Editing Skyscraper (section)

==Environmental impact==
{{Further|Bird-skyscraper collisions}}
{{more citations needed section|date=January 2017}}
[[File:30_St_Mary_Axe_from_Leadenhall_Street.jpg|thumb|274x274px|[[The Gherkin]] in London is an example of a modern environmentally friendly skyscraper.]]
Constructing a single skyscraper requires large quantities of materials like steel, concrete, and glass, and these materials represent significant [[embodied energy]]. Skyscrapers are thus material and energy intensive buildings.

Skyscrapers have considerable mass, requiring a stronger foundation than a shorter, lighter building. In construction, building materials must be lifted to the top of a skyscraper during construction, requiring more energy than would be necessary at lower heights. Furthermore, a skyscraper consumes much electricity because [[potable]] and non-potable water have to be pumped to the highest occupied floors, skyscrapers are usually designed to be [[HVAC|mechanically ventilated]], elevators are generally used instead of stairs, and electric lights are needed in rooms far from the windows and windowless spaces such as elevators, bathrooms and stairwells.

Skyscrapers can be artificially lit and the energy requirements can be covered by [[renewable energy]] or other electricity generation with low [[greenhouse gas emissions]]. Heating and cooling of skyscrapers can be efficient, because of centralized [[HVAC]] systems, heat radiation blocking [[window]]s and small surface area of the building. There is [[Leadership in Energy and Environmental Design]] (LEED) certification for skyscrapers. For example, the Empire State Building received a gold Leadership in Energy and Environmental Design rating in September 2011 and the Empire State Building is the tallest LEED certified building in the United States,<ref>{{cite web |url=http://inhabitat.com/nyc/empire-state-building-achieves-leed-gold-certification/ |first=Jessica |last=Dailey |title=Empire State Building Achieves LEED Gold Certification |work=Inhabitat.com |date=14 September 2011 |access-date=30 July 2013 |archive-date=28 June 2017 |archive-url=https://web.archive.org/web/20170628192334/http://inhabitat.com/nyc/empire-state-building-achieves-leed-gold-certification/ |url-status=dead }}</ref> proving that skyscrapers can be environmentally friendly. [[The Gherkin]] in [[London]], the [[United Kingdom]] is another example of an environmentally friendly skyscraper.{{citation needed|date=December 2023}}

In the lower levels of a skyscraper a larger percentage of the building floor area must be devoted to the building structure and services than is required for lower buildings:
* More structure – because it must be stronger to support more floors above
* [[Skyscraper design and construction#The elevator conundrum|The elevator conundrum]] creates the need for more lift shafts—everyone comes in at the bottom and they all have to pass through the lower part of the building to get to the upper levels.
* [[Building services]] – power and water enter the building from below and have to pass through the lower levels to get to the upper levels.

In low-rise structures, the support rooms ([[chiller]]s, [[transformer]]s, [[boiler]]s, [[pump]]s and [[air handling unit]]s) can be put in basements or roof space—areas which have low rental value. There is, however, a limit to how far this plant can be located from the area it serves. The farther away it is the larger the risers for ducts and pipes from this plant to the floors they serve and the more floor area these risers take. In practice this means that in highrise buildings this plant is located on 'plant levels' at intervals up the building.

===Operational energy===

The building sector accounts for approximately 50% of greenhouse gas emissions, with operational energy accounting for 80-90% of building related energy use.<ref name=":2">{{Cite journal|last1=Saroglou|first1=Tanya|last2=Meir|first2=Isaac A.|last3=Theodosiou|first3=Theodoros|last4=Givoni|first4=Baruch|date=August 2017|title=Towards energy efficient skyscrapers|url=http://dx.doi.org/10.1016/j.enbuild.2017.05.057|journal=Energy and Buildings|volume=149|pages=437–449|doi=10.1016/j.enbuild.2017.05.057|bibcode=2017EneBu.149..437S |issn=0378-7788|url-access=subscription}}</ref> Operational energy use is affected by the magnitude of conduction between the interior and exterior, convection from infiltrating air, and radiation through [[Glazing (window)|glazing]]. The extent to which these factors affect the operational energy vary depending on the [[microclimate]] of the skyscraper, with increased wind speeds as the height of the skyscraper increases, and a decrease in the [[Dry-bulb temperature|dry bulb temperature]] as the altitude increases.<ref name=":2" /> For example, when moving from 1.5 meters to 284 meters, the dry bulb temperature decreased by 1.85&nbsp;°C while the wind speeds increased from 2.46 meters per seconds to 7.75 meters per second, which led to a 2.4% decrease in summer cooling in reference to the [[Freedom Tower]] in New York City. However, for the same building it was found that the annual energy use intensity was 9.26% higher because of the lack of shading at high altitudes which increased the cooling loads for the remainder of the year while a combination of temperature, wind, shading, and the effects of reflections led to a combined 13.13% increase in annual energy use intensity.<ref>{{Cite journal|last=Ellis|first=Peter|date=15 August 2005|title=Simulating Tall Buildings Using EnergyPlus|url=https://www.nrel.gov/docs/fy05osti/38133.pdf|journal=National Renewable Energy Laboratory}}</ref>

In a study performed by Leung and Ray in 2013, it was found that the average [[energy use intensity]] of a structure with between 0 and 9 floors was approximately 80 kBtu/ft/yr, while the energy use intensity of a structure with more than 50 floors was about 117 kBtu/ft/yr. Refer to Figure 1{{where|date=January 2025}} to see the breakdown of how intermediate heights affect the energy use intensity. The slight decrease in energy use intensity over 30-39 floors can be attributed to the fact that the increase in pressure within the heating, cooling, and water distribution systems levels out at a point between 40 and 49 floors and the energy savings due to the microclimate of higher floors are able to be seen.<ref name=":3">{{Cite journal|last=Leung|first=Luke|date=December 2013|title=Low-energy Tall Buildings? Room for Improvement as Demonstrated by New York City Energy Benchmarking Data|journal=International Journal of High-Rise Buildings|volume=2|s2cid=6166727}}</ref>  There is a gap in data in which another study looking at the same information but for taller buildings is needed.

====Elevators====

A portion of the operational energy increase in tall buildings is related to the usage of elevators because the distance traveled and the speed at which they travel increases as the height of the building increases. Between 5 and 25% of the total energy consumed in a tall building is from the use of [[elevator]]s. As the height of the building increases it is also more inefficient because of the presence of higher drag and friction losses.<ref>{{Cite journal|last=Sachs|first=Harvey|date=April 2005|title=Opportunities for Elevator Energy Efficiency Improvements|url=https://www.aceee.org/sites/default/files/pdf/white-paper/elevators2005.pdf|journal=American Council for an Energy-Efficient Economy}}</ref>

===Embodied energy===

The [[embodied energy]] associated with the construction of skyscrapers varies based on the materials used. Embodied energy is quantified per unit of material. Skyscrapers inherently have higher embodied energy than low-rise buildings due to the increase in material used as more floors are built. Figures 2 and 3{{where|date=January 2025}} compare the total embodied energy of different floor types and the unit embodied energy per floor type for buildings with between 20 and 70 stories. For all floor types except for steel-concrete floors, it was found that after 60 stories, there was a decrease in unit embodied energy but when considering all floors, there was exponential growth due to a double dependence on height. The first of which is the relationship between an increase in height leading to an increase in the quantity of materials used, and the second being the increase in height leading to an increase in size of elements to increase the structural capacity of the building. A careful choice in building materials can likely reduce the embodied energy without reducing the number of floors constructed within the bounds presented.<ref>{{Cite journal|last1=Foraboschi|first1=Paolo|last2=Mercanzin|first2=Mattia|last3=Trabucco|first3=Dario|date=January 2014|title=Sustainable structural design of tall buildings based on embodied energy|url=http://dx.doi.org/10.1016/j.enbuild.2013.09.003|journal=Energy and Buildings|volume=68|pages=254–269|doi=10.1016/j.enbuild.2013.09.003|bibcode=2014EneBu..68..254F |issn=0378-7788|url-access=subscription}}</ref>

===Embodied carbon===

Similar to embodied energy, the [[Embodied carbon emissions|embodied carbon]] of a building is dependent on the materials chosen for its construction. Figures 4 and 5{{Where|date=July 2021}} show the total embodied carbon for different structure types for increasing numbers of stories and the embodied carbon per square meter of gross floor area for the same structure types as the number of stories increases. Both methods of measuring the embodied carbon show that there is a point where the embodied carbon is lowest before increasing again as the height increases. For the total embodied carbon it is dependent on the structure type, but is either around 40 stories, or approximately 60 stories. For the square meter of gross floor area, the lowest embodied carbon was found at either 40 stories, or approximately 70 stories.<ref>{{Cite journal|last1=Gan|first1=Vincent J.L.|last2=Chan|first2=C.M.|last3=Tse|first3=K.T.|last4=Lo|first4=Irene M.C.|last5=Cheng|first5=Jack C.P.|date=September 2017|title=A comparative analysis of embodied carbon in high-rise buildings regarding different design parameters|url=http://dx.doi.org/10.1016/j.jclepro.2017.05.156|journal=Journal of Cleaner Production|volume=161|pages=663–675|doi=10.1016/j.jclepro.2017.05.156|bibcode=2017JCPro.161..663G |issn=0959-6526|url-access=subscription}}</ref>

===Air pollution===
In urban areas, the configuration of buildings can lead to exacerbated wind patterns and an uneven dispersion of [[pollutant]]s. When the height of buildings surrounding a source of [[air pollution]] is increased, the size and occurrence of both "dead-zones" and "hotspots" were increased in areas where there were almost no pollutants and high concentrations of pollutants, respectively. Figure 6{{where|date=January 2025}} depicts the progression of a Building F's height increasing from 0.0315 units in Case 1, to 0.2 units in Case 2, to 0.6 units in Case 3. This progression shows how as the height of Building F increases, the dispersion of pollutants decreases, but the concentration within the building cluster increases. The variation of [[velocity field]]s can be affected by the construction of new buildings as well, rather than solely the increase in height as shown in the figure.<ref>{{Cite journal|last1=Aristodemou|first1=Elsa|last2=Boganegra|first2=Luz Maria|last3=Mottet|first3=Laetitia|last4=Pavlidis|first4=Dimitrios|last5=Constantinou|first5=Achilleas|last6=Pain|first6=Christopher|last7=Robins|first7=Alan|last8=ApSimon|first8=Helen|date=February 2018|title=How tall buildings affect turbulent air flows and dispersion of pollution within a neighbourhood|journal=Environmental Pollution|volume=233|pages=782–796|doi=10.1016/j.envpol.2017.10.041|pmid=29132119|issn=0269-7491|doi-access=free|bibcode=2018EPoll.233..782A |hdl=10044/1/58556|hdl-access=free}}</ref>

As urban centers continue to expand upward and outward, the present velocity fields will continue to trap polluted air close to the tall buildings within the city. Specifically within major cities, a majority of air pollution is derived from transportation, whether it be cars, trains, planes, or boats. As [[urban sprawl]] continues and pollutants continue to be emitted, the air pollutants will continue to be trapped within these urban centers.<ref>{{Cite journal|last=Borck|first=Rainald|date=1 May 2016|title=Will skyscrapers save the planet? Building height limits and urban greenhouse gas emissions|url=http://www.sciencedirect.com/science/article/pii/S0166046216000053|journal=Regional Science and Urban Economics|language=en|volume=58|pages=13–25|doi=10.1016/j.regsciurbeco.2016.01.004|bibcode=2016RSUE...58...13B |issn=0166-0462|hdl=10419/96835|hdl-access=free}}</ref> Different pollutants can be detrimental to human health in different ways. For example, [[Particulates|particulate matter]] from vehicular exhaust and power generation can cause asthma, bronchitis, and cancer, while [[nitrogen dioxide]] from motor engine combustion processes can cause neurological disfunction and asphyxiation.<ref>{{Cite journal|last1=Kim|first1=Ki-Hyun|last2=Kumar|first2=Pawan|last3=Szulejko|first3=Jan E.|last4=Adelodun|first4=Adedeji A.|last5=Junaid|first5=Muhammad Faisal|last6=Uchimiya|first6=Minori|last7=Chambers|first7=Scott|date=May 2017|title=Toward a better understanding of the impact of mass transit air pollutants on human health|url=http://dx.doi.org/10.1016/j.chemosphere.2017.01.113|journal=Chemosphere|volume=174|pages=268–279|doi=10.1016/j.chemosphere.2017.01.113|pmid=28178609|bibcode=2017Chmsp.174..268K|issn=0045-6535|url-access=subscription}}</ref>

===LEED/green building rating===
[[File:Shanghai Tower in 2015 (2).jpg|thumb|[[Shanghai Tower]], the tallest and largest LEED Platinum certified building in the world since 2015.]]
Like with all other buildings, if special measures are taken to incorporate [[sustainable design]] methods early on in the design process, it is possible to obtain a green building rating, such as a [[Leadership in Energy and Environmental Design|Leadership in Energy and Environmental Design (LEED)]] certification. An [[integrated design]] approach is crucial in making sure that design decisions that positively impact the whole building are made at the beginning of the process. Because of the massive scale of skyscrapers, the decisions made by the design team must take all factors into account, including the buildings impact on the surrounding community, the effect of the building on the direction in which air and water move, and the impact of the construction process, must be taken into account. There are several design methods that could be employed in the construction of a skyscraper that would take advantage of the height of the building.<ref>{{Cite journal|last=Ali|first=Mir|date=2008|title=Overview of Sustainable Design Factors in High-Rise Buildings|url=https://global.ctbuh.org/resources/papers/download/1308-overview-of-sustainable-design-factors-in-high-rise-buildings.pdf|journal=Council on Tall Buildings and Urban Habitat}}</ref>

The microclimates that exist as the height of the building increases can be taken advantage of to increase the [[Passive ventilation|natural ventilation]], decrease the cooling load, and increase daylighting. Natural ventilation can be increased by utilizing the [[stack effect]], in which warm air moves upward and increases the movement of the air within the building. If utilizing the stack effect, buildings must take extra care to design for fire separation techniques, as the stack effect can also exacerbate the severity of a fire.<ref>{{Cite journal|last1=Ayşin Sev|last2=Görkem Aslan|date=4 July 2014|title=Natural Ventilation for the Sustainable Tall Office Buildings of the Future|url=https://zenodo.org/record/1094381|doi=10.5281/zenodo.1094381|journal=Zenodo}}</ref> Skyscrapers are considered to be internally dominated buildings because of their size as well as the fact that a majority are used as some sort of office building with high cooling loads. Due to the microclimate created at the upper floors with the increased wind speed and the decreased dry bulb temperatures, the cooling load will naturally be reduced because of infiltration through the thermal envelope. By taking advantage of the naturally cooler temperatures at higher altitudes, skyscrapers can reduce their cooling loads passively. On the other side of this argument, is the lack of shading at higher altitudes by other buildings, so the [[solar heat gain]] will be larger for higher floors than for floors at the lower end of the building. Special measures should be taken to shade upper floors from sunlight during the overheated period to ensure thermal comfort without increasing the cooling load.<ref name=":3" />