Green Roof Embodied Energy

Though the embodied energy is high there are few toxicity issues involved in the manufacture of clay tiles.

Green roof embodied energy.

An example is cob using the earth available locally and mixing it with straw of which there are about 70 000 examples mainly in the south west of england. The embodied energy for green roof components are 23 6 kg m 2 5 pounds per square foot co 2 of green roof. Embodied energy is the energy consumed by all of the processes associated with the production of a building from the mining and processing of natural resources to manufacturing transport and product delivery. Assuming a generic industry root barrier drainage layer and 6 0 cm of substrate consisting of half sand and heat expanded slate by volume as was the case in the getter et al.

Their contribution to insulating and shading buildings can help significantly in reducing energy consumption and carbon pollution. On first thoughts a living roof be it turf or sedum might seem to have less embodied energy than say a clay tile. Our one square foot patch of green roof will save about 1 000 btus per year in cooling energy which means that it will take about 40 years to recover the process embodied energy of the green roof. This value is equivalent to 6448 g c m 2 which is significantly greater than 378 g c m 2.

What would happen to auckland if we put a green roof and green wall on every home. Some of the traditional ways of house building are extremely low in embodied energy. Because they are fired they can have an embodied energy of around 6 5 mj kg university of bath uk see wikipedia on embodied energy. Embodied energy does not include the operation and disposal of the building material which would be considered in a life cycle approach.

There can be occasional surprises. The main pollution issues with steel roofing are the dioxins produced during smelting and the pollutants produced in the manufacture of the usual pvc. Concrete has a lower embodied energy but greater toxicity in its emissions. Gsa s public buildings service agrees with oig report regarding maintenance for their green roofs.

Both sod roofs and lwa based lightweight aggregates roofs have been found to have a negative impact on the quality of their resulting runoff. In australia the energy benefits of green roofs are most pronounced in their ability to reduce summer cooling demands. To reduce the embodied carbon dioxide of cement which contributes roughly 8 of global carbon emissions rives de l yon france based company hoffman green cement technologies has developed h p2a high performance activation alkaline a cement formulation made from blast furnace slag a byproduct from steel production. While this is lower than steel sheet products like concrete tiles clay tiles high mass per unit area comes into play so clay tiles will have a higher embodied energy per total roof area than sheet products.

By comparison a cool roof on this building will save about 700 btus per square foot per year.