The Mandan and Hidatsa built earth lodges, partially dug down into the ground. Four large corner posts, then layers of logs, bundles of willows, grasses, and then a thick layer of dirt and the sod is reseeded onto the outer surface. A center smoke hole, double doors to insulate from wind blowing through. With the large thermal mass and deep insulation they stayed warm in the winters with small central fires.
Coincidentally, they were also decently cool in the summer. Especially since they also watered the floors then to keep the dust down. The evaporative cooling effect was pretty efficient.