Smaller Windows, Better Performance?

In Japan, a quiet design shift is taking place — homes are being built with smaller, fewer windows.

Traditionally, large windows symbolized comfort and openness.
But today, energy efficiency, cost, privacy, and safety are redefining what “good design” means.

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A 41-year-old office worker in Nagoya described his reaction after seeing his new house plan:

I grew up believing that big windows mean a good house. But ours had so few windows, all small. I was shocked at first.

Later, he found the interior still bright and comfortable:

The temperature is stable, and we don’t worry about glare or neighbors looking in.

Another homeowner in Karuizawa, Nagano, chose narrow fixed windows for security and easy cleaning:

Even without windows in the bathroom, I don’t mind. It’s cleaner and simpler.

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Behind this shift lies a practical reason: cost and insulation performance.

While Japan’s double and triple glazed windows offer superb insulation, they’re expensive. Builders realized that reducing total window area can achieve similar efficiency at lower cost.

According to the Japan Sash Manufacturers Association, new homes today have an average of 15.7 windows per house, down 4.2 since 2015.

About 70% of unwanted heat enters through windows in summer, so shrinking them saves both energy and money.

Even Japan’s revised building code now allows smaller window areas if lighting standards are met — aligning architecture with energy goals.

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Design always adapts to context: cost, climate, lifestyle.

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A Question for Cambodia

Could this approach work here — in a region where light, ventilation, and comfort depend so much on open air?

As we rethink sustainability, maybe “less opening” isn’t less design —
it’s design tuned to context.

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Source: Yomiuri Shimbun
Photos via Yomiuri Shimbun