Real-time visualization of Mechanical, Electrical and Plumbing (MEP) models is a common task in many applications areas, including Virtual Reality (VR) design review, 4D planning, and Digital Twins (DT). Still, ever increasing complexity of MEP models makes this a challenging problem, both in terms of memory consumption as well as rendering performance. When considering Building Information Models (BIM) in general, the concept of geometry instancing is often utilized, where the same geometry is re-used at several different locations, such as in the case of identical windows or doors. For some of the components in MEP models, like valves and radiators, it is possible to also take advantage of the instancing approach. However, a significant part of the geometry in a MEP model consists of straight pipes of varying dimensions and lengths, which—in contrast—are far from identical. As such, the common strategy to solve this problem in previous research has been to take advantage of various decimation techniques in order to simplify individual pipe geometries to reduce overall memory consumption and rendering complexity. In this paper we instead introduce the Unit Pipe, which—together with a non-uniform scaling transformation—makes it possible to represent all the different straight pipes with a single geometry reference. The technique is fully compatible with openBIM and the IFC file format, and in practice it can reduce the memory consumption for straight pipes by more than 90% without sacrificing the visual quality.