It feels like in two seasons at one time when standing in the doorway of a seaweed-thatched house in late May. Outside is scorching while inside is cool as if spring lingers on.

"Thanks to the grass roof and the stone walls, the house is cool in summer and warm in winter," said Liu Yuqi, the house owner.

It is one of the 95,000 so-called seaweed bungalows scattered in 317 villages in Rongcheng, a coastal city in Shandong province.