56 Leonard Street

All photos courtesy: 56 Leonard Tribeca/Promotional images

Five years ago Lloyd Alter of TreeHugger.com complained about Herzog and de Meuron's design for 56 Leonard St. in the Tribeca district of New York City, particularly how hard it was going to be to clean the windows. He thought that it signified the end of the condo boom in Condo Design Jumps the Shark. Sure enough, the crash came and the project went away.

Now it is back, and so are his concerns. Only this time it is much more than just the window washing.

Ever since David Owen wrote the Green Metropolis, followed closely by Edward Glaeser's Triumph of the City, it has become acceptable to say that everything tall and dense is green. It's got to the point that Jeanne Gang can justify building her aqua tower with floor to ceiling glass and radiator-fin balconies by saying:

The most important thing we can do for the environment is live in compact cities with mass transit,” argues Gang, “that reduce the reliance on the car and other resources.

She's right. But that doesn't give architects carte blanche to ignore energy. But that doesn't mean that architects should design those dense buildings as if they were trying to maximize the surface area and heat loss. Not only do the units at 56 Leonard all have floor to ceiling glass, but there are so many pushes in and out that there are top and bottom surfaces for almost every unit as well. It is almost an intellectual exercise in how much extra surface area can you design into a building.

In their defense, most of the balconies are not radiator fins, they are the tops of units, so they will have to be insulated. That makes them less of a heat loss problem and more of a maintenance one.

It isn't just vertical extravagance, a typical unit grabbed at random has six glass corners to increase surface area and heat loss.

Urban density is a wonderful thing, but it is not a Get Out Of Jail Free card, you still have to design like you give a damn, to borrow a phrase, about the problems we face, even if the purchasers of these units are rich enough to throw money out the windows.

We can't, as a society, afford to build like this any more.

Buildings Cooled with Sweat Mats

Photo courtesy: © Rotzetter ACC et al. / Advanced Materials

Heating and cooling systems are by far the most power hungry things in a building. Ways to make your home more energy efficient typically revolve around ways to make heating and cooling more efficient -- better insulation, weather proofing, smart thermostats, etc. But what if there was a way that buildings could cool themselves just like the human body does -- by sweating?

Researchers at ETH Zurich are developing a synthetic mat that could be applied to roofs and essentially allow buildings to sweat in order to cool off. The mat would soak up water when it rains and then, in high temperatures, shrink and "sweat" out that moisture, cooling down the building through perspiration.

In the human body, water is secreted from our skins and then the heat on the surface of our skin turns the water into vapor, which removes the heat and cools us down. The researchers says that same concept would work with these mats.

ETH Zurich explains, "For the sweating mats, the researchers used a special polymer, abbreviated to PNIPAM, which is protected by a water-permeable membrane. The mat can thus fill with water when it rains. PNIPAM's storage capacity is temperature-dependent. If the material becomes warmer than thirty-two degrees in direct sunlight, it shrinks up and adopts hydrophobic properties. This forces the water through the membrane to the surface of the mat, where is evaporates like sweat on our skin."

The researchers have tested this material on small model homes. One was covered with a 5 millimeter-thick PNIPAM mat while the other was covered with a conventional polymer. A lamp was shone on the houses to heat the surfaces. When the inside temperatures were compared, the PNIPAM-covered house warmed much more slowly. You can see the difference in the image above. The PNIPAM-covered house is on the right.

By the team's calculations, a full-size home with just a few-millimeters thick mat on the roof could shave off up to 60 percent of the energy needed to cool the house with air conditioning on a sunny July day. The researchers now want to make sure the material is frost-resistant before an full-scale trials are done.