High-rise buildings are like small cities packed into one vertical structure. Because these buildings are so large, it can be challenging to maintain an adequate environment for the occupants. You might be wondering how temperature is controlled in high-rise buildings, especially in terms of heat.
High-rise buildings are heated with temperature control that involves ventilation and air conditioning (HVAC) systems in addition to the actual act of heating. The most common heating systems for high-rise buildings are:
- Water source heat pump (WSHP) systems
- Hot water/chilled water systems
- Air-cooled heat pumps
The rest of this article will discuss everything you need to know about these heating systems, so you can gain a better understanding of temperature control in high-rise buildings as a whole. Read on for more information.
1. Water Source Heat Pump (WSHP) System
The WSHP system is the most commonly used in today’s high-rise buildings. This is because the water source heat pump system is the most energy-efficient among all currently available HVAC systems.
This is a heating and cooling system that’s refrigerant-based and served by a water loop. The other components of the system are:
- Pipe system/building water loop
- Metering device/thermal expansion device
- Heat exchanger
- 4-way reversing valve
- Coil system
Each unit or zone has a refrigerant-based heating system served by a water loop that circulates through the building. For heating, the water loop has its heat addition system. Heat addition is done through boilers. Boilers are used to keep the water in the building water loop at the optimal temperature for heating.
Refrigerant, currently a mixture of liquid and gas at a low temperature and low pressure, is directed to a heat exchanger. The refrigerant draws heat from the building water loop that passes through the heat exchanger, making it a warm, low-pressure gas.
This gas is then directed to a compressor. Compression increases the temperature of the gas, making it a superheated high-pressure gas.
Next, it passes through a 4-way reversing valve. The valve directs this superheated gas to a coil system that provides heating to a space through convection or radiation.
Losing its heat in the coil system, it exits as a low-temperature high-pressure liquid, which is then directed to a metering device (thermal expansion device).
It leaves the metering device again as a low-temperature low-pressure mixture of gas and liquid, ready to cycle through the heat exchanger and repeat the process.
Another advantage of this system is that it’s much less complicated than hot water/chilled water systems. WSHP uses fewer pipe systems than hot water/chilled water systems, has a less expensive cooling tower, and is easier to maintain.
2. Hot Water/Chilled Water System
A chilled water system is the traditionally used HVAC system used for high-rise buildings. It makes use of the following components:
- Cooling tower
- Insulated 4-pipe system
- Fan and coils system
This system uses a chiller to cool water that’s delivered to different spaces in a building to cool the air. Alternatively, to heat a space, a boiler system heats water in order to provide additional heating to an area of the building.
Centralized boiler systems or community heating is suitable for high-rise buildings 20-60 storeys or 262 – 656 ft (80 to 200 m) high.
Pumps push the water through a series of pipes to the area that needs to be heated or cooled. For cooling, chilled water is used to reduce the temperature of the heat exchanging coils located in separate areas. A fan then blows air over these chilled coils to create cool air.
On the other hand, hot water is pumped to coil units located in individual spaces for heating. Surface heaters like radiators give off heat through radiation or convection. The now cool water cycles back to the boiler to be heated again.
Though this system may be quick in response to the temperature and climate needs of the building’s occupants and users, it has several cons as well.
The disadvantage of this system is that it’s much more complicated than a WSHP system, considering that it requires more pipe systems and pumps. These need a more skilled professional when it comes to maintenance and repair.
As this is a centralized form of heating, it can affect the whole building when maintenance needs to be performed. This results in the need for some redundancy of systems, which can cause costs for a hot water/chilled water system to increase sharply.
Compared to the 500% efficiency of WSHP systems, hot water/chilled water systems are only 80%-90% efficient.
3. Air-Cooled Heat Pumps
These are the common solutions you can see in family residences and smaller hotels and motels. However, quite a few high-rise buildings, especially condominiums, still use air-cooled heat pumps to provide heating for their spaces.
Air-cooled heat pumps have heating/cooling units installed per area. These units can only cool and heat a small space, compared to WSHP or hot water/chilled water systems. So multiple units have to be installed.
Air-cooled heat pumps have indoor and outdoor equipment. In the outdoor unit, the refrigerant passes through a compressor to turn it into a superheated gas.
For heating, the superheated gas is directed to the indoor unit, which goes through the indoor coil system. Heat is then dispersed to the space through convection or radiation.
As the refrigerant is once again low or warm in temperature, it’s ready to return to the outdoor unit and the compressor to repeat the process.
One advantage of this heating system is that energy consumption can easily be monitored accurately by installing a unit per area, like per residence in a condo. Only one residence will be affected when maintenance needs to be performed on a unit. At the same time, operations can continue as usual throughout the rest of the building.
The main disadvantage of using individual air-cooled heat pumps is their effect on the aesthetics of the building. As each unit has its own exterior equipment, these can easily disrupt the external appearance of the building.
Also, the compressor located right outside each space can be a little noisy for end-users.
How To Determine the Best Heating System for Your High-Rise
There are a number of heating and cooling systems that you can choose from for a high-rise building. That choice will depend on several different factors:
- The function of the high-rise building itself
- The height of the building
- The complexity of the heating system
Let’s discuss each of these factors in greater detail:
Function of the Building
When determining the function of a high-rise building, you should consider the following questions:
- What is the building used for?
- Who will be visiting this building on a routine basis?
- Are there any unique factors that are individual to your particular building, like faulty insulation for example?
- Is the building residential or commercial?
- Will it be used for offices?
- Is it going to be a mixed-use building?
- How can temperature be maintained in this particular building (who will be in charge of maintenance)?
The function of the building will affect what system will be best to install, whether that be a central system or split units.
A central system would be more suited for commercial spaces as there are larger joint spaces. Split units are more suited to residential applications as controls would be more specific to each unit and can be more easily monitored.
The functionality of a high-rise is often directly linked to which heating system will best suit the individual needs of the building itself in addition to the occupants who will be frequenting the interior of the structure.
Height of the Building
One of the most distinctive features of a high-rise building is– you guessed it– height.
High-rise buildings are commonly found in commercial areas of larger cities. They are often used for both residential and commercial purposes, and depending on the intended functionality, they can have a wide range of different heights.
Britannica defines high-rises as buildings that go over the height people will be willing to walk. Most of these unique buildings are equipped with some type of vertical mechanical transportation like elevators and escalators. These transportation methods are more frequent in larger buildings and can help you determine exactly how large your building truly is.
Some skyscrapers can reach over 328 feet (100 meters) tall. While height varies from building to building, you should expect any high-rise to be significantly taller than most structures.
Because the height of high-rise buildings can vary so much, it’s essential to be aware of the exact height of your building to help determine how much or how little heating is needed for the space. This is because different heating systems are suitable for different amounts of square footage.
For example, the temperature closer to the ground can be vastly different from the higher floors of the building. This is caused by the stack effect, which involves the rising and falling of hot and cold air within the structure. This can cause a large gap between the heating demands of different floors.
There’s also the issue of static pressure. Pumps and boilers have a maximum system pressure. As the area the system has to service increases in height, pressure also increases.
Because of this, it’s important to note that most skyscraper structures can’t always rely on a single heating system. It’s common for these massive buildings to divide the serviceable area of a system into zones or sections, each one with a temperature maintenance system that meets the needs of that particular area.
An advantage of using sections for heating systems is that it won’t affect the entire building, only portions of it when maintenance and repairs are needed.
To put things simply, the height of a high-rise is essential in determining which heating system (or systems) is needed for the space.
Complexity of the Heating System
Some temperature control systems are more complex to install, and often have to be integrated into the blueprints of the building before it’s constructed. Other HVAC systems can be added on top of an existing structure.
When it comes to the complexity of the system, you need to keep in mind:
- The designer and planner: They’re in charge of the building’s plans and will see how the system is designed into the building’s structure. Complexity will affect the ease of the design process.
- The building manager: The system’s complexity will affect the ease of the building’s HVAC system maintenance and upkeep.
- The end-user: This refers to those who’ll be using the building. These include the owners of individual units (for condos), the employees of offices, or customers for commercial spaces. Complexity of systems can affect the ease of use and accessibility for end-users and their comfort levels.
- The owner: This can refer to the building owner and the end-users renting out or owning portions of the building. Complexity of the system can affect the cost of installation and maintenance of the HVAC system, which the owner/s will shoulder.
Heating Systems for High-Rise Buildings vs. Houses
Unlike heating a residential space, the systems needed to control the heat, ventilation, and air conditioning (HVAC) in a high-rise building are much more complicated. This is due to the sheer height of the building in addition to the needs of each individual section of the structure.
The main difference between temperature maintenance in high-rise buildings vs. houses is the amount of systems involved. High-rise buildings often require a combination of multiple systems, while homes are a lot smaller and therefore require less complexity.
High-rise buildings rely on systems that span the entire building to provide heating. Standard high-rise heating systems rely on a medium, like water or refrigerant, which is heated and circulated throughout the different areas of the building.
The system used depends on several factors, including the function and height of the building in addition to the complexity of the involved systems.
Here are the most common heating systems found in high-rise buildings:
- Water source heat pump (WSHP) systems
- Hot water/chilled water systems
- Air-cooled heat pumps
Hopefully, this article has helped you gain a better understanding of heating systems in high-rise buildings.
- Modern Building Services: Servicing High-Rise Living
- Nailor Industries Inc.: The Best HVAC System for High Rise Condo Developments
- Ken Philp ClimateCare: WHICH HEATING SYSTEM IS BEST FOR HIGH RISE CONDOS? A TORONTO HEATING QUESTION
- Architect: How to Heat and Cool a Supertall
- PDH Academy: Heating and Cooling the Tallest of Buildings
- Nailor Industries Inc.: How Water Source Heat Pumps Work
- Science Direct: Building Heating System
- YouTube: The Engineering Mindset: Heat Pumps Explained – How Heat Pumps Work HVAC
- Merriam Webster: HVAC
- Britannica: high-rise building
- ASHRAE: ASHRAE DESIGN GUIDE FOR TALL, SUPERTALL, AND MEGATALL BUILDING SYSTEMS
- The Engineering Mindset: Heat Pumps Explained