*4.2.1 Changes in the theoretical world*

First of all, observing recent trends in understanding problems related to houses, we have searched for problems which affect stability conditions. Consequently, as shown in the second column of **Table 2,** we have specified additional problems that


#### **Table 2.**

*Additional problems and requirements for sustainable housing design identified for the latest revision of the design guidelines [extracts] [12].*

#### *How to Design Sustainable Structures DOI: http://dx.doi.org/10.5772/intechopen.95012*

[10, 11]. Moreover, in order to cover all of the requirements for sustainable housing design, we added necessary elements, such as "equipment for harnessing renewable

After specifying the elements, we identified the variables and their desired values. Choosing one element, namely "thermal insulation," the rest of this section explains the details of identifying the variable and its desired value. First of all, we determined "thermal insulation performance" as the variable, considering two requirements, that is, "energy saving" and "improvement of indoor thermal performance," as well as the relevant stability conditions. Higher thermal insulation performance contributes to "environmental preservation" and "sustainable use of natural resources" due to a decrease in energy usage for air-conditioning and

When specifying the desired value, we observed trends in technology and systems related to housing thermal insulation performance. Japanese housing thermal performance has traditionally been low. Japan's building codes have not stipulated the standards of housing thermal insulation performance. Meanwhile, since 2000, a national voluntary system, namely the Japan Housing Performance Indication Standards (JHPIS), have provided four-level thermal insulation performance grades. Consequently, we determined the desired value to be the highest level in the

The above sustainable housing design guidelines produced in Japan have recently been revised. This latest revision has dealt with the three aspects as mentioned before: (1) changes in the theoretical world, (2) changes in the practical

First of all, observing recent trends in understanding problems related to houses, we have searched for problems which affect stability conditions. Consequently, as shown in the second column of **Table 2,** we have specified additional problems that

*Additional problems and requirements for sustainable housing design identified for the latest revision of the*

**Requirements for sustainable housing design**

• Considerations for homeworking, telecommuting, and lifelong learning

• Floor planning suitable for good communication among residents

**Stability conditions**

• Selfrealization

• Mutual help • Selfrealization

resources • Health (in crises) • Safety (in crises)

• Storage of electricity • Sustainable

heating, as well as residents' better "health."

*Environmental Issues and Sustainable Development*

thermal insulation performance grades of the JHPIS.

**Environmental, social, and economic problems related to housing**

• Breakdown risks in electricity systems due to increasing wind and solar

power generation

lifelong learning

communication

• Insufficient considerations for homeworking, telecommuting, and

• Problems resulting from insufficient

**4.2 The latest revision of the design guidelines**

world, (3) feedback from the users.

*4.2.1 Changes in the theoretical world*

**Type of problems**

Global/ general problems

Local/ particular problems (in Japan)

**Table 2.**

**284**

*design guidelines [extracts] [12].*

energy."

should be dealt with. Based on these problems, additional requirements for sustainable housing design have also been identified. After that, these additional requirements have been incorporated into the framework of "element-variable-desired value."

Choosing one requirement, namely "storage of electricity," the following describes the essentials of the identification and incorporation processes. In order to curb global warming, the utilization of renewable energy, particularly wind and solar power generation, is quickly increasing in many countries [13]. But the quantity of electricity extracted from solar and wind sources varies chiefly with the time of day, weather, and season. Therefore, a surge in wind and solar power generation is also raising the risks of power failures [14, 15]. In order to cope with such changing circumstances, we have added "storage of electricity" as a requirement for sustainable housing design. Besides, storing electricity leads to securing an emergency power source, which is one of the adaptation measures against climate change.

When incorporating the "storage of electricity" into the guidelines, we have added "storage battery" as a new material element. Subsequently, we have identified two variables of this new element: "type" and "linkage." The desired value of "type" has been specified as "stationary battery or electric vehicle battery." Meanwhile, the desired value of "linkage" has been determined to be "interconnection with the home electrical system."
