This is because the layers of grass in the thatched roof can stabilize the flow of air through them, and they don't readily trap or pass heat along. This is why they stay cool in summer, yet warm in winter, and are also very effective at blocking out sound.
這是因為層層疊疊的茅草頂可以穩定氣流、不易傳熱，因此茅草屋住來冬暖夏涼，隔音效果絕佳。