Friday, November 12, 2010

Solar Hot Water Systems: An Urban Renewable for the Northeast

As appeared in, written by Richard M. Cherry, Community Environmental Center

New York, NY, USA -- Using solar energy to heat water in the multifamily apartment buildings of the Northeast has traditionally been considered a challenge. It has generally been assumed that in a city like New York, the installation and implementation of solar panels, connecting pipes and water storage tanks would be dauntingly complicated and expensive. Too many high-rise buildings casting shadows, so the argument goes. (Or too many high-rise buildings, period). Add to that, a climate that would not be suitable for collecting solar energy the year-round.

But the Community Environmental Center (CEC) has discovered that the high cost of fossil fuels and the urgent need to mitigate the climate crisis are gradually leading New York City’s apartment-building owners to consider solar energy for domestic hot water in multifamily buildings. And in New York City more than 65 percent of the residential buildings are from 5 to 15 stories high, suitable heights for installing affordable SHW systems.

The Challenges   

The challenges to SHW in a city like New York cannot be ignored. In fact as CEC learned this past summer, implementing a 42-collector SHW system on 12,000 square feet of roof at Wadsworth Terrace in Northern Manhattan--the largest SHW system to date in a New York City apartment complex--these problems must be anticipated if at all possible and faced head-on.

While it is obvious that a structural engineer needs to assess the integrity of a roof—any roof—before an array of collectors can be installed, New York City presents unique difficulties: aging and uneven roof decks that are not easily hospitable to the installation of solar panels, and an army of building codes can delay implementation. The city’s fire codes require that a certain amount of roof space remain unobstructed and that pipes which cross a rooftop can be no more than 1-foot high.

There is that question of the pipes. How to connect the panels with water-storage tanks in a basement perhaps 6, 7 or 8 stories down? Is there room for the pipes to run inside a building’s structure, or will the pipes have to run along a building’s exterior walls? How much pipe will be needed? (The Wadsworth installation required 960 feet of pipe running between the panels and the holding tanks, and approximately 370 feet of pipe connecting those tanks to the building’s boilers.)

And of course urban basements come in a variety of awkward configurations and sizes, most of them small. The imaginative designer of a SHW system must explore collapsible tanks that fit around stairway landings, through narrow doors, and take up a minimum of space. 

Finally, and very importantly, is the question of cost. Although there is a New York State personal tax credit for “solar water heat” in multifamily residences (capped at $5,000), New York City’s tax incentives currently apply only to solar PV. In any case, NYC installation costs for solar are among the highest in the country.   

In addition, most solar thermal collectors are not manufactured in or around New York City, and the cost of shipping a medium-sized system of 20 panels, each of which weighs in the vicinity of 100 pounds, can be expensive.

These costs become problematic for a residential building owner who is looking for payback preferably within 5 years of the installation.

Challenges Are Not Obstacles

But these are challenges not obstacles. In a comparatively new field, the pioneers will always encounter unaccommodating regulations. To its credit, New York City’s Department of Buildings is trying to streamline the process involved with approving solar thermal designs and installations for residential buildings. By identifying problems early on, and sharing experience, CEC and like-minded companies committed to renewable energy in the Northeast can help future SHW installers acquire a more realistic idea of the costs and processes associated with implementing systems in multifamily buildings.

The vital argument in favor of solar thermal remains its potential. We need to think of solar thermal as one of a rainbow of energy solutions in an urban residential setting. True, in Manhattan, where apartment buildings can be 20-to-30 stories high, installation costs for solar thermal are often prohibitive. But in the boroughs of Brooklyn, Queens, the Bronx, and Staten Island, where the majority of residences are either stand-alone homes or 6- to 8-story buildings, solar thermal can be a cost-efficient, environmentally sound antidote to fossil fuels. And the majority of these low-rise apartment buildings do not stand in the shadow of taller ones, so that thermal can often be effective where solar PV cannot. 

Well-designed solar thermal systems in the Northeast can provide 50 percent of a building’s annual hot-water usage. There are roughly 3 million housing units within NYC, according to 2008 figures from the NYC Department of Housing Preservation and Development. So if even 10 percent of these buildings were to be outfitted with solar thermal installations, the energy saved would have an impact on the city’s consumption of fossil fuels. Simply by having a medium-sized SHW system on 300,000 roofs, there could be a reduction in the city’s use of oil and natural gas. And if a combination of lower hard costs and progressive tax incentives bring down the expense of implementing a SHW system, then those building owners would see a viable return on an investment within a reasonable amount of time.  

We must remain optimistic and determined about bringing SHW systems to residential buildings in U.S. cities, particularly in the Northeast, where the consumption of fossil fuels is high. CEC’s experience is that the rewards of persistence can be enormous. Already, increasingly sophisticated technology is enabling SHW systems to function effectively in Northern climates that have fewer days of sun than Southern climes. Installing these systems has created a call for new skills, and increased demand on the part of landlords will produce jobs for which these skills are needed.

If we can build a coalition of innovative builders, building owners and imaginative government agencies, then SHW systems will become an accepted part of our cityscapes. Both the industry and the environment will thrive.