How Does HVAC Work in a High Rise Building?

How Does HVAC Work in a High Rise Building?

HVAC systems are complex assemblies with many moving parts, with each component relying on the others to efficiently heat and cool a building. It can be difficult enough to have an effective system installed in a residence or a simple structure like a warehouse or small office. When the system is installed in a high-rise building such as those found in major cities, HVAC becomes incredibly convoluted. So how does it work?  

High Rise Buildings vs. Skyscrapers

A building is designated as a high rise if it has 13 stories or more. The 2015 International Building Code (IBC) states that “a building is considered a high rise when there is an ‘occupied floor’ more than 75 feet above the lowest level of fire department vehicle access.” There is no universally accepted height convention for a skyscraper, but high-rise buildings that exceed 40 stories fall into that category.

This distinction is important because structures under a certain height can still use conventional HVAC machinery and designs. On smaller high-rise buildings, HVAC machinery, including chiller plants, heat pumps, and cooling towers, can be installed on the roof and provide effective climate control for the whole building.

Super-tall towers are unable to be served by conventional HVAC systems once they surpass 40-60 stories. The standard systems are no longer efficient or effective. Skyscrapers require conventions to be abandoned and standards to be reassessed since now they don’t apply. Some of the unique challenges that skyscrapers present include:

  1. Temperature – When a skyscraper reaches more than a half-mile in height, temperatures on the lower stories can be dramatically different from the top floors. The outside wind temperature and speed at 100 floors have a significant impact on climate control.
  2. Scale – Installing an enormous HAVC system on the roof of a 100-story building doesn’t make sense from any standpoint – efficiency, cost, or size. The size of a system that would be needed to effectively cool and heat a skyscraper couldn’t be installed on the roof of the building.
  3. Pressure Differential – Heated air within a building rises via elevator shafts, stairwells, and atria. This air creates an internal pressure differential which is known as the stack effect. The stack effect also incorporates the impact of wind pressure as a “significant factor.” It can impact the operation of elevator doors and swing doors and create excessive airflow in areas where there shouldn’t be. 

How to Heat and Cool a Skyscraper

Skyscrapers are incredibly complex structures, with many internal and external factors to consider in their construction and design. Due to the unique challenges presented by super-tall skyscrapers, incorporating an effective HVAC system is a crucial consideration from the very beginning. Architects and engineers will now integrate HVAC systems into the original building designs rather than add them afterward. Some design firms have created hybrid systems to implement effective HVAC operations, while others have gone back to basics and created HVAC zones within the skyscrapers.
By creating multiple HVAC zones of 12-15 stories, each zone can have its own ventilation system, transformers, and water heater. According to IndustryTap, having multiple zones also “decreases the load on the cooling core and the overall energy consumption.”

HVAC zones offer building engineers and residents other advantages as well. As previously mentioned, the temperature difference and requirements between a lower-level zone and an upper-level zone can vary widely. Zoned HVAC areas allow for more flexible climate control.

Although new HVAC systems can take up valuable space within a skyscraper, the benefits outweigh the detractions. Older HVAC units cannot keep up with the widely varying temperate requirements, and less so every season as the effects of climate change continue to increase. Older systems naturally won’t work as efficiently in general as a newer unit. As urban real estate rental prices continue to soar, tenant expectations do as well. Zoned HVAC systems provide a viable, effective solution for these concerns.

Custom HVAC Systems in High Rise Buildings

As experts in high-rise HVAC needs and requirements for more than 50 years, our team can provide affordable, practical solutions for residential and commercial high-rise buildings. If your high-rise building requires an upgrade, contact Henick-Lane. We can custom design an HVAC solution that will keep your tenants comfortable and satisfied. Get started by calling 718-786-7277 today.