LiveRoof Hybrid Green Roofs Frequently Asked Questions

LiveRoof Hybrid Green Roofs Frequently Asked Questions

Energy savings What Can I Expect?

Green roofs have been proven to bring about significant energy savings, particularly during the summer cooling season in which single story buildings can experience a reduction of greater than 25% energy use.  Plants transform heat and soil moisture into humidity, to create natural evaporative cooling. Each gallon of water that is transpired by the plants or evaporated from the roof surface liberates 8000 BTU of thermal energy.

Why doesn’t the LiveRoof® system use filter cloth? And, won’t the soil run out the drain slots?

Filter cloth, like any filter, is designed to filter. Filters in time can plug up (think of your car’s air and oil filters, your furnace filter, coffee filter, etc.). When a green roof filter plugs up, then what? Hint bathtub (ok for water lilies, but not ok for green roof plants).

Because of the aggregate nature of LiveRoof® soil, the soil stays in the LiveRoof® module as it would if you poured it into a funnel. It’s like the square peg in a round hole scenario. In addition to this simple act of physics, the roots of your LiveRoof® plants bind the soil together and hold it in place.

The need for irrigation (beyond normal rainfall) will depend upon the plants selected, the local climate, and specific weather patterns.  Under normal circumstances, supplemental irrigation is seldom if ever required.  Even so, we suggest a backup irrigation system in the event of prolonged hot, dry, windy, sunny weather.  During very long bouts of dry weather, plants can go dormant, shrink up, and expose soil. This can increase maintenance requirements as weeds can become established in bare soil. Excessively dry soil also causes the evapotranspirative cooling effect of the green roof to be reduced.

Irrigating, even once per month during protracted dry weather, can keep your green roof looking its best and pay dividends through maintenance reductions and evaporative cooling. Irrigating during protracted hot dry weather is a personal choice, the cost is minimal and one has the piece of mind that if ever needed, the water will be there. Backup irrigation systems can range from spigot and hose to overhead irrigation (similar to what one might have in one’s yard.)

Those that have extreme drought resistance through some means other than the root system.  This means succulent, water-holding plants like Sedums, Alliums, Sempervivums, Delospermas and a few others.  The best LiveRoof® plants will both store water and have a special type of metabolism called ‘Crassulacean Acid Metabolism’, CAM for short.  CAM plants are unique in that under drought conditions their stomates (leaf pores) are open at night rather then during the day, as is the case with most plants.  CAM plants exchange gasses (oxygen and carbon dioxide) in the dark when it is cooler and less windy.  CAM plants are up to ten times more efficient with water conservation than non-CAM plants.

LiveRoof Hybrid Green Roofs Frequently Asked Questions

LiveRoof® plants have been selected for extreme drought tolerance, disease and insect resistance, long life, low maintenance, and beauty.  LiveRoof® plants are planted in the LiveRoof® modules at Hortech and other nurseries and cared  for until shipped to the job site.  Plants are selected by local horticulturists in order to meet the above objectives as well as the local climate and customer preferences.

Can I grow edibles with the LiveRoof system?

Numerous vegetables, herbs, and select fruits (such as strawberries and melons) may be grown on intensive green roofs that receive frequent watering, have ample sunlight, and have proper soil.

Edible plants require sufficient nutrients to support their rapid growth cycle and the energy needed to bear fruit.

When growing produce on green roofs, a blend of organic soil and traditional green roof growing media yields the best results; however, the soil will need annual amendments to maintain volume and provide sufficient nutrition.


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