- Break-even point

The break-even point is a point at which the present values of the incurred benefit and cost are the same [19]. The actual gain from using the GEWPro begins to occur after the break-even point. In this study, the break-even point was found to be 1.36 years (16.3 months) according to Equation (6).

$$\begin{aligned} \text{Break -- even point} \\ \rightarrow \text{Finding the year (n)} \\ \rightarrow \frac{(1+i)^{n}-1}{i(1+i)^{n}} &= \left\{ (\text{IP}\_{\text{G}}-\text{IP}\_{\text{C}}) + (\text{MP}\_{\text{G}}-\text{MP}\_{\text{C}}) \right\} / (\text{EA}\_{\text{C}}-\text{EA}\_{\text{G}}) \\ \rightarrow \text{when the interest rate (i) is 2.90\%,} \\ \frac{(1+0.029)^{n}-1}{0.029(1+0.029)^{n}} &= \{ (\\$60, 567.7-\\$14, 994.5) \\ &+ (\\$6139.5+\\$14, 359.4+\\$12, 807.8+\\$5701)-\\$4665.5 \} \\ &= 1.34 \\ \text{r. n = 1.36 year} \end{aligned} \tag{6}$$
  $\begin{aligned} \text{3. } \mathbf{n} = 1.36 \text{ year} \end{aligned} $ 

#### - Cost saving effect using equivalent annual worth method

The analysis of the construction cost saving effect utilizes the equivalent annual worth method in obtaining the ratio of the present worth of cost saving using automated method over the conventional method. Applying Equation (7), the cost saving effect of using the GEWPro was 12.2% for this study.

Cost saving effect using equivalent annual worth method =(annual cos t of conventional method − annual cos t of automated method) /(annual cos t of conventional method) ={(IAC + EAC + MAC) − (IAG + EAG + MAG)}/(IAC + EAC + MAC) ={(\$1748.9/year + \$411,340.1/year + \$544.2/year) −(\$7064.2/year + \$351,820.0/year + \$716.1/year + \$1674.8/year +\$1493.8/year + \$664.9/year)}/(\$1748.9/year + \$411,340.1/year + \$544.2/year) =0.122 (7)
