# Model-Based Dynamic Forecasting for Residential Construction Market Demand: A Systemic Approach
## 3 Results Concept of Construction Demand Forecasting Model
### Structure of Construction Demand Forecasting Model  
The construction demand forecasting model has a system structure system of the stock-flow diagram (Stock-Flow Diagram) and has two new construction demand forecasting module (Module I) and maintenance and demolition's construction demand forecasting module (Module II). It occurs when modules are connected in sequence.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Type** & **Quantitative Analysis** & **System Dynamics Analysis** \\ \hline Inference method & Existing empirical data & Cause and effect relationship between variables \\ \hline Analysis target & Static form & Dynamic form \\ \hline Analysis focus & Correlation between two variables & Cyclical relation among multiple variables \\ \hline Analysis goal & Numerical accuracy & Structural accuracy \\ \hline \hline \end{tabular}
\end{table}
Table 3: Comparison of prediction simulation types and features.  
Module I is a module for estimating new construction demand generated by changes in the construction market's external environment and is set based on the construction market size data from 2000 to 2015. Module I improves predictive reliability through a fitting process for optimal parameter estimation based on the amount of change in explanatory environmental variables such as various societies, economies, and institutions surrounding the domestic construction market. During this period, the construction demand forecast will be conducted from 2016 to 2030 after the significance test of the historical and predicted data on the new construction market's size. Module II occurs through systemic linkage with Module I. It is set based on the construction capital stock, and the flow amount changes according to the degree of inflow-outflow. New construction demand for the year generated in Module I is converted into value as it flows into the construction capital stock and begins to accumulate with the inflow to the previous point. As the value decreases over time, it is converted into maintenance and demolition demand, and the value is decreased until the set service life of the original type is reached.  
Maintenance demand forecasts are generated from accumulated construction capital stock. Depending on each asset's useful life, the facility's value regularly declines until the point of large-scale maintenance reinforcement [37; 38]. The value calculated at this point is captured as demand for maintenance [39]. At this stage, correction is necessary to estimate realistic maintenance demand. The actual maintenance demand is estimated by revising the pattern coefficient to reflect the trend, such as the recent increase in the amount of maintenance and the conversion coefficient to apply the maintenance cost to the new construction cost by construction type. The demolition demand forecast sets when the facility's function reaches zero, and each asset's useful life requires the demolition plan. At this stage, the value generated is the demand for demolition. Estimates of demolition demand are predicted by correcting the recent demolition trends and application of maintenance rate to estimate final demolition demand.  
The total construction demand forecast result is the sum of the new demand forecast calculated in Module I and the maintenance and demolition demand forecast in Module II. With the model design based on the integrated system, it is possible to calculate the demand forecasting results and the detailed step-by-step (new, maintenance, and demolition) forecasting results of the construction production process that occur continuously over time.