Which design feature is specifically intended to optimize solar gain?

Selecting large atriums as a design feature specifically intended to optimize solar gain makes sense as atriums can be designed to capture sunlight effectively. An atrium often consists of a large, open area that allows for significant natural light penetration, which can help heat the interior spaces of a building. When strategically located and oriented, atriums can maximize exposure to sunlight during the colder months, thereby harnessing the sun's warmth to reduce reliance on artificial heating. Additionally, the glass and open nature of the atrium encourages the collection of solar gain, which can enhance daylighting and improve the energy efficiency of the building.

Other design features, while they may have benefits in different contexts, do not serve the specific purpose of optimizing solar gain as directly. Open floor plans enhance spatial flow but do not inherently increase solar access. Flat roofs can be practical for certain applications but do not inherently promote solar gain unless integrated with solar panels or green roofs designed for such purposes. Exterior shading devices help manage solar gain by blocking excessive sunlight, which can be beneficial in hot climates but are not aimed at optimizing it. They are more about controlling the amount of solar gain rather than maximizing it.