Developing practical approaches and tools for optimizing zeb designs

In Japan, there is a growing demand for ZEB to achieve a carbon neutral society by 2050. At the same time, The Labor Standards Act has been revised to impose stricter upper limits on working hours. As a result, there is a pressing need to resolve the conflicting issues of ZEB design and improving productivity.

To address this issue, we have developed and put into practical use a new design tool called ZEB SEEKER. This tool automatically explores design proposals for achieving ZEB by integratively optimizing the specifications of the building envelope and equipment.

This tool uses GA to optimize combinations of building envelope specifications (such as insulation performance, window performance, and shading shape) and equipment specifications (such as air conditioning method, heat source type, heat storage capacity, lighting control method, hot water supply method) as variable parameters to achieve ZEB. Energy simulations are performed using WEB Program that complies with the energy calculation method of Japan’s building energy conservation regulations (ZEB evaluation in Japan is based on the rules of this program).

The tool has three main features. Firstly, it expands the scope of consideration. Traditional optimization in the energy conservation field of buildings has mainly focused on limited envelope elements such as window size, insulation performance, or partial considerations of equipment optimization like cooling water temperature for heat sources. In this case, nearly all envelope and equipment specifications related to energy conservation (about 50 types) are targeted.

Secondly, it includes an automatic equipment capacity determination function. energy simulations require not only building envelope and equipment specifications but also equipment capacity. This tool realizes automation of equipment capacity setting. This allows for the automatic calculation of a building’s energy performance by selecting building envelope and equipment specifications.

Thirdly, it includes a function to set the applicable level of customer needs. This function allows for the setting of the degree of fit of each choice for variable parameters to the customer’s needs on a 5-level scale. By optimizing not only energy conservation By optimizing this customer need value in addition to energy performance, it is possible to derive a ZEB design proposal that meets customer needs.

The tool has been applied to a large-scale building of 300,000 square meters. While achieving ZEB for large buildings has been extremely challenging, this tool successfully derived a design proposal to achieve ZEB through two days of input work and one week of calculations.