Extensive Green Roof R Value

Highlights green roofs u value was experimentally determined on a paslink test cell.

Extensive green roof r value.

The cooling effect of each green roof component was demonstrated. The plants in a green roof absorb water through their roots and then use surrounding heat from the air to evaporate the water while some roofs can reach temperatures of up to 90 f in the summertime these two features can allow. Published literature showing extensive green roofs have r values between 1 8 and 4 8 while intensive green roofs have r values between 5 and 20. A 2006 study by the university of michigan comparing costs of conventional and green roofs showed that on average installing a green roof costs about 22 00 sq.

They provide shade to the top of a building evapotranspiration. 15 to 50 per square foot. Sailor et al jbp 2011. Green roofs reduce the temperature of the building and the surrounding air in multiple ways.

Once you have more than r 20 in a roof assembly that is you meet the code things pretty much don t matter. For a conventional roof. The study looked at a range of benefits of green roofs including stormwater management improved health benefits. In other words go above r 20 and make green roof decisions for other reasons than energy.

The university of michigan performed a valuation study comparing a 2 000 square meter conventional roof and a green roof. The relation between u values and the substrate moisture was linear. A green roof may improve property values and marketability especially in urban areas with little green space. Green roof with rock wool substrate provided the higher energy savings.

Green roofs save energy compared to uninsulated roofs or poorly insulated roofs or even better black poorly insulated roofs. Trnsys software simulation was implemented to quantify the energy savings. 8 to 20 per square foot.