One of the most popular green building techniques right now is the installation of “green roofs.” As explained by Dean Marchetto, founding principal of Dean Marchetto Architects, P.C., in Hoboken, New Jersey, the concept starts with a traditional sealed, waterproof roof membrane, which is covered with a thick layer of a soil mix that absorbs a lot of water. The soil then is planted with sedem plants, which are leafy succulents that can thrive in arid conditions.

“One of the problems in urban areas is flooding when you get a real deluge,” explains Marchetto. “When the rains come down so fast it fills up your sewers and you have flooding, and it takes hours before it can all drain.” With this green technique, the roof acts as a catch basin and the soil and sedem plants act as a sponge and soak up much of that sudden inundation and then slowly release the water. “Not only does it absorb water and provide oxygen, it insulates your roof–so you have less heating costs and less cooling costs,” he says enthusiastically. “That’s among the most popular thing that developers are doing, because you can see it. A lot of green things you can’t see, because they’re in the heating system, they’re in the pipes, they’re in the insulation, but a developer wants to use those things for marketing purposes.”