Untold Proposals for the Future – Nikken Sekkei's Professional Services
Part 2: Creating New Social Value Through Facade Engineering (Part 2)

One of the services DEL provides is architectural facade design based on advanced analytical technologies. A facade serves as a mechanism for controlling the external and internal environments, and the way it is constructed affects the internal environment—including temperature, illuminance, and views.Furthermore, the shape of a facade has a significant impact on the landscape and the surrounding environment. To create facades that are both environmentally sustainable and aesthetically sophisticated, DEL continuously develops innovative solutions that span the fields of design, structure, building systems, the environment, and construction.
We spoke with Keishiro Tachi (Design & Technical Department, Tech Design Group Director), who leads facade engineering and environmental computational simulation at DEL, about the originality of Nikken Sekkei’s facade design and the social value it brings.

The underlying principle in Nikken Sekkei's facade engineering is "meticulous analysis of the relationship with the surrounding environment." This is because they place great importance on reflecting the urban environment in their architectural designs.

In particular, Nikken Sekkei has named a new environmentally conscious exterior system, focusing on small and medium-sized buildings in urban areas, "Envi-lope," and is working to develop it into a series. Envi-lope is a coined word combining Environment and Envelope, and proposes an exterior envelope with a low environmental impact.

The underlying aim is to simultaneously improve the environmental performance and value of small and medium-sized buildings through facade design. Small and medium-sized buildings tend to occupy narrow plots of land and are densely packed with buildings, making them susceptible to environmental influences such as lighting, ventilation, and views, not only due to their orientation but also due to their relationship with surrounding buildings. Furthermore, there are significantly more of these buildings than large-scale buildings, and the need for environmental improvement is increasing, including not only new construction but also renovations of existing buildings. Envi-lope is a facade system that comprehensively handles multiple environmental adjustments such as sun shading, lighting, and ventilation, achieving decarbonization while simultaneously creating a better internal environment.

The first example of this technology, "Envi-lope 01," was adopted for "Jimbocho SF I," which was completed in 2022. From the outside, it looks like a round object with a hole in the bottom of a pot completely covering the building. It's not an exterior wall, but rather an outer shell that combines solar radiation control and the preservation of views.

At "Jimbocho SFI," DEL analyzes the ever-changing movement and radiation of sunlight. Using its proprietary program, it performs an inverse analysis to derive the position and shape of shading objects from the radiation that requires shading, thereby deriving the shape of Envi-lope01.

Envi-lope01 aimed not only to improve the environmental performance of buildings but also to minimize materials and construction processes, thereby achieving decarbonization. At "Jimbocho SFI," from the outset of the project, we considered and jointly developed an exterior system made with the fewest possible components and processes with Seo Seisakusho (Takaoka City, Toyama Prefecture). A representative from Nikken Sekkei took notice of the molds used for Buddhist altar fittings that Seo Seisakusho, which originally manufactured Buddhist altar fittings, owned. They devised an exterior covering for the building by creating thin, pan-shaped metal parts using a metal press, connecting them with wire in a chain, and supporting them from above and below.

This metal fitting has crescent-shaped holes to allow visibility and airflow in areas where sun shading is not needed. The ideal location and type of holes vary depending on the orientation and height, so various hole patterns are possible. After conducting numerous simulations and clarifying the conditions, DEL arrived at the optimization of a cylindrical unit. This solution showed that covering the entire surface with just two types of metal fittings provides approximately 70% sun shading, approximately 70% openness, and approximately 70% visibility.

The components themselves are simple, but the installation locations are complex. How was the installation carried out?
Using a computer, we identified areas where sun shading was needed and determined the optimal shape for the metal fittings, including the orientation of the holes, mounting direction, and height. Based on this data, DEL devised a manufacturing control method that automatically attaches the metal fittings to the wires using machinery.

This exterior material, which consists of metal parts connected by wire in a chain, is small and lightweight, and can be delivered to the site by courier service instead of a dedicated truck, thus achieving CO2 reduction in material transport.

In small and medium-sized buildings, areas such as equipment balconies and fire escapes are often exposed on the surface. By completely covering these areas with an outer shell, we contribute to improving the streetscape. After completion, we verified the brightness of the sunlight shining through this mold and found that it created a light environment similar to the dappled sunlight that people find pleasant. The Envi-lope series, which creates spaces that people find pleasant while reducing environmental impact through the design of an outer shell covering small and medium-sized buildings, is currently in the development of its second phase.

Facades require consideration of all aspects, including environmental control, structure, details such as watertightness and airtightness, cost, and maintenance, and have a significant impact on the environment both inside and outside the building. In response, DEL offers technical studies and proposals for modern facades from both the perspectives of cutting-edge digital technology and manufacturing. In the initial stages of design, we maximize the added value of the building through studies using digital technology, such as simulations. From the mid-stage of design to the on-site manufacturing stage, we provide support to realize the design concept while rationalizing costs and constructability.
Building facades require not only environmental performance but also various social values such as views and design. It is precisely our strength as a group of engineers with diverse expertise that lies in our sincere approach to these complex challenges.