The following was published as part of my regular “Growing Greener” column in Public Garden magazine, Vol. 25 No. 1 (2010).  Public Garden is the flagship publication of the American Public Gardens Association. In “Growing Greener” I answer sustainability-related questions from public garden staff.

Q: What is the Living Building Challenge, and how is it different from the U.S. Green Building Council’s LEED rating system?

A: By the sound of it, you’d think the goal of the Living Building Challenge—to encourage the creation of “living buildings” that “function as elegantly and efficiently as a flower”—was tailor made for public gardens. Although it grew out of the Cascadia Region Green Building Council, a chapter of the U.S. Green Building Council, it is designed to push the industry—and LEED itself—to a whole new level. In the words of one observer, the Living Building Challenge makes LEED’s incremental system of credits that get tallied up to determine whether a project earns Certified, Silver, Gold, or top Platinum rating “look like something drawn up by Exxon.” (more…)

The annual meeting of the American Public Gardens Association always charges my batteries. This year’s meeting in St. Louis was no exception. Among other things, it gave me the kick in the pants I’ve needed to actually post the “Growing Greener” columns I write for Public Garden magazine, APGA’s flagship publication. In each issue, I answer sustainability-related questions submitted by public garden staff. You can find my column on the carbon footprint of homegrown food here. I’ll be adding additional columns over the next few days.

While I’ve been off for the past three weeks celebrating the holidays and doing site visits for a public garden project I’m working on, news of the following green city plans has been reported, courtesy of Inhabitat. 

For a neighborhood of Gothenburg, Sweden, currently covered with parking lots and football fields, comes this plan for a “garden block” nestled beneath a series of green roofs shaped like undulating hills. These green roofs insulate the buildings below while absorbing rainfall that can be purified for household use. The project also includes space for community cultivation of fruits and vegetables.

Meanwhile, outside of Milan is a planned development of high-rises with stacked planted terraces surrounding a large municipal park. The complex will be completely self-contained, with schools, sporting facilities, and a shopping center, saving energy by reducing the distance residents will need to travel in the course of their daily lives. Photovoltaic panels will help shade sunny windows while generating electricity, and solar water heaters will also slash energy use.

I admit it—I’m as seduced by the idea of verdant buildings as the next plant nut. On a purely aesthetic level, structures with living walls are a major improvement over the granite and glass monoliths that rise from the typical cityscape like enormous gravestones. But before we fall head over heels for green walls it’s worth asking whether they’re all they’re cracked up to be. Do they really, as touted, help insulate buildings, filter particulates from polluted city air, counteract the urban heat island effect, and create habitat for insects and spiders? Or are they just a green veneer, a 21st-century version of the fussy millwork that decorated Victorian buildings? Or worse, do they actually eat up more resources than they save? 

Even the green-minded bloggers at Treehugger and Inhabitat have been drooling over the latest designs, Daniel Libeskind’s 900-foot New York Tower, an upscale residential skyscraper with a section of glass curtain wall cut away to accommodate vegetated balconies, and Rotterdam-based MVRDV’s cluster of cone-like structures with concentric rings of boxwood-lined terraces intended for a new city south of Seoul. From a biological point of view, only one of the “11 Buildings Wrapped in Gorgeous Green and Living Walls” in this glowing review is interesting—Sharp & Diamond’s 50-square-meter green wall of wildflowers, ferns, and ground covers at the Vancouver Aquarium that seems to be based on plant associations found on cliffs, scree slopes, and other natural analogs. (If you haven’t seen it, take a look at The Urban Cliff Revolution, which suggests that these natural habitats have a lot in common with skyscrapers and other features of the modern city, and can serve as “habitat templates” for green walls and roofs.)

But what about the carbon footprint of the growing media used to create green walls, and any fertilizers used to sustain the plants? Is irrigation required? If so, is there an integrated graywater system in which used water from sinks, dishwashers, and other sources is cleansed by the plants and growing medium and piped back into the building to flush toilets? In short, do the environmental benefits of green walls outweigh the costs? I’d love to see some hard data.

Check out Habitat 2020, a nature-inspired building that makes today’s LEED Platinum structures look about as cutting edge as Stonehenge. “The exterior has been designed as a living skin, rather than a system of inert materials” used only for protection, reports Inhabitat. In fact, the building’s walls look a lot like the surface of a leaf seen under a microscope, with countless stomata, the openings that regulate plant transpiration and exchange of gases with the atmosphere. Like a leaf, the architectural skin automatically positions itself to let in sunlight — no artificial lighting would be needed during the day — funnel air into the building for natural cooling, and harvest rain water. It can even absorb moisture from the air. The concept is being developed for housing in China.