What is off-site fabrication in the context of building services?

Off-site fabrication refers to the process of manufacturing building components in a controlled environment, away from the actual construction site. This method enhances quality control, reduces construction timelines, and minimizes on-site labor. The pre-assembly of bathrooms as mentioned in the correct answer is a prime example of off-site fabrication. By constructing bathroom pods in a factory, builders can streamline the installation process, ensuring that the components are built to precise specifications and can be quickly integrated into the overall building structure when transported to the site.

The other options focus on alternative methods or planning strategies that do not align with the definition of off-site fabrication. On-site assembly relates to putting together components directly at the construction site, which contrasts with the idea of pre-manufacturing off-site. Designing buildings in software is related to architectural planning, not fabrication. Traditional construction methods involve techniques that typically occur on-site rather than utilizing pre-fabricated elements made elsewhere. Thus, the correct choice captures the essence of off-site fabrication effectively.