Council on Tall Buildings and Urban Habitat
 

CTBUH Database Terminology Definitions
Below are the terms used within the CTBUH Tall Building Database, together with their respective definitions.
Official Name
The official building name refers to the current legal building name. 

Former / Other Name
The term Former / Other Name refers to other names the building has commonly been known as, including former names, common informal names, local names, etc.

Type
CTBUH collects data on two major types of tall structures: “Buildings” and “Telecommunications / Observation Towers.”  A “Building” is a structure where at least 50% of the height is occupied by usable floor area. A “Telecommunications / Observation Tower” is a structure where less than 50% of the structure’s height is occupied by usable floor area. Only “Buildings” are eligible for the CTBUH “Tallest Buildings” lists.

Status
The CTBUH recognizes seven types of building status: Vision, Proposed, Unbuilt, Construction Stopped, Under Construction, Completed and Demolished.

Country
The CTBUH follows the United Nations’ definition of Country, and thus uses the lists and codes established by that organization.

City
The CTBUH follows the United Nations’ definition of City, and thus uses the lists and codes established by that organization.

Street Address
Street Address includes the street number and name, and is used to help determine the exact location of the project.

Building Function
A single-function tall building is defined as one where 85% or more of its usable floor area is dedicated to a single usage. Thus a building with 90% office floor area would be said to be an “office” building, irrespective of other minor functions it may also contain.

A mixed-use tall building contains two or more functions (or uses), where each of the functions occupy a significant proportion1 of the tower’s total space. Support areas such as car parks and mechanical plant space do not constitute mixed-use functions. Functions are denoted on CTBUH “Tallest Building” lists in descending order, e.g., “hotel/office” indicates hotel function above office function.

Structural Material
A steel tall building is defined as a building where the main vertical and lateral structural elements and floor systems are constructed from steel.
A concrete tall building is defined as one where the main vertical and lateral structural elements and floor systems are constructed from concrete.
A composite tall building utilizes a combination of both steel and concrete acting compositely in the main structural elements, thus including a steel building with a concrete core.
A mixed-structure tall building is any building that utilizes distinct steel or concrete systems above or below each other. There are two main types of mixed structural systems: A steel/concrete tall building indicates a steel structural system located above a concrete structural system, with the opposite true of a concrete/steel building.

Additional Notes:
1) If a tall building is of steel construction with a floor system of concrete planks on steel beams, it is considered a steel tall building.
2) If a tall building is of steel construction with a floor system of a concrete slab on steel beams, it is considered a steel tall building.
3) If a tall building has steel columns plus a floor system of concrete beams, it is considered a composite tall building.

Vision
A building design is said to be a Vision when it was conceived as a primarily theoretical design, with little or no plans of it ever be constructed.

Proposed
A building design is said to be proposed when it fulfills all of the following criteria:
1) Has a specific site
2) Has a developer/financier who owns the site
3) Has a full professional design team who are in the process of progressing the design beyond the conceptual stage
4) Has a dialogue with the local planning authorities with a view to obtaining full legal permission for construction
5) Has a full intention to progress the building to construction and completion

Only buildings that have been announced publicly by the client and fulfill all the above criteria are included in the CTBUH “proposed” building listings. Due to the changing nature of early stage designs and client information restrictions, some height data for “proposed” tall buildings that appears on the CTBUH “Tallest” lists is unconfirmed.

Unbuilt
A building design is said to be Unbuit when it was at one time considered a proposal or under construction, but was then permanently canceled.

Construction Stopped
A building project is given the status of Construction Stopped when construction has begun, but the project is currently on hold.

Under Construction (Start of Construction)
A building project is considered to be Under Construction when site clearing has been completed and foundation/piling work has begun.

Topped Out
A building project is considered to be Topped Out when a building has reached its final architectural height.

Complete (Completion)
A building is considered to be Complete – and added to the “Tallest Building” lists – if it fulfills all of the following three criteria:
1) topped out structurally and architecturally
2) fully-clad
3) open for business, or at least partially occupied

Demolished
A building is said to be demolished when a previously completed building is destroyed, dismantled, or otherwise removed.

Alteration/Recladding
A building is said to have undergone an alteration/recladding when a significant architectural alteration has occurred to an existing, completed building (this includes additions, partial demolitions, full building recladding, etc.).

Global Ranking
Global Ranking refers to a project’s height ranking against all buildings globally (according to architectural top) within its particular building type (Building or Telecommunications/Observation Tower).

Regional Ranking
Regional Ranking refers to a project’s height ranking against all buildings regionally (according to architectural top) within its particular building type (Building or Telecommunications/Observation Tower). Recognized regions of the world are Africa, Asia, Central America, Europe, Middle East, North America, Oceania and South America.

National Ranking
National Ranking refers to a building’s height ranking against all buildings nationally (according to architectural top) within its particular building type (Building or Telecommunications/Observation Tower).

City Ranking
City Ranking refers to a project’s height ranking against all buildings in that particular city (according to architectural top) within its particular building type (Building or Telecommunications/Observation Tower).

Official Website
Official Website refers to a building’s official webpage, generally created and maintained by the building owner or manager.

Height: Architectural
Height is measured from the level2 of the lowest, significant,3 open-air,4 pedestrian5 entrance to the architectural top of the building, including spires, but not including antennae, signage, flag poles or other functional-technical equipment.6  This measurement is the most widely utilized and is employed to define the Council on Tall Buildings and Urban Habitat (CTBUH) rankings of the “World’s Tallest Buildings.”

Height: Occupied Floor
Height is measured from the level2 of the lowest, significant,3 open-air,4 pedestrian5 entrance to the highest occupied7 floor within the building.

Height: to Tip
Height is measured from the level2 of the lowest, significant,3 open-air,4 pedestrian5 entrance to the highest point of the building, irrespective of material or function of the highest element (i.e., including antennae, flagpoles, signage and other functional-technical equipment).

Height: Observatory
Height, measured from the level2 of the lowest, significant,3 open-air,4 pedestrian5 entrance, to the building’s public observatory (which may be either internal or external).

Number of Floors Above Ground
The number of floors above ground should include the ground floor level and be the number of main floors above ground, including any significant mezzanine floors and major mechanical plant floors. Mechanical mezzanines should not be included if they have a significantly smaller floor area than the major floors below. Similarly, mechanical penthouses or plant rooms protruding above the general roof area should not be counted. Note: CTBUH floor counts may differ from published accounts, as it is common in some regions of the world for certain floor levels not to be included (e.g., the level 4, 14, 24, etc. in Hong Kong).

Number of Floors Below Ground
The number of floors below ground should include all major floors located below the ground floor level.

Number of Elevators
Number of Elevators refers to the total number of elevator cars (not shafts) contained within a particular building (including public, private and freight elevators).

Top Elevator Speed
Top Elevator Speed refers to the top speed capable of being achieved by an elevator within a particular building, measured in meters per second.

Tower Gross Floor Area (GFA)
Tower GFA refers to the total gross floor area within the tower footprint, not including adjoining podiums, connected buildings or other towers within the development.

Development Gross Floor Area (GFA)
Development GFA refers to the total gross floor area within the entire development in which the tower exists, and may therefore be at times the total sum of several towers and related low-rise buildings.

Number of Apartments
Number of Apartments refers to the total number of residential units (including both rental units and condominiums) contained within a particular building.

Number of Hotel Rooms
Number of Hotel Rooms refers to the total number of hotel rooms contained within a particular building.

Number of Parking Spaces
Number of Parking Spaces refers to the total number of car parking spaces contained within a particular building.

Current Owner
Current Owner refers to the organization(s) that is the current legal owner of a building.

Original Owner
Original Owner refers to the organization(s) that was the legal owner of a building at the time of its original completion.

Developer
Developer refers to the organization(s) that oversaw and coordinated the original planning, designing, financing, and construction of a building.

Design Architect
Design Architect refers to the primary organization(s) responsible for the architectural design of a building.

Associate Architect
Associate Architect refers to the organization(s) responsible for the completion of technical drawings and design details necessary for the realization of a building.

Structural Engineer
Structural Engineer refers to the organization(s) responsible for the design of the primary structural systems of a building.

MEP Engineer
MEP Engineer refers to the organization(s) responsible for the design of the mechanical, electrical and plumbing systems within a building.

Project Manager
Project Manager refers to the organization(s) responsible to manage a given building project through the design and/or the construction phase.

Main Contractor
Main Contractor refers to the primary organization(s) responsible for the construction of a building.

Other Consultant

Other Consultant refers to other organizations which provided significant consultation services for a building project (e.g. wind consultants, environmental consultants, fire and life safety consultants, etc).

Material Supplier

Material Supplier refers to organizations which supplied significant systems/materials for a building project (e.g. elevator suppliers, façade suppliers, etc).


Footnotes:
1This “significant proportion” can be judged as 15% or greater of either: (1) the total floor area, or (2) the total building height, in terms of number of floors occupied for the function. However, care should be taken in the case of supertall towers. For example a 20-story hotel function as part of a 150-story tower does not comply with the 15% rule, though this would clearly constitute mixed-use.
2Level:  finished floor level at threshold of the lowest entrance door.
3Significant:  the entrance should be predominantly above existing or pre-existing grade and permit access to one or more primary uses in the building via elevators, as opposed to ground floor retail or other uses which solely relate/connect to the immediately adjacent external environment. Thus entrances via below-grade sunken plazas or similar are not generally recognized. Also note that access to car park and/or ancillary/support areas are not considered significant entrances.
4Open-air: the entrance must be located directly off of an external space at that level that is open to air.
5Pedestrian: refers to common building users or occupants and is intended to exclude service, ancillary, or similar areas.
6Functional-technical equipment: this is intended to recognize that functional-technical equipment is subject to removal/addition/change as per prevalent technologies, as is often seen in tall buildings (e.g., antennae, signage, wind turbines, etc. are periodically added, shortened, lengthened, removed and/or replaced).
7Highest occupied floor: this is intended to recognize conditioned space which is designed to be safely and legally occupied by residents, workers or other building users on a consistent basis. It does not include service or mechanical areas which experience occasional maintenance access, etc.