Yet polystyrene is a fabulous insulator with r values that range from r 3 8 to r 4 4 per inch of thickness and so it s considered green because it helps save so much energy source.
Green roof thermal insulation.
In fact it s a form of plastic.
Green roofs temperatures have initially been found to be close to the air temperature and green roofs may also provide thermal insulation runoff reduction and carbon uptake but might require irrigation during dry periods.
Department of energy polystyrene insulation comes in rigid foam boards that make it easy to insulate any part of a building.
Insulation with a thermal resistance of at least 0 85hr ft2 degree f btu or at least 3 4 inch air space is added to the roof deck over an attic or 7.
In addition to thermal insulation a green roof also has a sound insulating effect.
The most common request i get from architects and engineers is for the r value of a green roof system.
The essence of the confusion lies in the difference between insulation and thermal mass.
The basic anatomy of a green roof consists of vegetation growing medium filter membrane drainage layer waterproof root repellant layer roofing membrane support for plantings above thermal insulation vapor control layer and structural roof support.
Thermal insulation in some cases a green roof may include thermal insulation typically a layer of extruded polystyrene.
The r stands for resistance as in thermal resistance.
Quieter environment indoors and outdoors.
Despite their rising popularity studies on green roofs thermal insulation performance are however limited.
According to etag 031 xps insulation with a cs 10 y 300 designation i e.
So you can also save on your heating bills in the winter.
Unfortunately the ability of a green roof to control the flow of heat energy cannot and should not be described only by an r value not even an adjusted equivalent or approximate r value.
In the winter the heat regulating effect of a sedum roof is less than in the summer because a green roof retains moisture.
The term r value has a very specific meaning.
These all factors should include enhancing the thermal benefits from the green roofs.
Polystyrene doesn t sound like a green material.
While this can be positioned below the roof deck installation above the waterproofing known as an inverted green roof is preferred as it further protects the membrane from condensation and physical damage.
Rather than keeping heat from migrating through the roof assembly the green roof acts as a heat sink that soaks up and retains thermal energy.
However a green roof with grasses or herbs contributes more to heat regulation because the substrate layer is thicker than for a sedum roof.
In climate zones 10 12 and 13 with 1 sq.
A compressive strength of 300 kpa declared in accordance with en 13164 is suitable for both green roofs and roof gardens.
Of attic floor area and where at least 30 percent of the free ventilation area.
The thermal mass effect is the most important energy related benefit of a green roof.
