concrete and/steel. 

Mass timber and cross-laminated timber (CLT) are considered the most sustainable materials for high rises and have been used across the world, but they also tend to rely on a single staircase design and are more expensive so these materials are not standard. Mixed-use tall buildings also have larger floor plates which banks usually require to be recognizable big box national chains (reducing walkability).

Whatever the building typology, it relies on proximity to a 15 minute street for walkability to address the biggest source of emissions: passenger vehicles. 

Why focus on smaller streets like Beverly and Pico, and not Wilshire Blvd which has an underground subway? There are few drawbacks to a wide street like Wilshire:

(1) it is an artery through the city for cars, and cannot realistically be calmed and slowed because it carries too much traffic. And in general, there are concerns about concentrating housing on noisy, dangerous, polluted commercial corridors because of the serious health effects.   

(2) The lots on Wilshire are large and the street has very little neighborhood serving retail. Big Box stores like Office Depot and BevMo are not “daily or weekly” needs. They also deaden the walkability because they don’t have a relationship with the street – like awnings, window displays, and open doors. City codes often mandate windows on retail, even pharmacies and big box stores, which are frequently blocked or covered with paper to deter theft. In general, TODs (Transit Oriented Development) are required by banks and financiers to fill their ground floor retail with national chains which tend to be fast-food; or are not daily and weekly needs.