YKK AP and residential businesses team up for housing performance improvement renovation as a way to solve the vacant house issue

In this project, we perform full-scale renovations of the entire home, leaving only structural material like pillars and beams. This means our products are installed on the building frame—just like when putting up a new house—which is totally different from partial renovations, such as replacing a single window. For a new build, window positions are obviously part of the construction process. But with renovation, you have to remove the wall while leaving the framework to install a window. You must consider the existing house’s condition and think about putting thermal insulation material around the window as well. No matter how much manufacturers like YKK AP know about windows, we lack the skills and know-how to install them. That’s why we needed the cooperation of residential business operators to implement this project. The important point of this project is that renovations are done to improve performance for thermal insulation and seismic resistance.

The Building Standards Act and other performance standards apply to new housing, but because there are no clear criteria for renovation, businesses and homeowners decide on the necessary performance. For this project, our standards are Thermal Insulation Performance Level 6 and Seismic Resistance Level 3.

New builds must meet or exceed Thermal Insulation Performance Level 4 in 2025 and Level 5 in 2030. We are aiming for Level 6, which is higher than both of these. Our goal of Seismic Resistance Level 3 means the house will not collapse during an earthquake registering 6 Upper to 7 on the Seismic Intensity Scale. People can continue living in the house, which safeguards their lives and assets. In contrast, Level 1 means the house will not be immediately destroyed, but is at risk of serious damage.

APW 330 high-performance vinyl windows and APW 430 high performance triple-glazed vinyl windows are used to achieve this performance. These products provide roughly four to seven times better thermal insulation than the single-pane, aluminum-framed glass windows in many existing housing stock units. We suggest which to use according to the performance and cost considerations of each project. We provide our Frame II products for seismic resistance at windows and doors. Windows and doors are weak points. We use simulations to suggest how many products should be installed in what locations to retrofit them and reach Level 3, even for large windows and doors.

This Kyomachi home was built 112 years ago and is located right across from Daigoji temple, a UNESCO World Heritage Site. We replaced all 14 of the single-pane, aluminum-framed windows with vinyl windows. We also installed thermal insulation in the ceiling, walls, and floors, which had none. The Kyoto Daigo House’s thermal insulation performance is over seven times higher than before the renovation. It’s comfortable while also saving energy, with annual heating and cooling costs roughly 50% lower than before. We used a FRAME II at one location to achieve strength equivalent to Seismic Performance Level 3 without having to cut back on windows or floor space.

The completed Kyoto Daigo House serves mainly as a model home for professional users, and is utilized to offer performance improvement renovation expertise and share information with the local community. A cumulative total of 300 professional users have visited, and about 30 regular couples looking for homes have taken tours. Mizushima works with these customers at the house. He said, "I know that performance has been improved when someone who just stepped into the entryway says, ‘Something seems different.’ Even if visitors don’t comprehend the performance levels, numerical values, or other slightly difficult concepts, they can feel whether the inside of the house is warm or cool. I’m glad we are part of this project so we can at least show people that performance improvement renovation is a housing option." He spoke about the significance of the project as follows: "At first I thought it would be too much to use windows with the same performance level as those in Hokkaido. However, I don’t like the phrase ‘too much’ anymore (laughs). Comfort is relative to high specifications—there’s no such thing as too much when it comes to comfort."

This isn’t just a demonstration project—another aim is to teach nationwide business operators about this technical expertise and business model. During construction, we hold tours to showcase things that cannot be seen after the project is completed, such as the state of seismic performance and foundation retrofitting, as well as thermal insulation material and airtight installation methods. When the renovation is complete, we conduct tours to show what the building looks like and share information about the renovation concept. It’s true that this involves revealing our expertise to local businesses in the same industry, but this project is done with cooperation from members who agree with our thinking about performance improvement renovation. These tours have been attended by a total of 3,000 business, and we have communicated and exchanged opinions with them as more people have gotten involved in the project.

Through these projects, we have learned it is possible to achieve Thermal Insulation Performance Level 6 and Seismic Performance Level 3 by renovating homes. We’ve also heard from member businesses and tour participants about many different issues, such as how to choose a building and structural problems revealed after demolition. Renovation can be difficult to understand, laborious, and troublesome, creating a bottleneck for people who want to get into this business. We started the Association of Performance Improvement Renovation in October 2021 with the goal of building an environment that facilitates housing performance improvement renovation projects, and of helping promote and popularize this market. We publicize information about the overall workflows and processes, from property selection to transfer. We also offer partner services from specialized companies in each field and various tools and support to handle wide-ranging concerns. Current members include contractors, real estate companies, renovation businesses, and distributors. We created the Association of Performance Improvement Renovation as one way to solve the issues we encountered during projects. I think the next step is making it into a hub not only for communication between members, but also for matching between members, and between members and general customers.