Green roofs — roofs that consist in part of plant material —are considered environmentally friendly and a vital component of our planet's striving for sustainability. Let this architect explain why, and how they work.
Those caught up in the enthusiasm of the environmental movement and trendy green design may think of green roofs as a modern phenomenon, but they have in fact been around for thousands of years. One of the seven wonders of the ancient world, the famous Hanging Gardens of Babylon were an early form of 'green roof''. Many cultures throughout the centuries have used earthen and planted layers as roofs and sometimes as fully functional plazas or ceremonial spaces atop structures. But as our technologies have become more sophisticated, and our awareness of environmental and energy concerns more keen, green roofs have evolved to become more efficient, less costly, lighter in weight, and thus more attractive to a much wider audience.
First, green roofs can capture rain- and snowfall, thereby reducing the roof's eventual run-off of stormwater that must then be piped elsewhere, filtered, treated, and recirculated for eventual human use. Instead that captured water recirculates back to the atmosphere through the plant cycle of absorption, filtration and aspiration. Second, green roofs can reduce the heat-island effect in urban areas, in which the heat captured by a roof and re-radiated later can create an urban 'heat island', significantly altering local climate and pollutant and smog levels. Third, green roofs re-oxygenate the surrounding air via the transpiration of plants. Fourth, green roofs provide a 'wearing layer' of plant material that intervenes between the roof structure and the elements, potentially lengthening the effective service life of the roof. Fifth, green roofs may provide habitat for plants, animals and insects that in turn contribute to the overall biodiversity of a region. Sixth, green roofs may contribute significantly to the quality of life of users and neighbors, by offering improved views, passive and active green and social spaces, and the possibility of more synergistic facilities.
Green roofs are also sometimes referred to as living roofs, planted roofs or vegetated roofs. Typically, such roofs include all of the basic components of any traditional roof: structure, insulation, waterproofing membrane or system, wearing surface, ballast (material applied to keep roof materials in place against uplift under extreme wind conditions), and flashings and trims. But green roofs go further, incorporating systems for moisture retention and/or drainage, formulated growing materials for plants, and the actual plant materials themselves. They may also incorporate other amenities, such as walkways, patios, running tracks, gardens, trees, benches, arbors, and other such structures. While a great many green roofs are flat or nearly flat, there are also growing numbers of slope d (some quite steeply) green roofs, as well as vertical or near-vertical green walls.
To understand a green roof, simply imagine a standard roof atop a typical structure — whether warehouse, school, office building, apartment tower, museum or civic center — then envision an additional overlay of waterproofing, soil, and plants, and you have a fairly accurate picture. Though the details can become quite a bit more sophisticated, of course, this rather simple concept is changing the way architects and others imagine the buildings of our collective future. Many green roofs have been and are being created and constructed each day on structures of all types around the world. Here's why they are important to our evolving relationship with the environment and energy use, and how one creates them.
Moving next up the scale of depth and intensity is the green roof upon which lightweight or occasional human use is anticipated. Now weighing in at as much as 75 pounds per square foot, such roofs will generally have thicker soil or organic medium layers of up to as much as one foot or more. While these roofs also incorporate a waterproof membrane or drainage layer and mineral-enhanced organic medium, they may also include a wider variety of plants, shrubs and even small trees. Such roofs serve well as adjunct recreational spaces for condominiums, apartments, museums, university buildings, civic facilities and the like. The complexity of such roofs raises their demand for continuing irrigation, maintenance and care.
Green roofs are most often categorized by their relative intensity of human use, and thus the depth, complexity and weight of the total of all roof materials and system components. The lightest intensity of human use is, of course, zero. Green roofs that contemplate zero human use, and are thus inaccessible, can be kept the thinnest and lightest, and can be designed to require little or no long-term maintenance. Weighing in at around 15 pounds per square foot when dry, and perhaps 30 pounds per square foot when fully wet, such green roof systems typically include a waterproof membrane or drainage layer, topped by a 3 to 4 inch thickness of formulated organic growing medium supplemented with minerals, supporting plants such as sedum, grasses, herbs and other hardy landscape materials. Once established via initial irrigation, such roofs may require very little long-term maintenance. Such roofs can be ideal for warehouse and industrial roofs.
评论
blog and I аm inspiгed! Extremely helpful info sρecifically thе final part :) I tаke
carе οf such info much. I was ѕeеking this рarticular info for a very lеngthy time.
Thank you and best of luck.
mу web-site ... yaz lawsuits