Mixed-Use Programming Skill

COMMERCIAL

CIVIC / INSTITUTIONAL

RECREATION

INFRASTRUCTURE

2. Mix Optimization Framework

Determining the right mix of uses requires balancing demand analysis, supply constraints, standards, and the qualitative goal of creating a vibrant, 24-hour place.

2.1 Demand-Driven Analysis

Demographic Analysis:

• Current and projected population by age, household type, and income
• Household size distribution determines unit mix (1-person households = studios/1BR; families = 2-3BR+)
• Income distribution determines affordability requirements and retail/F&B spending capacity
• Employment projections determine office and commercial space demand

Market Study Inputs:

• Residential absorption rate: how many units per year can the local market absorb? (typically 50 - 200 units/year in a mid-sized market, 200 - 1,000+ in a major city)
• Office absorption: how much new office space is being leased per year? (5,000 - 30,000+ m2/year in growing markets)
• Retail vacancy rate: if existing vacancy is above 10%, new retail supply should be cautious
• Hotel occupancy: if existing occupancy is above 70%, there may be capacity for new rooms
• Visitor/tourist projections: drive hotel, F&B, and destination retail demand

Spending Capacity:

• Retail spending per capita: $5,000 - 15,000 / year in developed economies
• If a new neighborhood of 10,000 people generates $100M in annual retail spending, and retail achieves $3,000 - 6,000 / m2 in annual sales, the neighborhood supports 17,000 - 33,000 m2 of retail
• F&B spending: typically 25 - 40% of total retail spending
• This demand will not all be captured locally: assume 30 - 50% capture rate for convenience, 10 - 20% for comparison

2.2 Supply-Driven Constraints

Site Capacity:

• FAR (Floor Area Ratio): determines total buildable floor area. FAR 2.0 on a 10 ha site = 200,000 m2 GFA
• Height limits: determine maximum floors and therefore maximum density
• Coverage/footprint: determines how much of the site is built vs. open space
• Setbacks: reduce usable footprint

Infrastructure Capacity:

• Water and sewer: calculate demand per use (residential: 150 - 250 L/person/day; office: 50 - 80 L/employee/day)
• Transport: peak-hour trip generation by use must not exceed road and transit capacity (see references/land-use-guide.md)
• Power: substation capacity for the district
• Digital: fiber and telecoms infrastructure

Parking Capacity:

• Parking requirements by use (see references/land-use-guide.md)
• Parking structures consume significant area: 1,000 parking spaces = approximately 30,000 - 35,000 m2 of structured parking GFA
• Reduce parking ratios near transit to free up development capacity

2.3 Standards-Based Benchmarks

UN-Habitat Recommendations:

• Residential floor space: 40 - 60% of total district
• Economic (commercial + civic) floor space: 40% minimum
• Street/public space: 30 - 45% of total land area
• Green/open space: 15 - 20% of total land area
• Density: 150+ people/ha for efficient transit and services

LEED-ND (Neighborhood Development):

• Mixed use: minimum 3 diverse uses within 400m walk for credit
• Housing diversity: minimum 3 housing types (size, tenure, price point)
• Community facilities accessible within 400m walk

Jane Jacobs' 4 Conditions for Diversity (The Death and Life of Great American Cities):

1. Mixed primary uses: minimum 2 primary functions that bring people out at different times
2. Short blocks: block perimeters of 120 - 240m (not exceeding 400m) for pedestrian permeability
3. Buildings of varied age and condition: mix of new and old allows diverse economic uses
4. Sufficient density: enough people to support diverse uses (she cited 100+ dwellings/acre in some contexts)

2.4 The 24-Hour Neighborhood Test

A well-mixed neighborhood generates activity at all times. Test the proposed mix against this framework:

Red flags: If any time period shows no activity-generating use, the mix is deficient. Common gaps:

• Weekday daytime dead zone: insufficient office or institutional use
• Evening dead zone: insufficient residential, F&B, or cultural use
• Weekend dead zone: insufficient residential or visitor-attracting uses

3. Use Mix by Context

Use the following recommended ratios as a starting point, then adjust based on demand analysis and site-specific factors.

Recommended Mix Ratios (% of total GFA)

Land Use Ratios (% of total site area, not GFA)

4. Retail and Commercial Sizing

4.1 Retail Space Per Capita

• Developed economies: 1.5 - 2.5 m2 of retail GFA per person in the catchment
• Developing economies: 0.5 - 1.0 m2 per person
• Over-retailed markets (US suburban): 4.0+ m2/person - avoid over-supply

4.2 Convenience Retail Sizing

Catchment: 500m radius / 5,000 people minimum Typical components:

Total convenience retail: 1,000 - 4,000 m2 for a neighborhood of 5,000 - 10,000 people

4.3 Comparison Retail Sizing

Catchment: 2 km radius / 25,000+ people Typical components:

4.4 Food and Beverage Sizing

• F&B per capita: 0.3 - 0.5 m2 GFA per person in the catchment
• Seat count: 200 - 350 seats per 10,000 people
• Typical mix: 40% restaurants, 30% cafes, 15% fast-casual/takeaway, 15% bars
• Average size: cafe 80 - 150 m2, restaurant 150 - 400 m2, bar 100 - 300 m2
• F&B needs foot traffic: locate at intersections, transit stops, ground floors of office/residential, facing public spaces

4.5 Office Space Sizing

• Per employee (NIA): 10 - 15 m2 traditional; 6 - 10 m2 co-working/hot-desk; 15 - 25 m2 creative/tech
• GFA to NIA ratio (office): typically 75 - 85% (15 - 25% core, circulation, plant)
• Floor plate: 200 - 2,500 m2 per floor (varies by market and building type)
• Employment density: 1 employee per 10 - 15 m2 NIA (traditional), 1 per 6 - 10 m2 (co-working)
• Office generates demand for: F&B (lunch), convenience retail, fitness, childcare, transit

4.6 Hotel Sizing

• Demand proxy: 1 room per 1,000 visitor-nights per year (from tourism data)
• Room size: budget 18 - 22 m2, midscale 25 - 35 m2, upscale 35 - 55 m2, luxury 50 - 100+ m2
• GFA per room (including lobby, F&B, back-of-house): 45 - 80 m2 total per key
• Typical urban hotel: 100 - 300 rooms; boutique: 30 - 80 rooms
• Hotel generates demand for: F&B, retail, transit, event space, wellness

4.7 Ground Floor Design Rules

• Active ground floor depth: 8 - 15m for retail, 6 - 10m for cafe/restaurant (deeper = less natural light)
• Ground floor ceiling height: 4.0 - 5.0m clear (allows mezzanine, signage, servicing, future flexibility)
• Frontage requirements: minimum 6m per retail unit; maximum 15m without an entrance break
• Transparency: minimum 60% glazing on ground floor facades facing public space
• No blank walls: every ground-floor facade facing a street or public space must be active (retail, F&B, lobby, community use, display window, or at minimum an art wall)
• Servicing: rear access for deliveries; no roller shutters or loading docks on primary frontages
• Residential ground floors: if residential at ground, elevate 0.5 - 1.0m above sidewalk for privacy, or set back behind a private garden zone (2 - 3m)

5. Community Facility Requirements

Use the following thresholds and sizing formulas to determine when and how large community facilities should be in a development program.

5.1 Education

Sizing formulas:

• Early childhood: 3.5 - 5.0 m2 indoor space per child + 7.0 m2 outdoor per child; assume 50 - 100 places per center
• Primary: 5.0 - 8.0 m2 per student (building), 10 - 15 m2 per student (site); assume 300 - 600 students
• Secondary: 8.0 - 12.0 m2 per student (building), 20 - 30 m2 per student (site); assume 800 - 1,500 students

Co-location: Schools should share facilities (sports fields, halls, libraries) with the community for after-hours use. Design for dual access.

5.2 Healthcare

5.3 Community and Cultural

5.4 Community Center Programming

A typical 1,500 m2 community center should include:

• Multi-purpose hall (250 - 400 m2): events, markets, fitness, performances, elections
• Meeting rooms x 2 - 3 (30 - 60 m2 each): community groups, classes, tutoring
• Kitchen (30 - 50 m2): event catering, cooking classes, community meals
• Office (50 - 100 m2): community organization, local council presence
• Reception / foyer (50 - 100 m2): information, display, casual meeting
• Storage (50 - 100 m2): furniture, event equipment, supplies
• Restrooms: sized for hall capacity (1 WC per 25 people)
• Outdoor space: terrace, garden, or plaza connection for overflow

6. Vertical Mixed-Use Design

When multiple uses are stacked in a single building, follow these rules.

6.1 Typical Stacking Order (Bottom to Top)

1. Basement / Below grade: Parking, service, plant rooms, storage
2. Ground floor: Retail, F&B, lobby (residential or office), community use
3. Level 1 - 2 (Podium): Office, medical, co-working, hotel lobby, community, childcare
4. Level 3+ (Tower): Residential or hotel above; office in middle levels

Rationale: Retail needs street frontage and foot traffic (ground only). Office tolerates podium levels with limited natural light on lower floors. Residential benefits from upper floors (views, light, quiet, privacy). Hotel can go anywhere above ground but benefits from views.

6.2 Separate Entries and Cores

• Residential entry: dedicated lobby at street level, separate from retail and office; direct access to residential elevators; secure access control
• Office entry: dedicated lobby, often grander and more public-facing; separate elevator bank
• Retail entry: direct from street at grade; no shared lobbies with residential
• Service entry: at rear or side, not visible from primary public frontage; dedicated service elevator for deliveries
• Hotel entry: prominent street presence with porte-cochere or canopy; dedicated elevator to guest floors

6.3 Structural Considerations

• Column grid: Retail prefers 8 - 10m spans (flexible, open floor plans). Residential prefers 6 - 8m (wall positions). Office prefers 9 - 12m (open plan). Use a transfer structure at the transition (typically at podium roof level).
• Floor-to-floor height: Retail ground floor: 4.5 - 5.5m. Office: 3.6 - 4.2m. Residential: 2.8 - 3.3m. Hotel: 3.0 - 3.6m. Parking: 3.0 - 3.3m.
• Load-bearing: Retail and parking floors need higher live loads (5 - 10 kPa). Residential typically 2 - 3 kPa.

6.4 Servicing and Logistics

• Separate waste collection for residential (domestic) and commercial (trade waste)
• Dedicated loading dock for commercial tenants: minimum 1 bay per 5,000 m2 commercial GFA
• Residential move-in/move-out logistics: dedicated service elevator and staging area
• Mechanical, electrical, and plumbing (MEP) systems are typically separate for each use (different requirements, metering, and operating hours)

6.5 Podium and Amenity Deck

• The roof of the podium (typically Level 3 - 5) is the ideal location for shared amenity:
  • Residential amenity: pool, gym, garden, BBQ, lounge, co-working
  • Office amenity: terrace, meeting rooms, outdoor workspace
  • Shared: can be combined if access is controlled
• Podium roof level often provides the largest continuous outdoor space in a high-rise mixed-use building

7. Reference Links

Use the following reference for detailed space standards, parking rates, trip generation, revenue assumptions, phasing logic, and absorption rates:

• Detailed land use guide: See references/land-use-guide.md for comprehensive space standards per use, parking and trip generation rates, revenue and cost assumptions, phasing logic, and absorption rates.

Key External References:

• Jane Jacobs, "The Death and Life of Great American Cities" (1961) - the foundational text on mixed-use urbanism
• UN-Habitat, "A New Strategy of Sustainable Neighbourhood Planning: Five Principles" (2014)
• ULI (Urban Land Institute), "Mixed-Use Development Handbook" (2003)
• ITE Trip Generation Manual (10th Edition) - vehicle trip rates by land use
• LEED-ND v4 Reference Guide - mixed-use and diversity credits
• Congress for the New Urbanism, "Sprawl Repair Manual" by Galina Tachieva (2010)
• Steuteville & Langdon, "New Urbanism: Best Practices Guide" (4th Edition)
• NACTO Transit Street Design Guide (2016) - transit-oriented mixed-use design
• World Bank, "Planning, Connecting, and Financing Cities-Now" (2013)