When selecting a building material supplier, contractors may take into consideration a large number of criteria that are often subjective and hard to measure. Including them all in the evaluation may be beneficial, yet in practice it may generate many complications. A solution is provided by one of the multicriteria analysis methods. The article describes the criteria employed in the evaluation of building material suppliers. One multicriteria analysis method, namely the analytic hierarchical process (AHP), is argued to be a useful alternative. An example of its application involving its basic and the more sophisticated variant, the fuzzy analytic hierarchical process (FAHP) with extent analysis method, is presented. As the results reveal, real decisive problems require methods resembling human reasoning, which is often characterized by uncertainty and subjectivity of evaluation. The real problem presented in the paper proves that the FAHP method may have a practical application.

Contractor prequalification makes it possible to admit for tendering only competent contractors. The undertaken decisions demand taking into consideration many criteria, including among others, experience and financial standing of the candidates. It is often difficult to be quantified. The objectives of the construction owner in a given project are also meaningful. All these factors cause difficulties in working out a mathematical prequalification model. In the paper a model based on fuzzy sets theory is proposed. It takes into consideration both different criteria, objectives and evaluations of numerous decision ‐ makers. To illustrate the model operation a simple numerical example is presented. Santrauka Išankstinis rangovų kvalifikacijos vertinimas leidžia dalyvauti konkurse tik kompetentingiems rangovams. Priimant pradinį sprendimą, reikia atsižvelgti į daugelį kriterijų, tarp jų į kandidatų patirtį ir jų finansinę padėtį. Šiuos kriterijus paprastai sunku įvertinti kiekybine išraiška. Taip pat svarbūs ir statytojo tikslai nagrinėjamame projekte. Šie išvardyti veiksniai sukelia sunkumų, rengiant matematinį išankstinio rangovų vertinimo modelį. Straipsnyje pasiūlytas neapibrėžtųjų aibių teorija pagrįstas modelis. Jis apima skirtingus kriterijus, tikslus ir sprendimus priimančių asmenų gausius vertinimus. Pateiktas nesudėtingas skaičiavimo pavyzdys rodo pasiūlyto modelio taikymą.

A competent construction contractor is one of the indispensable conditions of a proper process and completion of a construction project. The article presents analysis results of the main criteria considered by Polish public clients in contractor competence evaluation. Research was carried out on the basis of demands stated by clients in restricted tenders announced in 2007. The author also presents research results of the methods and criteria for construction contractor selection, used by Polish private clients. To carry out the research a questionnaire was sent to 27 private clients at the turn of 2006/2007. The results of the research show that public clients in most of the restricted tenders use just one of the criteria used to qualify a candidate to the second stage of tender procedure and it is usually the contractor's experience. Generally, it is characterised by the number of realised projects similar to the ordered one. For private clients, in contractor competence evaluation, technical possibilities of a contractor are especially valued. Experience in similar investments realisation, their quality, the equipment owned, and the staff are the top qualities in the rankings. Appreciated, although to a smaller extent, is also financial reliability of a contractor. Yet, criteria connected with project management are those which are the least valued ones. Santrauka Statybos rangovo kompetencija - viena iš privalomu salygu tinkamai vykdyti statybos projekta ir užtikrinti, kad jis bus užbaigtas. Straipsnyje pristatyta Lenkijos viešojo sektoriaus klientu nustatytu svarbiausiu rodikliu rangovo kompetencijos vertinimo analize. Tyrimo metu buvo remtasi klientu reikalavimais, nustatytais uždaru konkursu, vykusiu 2007 m., metu. Autore taip pat pristato Lenkijos viešojo sektoriaus taikomu metodu ir rodikliu statybos rangovu atrankai tyrimu rezultatus. Tyrimo metu klausimynas buvo išsiustas 27 klientams. Tyrimu rezultatai parode, kad viešojo sektoriaus užsakovai daugumoje uždaru konkursu pirmame etape kandidatui vertinti naudoja tik viena rodikli ir tai dažniausia yra rangovo patirtis. Bendruoju atveju vertinama pagal igyvendintu projektu, panašiu i konkursini, skaičiu. Privačiame sektoriuje vertinant rangovo kompetencija ypatingas demesys kreipiamas i technines rangovo galimybes. Panašiu investiciniu projektu vykdymo patirtis, darbu kokybe, turima iranga ir personalas yra pagrindiniai atrankos rodikliai. Finansinis rangovo patikimumas vertinamas, bet rečiau. Rodikliai, susije su projektu valdymu, vertinami labai retai.

The paper presents an approach to evaluating a building throughout its whole life cycle in relation to its sustainable development. It describes basic tools and techniques of evaluating and analysing the costs in the whole life cycle of the building, such as Life Cycle Assessment, Life Cycle Management, Life Cycle Cost and Social Life Cycle Assessment. The aim of the paper is to propose a model of cost evaluation throughout the building life cycle. The model is based on the fuzzy sets theory which allows the calculations to include the risks associated with the sustainable development, with the management of the investment and with social costs. Costs incurred in the subsequent phases of the building life cycle are analysed and modelled separately by means of a membership function. However, the effect of the analysis is a global cost evaluation for the whole life cycle of the building.

One of the contract awarding systems in public sector in Poland is the Design & Build system. In this system, a client concludes a contract agreement with only one company, a contractor, in order to carry out both design and construction of works. While deciding on this form of delivery of a public project, the client is obliged to conduct a single proceeding aiming to select the contractor. In this paper, public works contracts awarded in the D&B system in Poland are analysed, whilst attention was put on the contracting modes and assessment criteria. The results are assessed against the experience of other countries and recommended methods for selection of the Design and Build contractor.

The article presents briefly several methods of working time estimation. However, three methods of task duration assessment have been selected to investigate working time in a real construction project using the data collected from observing workers laying terrazzo flooring in staircases. The first estimation has been done by calculating a normal and a triangular function. The next method, which is the focus of greatest attention here, is PERT. The article presents a way to standardize the results and the procedure algorithm allowing determination of the characteristic values for the method. Times to perform every singular component sub-task as well as the whole task have been defined for the collected data with the reliability level of 85%. The completion time of the same works has also been calculated with the use of the KNR. The obtained result is much higher than the actual time needed for execution of the task calculated with the use of the previous method. The authors argue that PERT is the best method of all three, because it takes into account the randomness of the entire task duration and it can be based on the actual execution time known from research.