Moving away from simple replacement: How to approach ZEB Renovation (Part 2)

「『単純リプレース』＝既存設備を高効率機器へ単純に置き換えること」をやめ、ZEB化を目指す上では、まず環境性能BEIを把握すること。建物の一次エネルギー使用量のうち空調と照明が占める割合は大きく、リノベーション手法毎に、どのようにその環境性能が改善されるのか、どの程度のコストがかかるのかを「見える化」し、ZEB認証取得までの道筋をクライアントと共有することが重要です。

For example, from the perspective of environmental performance and comfort, it is desirable to make the building envelope highly heat-resistant and insulated, but depending on the client, there are cases where such an investment is difficult. In such cases, we propose "cases that emphasize cost-effectiveness" and "cases aimed at obtaining ZEB certification" along with costs based on the environmental performance BEI of each measure, so that the business operator can make a choice according to their investment plan (long-term repair plan). In some cases, ZEB was achieved without increasing construction costs compared to simple replacement.

This kind of "visualization of environmental performance" is done using energy saving calculations (WEBPRO), but it is a lot of work to calculate multiple cases with different situations in parallel. We have developed a tool that streamlines this energy saving calculation, and it has become possible to delve deeper into technical considerations at the early planning stages. This has enabled us to respond to more clients' requests for ZEB renovations.

Starting in April 2024, businesses that sell and rent buildings will be required to display energy-saving performance labels in advertisements, etc., and there is an increasing need to understand and improve environmental performance. In this context, this tool (aside from achieving efficiency) lowers the hurdle for in-house designers to make efforts to "visualize environmental performance."

We have obtained ZEB certification through Renovation for a total of six buildings to date, all of which are tenant office buildings (as of April 2024). Obtaining certification is not the end of the process; subsequent follow-up and data verification during operation are also important.

The impact of "simple replacement" is evident in the daily energy consumption of a building, but it is difficult for business operators and building managers to grasp this. Therefore, we try to show this data in an easy-to-understand manner as the environmental performance BEI and the magnitude of energy consumption. If equipment is oversized through "simple replacement," it can easily lead to a deterioration in environmental performance.

In order to realize ZEB, downsizing through capacity optimization is an important point, but as a result, clients are particularly concerned about whether there will be complaints from tenants during operation. For example, in addition to being able to implement a significant downsizing as in the verification example (see figure below), it is important to show the client with numbers that the building is being operated efficiently. We believe that feeding this back into future designs is important in reducing energy consumption in existing buildings and even the entire city.

The government has set a goal of achieving ZEB status for the average stock of buildings by 2050. To achieve this goal, there is no doubt that the immediate mission will be to Renovation existing buildings to become ZEBs. However, to achieve the essential goal of "realizing a carbon-neutral society" that lies beyond "ZEB status for the average stock of buildings," these energy-saving efforts alone will not be enough.

Manufacturing approaches such as ingenuity in production (using materials and equipment with low environmental impact in the manufacture of building materials and equipment), circular design that minimizes waste, and design that takes biodiversity into consideration are becoming more important. As MEP Engineering, we are expected to work in collaboration with not only our clients, but also with various other professions and fields.