This paper provides an overview of modern approaches to the design of mechanical installations, with a special emphasis on advanced technologies that enable energy efficiency, sustainability and cost reduction. The paper explores the application of ISO, EN, HRN and DIN standards and ASHRAE and VDI guidelines, as well as their role in ensuring technical, safety and environmental conditions. The importance of nearly zero-energy buildings (nZEB) and the integration of renewable energy sources (solar panels and geothermal heat pumps) are shown. The work also addresses cleanrooms and smart homes, which show how digitization and automation can facilitate the management of mechanical installation systems, while simultaneously reducing energy consumption. The paper describes how digitization, laser measurement and concurrent engineering significantly improved the design processes of mechanical installations. In cooperation with the company, an example of designing mechanical installations using 2D and 3D software was presented. Within the example, the design process in software is presented: calculation of losses and gains, selection of equipment, positioning of mechanical installations and dimensioning of pipelines. A comparison of designing in 2D and 3D software was made through the possibilities offered by the software and the time required to perform the task. The work demonstrated the advantage of 3D design in terms of reducing errors, speeding up the design process and improving collaboration between engineering teams. It is also shown how the digitization of design, through Revit software, significantly improves the efficiency and precision of design.