The procurement process includes the formation of the needs of the contracting authority, planning, initiation and preparation of procurement, procurement execution, conclusion, execution and evaluation of the results of the procurement contract (Public Procurement Office).

In summary, the procurement process can be divided into three stages:

• Preparation,
• Purchasing and signing contracts,
• Contractual fulfillment of obligations.

1st stage

During the preparation for public procurement, the contracting authority conducts market research, prepares the procurement list, fulfillment of obligations, evaluates the possibilities of products and works by purchasing according to the electronic catalog. The procuring entity must assess whether the environmental protection criteria and energy efficiency requirements apply to the planned public procurement.

After the analysis of the market and the goods, a procurement plan is prepared, which indicates when and how it is planned to purchase the specified goods or services.

The most common errors at this stage are the incorrect calculation of the purchase value, the calculation of surplus materials and works, the underestimation of sustainable development indicators and the consequent choice of the wrong purchase.

This is due to the uncertainty when official project drawings and material sheets do not correspond to reality or are inaccurate, so additional efforts are needed to check the reliability of the drawings and material sheets. Often inaccuracies in the design of documents prepared by the classical method result from dishonest designers and architects. For example, an architect designed a floor space of 498 m², adjusts by hand up to 500 m². Such minor inaccuracies distort the original project.

At this stage, the application of BIM technology can avoid most errors if the tender provided true information about the object. Whereas the information model of a building is an accurate set of project data, it allows to analyze all the indicators that affect the construction. Material lists would automatically provide detailed information on the quantities of each element and each type of substance. Accidental or deliberate errors and discrepancies made by designers in the design documents will be detected (Clash detection).

During procurement planning, the contracting authority has to prepare a procurement list. Tenders are often organized by unscrupulous customers in the field of construction, as a result, there are inaccuracies and opportunities for unfair competition in the procurement list. In order to avoid inaccuracies, it is proposed to use BIM technologies for the estimation of construction works in the pre-procurement phase.

Using BIM software will save time when calculating a preliminary project estimate. The program performs calculations and generates the reports automatically. Quickly estimating construction costs allows to increase the accuracy of the procurement list and prevent unfair tenders.

2nd stage

At this stage, the Public Procurement Commission evaluates the bids, makes a decision on the winner, prepares, coordinates and signs the contract with the winner of the public procurement tender.

According to the report “Violations of the Public Procurement Law Detected during the EU Public Audit”, it can be stated that the most common financial errors at this stage are related to the execution of public procurement procedures and the implementation of procurement contracts:

• unreasonably high qualification requirements set in the procurement documents, disproportionate to the object of the procurement and artificially restricting the competition of suppliers;
• the qualification or tender of the winning supplier does not meet the requirements of the procurement documents, for example, the supplier’s tender has been assessed as suitable and recognized as the winner, even though the supplier did not meet the qualification specified in the procurement documents;
• technical specifications do not ensure competition and discriminate against suppliers, e.g. in terms of purchase, Hight, Material, Volume, Measuring unit, specific model, brand or manufacturer is indicated.

In addition, tenders are often organized by workers with little experience in construction work, who find it difficult to assess all financial, technological, sustainable development and environmental indicators, and therefore evaluate tenders against the lowest price criterion. The cheapest variant may not always be the most economical, as the technical quality of the product and the lifespan of the construction site are important. Contractors often reduce the competitive price in the hope of reducing their costs in order to guarantee themselves a sufficient amount of work and remain competitive. Reducing costs decreases the quality of work. When customers choose a contractor based on the principle of the lowest price, they run the risk of significant problems and losses in the operation of the buildings.

Each tender participating in a public procurement tender can be described by a set of indicators. Indicators can be qualitative and quantitative. The values of quantitative indicators are calculated using recommendations, price lists, normative documents, manuals, comparing the object of procurement with analogues, etc. The values of qualitative indicators are usually determined by expert (based on expert experience) methods.

If tenders for a public tender were to be assessed on the basis of a set of indicators rather than the lowest price, a mechanism would emerge in the market that would allow construction organizations using advanced methods to win by submitting a more expensive tender. Judging by the criterion of the most economically advantageous tender, the procurement contract shall be awarded to the company which has submitted to the contracting authority the most advantageous tender selected on the basis of the indicators related to the object of the procurement.

Multi-objective decision-making methods (MCDM) help to make decisions by evaluating several or more often conflicting indicators. The award decision would take into account quality, price, technical merit, aesthetic and functional characteristics, environmental characteristics, operating costs, efficiency, warranty and technical assistance, delivery date, delivery or completion time. The state, as the customer, would receive a project with lower construction and operating costs, and the project will not harm the environment during both production and operation.

3rd stage

It is the fulfillment of contractual obligations. The construction object must be completed on time, not exceeding the contract price. The builder must ensure the building as a final product the functionality, high quality and service life in accordance with normative regulations. At this stage, the Contracting Authority coordinates the performance of the contract, evaluates the object both during construction and the final result, initiates the amendment of the contract if there is a need to change certain conditions set out in the contract.

Upon fulfillment of the obligations specified in the procurement contract by the Supplier, deeds of acceptance-transfer of goods, services or works shall be signed, storage of construction documents shall be ensured in accordance with the procedure established by normative construction technical documents and rules. The information model of the building can help to generate the stages of work, according to which the contracting authority can control the execution of construction, follow the schedule of works. Seeing the changes in the 3D model, it is possible to anticipate the shortcomings or inconsistencies of the project, to make a decision on the extension, modification or termination of the contract.

Documents archiving are the preparation of documents for archival storage in accordance with the requirements of the EU country document management and accounting rules. Creating a complete building an electronic file, a lot of time take to mark changes in drawings and specifications and prepare detailed photos. According to BIM technology changes in all documents will automatically appear after correction in one of the related drawings using the software generated by the detailed photograph. In addition, the resulting 3D model can be applied later during operation or by creating a digital city model.