Convection: liquids and gases transfer heat this way --> motion of the medium between regions of different temperatures.
Fireplaces --> produce natural convection --> warm air rises and is replaced by cold air
Most space heating systems operate via convective heat transfer (forced air)
Was effectively used centuries ago in American Southwest (Mesa Verde).
Sandstone dwellings and walls would absorb much sunlight during the day and then re-radiate that as heat at night.
In general, recovering incident solar radiation via subsequent thermal radiation of materials is not practical