Chapter 4-3: Distribution Center Scale Calculation - Building & Site Area

Section 11: Building Area Calculation

This material explains the legal regulations, structural specifications, and simulation mechanisms involved in the "Building Area Calculation" of a distribution center.

It is a step to visualize the specific shape of the building by adding dimensional concepts, such as "aspect ratio" and "number of floors", to the aggregated value (area) of the logistics space. The key points are summarized and explained below.

1. Importance of Site Selection and Legal Regulations

The construction of a distribution center involves an enormous amount of legal regulations, such as the City Planning Act (zoning), the Building Standards Act, and the Fire Service Act.

Need for Expertise: While site selection requires the expertise of specialists (such as architects), having an image of the "site area (building area)" in the initial stages is extremely crucial for internal company studies.
Calculations as Reference Values: The drawings and dimensions provided by Tera Calculation 2 are strictly "concept diagrams to calculate an estimated area," and finalizing them requires design by qualified professionals.

2. Building Shape and Structural Specifications

These are setting items to convert the area into specific dimensions (width and depth).

Building Aspect Ratio: 1:1 or 2:1 are rare; rectangular shapes like 3:2 or 4:3 are frequently adopted.
Outer Walls, Pillars, and Firewalls:
- Outer Walls: Thickness is 200mm. The projected area is calculated based on the wall thickness center (100mm inside).
- Pillars: 700mm square for a single-story building. They increase in thickness by 100mm for each additional floor, with a presumed pitch of 10m.
- Firewalls: Must be installed for every 1,500㎡ of total floor area.

3. Elevations (Height) and Multi-Story Concepts

Floor Height Settings: The 1st floor assumes a raised-floor style (1,000mm). The height above the floor for each story is 7,000mm, and floor height is calculated assuming a floor thickness + beam height of 1,000mm.
Eaves and Building Coverage Ratio:
- Eaves are roofs for rain protection, and 50% of their area is added to the building's projected area.
- Calculation of Building Coverage Ratio: Calculated by (Building Projected Area + Eaves Area × 50%) ÷ Site Area.
Vertical Transport Equipment: In buildings with 2 or more floors, the area for a 1.5m wide emergency staircase and a freight elevator (2.3m square × 1.5 sets) is automatically added for every 1,500㎡.

4. Special Case: Separating the Automated Warehouse

Usually, a center is completed in a single building, but there are cases where an automated pallet warehouse is built as a separate building using a "rack-supported building" structure (where the racks also serve as the building's framework).

Avoiding Atrium Structures: Because automated warehouses are high-rise, incorporating them into the main building creates an atrium structure without floors, affecting cost and structural integrity. Considering whether to make it a separate building also impacts the layout, such as the aisle width within the site.

5. Simulation of 40 Building Type Patterns

Tera Calculation 2 simultaneously calculates 40 patterns of building types combining the following elements, providing them as a summary list (which can be exported to Excel).

Presence of Separate Building (2 categories)
Number of Floors (Up to 5 floors)
Presence of Eaves (2 categories)
Berth Layout Faces (2 categories)

The building information obtained from this summary list becomes the foundation for the next step, "Site Area Calculation".

Building Area Calculation Screen
The logistics space is the sum of the areas of each facility. It is purely a concept of area and has no concept of dimensions.

Building Area Calculation calculates building dimensions using the ratio of building width to depth.

The location where a distribution center is constructed is called the site, and depending on the site, there are various legal regulations (location conditions). Even just looking at the City Planning Act, areas are divided into 13 use zones, such as residential, commercial, and industrial. Additionally, there are the Building Standards Act, Fire Service Act, Radio Act, and coordination with local residents; site selection has so many considerations that only an expert can handle it.

During site selection, the required land area (or building area) is always necessary. Outsourcing this takes time and cost, and internally it adds the burden of conducting field investigations (setting prerequisites for area calculation).

Tera Calculation 2 is an educational software teaching the methods and procedures for calculating the area scale of logistics spaces from shipping data, but we added a software module for calculating site area (building area) to provide reference materials during site selection. Please be aware that this calculated value is a reference and not a finalized area; for the final area determination, please modify the calculated values in conjunction with other conditions and separate documents.

Only with a design blueprint from a qualified professional (1st or 2nd-class architect) can a building be constructed; unqualified persons cannot finalize building specifications. However, it is possible and necessary to have a conceptual image of the distribution center's area and scale.

The building diagrams shown in Tera Calculation 2 are conceptual images, not blueprints. The building dimensions shown in Tera Calculation 2 are provisional dimensions used solely for calculating estimated areas.

Item 1: Building Aspect Ratio

The space area aggregation in Tera Calculation 2 does not have a concept of dimensions. Building dimensions are calculated by specifying the building's aspect ratio. Aspect ratios of 1:1 or 2:1 are rare, and many distribution centers have a rectangular shape such as 3:2 or 4:3.

Item 2: Outer Walls, Pillars, and Firewalls

Pillars require strength (material, thickness, vertical and horizontal dimensions) to support the building, but in a multi-story distribution center, the walls also play a role in maintaining building strength (known as structural walls). Therefore, once built, the walls cannot be altered, such as by making openings.

In Tera Settings, the outer walls are 200mm, pillars are 700mm * 700mm for a 1-story building, increasing by 100mm per additional floor, with a pillar pitch of 10m.

The building's projected area calculation is based on the center of the outer wall thickness (if wall thickness is 200mm, it's 100mm inwards).

Modifying the Tera Settings for outer wall thickness, pillar span, and firewall thickness will reflect in the area calculations.

Item 3: Floors, Beams, and Elevation Dimensions

The 1st floor is a raised-floor style of 1,000mm, and the height above the floor for each story is 7,000mm. The floor height is calculated assuming a floor thickness + beam height of 1,000mm.

Item 4: Multi-Story and Eaves

Eaves are the rain-protection roofs installed at the receiving/shipping entrances of a distribution center. Buildings with 3 or more floors often have no eaves, and instead adopt a shape where trucks enter the building (referred to as a built-in berth type in Tera Calculation).

50% of the eaves area is added to the building's projected area, and Building Coverage Ratio = (Building Projected Area + Eaves Area * 50%) / Site Area.

Item 5: Emergency Staircases and Elevators

For buildings with 2 or more floors, the area for emergency staircases and elevators is added. In Tera Calculation, a firewall is installed for every 1,500m2 of the total building area, and a 1.5m wide emergency staircase and (2.3m * 2.3m freight elevator area * 1.5 sets) are added for every 1,500m2.

Item 6: Main Building / Separate Automated PL Warehouse

Normally, a distribution center is completed in a single building rather than multiple buildings. However, occasionally there is a case where the automated warehouse is built as a separate building using a rack-supported building (a building without pillars where wall and roof materials are attached to the rack components). Although rare, it impacts the site layout (especially the site aisle width), so we decided to incorporate it into Tera Calculation 2.

To increase ROI, automated warehouses have many tiers; when there are many tiers, the 2nd and 3rd floors become an atrium structure. A building structure without floors (atrium) is not ideal structurally or financially. When introducing an automated warehouse, whether to make it a separate building or integrate it into the distribution center (main building) is a matter worth considering.

Item 7: Calculation of 40 Building Type Patterns

The 40 building type patterns consist of: Separate Building Category 2 (Separate Building A and Separate Building B have the same area) * 5 Floors * 2 Eave Options * 2 Berth Faces = 40 combinations. The areas and key dimensions of these 40 patterns are calculated and compiled into a summary list (which can be exported to Excel). The Site Area screen obtains building information from this list.

Item 8: Building Specifications and Multi-Story Center Calculations

By changing settings such as the number of floors or presence of a separate building on the Building Area screen, you can see changes in the display of the vertical and horizontal dimensions of the building (main building), but this is a temporary display and is not reflected in the Site Area calculation. (The 40 Building Type Patterns calculation is used for the Site Area calculation).

Item 9: Main Building Floor Plan Dimensions

The dimensions of the building (main building) are displayed on the Building Area screen. You can change the vertical dimension to verify the horizontal dimension, but this is a temporary display and is not reflected in the Site Area calculation.

Item 10: Main Building Elevation Dimensions

Although not used in area calculations, vertical (height) dimensions are displayed to help form an image of the building.

Item 11: Separate Automated PL Warehouse Floor Plan/Elevation Dimensions

Diagrams and approximate dimensions of the Automated PL Warehouse (Rack Building) when adopting a separate building are provided.

Section 12: Site Area Calculation

This material explains the process of "Site Area Calculation", which determines the final land utilization in distribution center design, and the external environment (movement paths and legal regulations) that must be considered.

The focus is not only on the building scale, but also on how to secure truck movements, safe pedestrian paths, and legally mandated open spaces. The key points are summarized and explained below.

1. Securing Site Layout and Truck Movement Paths

When placing a building on a site, the most important aspect is the efficient and safe movement of vehicles.

Calculation of Truck Turning Paths: Spaces tailored to the characteristics of the receiving berths (mainly large trucks) and shipping berths (mainly a large volume of small trucks) are required.
Aisle Width Standards: An effective width of "Truck Turning Radius + minimum 1m" is deemed the bare minimum.
Securing Pedestrian Paths: In large centers, over 500 people may pass through in total, making it essential to secure safe walking routes that avoid interference with trucks.

2. Calculation of Building Coverage Ratio and Floor Area Ratio

Legal restriction values vary depending on the "Use Zone" where the facility is located. In Tera Settings, calculations generally use a Building Coverage Ratio of 60% and a Floor Area Ratio of 200% as standards.

Building Coverage Ratio Formula:
(Building Projected Area + Eaves Area × 50%) ÷ Site Area
Floor Area Ratio Formula:
(Total Floor Area + Virtual Floor Addition) ÷ Site Area

3. Other Necessary Spaces Within the Site

Besides the building and aisles, the following spaces must be secured on the site.

Vehicle/Waiting Related: Employee parking/bicycle parking, and waiting spaces for receiving trucks.
Environmental/Legal Restrictions: Securing open spaces such as "green spaces" mandated by local ordinances.

4. Variations in Layout Based on Building Configuration

Depending on the shape and efficiency of the site, simulations are performed by combining the following elements.

Number of Building Floors: How many stories to build relative to the land size.
Presence of Separate Building: Whether to place the automated warehouse (rack building) as a separate structure or incorporate it into the main building.
Berth Format: Whether to use a format extending rain-protective "eaves", or a "built-in building (built-in berth type)" format where trucks drive inside.
Berth Layout Faces: Whether trucks dock on 1 face or 2 or more faces.

Summary: The Complete Picture of Distribution Center Scale Calculation

Through the steps up to this point, all the following data has been gathered.

The required volume for "Receiving, Shipping, and Storage" derived from physical volume analysis.
The area of "each logistics space" calculated from operational and equipment studies.
The "building shape (width, depth, height)" from architectural specification studies.
The "required land area" from site studies.

With this, the process of logically deriving the scale of a "massive, visible facility" known as a distribution center from the "invisible numbers" of shipping data is complete.

When incorporating a building into a site layout, it is crucial to secure truck movement paths (truck turning aisles) simultaneously with the building coverage ratio and floor area ratio.

Receiving berths handle many large trucks, while shipping berths handle small trucks but tend to require a large number of berths. A truck aisle (effective width) = Truck Turning Aisle + 1m is the minimum requirement.

Besides truck paths, the site requires parking lots, bicycle parking, truck waiting spaces, and legally mandated green spaces. In particular, securing safe pedestrian paths (over 500 people passing through in large centers) that avoid interference with trucks is vital.

Item 1: Building Coverage Ratio and Floor Area Ratio

The building coverage ratio changes depending on the use zone (an area classification divided into 13 zones based on use to form a planned urban area). Since there are areas where construction is impossible, please verify using other publications.

The calculation is Building Coverage Ratio = (Building Projected Area + Eaves Area * 50%) / Site Area, and Floor Area Ratio = Total Floor Area (with virtual floor addition) / Site Area. Tera Settings calculate using a Building Coverage Ratio of 60% and a Floor Area Ratio of 200%.

Item 2: Number of Building Floors
Item 3: With/Without Separate Building
Item 4: Berth Eaves / Built-in Building
Item 5: 1 Berth Face / 2 Berth Faces

Section 13: Tera Calculation Layout Example

This material visually explains the "Layout Example and Operational Image", which represents the culmination of distribution center design. It summarizes how the numerical values calculated thus far are arranged and function within the actual building.

The key points are summarized and explained below.

1. Operational Flow and Principles of Inventory Management

The basic concepts for efficient operations are demonstrated.

Inventory Principles: Pallet (PL) storage is the standard, utilizing automated warehouses, motorized racks, and fixed racks as primary equipment. Loading methods employ both "Single Loads" (1 item per pallet) and "Mixed Loads" (multiple items).
Flow by Shipping Format:
- Case Shipping: Retrieved directly from the inventory area, sorted, and transported to the shipping area.
- Piece Shipping: Picked in the shipping operation area (flow racks/medium-duty racks). Items are appropriately replenished from the inventory area to these racks.
Inspection Operations: An "inspection-less" operation is basically assumed, enhancing efficiency by randomly sampling and inspecting only specific shipping destinations.

2. Optimization of Spatial Layout (Layout Diagram / 3D)

Based on the calculated areas, spatial utilization including the vertical dimension is proposed.

Office Placement: In addition to placing the office on a part of the 1st floor, the upper part of the 1st floor (mezzanine), which tends to become dead space, is actively utilized.
Area Guidelines: As an example, an arrangement allocating 50㎡ to the 1st-floor office and 150㎡ to the mezzanine is shown.
Visualization: Based on the calculated area data of logistics equipment, Tera Calculation 2 generates 3D image diagrams and layout plans, allowing users to intuitively grasp the scale of the completed facility.

3. Post-Creation Evaluation

After creating the layout and 3D images, the final evaluation step (Item 5) reconfirms the overlap of movement paths, operational efficiency, and compliance with legal restrictions.

Summary: The Goal of Distribution Center Scale Calculation

With this material, the entire process of deriving the physical appearance of a logistics center from shipping data is complete.

Data Analysis: Identify the required inventory and physical volume from shipping records.
Space Calculation: Calculate the areas for receiving, shipping, storage, and operations.
Building & Site Design: Determine the exterior shape by factoring in aspect ratio, number of floors, and truck movement paths.
Layout Creation: Place the equipment and create the final drawings/3D models, including mezzanine utilization.

Based on this design proposal, the process advances to the actual "Selection of Material Handling Equipment", "Detailed Architectural Design", or the "Final Judgment on Return on Investment".

Item 1: Tera Calculation Values

The video on the left is a 3D image conceptualizing the layout based on the logistics equipment areas from Tera Calculation 2_Distribution Center Scale Calculation.

Item 2: Flowchart

Inventory principle is PL storage. Main equipment: Automated PL Warehouses, Motorized Racks, and Fixed PL Racks. PL loading includes single and mixed loads.

Case shipping involves retrieval from the inventory area, sorting, and transport to the shipping area by destination.

Piece shipping involves picking in the shipping operation area, with replenishment from the inventory area to the flow racks and medium-duty racks in the shipping operation area.

Assumes inspection-less operation; specified shipping destinations are extracted for inspection.

Item 3: Layout Diagram

Item 4: 3D Image

The office is partially on the 1st floor, utilizing the upper area of the 1st floor (mezzanine) as much as possible.

Office: 1st floor 50㎡, Mezzanine 150㎡.