Polyculture on an Urban Scale

Gardeners and farmers have practiced a symbiotic method of planting for centuries.  Called companion planting, specific plants are combined to return lost nutrients to the soil, to control pests and to aid pollination. For instance, American Indians planted corn, pole beans and squash together so that the corn stalks served as a trellis for the climbing beans and squash. Even small gardens can take advantage of this approach by mingling marigolds with other plants to repel aphids and attract their natural predator. While cities do not often have large areas available for re-design, sometimes waterfront and post-industrial sites become open for new development. What if urban design had a similar approach resulting in the companion placement for new buildings and landscapes forming an urban polyculture?

Mandates requiring sustainable architecture have three priorities: 1. sensitive building orientation; 2. maximize natural daylighting and ventilation; and 3. at least 80 percent of the operational energy required comes from the building itself. In more detail, building orientation is important because depending on the local climate, buildings need to defensively position themselves in order to minimize harmful exposures – for instance to avoid the summer sun in southern locations or winter wind in northern locations – and to maximize beneficial exposures. Building envelopes that thicken with reflective shading devices, insulated glazing, light trays to control daylight as well as operable windows to take advantage of breezes on days with mild temperature will require less summer cooling as there will be fewer light fixtures emitting heat. Local energy sources such as solar voltaics for hot water heating, geo-thermal heat pumps working with air temperatures that need less adjusting, and other engineered equipment will allow buildings to be more self-sufficient and less reliant on diminishing natural resources. If this thinking is broadened to the community scale, how might that affect urban plans?

Suppose buildings were arranged so that one vegetated screen wall protected the southern-most exposure of one building with the others benefiting from the subsequent shade. Then their placement could be refined to channel prevalent breezes creating wind tunnels for turbines and windmills. Instead of slowing and then disposing stormwater in remote municipal treatment facilities, water could be gathered in reflecting ponds to bounce light into buildings. Small waterfalls could provide natural air cooling if they could take advantage of breezes, and if the pools were a sufficient depth, the consistent temperature could reduce the energy required for heating and cooling equipment.

By clustering buildings to take advantage of their proximity, they can assist each other in what natural forces they attract and repel. The result would be increased productivity. Planning for zero-carbon cities usually means reducing waste, improving a building’s ability to respond to light and air, and specifying more-efficient and more-accurately sized engineered equipment that generate local power for energy needs. People are fragile and need shelter; but they also like to be comfortable. Polyculture as a design approach might mean that their needs, physical and emotional, are satisfied more naturally.