Similar results are found for multi-family housing in an urban setting. Solara, a 238-unit apartment complex by Weber + Thompson for Simpson Housing in the Lake City neighborhood of Seattle, arranges housing in three buildings surrounding an urban courtyard. The units facing the courtyard are more desirable, are renting more quickly and for a higher price than the streetside units, thus compensating the developer for building at less than allowable site coverage.

Value to commercial development

As the density of urban development increases so do the economic benefits reaped from urban parks, courtyards and plazas. Within an urban core these spaces provide public gathering spaces that are essential for civic life. And where people go, development and money soon follow.

In New York City, the 9-acre Bryant Park was recently transformed from a derelict, unsafe place that people avoided into flower gardens and lawns, coffee kiosks and restaurants with hundreds of moveable chairs. Nearly 4,000 office workers and tourists visit the park per day, and 10,000 for special events. The park has spurred renovation of the retail area in the surrounding district, and occupancy rates, property values and rents have gone up. The park will be economically self-supporting in the next five to seven years and will continue to fuel the neighborhood’s economy.

Using an urban park to stimulate economic development is not a new idea. In New York during the 1850s, Frederick Law Olmsted justified the purchase of land for Central Park by the increased value of land surrounding the park and the tax revenues it would generate. By 1864, there was a $55,880 net return in annual taxes over what the city was paying for land and improvements. By 1873, the park cost $14 million but was responsible for an extra $5.24 million in taxes each year.

Other success stories:

For many communities, the purchase of land for a park or open space is a one-time investment that boosts property values and swells the tax coffers long after the land is paid for.

Open vegetated areas and even street trees can save billions of dollars by providing free ecological services, such as flood control and stormwater management, improving water quality and cleaning our air. Recently groups as diverse as the non-profit American Forests and the U.S. Army Corps of Engineers have been putting a price tag on those environmental benefits.

An acre of open, vegetated land can absorb the first inch of rainfall before it runs off. When rain falls on open ground, it is filtered and cleaned by plants and soil and returned to either the atmosphere, ground water, and during peak flows, to streams. Ground covered with pavement or buildings does not absorb rainfall, which must be collected in drains and diverted to treatment facilities by storm sewers. Within current regulations, this storm water must be treated to remove solids, oils, fertilizers and other pollutants, and this is generally handled on site by constructed detention or retention ponds, and paid for by developers.

An American Forests study, documenting the loss of trees in the Puget Sound region between 1972 and 1996, found there was a 37 percent decline in areas with high tree coverage (greater than 50 percent) and a near doubling of the areas with low tree cover, set at less than 20 percent coverage. This resulted in an increase of peak storm water flows by 35 percent. Replacing all this capacity with engineered systems would cost $5.9 billion.

According to the Army Corps of Engineers, flood damage in the U.S. averages $4.3 billion per year. Along the Napa River in Northern California, floods have caused an average of $10 million in damage every year since 1960. Like many other rivers, it has been channeled, dammed, retained and dredged, but seasonal peak flows still defy engineering interventions. Finally the Corps decided to “let the river be a river” where soft undeveloped land and wetlands within the flood plain can absorb the peak flows naturally. Five hundred acres of flood plain land are being purchased, homes demolished, levees lowered and bridges razed. It will cost $160 million to solve a problem that has caused $500 million in damage since 1960.

Communities nationwide spend billions of dollars to filtrate contaminants out of drinking water. When watershed lands are developed, lawn and garden chemicals, oils, sediment and septic overflow get into sources of drinking water. Many communities are realizing that it is cheaper to keep water clean than to filter it. For example, New York City found it would cost $1.5 billion to purchase watershed lands to protect upstate drinking water supply and $6 billion to $8 billion to build a filtration plant if those lands were developed.

Trees are essential to the air we breathe. Through photosynthesis, trees absorb carbon from carbon dioxide and return oxygen to the air. Other pollutants are also removed such as nitrous dioxide and sulfur dioxide. In the Puget Sound region, trees remove 78 million pounds of pollutants per year. This represents a value of $19.5 million if the air were cleaned by industrial means.

“Too often communities are presented with a false choice between economic growth and environmental protection,” according to planner Holly Thomas. “Successes in attaining and sustaining economic health depends on recognizing the economic contribution that undeveloped land already makes.”

Open spaces are the natural capital for our communities. They bring pleasure, recreation, and places for community celebration and spiritual retreat. They are essential to our life, health and welfare. Preserving, planning and providing for them is an investment we all profit from. The question for citizens, government and developers is can we afford not to make this investment?

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• An evergreen manifesto
  
• Finding an identity in the forest
  
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• Lifting our sights beyond ‘our’ sites
  
• Volcanic legacies
  
• Collaborating from the ground up