Advanced Building Technology A

Introduction to Advanced Building Technology A

High Rise Core Design

High Rise Structure

Circular Economy & Lean Construction

High Rise HVAC System

Assignment 2

High Rise Water Supply

Integrated Project: Assignment 2

Explore

High Rise HVAC System

Discussion 4

References

Lecture Webcast

Challenges in designing HVAC for high rise

Designing HVAC systems for a high-rise building can pose many challenges, such as:

Providing adequate ventilation and indoor air quality for the occupants, while minimizing the energy consumption and the risk of cross-contamination between floors.

Selecting the optimal location and size of the equipment, considering the available space, structural constraints, and rigging difficulties.

Balancing the pressure and temperature variations across different elevations and orientations of the building, and accounting for the effects of wind and stack effect.

Optimizing the operation and control of the HVAC systems to match the varying load conditions and occupancy patterns of the building.

These challenges require careful analysis and design of the HVAC systems, as well as coordination with other disciplines, to achieve high performance and energy efficiency.

Common types of HVAC System for High Rise

High-rise buildings require air conditioning systems that can efficiently cool large spaces and maintain a comfortable indoor environment. There are several types of air conditioning systems that can be used in high-rise buildings, including:

Central water-cooled system: This system is equipped with a central cooling tower and a boiler, and has water-sourced heat pump units in each apartment to maintain optimal temperature throughout the building

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Chilled water system: This is the most popular air conditioning system in commercial buildings due to its higher efficiency. It uses chilled water to cool the air and distribute it throughout the building.

Variable refrigerant flow (VRF) system: This system uses refrigerant as a cooling medium and can provide heating and cooling simultaneously to different zones within the building.

Split system: This system is ideal for smaller high-rise buildings, where 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.

The efficiency of air conditioning systems for high-rise buildings depends on several factors:

the building’s size

the number of occupants, and

the climate

However, the variable refrigerant flow (VRF) system is considered one of the most efficient air conditioning systems for high-rise buildings . This system uses refrigerant as a cooling medium and can provide heating and cooling simultaneously to different zones within the building . It is also more energy-efficient than other air conditioning systems, such as central water-cooled systems and chilled water systems .

HVAC System Issues

Air conditioning systems are prone to several problems that can affect their performance and efficiency. Here are some of the most common problems with air conditioning systems and how to fix them:

Electrical problems: Electrical issues such as a blown fuse or a tripped circuit breaker can cause the air conditioner to stop working. In some cases, the problem can be with the thermostat or the blower belt.

Resetting the circuit breaker panel or replacing the thermostat can help fix these issues ⁠

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Low refrigerant charge: Low refrigerant levels can cause the evaporator coil to freeze, leading to low temperatures. A leak is usually the reason why an air conditioner would be low on refrigerant.

Only qualified and licensed AC technicians should detect and fix this problem ⁠

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Thermostat malfunctioning: A malfunctioning thermostat or incorrect calibration can cause trouble switching on the AC unit. Dial-type thermostats are more often subject to calibration problems, but sometimes newer programmable thermostats are also not easy to program.

Consulting the thermostat manual and replacing it if necessary can help fix this problem ⁠

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Dirty air filters: Accumulation of dust and grime in the AC filter can cause the air conditioner to repeatedly run without reaching a set temperature, leading to frozen AC coils.

Regular cleaning and maintenance of air filters can help deal with this issue ⁠

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Leaking ducts: Leaking ducts can cause cool air to escape, leading to poor cooling performance and higher energy bills.

Sealing ducts with mastic sealant or metal tape can help fix this problem ⁠

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Frozen evaporator coils: Frozen evaporator coils can cause low airflow and poor cooling performance. This issue is usually caused by dirty air filters, low refrigerant levels, or blocked return vents.

Clogged condensate drain: A clogged condensate drain can cause water to back up into the air conditioner, leading to water damage and mold growth. Cleaning the drain line with bleach or vinegar can help fix this problem .

Worn-out fan belt: A worn-out fan belt can cause a squealing noise from the AC unit and poor cooling performance. Replacing the fan belt can help fix this problem .

Some possible solutions to the challenges of designing HVAC systems for a high-rise building are:

Using a dedicated outdoor air system (DOAS) that delivers fresh air to each floor independently, and a variable refrigerant flow (VRF) system that provides heating and cooling to individual zones within each floor1. This can improve the ventilation and indoor air quality, reduce the energy consumption and the risk of cross-contamination, and allow for more flexibility and control of the thermal comfort1.

Installing the HVAC equipment on intermediate floors or in vertical shafts, rather than on the roof or the basement, to reduce the length and size of the ducts and pipes, and to facilitate the maintenance and replacement of the equipment2. This can also free up valuable space on the roof for solar panels or green roofs2.

Applying computational fluid dynamics (CFD) modeling to simulate the airflow and temperature distribution in the building, and to optimize the design of the HVAC systems and the building envelope3. This can help to balance the pressure and temperature variations across different elevations and orientations, and to mitigate the effects of wind and stack effect3.

Incorporating heat recovery ventilators (HRVs) or energy recovery ventilators (ERVs) that exchange heat and moisture between the exhaust air and the supply air, and reduce the heating and cooling loads of the HVAC systems. This can also enhance the indoor air quality by reducing the humidity levels and diluting the pollutants.

Implementing smart sensors, meters, and controllers that monitor and adjust the operation and control of the HVAC systems based on the real-time data of the indoor and outdoor conditions, and the occupancy patterns of the building. This can improve the energy efficiency and the thermal comfort of the HVAC systems, and provide feedback and insights to the building owners and operators

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