Green Roof Solar Absorptance

Absorb factor fraction of incident radiation absorbed.

Green roof solar absorptance. 29 figure 3 2 3d mo del of rinker hall s aiz et al 2006 compared common flat roof white roof and green roof by three characters. For the newly finished taylor street storage facility in north east dc a 17 500 square foot green roof with fully integrated solar panel arrays showcases a value stacked elegant design that provides both a cost effective solution to stormwater management without forfeiting the solar panels that generate income via federal tax incentives and dc s superb solar production based financial incentives. The results show that white roof and green roof have a much lower solar absorptance than grey common roof. Perhaps that is why some folks now call them vegetative roofs 2 if energy is your deal add more insulation to your roof and install a reflective membrane and be done.

Besides to keep the green roof green you have to water it. This green roof module allows the energy modeler to explore green roof design options including growing media thermal properties and depth and vegetation characteristics such as plant type height and leaf area index. The solar reflectance index can be used in cool roof calculations to demonstrate compliance with leed leadership in energy and environmental design a voluntary environmental certification system developed by the u s. Green red and brown.

The roof solar absorptance is the proportion of the total incident solar radiation that is absorbed by the roofing material the remainder is reflected. As noted in the draft astm standard standard guide for selection of roofing waterproofing membrane systems for vegetative green roof systems vegetative roof systems can be adversely affected by either excessive or insufficient drainage capacity. Conductance w thermal capacity kj an d solar absorptance. The key property of a green roof is its low solar absorptance which causes lower surface temperature thereby reducing the heat flux through the roof.

Approximated white smooth surfaces. Solar energy absorbed depends on surface color. 3 it works better and costs less than adding dirt and grass. The first concern of the designer when addressing drainage should be to insure that the system can efficiently percolate and discharge the underflow associated with mandated design storms.

A roof with a lower solar absorptance will reflect more heat than a roof with a higher solar absorptance and will keep the roof space and dwelling cooler on a hot day. Savings in annual energy use are just over 1 but summer cooling load is reduced by over 6 and reductions in peak hour cooling load in the upper floors reach 25. The model has been tested successfully using observations from a monitored green roof in florida. The solar absorbance also exhibited the highest σ value standard deviation value indicating its important role in interactions with other factors followed by thickness.