The selection of one system in the building process can have a great effect on other systems within that building. For instance, structural systems which do not allow large floor to floor heights can create havoc on running ductwork in an HVAC system. In Macalister Hall, there are system interactions which dictate certain elements of other systems, a few of these interactions will be discussed in the following section.

Architectural System vs. HVAC System:

The decision in use of certain construction materials and design decisions affected the size of the HVAC system. The use of CMU construction with no insulation leads to a larger HVAC system, but the lack of fenestration on the first floor lead to smaller loading on that level. Additionally, the development of the basement level as a usable space provided less loading than if it was above ground, since the walls retain the thermal comfort of the earth and there are no infiltration losses.

From a finishing standpoint, the decision to use an acoustical ceiling throughout the complex allowed the HVAC system to utilize a return air plenum, instead of a ducted return system.

Architectural System vs. Structural System:

The architectural requirement for a building that is seven stories tall and rectangular in shape had a definite impact on the structural system. Additionally, the use of precast concrete panels on the facade added another angle to the structural system. Steel spandrel beams had to be added to accommodate the precast panels. The size of the building also has a direct effect on the size of the concrete columns throughout the space.

Fire Protection vs. HVAC System:

The fire protection system works together with the HVAC system to aid in the exhaustion of smoke during a fire event. Duct detectors located in the return ducts cause the air handling unit to turn off in the event of smoke detection, so that smoke is not circulated through the building by the air handler. Also, smoke exhaust fans will help to remove smoke from large areas when the fire alarm system is activated. The fire protection system is almost always interlocked with the HVAC system in order to prevent hazard and loss of life.

Optimal Construction Process:

In construction, the architectural system is usually the first system selected, followed quickly by the structural system. These two systems often dictate the major elements of the HVAC, electrical, and other remaining systems in a building. To optimize the design process, all of the engineers should meet at the beginning to plot out the type of space they will require, both in floor area and in verticality. Mechanical engineers usually complain about a lack of shaft space, while electrical engineers require closets for lighting panels and large transformer rooms. If the engineers worked together as a team from the start, these problems could be curtailed before they even begin.