Perspective economy: how BIM helps Pridex to reduce construction costs and how much can design errors cost

Fit-out is the process of equipping a building with engineering systems, building interiors and creating multimedia infrastructure. Since the 2010s, the complexity level of fit-out projects and office space in particular, has grown significantly: the number and complexity of systems that require mutual coordination has increased, and the volume of project documentation has expanded.

All of this has led to a multiplication of the cost of design errors. A pipe installed in the wrong place, or a hole for the duct located few centimeters to the left than needed, can lead to collisions — inconsistencies with other utilities and interior elements. Timely identification of collisions has become one of the main economic prerequisites for the introduction of BIM in fit-out projects: firstly, the manual search for such errors is becoming increasingly labor-intensive, and secondly, the elimination of any missed discrepancy at the construction phase can lead to a serious loss of time and money.

The work was carried out on two floors of the office space of 2200 square meters each and included the installation of power and electrical equipment, installation of water supply, sewerage, cooling, automatic fire extinguishing systems, etc. The cost of most of these services was estimated without taking into account the commissioning work.

We compared the documentation corrected with the help of BIM with its original version and estimated the potential cost of eliminating the discrepancies detected. To do this, we calculated the potential labor costs required to successfully eliminate collisions (including mainly dismantling and re-installation of equipment or interior elements), as well as the cost of replacing materials that are not subject to reuse, or in some cases the purchase cost of additional materials.

According to our estimates, unresolved collisions in the drawings can lead to additional costs associated with the rework amounting to 15−25% of the cost of installation work, and up to 5−10% of additional material costs associated with the inability to reuse the already installed material. In general, the use of BIM in this project led to a cost reduction of 4.9% of the total cost, of which 3% was work, and 1.9% - materials. The greatest savings were achieved by installation of cooling systems (1.54% of the total project cost), as well as an automatic water fire extinguishing system (1.2% of the total project cost). In the first case, this is caused by the greater volume of labor that would be needed to eliminate inconsistencies compared to other sections, and in the second — by a large share of this section in the project budget.