Last Spring I took a picture of a perfectly proportioned bird's nest, perched on a carefully painted brick mould at a home we had built many years ago. It was over a window at the end of a long porch, tucked just under the eave and facing the southeast and the morning sun.
It wasn't until a few days later as I was uploading the images from my camera that I realized that the nest wasn't empty. As I zoomed in I was able to clearly make out the owner/builder nestled low in her nest, safely camouflaged but wary of my presence, presumably incubating her growing family.
Green Building has been defined in Wikipedia as "...the practice of creating structures and using processes that are environmentally responsible and resource efficient throughout a building's lifecycle: from siting to design, construction, operation, maintenance, renovation, and demolition."
Typically when we talk about "green building" we use the phrase to describe the construction of a man-made structure such as a home or office building, but why not apply these concepts to a natural structure to test them for their validity, after all what could be "greener" than a bird's nest?
The first part of this definition describes the process of building green as being "environmentally responsible and resource efficient". In other words we should be mindful of the journey and not just the destination, being careful not to damage our environment or waste natural resources along the way. Clearly this small bird made an insignificantly small demand on local resources by using recycled materials, and her aerial material recovery and delivery technique had little or no impact on the local environment. As a matter of fact one could argue that she had a net positive impact on her environment by collecting waste and her very presence and activity have contributed to the aural and visual landscape.
How does this project measure up when evaluated by green principles over the structure's life-cycle? How did she do on the siting of her little home? It seems to be well protected from the elements, not requiring any significant resources for shelter from rain or snow by making practical use of existing infrastructure. Its presence is not overbearing or dominant, tucked unobtrusively out of sight and its orientation to the southeast allows her to benefit from the warmth of the early morning sun. When she is busy collecting food in the early morning she can be content that her growing family is safe and warm, and as the sun passes overhead the nest will stay cool in the shade on warm summer afternoons.
How did she do on practical design? She has easy access without sacrificing security and the compact floor plan keeps maintenance to a minimum and retains heat while she roosts. The clever use of interwoven naturally occurring materials reinforced with a low impact, light, organic adhesive (mud-clay mix) makes for a lightweight reinforced form of concrete without the cement. The resulting structure is easily maintained or repaired with abundantly available and affordable local materials. This shouldn't surprise us, if you think about it, her ancestors were the first adopters of this early form of straw bale construction and they have been building millions of homes this way for thousands of years, all around us.
The final measure of a green structure is the impact of demolition and reclamation when it has fulfilled its purpose and is of no further use to its occupants. It should be easy to see that this project meets our standard on all levels; once abandoned and not properly maintained, the materials are dismantled by naturally occurring weather events and everything that is not salvaged by the next green builder gradually composts and returns to the soil, "dust to dust".
Of course it comes as no surprise that natural shelters should pass the green standard with flying colors, but the comparison is helpful in breaking down a definition of building green. It also gives us an opportunity to focus on what nature can show us if we adopt a little humility and take the time to "zoom in" and really see what we so often take for granted.