Technology Integration: HVAC

Sept. 1, 2008

HVAC System and Building Integration

By David J. Fruchtman, PE

Good heating, ventilating, and air-conditioning systems are important features of every modern building. When these systems are carefully integrated into the building design, occupants can enjoy a comfortable environment in aesthetically pleasing architecture. Mechanical systems will impact many building elements, including the floor area and layout, ceiling design, roof design, planters, and other site features.

Floor Area and Layout
Most mechanical systems impact floor layouts of a building. Some systems require a single large mechanical room for equipment such as air handlers. Other systems require multiple closets for equipment such as water source heat pump units. Yet others require air shafts to move conditioned air from floor to floor. Poor placement of these spaces could adversely affect movement in the space or result in the loss of valuable lease space. Wherever possible, equipment rooms should be located adjacent to elevator shafts, electrical equipment rooms, shell and core bathrooms, or other such spaces so that all utility spaces are grouped together. The equipment should be integrated into a location that will work regardless of future tenant needs.

Mechanical equipment may be noisy. Noise and/or vibration could easily be transmitted from the mechanical equipment to adjacent occupied spaces. Wherever possible, large mechanical spaces should be located across corridors or alongside storage rooms, lunch rooms, or other spaces that are not regularly occupied and are not noise sensitive.

Ceiling Design
Adequate ceiling space is essential for an effective HVAC system. Inadequate space will dictate the use of expensive rectangular sheet metal ductwork, sheet metal transitions, and offsets. These are expensive to install and sometimes cause system performance problems. Round ductwork is less expensive and more efficient than sheet metal ductwork. Flexible ductwork, which is frequently used these days, should only be used where there is adequate ceiling space. Making a ceiling space too small will eliminate this potentially considerable cost savings.

Roof Design
To reduce the loss of rentable floor area, mechanical equipment is often located on the roof of a building. There are many other advantages to this, including easy accessibility for equipment service and maintenance. In addition, the rooftop location is an ideal place for discharging flue gasses and cooling tower plumes. Rooftop equipment located above prime top floor residential or office space must be mounted on suitable bases and spring isolated to reduce noise and vibration transmission to the building. To shield the equipment from view, suitable parapets and screens must be employed.

Planters and Other Site Features
Some types of mechanical systems are best suited for an on-grade installation. This is common for some small buildings and single-family residences. One advantage of on-grade installations is that the vibrating elements are located on grade and not in or above occupied spaces. Another is that equipment is readily accessible for service and access. Care must be taken, however, in placing this equipment. Many jurisdictions do not allow it to encroach on the required side and rear property line setbacks. Walkways and pedestrian paths must be designed to skirt around the equipment. Planters and landscaping should conceal the equipment but allow for access for service and maintenance.

The goal of any architect should be to create a comfortable and aesthetically pleasing building. This can be achieved by not only understanding building features but also understanding the requirements of the mechanical system and integrating the two together.

David J. Fruchtman ([email protected]) is a licensed professional engineer in the states of California, Nevada, and Arizona. He is president of Fruchtman and Associates, a Los Angeles-based firm specializing in design, consulting, and forensic engineering services related to HVAC, plumbing, and fire protection systems.

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