Yesterday in Denver, members of the Obama administration outlined how $4 billion will be spent to green the nation’s public housing projects. $500 million will be spent on training workers to do the retrofitting work, and the rest will go towards the improvements themselves. The list of initiatives that have been made public so far are fairly rudimentary, and include better windows, insulation, and, of course, changing light bulbs.
Does that mean that we’re really spending $500 million to train a phalanx of light bulb installers? It shouldn’t. There are a slew of other improvements that could be carried out. To be sure, retrofitting a building rather than starting from scratch limits your options–passive buildings, for example, require design features involving the very footprint of the building. But there are a number of big interventions that could be made, which just might serve as beacons to the entire green building movement. Here are six options.
Building contractors seldom think about heat loads–and that’s a problem, because the side of an enormous brick building absorbs heat, making the interior more costly to cool. The most low-tech intervention is simply to add trees, and trellises for climbing plants on the sunny side of a building. Higher up, solar blinds would work. These are already common in high-rise buildings–the New York Times building, for example, is covered in them. Elsewhere, at the 1234 Howard Street condo development in San Francisco, adjustable louvers–which are really just industrial-sized venetian blinds–allow natural light to be adjusted throughout the day:
Green roofs are more than simply cool concepts: Shading the roof of a building reduces electricity spent on cooling. What’s more, they can readily be deployed as retrofits to old buildings with roofs already crowded by mechanical equipment. (Pictured here: A retrofit installed by Cook+Fox.) A cheaper alternative is a “cool roof”–which is shaded and painted white, to reflect heat.
Cutting-edge tech can already recycle a building’s waste water, but that’s beyond the scope of a retrofit. But gray water recyclers–which purify and reuse water from sinks and drains, but not toilets–can be installed. Another possibility are rainwater collectors. These would collect water on the grounds of a housing complex, and on the roof, and return it to cisterns which would be used for all non-drinking applications. Here’s one example, as it would work on a small building like a house–though the systems can be readily scaled up:
No Wind Turbines, Photo Voltaics or Geothermal
Sure, these technologies are neat-o, but none of them are feasible for a retrofit within a city. Photovoltaics are far too expensive: Their payback time–the money they save, versus how much they cost to set up–is one reason why they’ve been scrapped in real-life green highrises. Wind turbines, meanwhile, are both expensive and unproven–it’s still unclear if any wind technology can be efficiently implemented in cities, where the wind is both weak and turbulent. Finally, geothermal wells aren’t practical in New York–that would mean drilling into bedrock, thousands of feet deep. But that doesn’t mean there aren’t other ways to provide for a building’s energy needs. Better alternatives exist…
The future of power is distributed, rather than via centralized plants. One way to speed that change is by using cogenerators, which use natural gas to generate electricity and heat–and they generate enough electricity that the excess can be resold into the grid. The benefits are two-fold: First, you skirt the massive carbon footprint involved in using electricity from coal-fired plants. Second, the heat itself generated in the process is used either to generate heating for the building, or to generate electricity–which is a big deal, since some estimate that the U.S.’s waste heat alone could generate 20% of the electricity we use. Co-generation is huge in Europe–50% of Germany’s electricty is co-generated–but is extremely rare in the U.S. partly because old laws haven’t created the right building incentives. But cities can readily make them happen–One Bryant Park, New York’s greenest tower, completed earlier this year, uses them. It’s been estimated that the payback period for cogenerators is a scant four years.
Power used at peak times is extremely carbon heavy, because when the grid is maxed, it relies on the oldest, least efficient power plants. Simply offloading energy demands to off-peak times increases efficiency. Which is where so-called absorption chillers come in: These use electricity to generate ice at night. During the day, that ice is used to cool a building. It’s already a proven techology–One Bryant Park uses these as well.