“I much enjoy the pergola at the end of the sunny path. It is pleasant while walking in full sunshine, and when that sunny place feels just a little too hot, to look into its cool depth, and to know that one has only to go a few steps farther to be in shade, and to enjoy that little air of wind that the moving summer clouds say is not far off, and is only unfelt just here because it is stopped by the wall. It seems wonderfully dark at first, this gallery of cool greenery, passing into it with one’s eyes full of light and colour, … but on going into it, and sitting down on one of its broad, low benches, one finds that it is a pleasant subdued light, just right to read by.”
Chief among the climatic elements we seek is sunlight. It provides us with food, health, warmth, and the ability to see our surroundings. No wonder humans are phototropic: We are drawn to the light, and we orient ourselves to it when standing or sitting. Even at the same temperatures, many more people go outdoors on sunny days than on cloudy ones.
Still, even in temperate climates, we seek to escape from the sun’s blaze and glare in summer. As perceived warmth increases, our preferred outdoor place shifts. The threshold temperature where most people switch from seeking sun to seeking shade has been established at about 22ºC/ 72º F.
Shade is needed to prevent bodily overheating and dehydration. Shade offers coolness and moisture. In shade, we can rest our eyes and we can hide. Shade is particularly needed by the elderly, whose eyes are increasingly sensitive to light. Studies at assisted living facilities have found that outdoor amenities like walkways and seats will go unused until they are provided with shade.
The sun comes first, though, because without it there is no shade.
Because we are drawn to the light, especially sunlight, and held there, light is a social glue, creating our most-used places. Design should insure sunlight to highlight the busiest, most important places—intersections, activity nodes, urban squares. Otherwise, people will walk to the wrong places, causing confusion.
Since sunlit places are observable only in contrast to dark spaces, a pattern of light and dark evolves naturally. “Positive hospitality…,” Olmsted observed, “is to be achieved chiefly by the alternation of light and shadow.” It has characterized preferred locations since the dawn of the species. Our places of origin—savannas with copses of trees—and our favorite places now—grassy parks with trees—evince the same pattern. Attractive paths replicate the same tapestry of light and dark, moderating extremes of weather and offering refuges and prospects.
A critical moment of light/dark contrast occurs at a gateway to an open space. The darkness at the entry provides a refuge with a view at the point where the decision to enter the open space is made. The darkness is ideal indoors or out because the visitor can remain hidden while scanning the sunlit space for safety and orientation. Just as Frank Lloyd Wright crafted dark, low entries into high-vaulted rooms bathed in light, so Olmsted placed arches or short tunnels opening onto lakes and meadows, such as Endale Arch leading into Long Meadow in Brooklyn’s Prospect Park.