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. Operational energy use is affected by the magnitude of conduction between the interior and exterior, convection from infiltrating air, and radiation through 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 as the altitude increases. For example, when moving from 1.5 meters to 284 meters, the dry bulb temperature decreased by 1.85oC 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. 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 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. 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