HEAT = ENERGY ?

Those of you in the know need no introduction to Terreform One. They are urban ecological innovators, inventors, architects, scholars, teachers, and hopefully can save us all with their treehouses and soft bubbly cars. Mitchell Joachim won the 2010 TED fellowship award, has been featured in many magazines, and was a guest on The Colbert Report (really funny!) Every summer, at least for the last two, they've held international workshops for young architects at their headquarters at MEx Metropolitan Exchange Building (33 Flatbush Ave) also our headquarters. The event is called Terrefarm; it consists of a seminar series, field trips, and an intensive charrette. This year there have been lectures given by many worthies such as Dickson Despommier, Vito Acconci, and even yours truly got a word in. Some of these images are of the workshop activities and of the MEx building.




Part of what I discussed in my lecture about green roofs was the energy savings, or lack of, green roofs produce based on the recent research. This portion of my lecture got some attention after words in the blogosphere. I'm a passionate green roofer; believing it is one of the crucial solutions to urban pollution and climate issues. I bring up flaws in the industry in my lectures only to promote ways to improve the green roof industry not to put it down.





In 2006 Columbia University's Center for Climate Systems Research published a report on green roofs stating that surface temperatures at the roof membrane on standard roofs can be more than 72 F higher than on green roofs at midday in the summer. The study is filled with great information about hydrology, urban heat island effect, air pollution, and how green roofs are a viable part of the solution to these challenges. This year Columbia came out with another study based on a green roof on The Con Edison learning facility in Long Island City, Queens. A key finding of this study shows that the green roof, consisting of 21,000 plants, on The Con Ed Learning Center reduces summer heat gains by up to 84 percent and winter heat losses by up to 37 percent, compared to a black roof. The white roof reduces summer heat gains by up to 67 percent. The report also stated that this translates into an estimated annual cost savings of $330 to $350 for heating and $225 for cooling. Hhhhhhmmmm.... that’s not too big of a yearly savings.

Today I read a press release discussing the findings of a study on various types of green roofs taking place in Texas by the Lady Bird Johnson Center. The study used metal boxes as mini-roofs to test out the green roofs.During one 91-degree day of the study, for example, a black topped box without air conditioning reached 129 degrees inside. Meanwhile, the green roof replicas produced indoor temperatures of 97 to 100 degrees Fahrenheit.



An even greater temperature difference was found on roof surfaces where black-top roofs reached 154 degrees Fahrenheit on that 91 degree day. By comparison, the soil temperature of the green roofs was between 88 and 100 degrees Fahrenheit.

There is overwhelming data that green roofs significantly lower temperatures in the summer and retain heat during the winter. And yet this hasn’t translated into cost savings nor is there any significant incentive program by NYSERDA, a state agency that offers funds for solar panels and insulation but not for green roofs ☹
So why are green roofs not saving us more energy if they reduce the temperature of the roofs so much during the summer??
I DON”T KNOW…..to be continued…..