打ち水大作戦2026参加者からの感想 Vaporization Cooling

8月に入り、連日３４度を超える酷暑が続き、エアコンの効きも悪くなった。外を見ると、テラテラの太陽に照らされたアスファルトが見える。直視するだけで目が焼けそう。さぞかしコンクリートは過熱していることだろうと思った時、打ち水を思いつきました。洗面器からピシャッと水を打つ。その２、３分後にはアスファルトを通り抜ける風が少し涼しくなっていました。

建物の外壁に打ち水するのもお勧めです。緯度が低い地域では、太陽光が強烈です。その強い光エネルギーが、蓄熱量の多い建物が熱されて蓄積し、日が沈んでから外は涼しくなりかけている夕方から夜にかけて、室内温度が上がります。石やコンクリートなど蓄熱量の多い建物からのエネルギーが遠赤外線となって、中の人に放射されているのです。ステーキはじっくり焼けば美味しいけど、石焼ビビンパにははりたくないですよね？だから、昼のうちに外壁に打ち水して温度を下げておきます。

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As August began, the sweltering heat continued, with temperatures exceeding 34 degrees Celsius every day. The air conditioner was also becoming less effective. Looking outside, I could see the asphalt glistening under the blazing sun, and it almost hurt my eyes just to look at it. Just as I was thinking that the concrete must be scorching hot, I had the idea to splash water on it. I splashed water from a basin, and two or three minutes later, the breeze blowing across the asphalt felt a little cooler.

We also recommend sprinkling water on the exterior walls of buildings. At lower latitudes, the sunlight is intense. That strong solar energy heats buildings with high heat storage capacity, causing them to store a large amount of heat. As a result, indoor temperatures can rise from evening into the night, even after the sun has gone down and the outdoor air begins to cool. The energy stored in materials such as stone and concrete is released as far-infrared radiation, which radiates heat toward people inside the building. A steak is delicious when cooked slowly, but you wouldn’t want to use that method for stone-grilled bibimbap, would you? That’s why you should sprinkle water on the exterior walls around noon to lower their temperature before the evening.