Why are Aeon Malls Comfortable Even on "Extreme Heat Days"? Creating a Sense of Coolness Using Lighting Color Temperature in Addition to Air Conditioning

Endo Lighting Co., Ltd. (Headquarters: Chuo-ku, Osaka; President and CEO: Kunihiko Endo; Tokyo Stock Exchange Standard Market: Securities Code 6932; hereinafter "Endo Lighting") proposes creating indoor spaces that do not rely solely on air conditioning but also utilize the color of lighting (color temperature).

Here, we introduce case studies of the use of dimmable and color-tunable lighting at "Kurunto" (Nagai City, Yamagata Prefecture), a facility for play and learning, and Aeon Mall Ota (Ota City, Gunma Prefecture).

Lighting in the "Picnic Court" indoor plaza at Aeon Mall Ota. Left is summer, right is autumn. The light color can be changed according to the season.

With ingenuity, lighting can create spaces that feel cool or warm, and it is one of the elements that create visual and psychological comfort according to the season and time of day. Endo Lighting supports the creation of comfortable indoor spaces even in hot seasons through dimmable and color-tunable lighting and wireless control systems.

The increasing value of comfortable indoor spaces in an era of "extreme heat"

In 2025, the number of locations nationwide recording temperatures of 40°C or higher was the highest on record, and in 2026, the Japan Meteorological Agency will newly define "extreme heat days" as days with temperatures of 40°C or higher in its forecast terminology. The extreme heat of summer has become a social issue, to the extent that a term is needed to indicate more dangerous heat, in addition to "very hot days" (35°C or higher).

Amidst this, the value of indoor spaces where people can spend time comfortably even in hot seasons is increasing. Public and commercial facilities are expected to serve as "places to be" where children, families, and local residents can stay with peace of mind. In addition to temperature control by air conditioning, a perspective that adjusts the overall comfort and impression of the space is becoming important. One of the clues to this is the light environment.

Heat is influenced not only by actual temperature but also by "how things look."

People feel heat and coolness not only from room temperature but also from the color and brightness of light. Generally, light with a high color temperature and a bluish tint tends to give a refreshing and cool impression, while light with a low color temperature and a reddish tint tends to give a feeling of warmth.

The influence of lighting color temperature on the perception of coolness and warmth is known in the field of lighting design. Even at the same room temperature, lighting with a low color temperature tends to make people feel warmer, while lighting with a high color temperature tends to make them feel cooler. This relationship is known as the "hue-heat effect." A demonstration experiment (※) involving Doshisha University and others showed that there is a difference of approximately 2°C in perceived temperature between warm lighting at 3000K and cool lighting at 5500K, in both cooling and heating conditions.

However, this indicates the possibility that the perception of people changes depending on the color of the light, rather than that lighting lowers the actual room temperature. By combining the light environment with temperature control by air conditioning, indoor spaces can be made to feel more comfortable in hot seasons. From this perspective, the use of dimmable and color-tunable lighting is expanding in public and commercial facilities.

※ Intellectual Office Environment Promotion Council "Commercialization of Lighting and Air Conditioning Interlocking Control System Based on HUE-HEAT Effect" (December 15, 2021) https://www.kri.or.jp/news-event/img/pressrelease_20211215a.pdf

Case Study 1: "Kurunto" (Nagai City, Yamagata Prefecture), a facility for play and learning

Lighting in the entrance of "Kurunto." Left is 6000K in summer, right is 3500K in spring, autumn, and winter. The impression of light is changed according to the season.

"Kurunto" in Nagai City, Yamagata Prefecture, is a complex facility for play, learning, and interaction, integrating an indoor playground and a library. It was completed in 2023 as a community gathering place used daily by a wide range of generations, including children and families.

At the facility, the color temperature of the lighting in the entrance, which first welcomes visitors, is switched according to the season. In summer, it is set to 6000K (left photo above) for a cool impression, and in spring, autumn, and winter, it is switched to 3500K (right photo above) for a warm impression, with automatic scheduling.

Nagai City explains that this operation is intended to visually convey coolness and warmth, which are difficult to convey through temperature alone, to visitors and to create a space where they can spend time comfortably regardless of the season.

The facility side perceives that the automatic switching of the entrance lighting according to the season greatly changes the first impression of the space. In particular, when entering from the hot summer outdoors, some visitors have commented that the refreshing, cool light provides a sense of relief as if their perceived temperature has decreased.

The facility aims to be a "comfortable space for citizens to visit anytime." The lighting design at the entrance, which changes with the seasons, sets the first impression upon arrival and supports the creation of a space that serves as a community "third place" for play, learning, and interaction.

Case Study 2: Aeon Mall Ota (Ota City, Gunma Prefecture)

Lighting in the "Picnic Court." Left is daytime, right is evening. During the day, a refreshing light reminiscent of a blue sky creates a visual sense of coolness.

Aeon Mall Ota, which was renovated in April 2024 in a region that is hot in summer and experiences the Akagi Oroshi wind in winter, has created an indoor plaza "Picnic Court" in the center of the food court where children and families can spend time throughout the year, regardless of the heat or cold.

The light design supports the creation of this space. A large light film fixture resembling the sky is installed above the plaza. By switching light scenes according to the time of day, such as morning, noon, evening, and night, as well as seasons such as spring, summer, autumn, and winter, the impression of the same indoor plaza changes according to the time of day and season.

These light changes are performed according to a preset timetable. The light scenes are designed to reproduce the transition of natural light throughout the day, from the morning sky color to the daytime sky color, evening, magic hour, and night lights.

During daytime and summer scenes, a refreshing light reminiscent of a blue sky spreads. In contrast, during evening and autumn scenes, a warm light creates a calm impression. This is a light environment design to create a space where one can feel the transition of the sky and seasons while indoors.

Aeon Mall Ota believes that the ceiling colors visible to users relaxing on the artificial turf enhance the spatial experience. They also believe that the seasonal light effects, combined with other spatial designs within the mall, have the effect of conveying a sense of season and outdoor feeling to visitors.

An Aeon Mall Ota representative said, "Especially in the summer, when means of enhancing indoor comfort tend to be limited to air conditioning, the color of the light that creates a visual sense of coolness softens the overall impression of the space and adds a refreshing element. We believe it contributes to creating an environment where people can spend time in a cool and open atmosphere, even on days when it is extremely hot outside."

This light environment contributes to making the food court more than just a place to eat, but a place to be indoors where families can enjoy meals and breaks with a picnic-like atmosphere.

Achieving "Light Operation" with Dimmable and Color-Tunable Lighting

Endo Lighting proposes the creation of light environments tailored to the specific uses of each facility through its next-generation dimmable and color-tunable LED series "Synca," "Tunable LEDZ" with dimmable and color-tunable functions, and wireless control system "Smart LEDZ."

"Synca" supports a wide range of color temperatures close to natural light, from 1800K, equivalent to a candle flame, to 12000K, equivalent to blue sky light. In addition to 121 color variations, it also supports time-based control and scene settings. It enhances the impression of a space and the visitor experience by changing the light environment according to how the facility is used – cool in summer, calm in winter, and colorful for events.

These do not lower the room temperature through lighting, but are a concept that utilizes the light environment as an element to enhance visual and psychological comfort, assuming temperature control by air conditioning.

※ The cases introduced this time include dimmable and color-tunable fixtures such as "Tunable LEDZ" in addition to "Synca."

Product Information: https://www.endo-lighting.co.jp/products/pickup/synca/

Related Information

Nagai City Play and Learning Exchange Facility "Kurunto"

https://www.endo-lighting.co.jp/projects/nagaishi-kurunto/

Aeon Mall Ota Picnic Court

https://www.endo-lighting.co.jp/projects/aeonmall_oota/

Company Profile: Endo Lighting Co., Ltd.

Company Name: Endo Lighting Co., Ltd.

Headquarters: ENDO Sakaisuji Building 8F, 1-7-3 Bingomachi, Chuo-ku, Osaka 541-0051

TEL: 06 (6267) 7095 (General) FAX: 06 (6267) 7096

President and CEO: Kunihiko Endo

Founded: September 1967

Established: August 1972

Capital: 5.155 billion yen

Business Activities: Planning, design, manufacturing, and sales of various lighting fixtures; sales of interior furniture and goods

Fiscal Year End: Annually, March 31

Sales (Consolidated): 55.473 billion yen (Fiscal Year ending March 2026)

Number of Employees (Consolidated): 1,648 (As of the end of March 2026)