**3.1 Housing-related problems and requirements for sustainable design**

Housing-related problems and requirements for sustainable housing design have been demonstrated in **Table 1**. We have first selected main global and general issues, considering the conditions for sustainability. The first two items, "global


*Notes: (1) Housing-related problems listed in this table are only main global and general issues. If intending to create design guidelines for a region or country, system designers need to add local and particular issues of that region or country to the problem list [9]. (2) This housing design study deals with issues that can occur after housing sites are determined. Therefore, matters concerning housing land development or site selection are excluded from this table. Instead, such issues are handled in the study on urban design [16].*

#### **Table 1.**

*Housing-related problems and requirements for sustainable design.*

warming and climate change" and "environmental issues related to building materials," are significant problems linked to environmental conditions. The other issues are chiefly related to well-being conditions, such as health and safety. Choosing five items from the table, this section briefly explains the outlines of the problems and the requirements for sustainable design.

## *3.1.1 Global warming and climate change*

The IPCC's Fifth Assessment Report has concluded that cumulative emissions of CO2 largely determine global mean surface warming [1]. The amount of CO2 in the atmosphere has been obviously increasing due to human emissions [1, 17]. In order to cut CO2 emissions, the housing sector must reduce energy originating from fossil fuels. Therefore, two mitigation measures, namely saving energy and using renewable energy, are significant as the requirements for sustainable design [1]. Moreover, the necessity of enhancing the sinks of CO2 requires increasing green spaces [1].
