new construction solutions with the use of new technologies as well as random nature of
events influencing the whole life cycle encourage to make an attempt to include the risk
in models and analyses (Shevchenko et al. 2008; Zavadskas et al. 2010). Therefore, the
choice of a model is very important. The authors (Durairaj) present briefly the review of
chosen LCC methodologies and tools taking into consideration the following specific
cost models on the basis of their framework and limitations. They emphasize the
importance of risk analysis and sensitivity analysis the aim of which is to isolate
predominant costs and identify relationships between cost drivers and design changes.
In case of construction projects time period is long from a concept to exploitation and
maintenance of a building. The risk taken into consideration in models is perceived as a
possibility of deviation from an expected result. This risk is treated as a negative factor
causing an increase of costs. It is a starting point for the estimation of the range of costs
possible to incur in life cycle. The range of costs for separate construction works or all
costs in NPV model are presented through curves (in this paper). Cost ranges and
estimation of probability allow to assess financial reserves more precisely. There are
many methods of risk assessment, applied at chosen stages of an investment process
(Shevchenko et al. 2008; Zavadskas et al. 2010; and EIC 62198). In this paper the risk
was assessed with the use of PERT approach. It is a widely applied method which uses
the properties of Gaussian distribution. The method is employed in different areas,
including selection where different criteria of a decision-maker are taken into account
(Hatush and Skitmore 1997) When it comes to investment undertakings, the method is
applied in order to determine deviations from the planned schedule and budget. Basic
parameters essential to use the standardized Gaussian distribution are: mean value
(Eq.1) and standard deviation (Eq.2). Next we receive a curve in which a certain
time/cost value corresponds to probability of its occurrence.