In the present world affected by climate change, developing agricultural technologies to adapt to climate change is one of the most important challenges to mitigate the impacts of climate change on food security. In fact, many researchers and engineers are also working to develop adaptation technologies.If there is a low-cost, easy-to-use tool to evaluate such technologies, it will facilitate initial evaluation to consider the appropriate technical development perspective. Accordingly, this paper tries to develop a simple model structure for the tool and consider how best to use the evaluation tool, based on the achievements of a previous study. To enable simple calculations in a spreadsheet, an input-output model is applied to the model structure, assuming minimal impact of shocks on national nominal income. Comparisons of projection results by two alternative candidate models with those by a comprehensive but complex simulation model including flexible and realistic assumptions show that the developed simple models result in realistic and robust projections of real consumption and social welfare index. Accordingly, an evaluation tool based on simple model structures will enable a low-cost initial evaluation with social welfare as a criterion.