There seems to be a growing trend that needs to be corrected. For sustainable building and rating systems advocates including Hong Kong BEAM and US LEED often encourage more, more, more. It might be more site greenery, or in the case of LEED more ventilation. However, I foresee a tragic mistake associating “more” with sustainable.
For site greenery, I am not saying we should ignore soft landscaping, greening the landscape is beneficial, aside from the physiological benefit, greenery creates a micro-climate zone that can provide sun shading, and help lower the ambient temperature. Hence, a well designed micro-climate zone will lower the environmental impact and reduce building operating costs. Additionally replacing those endless lakes of concrete with soft landscaping mitigates the urban heat island effect.
Property designed soft landscaping, and I include green roofs in that sector, have a positive impact, particularly when outdoor air is drawn from these miniature micro-climatic zones.
Under LEED rating system extra credit can be achieved, encouraging designers to exceed ASHRAE’s (the ventilation experts) recommended ventilation rate by 30%. The increased operating cost for moving, filtering, treating the additional air volume is an extravagance that has seemingly been overlooked.
Designers, including the creators of rating tools, should take a comprehensive holistic approach, simply demanding more soft landscaping needlessly increases the demand for primary resources, like soil and water, and secondary resources including irrigation systems, piping to service the larger requirement. All I am asking Think! before we demand more.
~~ John Herbert, Kelcroft, Consultant