## 3 Methodology
### Sharpening the Resultant Function  
To obtain a well-defined, non-fuzzy result, the fuzzy result function should be de-fuzzified in the final modelling step. The centre-of-gravity method was adopted in the developed model. This is the most common and most widely used sharpening method and, in the issue under study, it ultimately provided good results.  
Figure 4: Graphs of the membership function for possible changes in the planned number of working hours up to 500 man-hours.  
Figure 3: Time index in the range of up to 500 man-hours.  
As a result of defuzzification, 4 specific coefficients are obtained relating, respectively to the technology of the implementation of the works, the on-site organisation of the works and the management of the implementation and the design features, according to the adopted division.  
Based on the four sharpened values of the specific coefficients, a single correction factor is finally calculated which can be directly applied to the planned labour and which will collectively consider the influence of all groups of factors simultaneously.  
The importance of each group of factors is at a similar level, but they nevertheless differ from each other. For each factor group, a normalised group impact weight was calculated based on the average weights of the factors that make up the group. The calculation consisted of dividing the sum of the factor weights of a given group by the sum of the weights of all factors included in the study. The sum of the normalised factor group weights is 1. The values of the normalised impact weights for each factor group are, respectively:  
1. Organisational factors, group \(Z_{1}\)--standardised weight = 0.241;
2. Technological factors, group \(Z_{2}\)--standardised weight = 0.253;
3. Management factors, group \(Z_{3}\)--standardised weight = 0.222;
4. Design factors, group \(Z_{4}\)--standardised weight = 0.284.  
Once the sharp values of the specific coefficients are obtained in the model's output, the normalised weights are used in the process of determining a single aggregate adjustment factor for the planned number of man-hours, according to the following formula:  
\[Z=0.241\times Z_{1}+0.253\times Z_{2}+0.222\times Z_{3}+0.284\times Z_{4} \tag{5}\]  
where: \(Z\)--coefficient correcting the planned duration of construction works; \(Z_{1}\)--specific correction coefficient in the area of organisation; \(Z_{2}\)--specific correction coefficient in the area of management; \(Z_{4}\)--specific correction coefficient in the area of design.  
The obtained result is a percentage indicator suggesting a change in the planned number of man-hours for an individual construction project. The product of the \(Z\)-factor or one of the specific coefficients and the planned number of man-hours is the value of the suggested change in the number of man-hours due to the impact of factors influencing the planning of the construction workforce. The suggested change to the number of man-hours can be either a reduction, an increase or leaving it unchanged. The revised number of man-hours will directly translate into the quantitative planning of employment at the site for the timely completion of the construction project. Embedding the construction works into the overall progress schedule will also be based on this number of man-hours.