The Basics of Air Handling Units in Skyscrapers
Building science is becoming ever more complex, with automation, sustainability and occupant comfort all priorities for operations staff. Having a basic understanding of air handling can be helpful to our readers even though most commercial HVAC systems are computer controlled. JDC Mechanical Ltd. has journeymen HVAC technicians to help you through the challenges that come with system operation and even failure.
What are Air Handling Units (AHUs), and how do they work?
You may be surprised to learn that buildings can have several different types of AHUs. The most common types are: large, roof-mounted units that supply the entire building with air. Older buildings may not have return ducts and rely on leaky buildings to remove air from the inside. However, newer buildings tend to have many smaller units and are air tighter, so the pressure inside the building is maintained. Make-up air units are another common piece of air handling equipment which can blend, re-circulate or even supply only fresh air to an area.
Air handling units are critical components of a building’s heating, cooling, and ventilation systems. They provide heating and cooling to a building’s interior spaces and are typically located on the roofs of buildings. Other units have only a fan and supply air to a specific area. Fan coil units are the most common type of air handling unit. Some skyscrapers have several units in a single complex. Heat recovery ventilators are our specialty and can be integrated with your existing system, though some restrictions or modifications may apply.
High-rise buildings are designed to maximize space in an urban environment, which can make maintaining a comfortable temperature a challenge. There are several types of HVAC systems for high-rise buildings, including heat recovery. These systems are complex and must accommodate many conditions within a building. This can be a difficult process for a single company. Thankfully, there are ways to optimize the performance of HVAC systems in high-rise buildings.
Re-circulation of stale air
Engineers in skyscrapers are concerned with the re-circulation of stale air in buildings. Circulating fresh air is a challenging task in a 100-story building, which is why they use mechanical areas to exchange inside air with outside air. Whether it’s air conditioning on the 100th floor or a toilet flushing system, it’s crucial to keep the building cool and fresh. If you are having complaints from tenants about odours or pockets of air stagnation, contact us at (403) 860-8437.
HVAC design strategies include avoiding subcooling and capacity modulation. However, humidity control is perhaps the most important factor. This is because moisture issues can damage a building and compromise occupant comfort. To ensure occupant comfort and reduce costs, facility managers should consider cost-effective strategies for humidity control. Relative humidity levels are generally between 20 and 60 percent. The HVAC design team can help to achieve this by determining acceptable humidity levels for each building occupant.
Excessive moisture in a commercial building results from the failure to control humidity and airflow. The most common source of excess moisture in hot, humid climates is the uncontrolled flow of outdoor air. Unfortunately, most commissioning techniques do not accurately predict airflow, so owners cannot pinpoint moisture-control problems before accepting a building into service. To remedy this problem, a team of professionals is developing a computerized tool to estimate indoor and outdoor air flow rates and humidity levels in commercial buildings.
To our valued readers, as summer nears, taking the time to do a seasonal assessment of your cooling equipment could save you from a costly failure during another period of extreme heat this summer.