Editing Skyscraper (section)

===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>