How Tall is a "Tall" Building??

What is a tall building? How is a building's height measured? What do terms like "supertall" and "mixed-use" actually mean? These and other questions are answered in the CTBUH Height Criteria, the official rules whereby tall buildings are defined and heights are measured.
What is a Tall Building?
There is no absolute definition of what constitutes a “tall building.” It is a building that exhibits some element of “tallness” in one or more of the following categories:
a) Height Relative to Context:                 It is not just about height, but about the context in which it exists. Thus, whereas a 14-story building may not be considered a tall building in a high-rise city such as Chicago or Hong Kong, in a provincial European city or a suburb this may be distinctly taller than the urban norm.
b) Proportion Again, a tall building is not just about height but also about proportion. There are numerous buildings that are not particularly high, but are slender enough to give the appearance of a tall building, especially against low urban backgrounds. Conversely, there are numerous big/large footprint buildings that are quite tall but their size/floor area rules them out as being classed as a tall building.
c) Tall Building Technologies:         If a building contains technologies which may be attributed as being a product of “tall” (e.g., specific vertical transport technologies, structural wind bracing as a product of height, etc.), then this building can be classed as a tall building. Although number of floors is a poor indicator of defining a tall building due to the changing floor to floor height between differing buildings and functions (e.g., office versus residential usage), a building of perhaps 14 or more stories – or more than 50 meters (165 feet) in height – could perhaps be used as a threshold for considering it a “tall building.”
What are Supertall and Megatall Buildings? The CTBUH defines “supertall” as a building over 300 meters (984 feet) in height, and a “megatall” as a building over 600 meters (1,968 feet) in height. As of June 2015 there were 91 supertall and 2 megatall buildings fully completed and occupied globally.
How is the Height of a Tall Building Measured?
The Council on Tall Buildings and Urban Habitat (CTBUH) recognizes tall building height in three categories:
1. Height to Architectural Top: Height is measured from the level1 of the lowest, significant,2 open-air,3 pedestrian4 entrance to the architectural top of the building, including spires, but not including antennae, signage, flag poles or other functional-technical equipment.5 This measurement is the most widely utilized and is employed to define the CTBUH rankings of the "World's Tallest Buildings."
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2. Highest Occupied Floor: Height is measured from the level1 of the lowest, significant,2 open-air,3 pedestrian4 entrance to the finished floor level of the highest occupied6 floor within the building.
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3. Height to Tip: Height is measured from the level1 of the lowest, significant,2 open-air,3 pedestrian4 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).
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Footnotes: 1 Level:  finished floor level at threshold of the lowest entrance door. 2 Significant:  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 that 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. 3 Open-air: the entrance must be located directly off an external space at that level that is open to air. 4 Pedestrian: refers to common building users or occupants and is intended to exclude service, ancillary, or similar areas. 5 Functional-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). 6 Highest 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.
Number of Floors The number of floors 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).
Criteria for Co-joined Buildings A building complex is considered to be a single, co-joined building (as opposed to two separate buildings connected by skybridges or other elements) when 50 percent or more of the total building height is connected. Exceptions to this 50 percent rule can be made in cases where the form of the building creates a coherent arch, creating a singular architectural expression and thus a co-joined building – to be judged by the CTBUH Height Committee.
Building Usage Building vs. Telecommunications Tower: A tall “building” can be classed as such (as opposed to a telecommunications/observation tower) and is eligible for the "Tallest” lists if at least 50 percent of its height is occupied by usable floor area.		To enlarge, click here
Single-function and mixed-use buildings
A single-function tall building is defined as one where 85 percent or more of its total floor area is dedicated to a single use. A mixed-use tall building contains two or more functions (or uses), where each of the functions occupies a significant proportion7 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” lists in descending order (e.g., “hotel/office” indicates hotel function above office function).		To enlarge, click here
Footnote: 7This “significant proportion” can be judged as 15 percent 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 percent rule, though this would clearly constitute mixed-use.
Building Status
Complete (Completion) A building is considered to be "Complete" (and officially added to the CTBUH Tallest Buildings lists) if it fulfills all of the following three criteria: 1) Topped out structurally and architecturally8 2) Fully-clad9 3) Open for business, or at least partially occupiable  Footnotes: 8The topping out architecturally of a building implies that ALL structural and finished architectural elements are in place. 9The omission of a small number of cladding panels to allow fixing of a construction hoist while interior fit-out of some building areas is continuing does not affect the status of “fully clad.” Under Construction (Start of Construction) A building is considered to be "Under Construction" once site clearing has been completed and foundation/piling work has begun. Structurally Topped Out A building is considered to be "Structurally Topped Out" when it is under construction, and the highest primary structural element is in place. Architecturally Topped Out A building is considered to be "Architecturally Topped Out" when it is under construction, and has reached its full height both structurally and architecturally (e.g., including its spires, parapets, etc.). On Hold A building is considered to be "On Hold" when construction works had begun, but work on-site has been halted  indefinitely, however there is still an intent to complete the construction to the original design at a future date. Never Completed A building is considered to be “Never Completed” when construction works had begun, but work on-site was halted and never resumed. The site may go on to accommodate a new building, different to the original design, that may or may not retain the original construction. Proposed A building is considered to be "Proposed" (i.e., a real proposal) when it fulfills all of the following criteria: 1) Has a specific site with ownership interests within the building development team 2) Has a full professional design team progressing the design beyond the conceptual stage 3) Has obtained, or is in the process of obtaining, formal planning consent/legal permission for construction 4) 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. The source of the announcement must also be credible. Due to the changing nature of early stage designs and client information restrictions, some height data for proposals may be unconfirmed. Vision A building is considered to be a "Vision" when it either: 1) Is in the early stages of inception and does not yet fulfill the criteria under the “proposal” category, or 2) Was a proposal that never advanced to the construction stages, or 3) Was a theoretical proposition Demolished A building is considered to be "Demolished" after it has been destroyed by controlled end-of-life demolition, fire, natural catastrophe, war, terrorist attack, or through other means intended or unintended.
Structural Material
A steel tall building is defined as one 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 and 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. This post originally appeared on CTBUH.

THE UNDERMINED IDEA : ECO FRIENDLY BUILDING MATERIALS


ECO-FRIENDLY BUILDING MATERIALS

Today many people that are building or remodeling their houses choose to use eco-friendly building materials. An eco-friendly building material is one that increases the efficiency of energy used and reduces impact on human well-being and the environment. There are many different materials that can be used that are eco-friendly; from foundation, to insulation, to interior and exterior wall finishes, flooring, and countertop materials.

Categorization of Materials

Categorized based on Activity and Vendor Specific

1. Civil materials

2. Water-proofing and Chemical additives

3. Paving, flooring, dado and similar finishes

4. Paints, colors, white washing, distempering and wood finishes

5. Wood work

6. Roofing and ceiling

7. Doors and windows

8. Water supply and sanitary fittings

9. Electrical works

10. Fire fighting system

11. Miscellaneous

12. Excavation work

13. Road works

Evaluating Eco-friendly Materials

Why eco-friendly materials?

· Phenomenal growth in the construction industry that depends upon depletable resources.

· Production of building materials leads to irreversible environmental impacts.

· Using eco-friendly materials is the best way to build a eco-friendly building.

Stone quarrying leads to eroded hills, like this picture showing the site of makarana marble quarry, brick kilns in the fringes of the city lead to denudation of topsoil, dredging for sand damage the river biodiversity etc.

What is Eco-friendly material ?

· Dictionary: describes a product that has been designed to do the least possible damage to the environment

· US EPA – EPP program defines as:
“…products or services that have a lesser or reduced effect on human health and the environment when compared with competing products or services that serve the same purpose…”

Thus we talk of two issues – one that it does the least possible environmental damage and two that it is a comparative scale as there are very few materials that are completely eco-friendly.

One more point to note when we talk of eco-friendly construction is that it consist of two parts – Material and Technique.

A material by itself can be eco-friendly, e.g. Bamboo.

Or Even conventional materials can become eco-friendly based on the construction technique that is used. e.g. rat trap bond developed by Lauri Baker, which require less number of bricks and are more heat insulating than normal walls and therefore eco-friendly.

Properties

The various properties of the Eco-friendly materials and techniques are –

Materials can be eco-friendly also if they can assist in reduction of the energy used in the building during operation and maintenance.

it is difficult to get a material that has all these properties, and it thus becomes a comparative assessment to identify eco-friendly materials.

Source of Material

a. Renewable source

Rapidly renewable sources e.g. wood from certified forests

b. Reuse of Waste

Salvaged products –e.g. old plumbing, door frames

Recycled contents – agriculture/ industrial waste e.g. Bagasse Board

Embodied Energy

Scalar total of energy input required to produce the product including transporting them to the building site

Aluminium and steel has the most embodied energy because to the high energy required to produce them. Compared to timber that requires very less energy for production.

Reduce Pollution

Air Pollution- Use of materials with low VOC emissions e.g. Cement Paints

Water Pollution – Materials that prevent leaching.

Land Pollution- Materials that reuse waste that would otherwise have resulted in landfill. e.g. Flyash Bricks.

Performance

Reduce material use

These are energy efficient and also help reduce the dead load of a building. e.g. Ferrocement

Durability & Life Span

Material that are exceptionally durable, or require low maintenance e.g PVC pipes.

Materials can be eco-friendly based on how they perform. Use of certain material or techniques can reduce the amount of material required.

Durability – The longer the life of a material the lesser it is required to replace and thus reduces the quantity required to produce.

Energy Conservation

Materials that require less energy during construction e.g. precast slabs.

Materials that help reduce the cooling loads- e.g – aerated concrete blocks.

Products that conserve energy – e. g. CFL lamps.

Fixtures & equipments that help conserve water e.g. Dual flush cisterns

Recyclable

Reuse or Recycle as different product e.g. steel, aluminum.

Biodegradable – that decompose easily e.g wood or earthen materials.

Eco-friendly Materials

Conventional Eco-friendly materials

1. Bamboo, Bamboo Based Particle Board & Ply Board, Bamboo Matting

2. Bricks sun dried

3. Pre-cast cement concrete blocks, lintels, slab. Structural and non-structural modular elements

4. Calcined Phospho-Gypsum Wall Panels

5. Calcium silicate boards and Tiles

6. Cellular Light Weight Concrete Blocks

7. Cement Paint

8. Clay roofing tiles

9. Water, polyurethane and acrylic based chemical admixtures for corrosion removal, rust prevention, water proofing

10. Epoxy Resin System, Flooring, sealants, adhesives and admixtures

11. Ferro-cement boards for door and window shutters

12. Ferro-cement Roofing Channels

13. Fly-ash Sand Lime Bricks and Paver Blocks

14. Gypsum Board, Tiles, Plaster, Blocks, gypsum plaster fibre jute/sisal and glass fibre composites

15. Laminated Wood Plastic Components

16. Marble Mosaic Tiles

17. MDF Boards and Mouldings

18. Micro Concrete Roofing Tiles

19. Particle Boards

20. Polymerised water proof compound

21. Polymerised water proof compound

22. Portland Pozzolana Cement Fly-ash / Calcinated Clay Based

23. Portland Slag Cement

24. RCC Door Frames

25. Ready Mix Cement Concrete

26. Rubber Wood Finger Joint Board

27. Stone dust

28. Water proof compound, adhesive, Polymer, Powder

Potential Eco-friendly materials & techniques

1. Bagasse Board – BMTPC

2. Bricks from Coal Washery Rejects -CBRI, Roorkee

3. Building Blocks From Mine Waste – SERC

4. Burnt Clay FlyAsh Bricks – CBRI, Roorkee

5. Coir Cement Board – CBRI, Roorkee

6. Compressed Earth Blocks – BMTPC

7. EPS Composites and Door Shutters -CBRI, Roorkee

8. Fibre Flyash Cement Boards -BMTPC

9. Fibre Reinforced Concrete Precast Elements, Wall panels, Blocks, Manhole Covers – SERC

10. Fibrous Gypsum Plaster Boards – CBRI, Roorkee

11. Flyash Cellular Concrete, Flyash Cement Brick, Blocks – BMTPC

12. Flyash Lime Cellular Concrete – CBRI, Roorkee

13. Flyash Lime Gypsum Brick – BMTPC

14. Insulating Bricks from Rice Husk Ash- Central Glass and Ceramic Research Institute, Kolkata

15. Jute Fibre Polyester -BMTPC

16. Non Erodable Mud Plaster – CBRI, Roorkee

17. Polytiles – CBRI, Roorkee

18. Timber from trees such as Poplar, Rubber, Eucalyptus – BMTPC

19. Precast walling roofing components – CBRI, Roorkee

20. Prefab Brick Panel System – CBRI, Roorkee

Recommended eco-friendly alternatives

1. Structural System –

Alternatives to Cement Concrete (plain / reinforced) – cement, sand, aggregate, steel

Base Materials for R.C.C. and Steel Systems

a. Pozzolana Material content (Fly-ash / Slag / Calcinated Clay) attained through use of Blended Portland Cement (BPC) and /or direct addition of pozzolana material

b. Sand and aggregate from pulverized debris and /or sintered fly-ash for concrete and mortar

c. Recycled steel forms and reinforcement bars

Alternatives Systems

a. Ferro cement and

b. Pre-cast components for columns, beams, slabs, lofts, balconies, roofs etc.

c. Ready Mix Concrete

d. Use Resinous curing agents

2. Masonry

Alternatives to Fired clay bricks, cement concrete blocks, stone

a. Use of Fly ash + sand + lime bricks / blocks

b. Pulverized debris + cement bricks / blocks,

c. Industrial waste based bricks / blocks,

d. Aerated lightweight BPC concrete blocks,

e. Phospho-Gypsum based blocks

f. Lato blocks (laterite + cement)

3. Mortar

a. Sand from pulverized debris and / or sintered flyash

b. Pozzolana Material content

4. Plastering – Alternatives to Cement, sand, plaster of paris, gypsum

a. Calcium Silicate Plaster

b. Cement Plaster

c. Use of Fiber reinforced clay plaster

d. Phospho-Gypsum Plaster

e. Non-erodable Mud Plaster

f. Use Resinous curing agents

5. Roofing and ceiling- Alternatives to Ferrous / non-ferrous sheets, tiles, thatch

a. Fibre Reinforced Polymer Plastics instead of PVC and Foam PVC, Polycarbonates, acrylics & plastics

b. Micro Concrete Roofing Tiles

c. Bamboo Matt Corrugated Roofing Sheets

6. Flooring, paving and road work –Alternatives to wood, stone, ceramics, concrete

a. Fly ash / industrial waste / pulverized debris blocks in BPC

b. Lime-pozzolana concrete paving blocks for all outdoor paving.

c. Bedding sand from pulverized debris

7. Tiles for interiors

a. Terrazzo floor for terraces and semi covered areas

b. Ceramic tiles (non-vitrified)

c. Mosaic Tiles/ Terrazzo Flooring

d. Cement Tiles

e. Phospho-Gypsum Tiles

f. Bamboo Board Flooring

8. Windows, Doors and openings –

Steel, aluminum, timber, glass, R.C.C., PVC, Stone

a. Ferro cement and Pre-cast R.C.C. lintel, chajja and jalis

b. Masonry bond combinations for jali work

Alternatives to Timber and Aluminum / Steel frames

a. Ferrocement

b. Pre-cast R.C.C. Frames/ Frameless Doors

c. Bamboo Reinforced Concrete Frames

d. Hollow recycled steel channels and recycled Aluminium Channels and Components

Shutters and Panels – alternatives to timber, plywood, glass, aluminum

a. Red Mud based Composite door shutters,

b. Laminated Hollow Composite Shutters

c. Other wood alternatives

9. Electrical

Alternatives for Aluminum, brass, PVC, G.I., S.S.

a. Use unplasticised PVC or HDPE products

b. Where applicable use products with recycled aluminum and brass components

10. Water supply, Sanitary and Plumbing System

a. R.C.C., uPVC, G.I., C.I. pipes instead of lead, A.C. pipes

b. Where applicable use products with recycled aluminum and brass components for fittings, fixtures and accessories

c. Use Polymer Plastic (Random) hot / cold water system instead of G.I.

d. Manholes and covers – use Pre-cast cement concrete and high strength unplasticised PVC instead of C.I.

11. Wood

Renewable timber from plantations with species having not more than 10 year cycle or timber from a government certified forest / plantation or timber from salvaged wood

Plywood should be phenol bonded and not urea bonded

Use of MDF Board

Instead of Plywood:

Bamboo Ply/Mat Board/ Fibre Reinforced Polymer Board,/ Bagasse Board /Coir Composite Board /Bamboo mat Veneer Composite/ Finger Jointed Plantation Timber Board / Recycled Laminated Tube Board / Aluminium-Foil+Paper+Plastic Composite Board.

e. Use of Mica Laminates and Veneer on Composite boards instead of natural timber.

12. Water proofing chemicals, additives, sealants and adhesives

a. Use of water based chemicals instead of solvent based.

b. Epoxy resins instead of tar felt / pitch

13. Painting, Polishing, Priming and similar surface finishing

a. Use of Cement Paint / Epoxy Resin Paint for external surfaces

b. Use of Water based paints, enamels, primers and polishes

Faswal is a great alternative to traditional foundation materials. It uses waste materials from wood mixed with cement to create a strong and durable foundation material. Faswal can be used instead of cinder blocks and is excellent for bottom foundation and wall construction. It is naturally strong, fire and wind and sound resistant, and has excellent insulating factors.

Two great choices for insulation are straw bale and cotton. Straw bale is used for many reasons; it is generally less expensive than other forms of insulation and has great insulating factors. It is very durable and can easily support a lot of weight; additional supports are not usually needed, which cuts down on the use of treated lumber

Cotton insulation is a good alternative to fiber glass insulation. This type of insulation is derived from natural cotton fibers that are recycled into insulation. It is very convenient and comes in a similar batting shape as traditional insulation. It is also very easy and safe to install and has a high fire rating and wonderful sound insulating qualities.

Earth plaster and milk paints are excellent eco-friendly choices for building materials. Earth plaster is made out of mud and can be used as an interior or exterior finish. You can manipulate the plaster to create various finishes; including curves, angles, and clean finished walls. It does not need to be painted, as it comes in a variety of colors that are natural to the mud.

Milk paints are made up of milk earth and pigments from the earth in a variety of colors. Milk paints provide for a wide variety of colors without the use of harsh chemicals that are found in traditional house paints.

There are some great choices for eco-friendly flooring; cork flooring, bamboo, and recycled wood flooring are all excellent options. Cork flooring is a great alternative to wood; it is environmentally friendly; it only uses the bark from the tree and does not kill the tree as a result from harvest. The bark is a great renewable resource as it grows back completely within nine years. Cork flooring is very comfortable, durable, and insulating, and can last for many years.

Bamboo is another great choice for a renewable resource. Bamboo is not a wood at all, but rather a grass that only takes three years to fully mature. When processed, bamboo can have an attractive appearance similar to wood flooring. It is a very strong and durable type of flooring and performs very much like a traditional hardwood floor.

If you are determined to have wood floors, recycled wood flooring is a great option. This type of flooring often uses hardwood that would otherwise never be used again. The wood may be taken from demolition sites or trees that were torn down but never used. It is often cheaper to prepare recycled wood instead of new wood product and is just as beautiful and durable as new wood.

There are even materials for countertops that are eco-friendly. Two great choices are recycled glass/cast concrete and recycled plastic. Recycled glass/cast concrete uses both recycled glass and concrete with recycled materials in it. The glass used in this material can not be broken down any further, so it is a good fit for countertop construction. It can also be used in the bathroom and surrounding fireplaces.

Recycled plastic is another good option for countertops. You can obtain many different styles using different types of recycled plastic. It can also be used in bathrooms and other places around the home. It is very durable and can stand up to heat, depending on how it is manufactured, and is very water resistant.

There are many different eco-friendly building materials available on the market today. You can virtually build and furnish an entire home from only eco-friendly materials. Eco-friendly materials are not only good for the Earth, but are equally good for your wallet. Many of the building materials that are eco-friendly have great insulating factors or are cheaper to produce than traditional materials.

This post originally appeared on theconstructor.org