In comparison to office buildings, lab buildings require larger shafts to transport significantly higher volumes of supply and exhaust air. These larger air volumes also need to be transported horizontally on each floor to reach individual labs. The maximum duct length from the shaft to the most remote lab is determined by the maximum duct section before it becomes unreasonably large. The optimal horizontal distribution of air ducts influences the location of vertical riser shafts on the floor plate.

While fresh air can be taken in at various locations, used lab air must be exhausted at the top of the building. Most lab buildings rely on large plant rooms at the base and top of the building. Intake is often pushed from the bottom, and exhaust is pulled from the top. The shaft space requirement for lab air grows with each additional floor.

Air suppy and exhaust shafts can be freestanding or bundled with lifts and stairs to form a service core.

Lab riser shafts generally fall into two categories: centralized and massive, as seen in R&D buildings, or distributed and numerous, as observed in educational labs. In both cases, as more floors are stacked, more floor plate area is lost to shafts.

Labs with centralized shafts allow the rest of the floor to remain unobstructed, making them ideal for open-space and highly adaptable floor layouts. However, this setup may lead to less adaptable ambient conditions in different parts of the open-space lab floor. Achieving highly controllable air temperature and humidity conditions is more feasible in smaller, enclosed labs that are individually served with air and cooled by a dedicated source. While the open-lab layout is achievable with centralized shafts, labs with centralized shafts often adopt a cellular layout.

Typically, labs with centralized shafts have a stubby rectangular plan. As the floor plate elongates, linear lab air supply and exhaust ducts also become longer. This can result in prohibitively large duct sections at the point of shaft entry, increasing both the ceiling installation space and the floor-to-floor height.        

In the distributed shaft scheme, one riser shaft typically serves one or two labs. This approach is commonly employed in educational labs with a predominantly fixed cellular lab layout. Typically, four to twelve shafts can accommodate eight to twelve inline labs.

The length of horizontal air ducts is constrained by the depth of the lab from the facade to the shaft, requiring less overhead space. Primary distribution ducts or plenums that connect the distributed shafts to the air handling units are usually located on technical floors at the bottom and top of the building.

Distributed shafts are typically positioned between the labs and the circulation corridor in the middle of the building. The length of the building is restricted by the maximum tolerable travel distance, usually reached with 10 or 11 double-wide labs placed side by side, equating to a distance of 70 to 80 meters.

Noteworthy are the rare deviations where the distributed shafts are moved to the exterior of the building. In Bristol University labs, the shafts alternate with windows, forming a thick facade. The Bioturm in Basel (not represented on this site) has shafts on the facade turned at the right angle so that narrow write-up niches can be placed in between.

The shell essentially becomes core. 

Apart from clearly "centralized" or "distributed" shafts, there are buildings with several smaller centralized – or one can say distributed – medium-size risers. Hybrid schemes are often predicated on complex site and plan geometry or pre-existing building conditions. Insufficient clarity in the shaft and core layout is likely to result in convoluted duct and lab floor layouts.