Green Roof For a Park Slope Brownstone
How cool is this. A Park Slope couple decided last year that they wanted to build a green roof atop their brownstone and found, through the Brownstoner Forum, a local design firm called Prospect Architecture (which, in the spirit of full disclosure, also advertises on the Forum). The project, which combined a green roof, photovoltaic…
How cool is this. A Park Slope couple decided last year that they wanted to build a green roof atop their brownstone and found, through the Brownstoner Forum, a local design firm called Prospect Architecture (which, in the spirit of full disclosure, also advertises on the Forum). The project, which combined a green roof, photovoltaic array (solar power) and roof deck, is pretty unusual because of its small scale—most green roofs in the city to date (and there aren’t that many of them) have been on larger buildings. Here’s how the architects describe it:
Our design incorporates an intensive (which refers to the use of larger plants) green roof, a large Ipe wood (like teak) deck, a metal and Ipe roof over part of the deck, an aluminum clad bulkhead. A wall and trellis hide new a/c compressors. Solar panels will be installed on top of the roof over the deck, the bulkhead roof and in front of the a/c compressors and will provide roughly 50-60% of the clients power needs including the a/c system. Additionally, our design is experimenting with various shade tolerant plants, like ferns beneath the front solar array, which is expected to help cool the arrays and maintain their top efficiency as well as retain more moisture than the gravel alternative.
The design provokes a feeling of walking through a small meadow while at the same time reminding one of the city that is all around. It is a private oasis with distant vistas of Manhattan and the surrounding neighborhoods of Brooklyn. The planters and benches around the perimeter of the deck add greenery and carry one’s eye past the immediate rooftops to the more panoramic of views. On the south side of the garden, an aluminum-clad wall fashioned with vine covered trellises shield one from the sight and sound of the mechanicals. The specific placement and structure of the architectural elements not only maximize the use of the entire roof, but the modern design acts as a representation of the dichotomy between city and nature.
And what about the cost? A little over $200 a square foot, including demo, structural enhancement, new stairs and bulkhead. Lots more pics on the jump.
If you’ve done, or are in the midst of doing, a cool interior or exterior project like this that you’d like to share, please send us an email at brownstoner@brownstoner.com.
I’m looking for a source of quality, reasonably priced Ipe. Can anyone suggest a place? Thanks.
Melissa
This is so cool! I’ve been googling “green roof” and “roof deck,” because my husband and I are thinking of buying a house (typical Philadelphia brick structure–sort of a brick brownstone) to rehab, and we’ve wondered about the possibility and cost of doing some sort of green roof/roof deck combo, with solar panels! This is exactly what we had in mind! It’s great to know that we can still do this, even with a small area!
This is a beautiful green roof, and with many features like structural reinforcement, decking, stone pavers, and a wide diversity of plant species, I can understand how this became such an expensive project. Most green roofs don’t cost as much as $200 per sq. ft., it’s more like $20. This project obviously included a lot of structural work which brought the price up so much.If you’re interested in installing a more affordable green roof or finding out more about them, visit my website: http://www.alivestructures.com or contact me directly at marni@alivestructures.com
Best, Marni Horwitz
What did the 4800 watt (dc) Sunwize standard grid-tie system consisting of 24 Sanyo 200 watt high efficiency module cost to purchase and install? What is the life expectancy of the system? What are the maintenance costs?
It is nice to see so much interest in Green roof projects. I wanted to offer responses to some of the comments from my perspective, as the architect.
IPE – A question was raised about ipe’s sustainability. Unfortunately, it is a mixed bag. Ipe is not considered a combustible material by the building department because of its natural flame resistance, which allows you to build a larger deck space than the 20% allowed for combustible material on a roof (see section 27-338 (J) in the NYC Building Code). Ipe is a better alternative than the fire treated wood (which is filled with chemicals) that also has a non-combustible rating. We searched to find a supplier of FSC certified Ipe and despite some companies claims that they do carry it, when ask for the chain of possession letters to verify the FSC authenticity, they could not follow through. We felt that despite the wood coming from a Brazilian forest, the longevity of this wood partially, although definitely not completely, made up for its use. It is expected that because this wood has been sealed, it will likely last 50 years. Other non-combustible materials like recycled plastics or masonry pavers could have been used, but for aesthetic reasons they were not chosen. As more attractive products and solutions continue to come on line, future projects will continue to push the sustainability envelope.
LEGALITY – In response to another question, this project, as with all of our larger projects, had a full plan examination by the DOB rather than a professional self certification. This assures that another set of eyes other than ours is scouring our designs to make sure that they meet the codes. This project’s plans were approved by the DOB and the construction followed the plans. As another poster suggested, there is too much liability to go against the codes and the DOB.
SOLAR POWER – The PV system is a 4800 watt (dc) Sunwize standard grid-tie system consisting of 24 Sanyo 200 watt high efficiency modules. The PV array will be split between the deck roof (9 modules), the bulkhead (5 modules) and an angled array at the front of the roof (8 modules). The efficiency of the technology does not lessen the benefit of solar power. The efficiency of a coal plant matters because its energy source is polluting the environment and destroying ecosystems; the efficiency of solar power relates only to the amount of solar radiation on a particular area that is absorbed by the panels. No harm or true loss occurs if 80% of the solar radiation hitting that panel is not converted to electricity. The government rebate programs for NY State pay just over 50% of the project costs for all systems up to 10KW, which calculated at current electrical prices pays for itself in 11-12 years. The actual payback will likely be closer to 7-8 years due to the continuing cost increases in electricity. The bottom line is that solar is economically viable as it currently exists. Grid connecting the PV system was mentioned in a negative light in one comment, but to think of it in another way, while you are not able to be independent of the grid and use your solar power when the rest of the city blacks out by being grid tied (incidentally the only way to get the 50% rebates is through grid connection), you also don’t have to have a whole room in your house devoted to large batteries that are not very sustainable.
As to Bloomberg’s green roof tax rebate, we are currently looking into it and will post back with other information once we have verified the criteria.
For additional pictures, you can visit http://www.prospectarchitecture.com.
Additional sustainable elements in this project were air sealing the entire house, 6″ of spray foam insulation under the roof and in the walls and ceiling of the bulkhead, operable casement windows in the bulkhead to allow for the natural stack effect in the summer to draw out the hot air, low VOC construction materials, and 14 SEER energy star AC units (rather than the 10 SEER rating allowable when the project was started), and a drip irrigation system in conjunction with mostly drought tolerant plants.
We would like to acknowledge the following companies for their essential contributions to the Project: Earth Pledge for green roof consulting, Exquisite Décor and Karamel Cabinetry for carpentry, Town and Gardens for landscaping, Duce Green Construction for the solar installation, and WP Hickman for roof consulting and material manufacture.
Thank you,
Jeremy Shannon
Principal Architect
Prospect Architecture
Nice idea, and nice execution. Get some extra insurance – my neighbor’s roof already leaks, causing damange to our home, which was gut renovated not long ago. Last thing I was is some weeds or sod poking into my bedroom, or worse yet, a chinese water torture when it rains.
Not for attached houses, thank you.
Just for everyone thinking about photovoltaics, the supply of these will probably jump greatly over the next 10 years. Microchips are moving away from silicon into more exotic materials, so all the silicon wafer factories will need someone to sell too.. Of course demand may greatly increase too.
Right now solar water heating is economical in NY. NY is a bit too hot in the summer for photovoltaics to be efficient when you need them most. PV’s like very cool temperatures.
As for efficiency, the best PV’s are over 40% efficient, much more efficient than plants. But most PV arrays are engineered for low cost so they use silicon scraps and are only about 10% efficient. The higher end stuff is used for things that move (solar cars), or need to be light (satellites).
but why wouldn’t they want to maximize the number of solar panels they have on the roof. seems doubtful that the few panels they seem to have will really cover that much of their electrical useage. i think the word green is again being overused on this site. it’s more green than not, but come on it’s all marketing not real environmental conciousness. I mean come on, why aren’t we all talking about ripping up the concrete in front of our houses? That would help the earth as well in terms of lowering the heating of our city and limiting runoff. But no, it’s the roof we must cover with plants that we will then hardly ever see and will never want to weed.
I was the one who asked about the sustainability of ipe. I had a feeling, but didn’t want to sound like a naysayer because it does look beautiful. I guess what I want to know is…Is this really a GREEN roof or is it just fashionable right now for it to look that way? I checked into ipe recently for my deck and decided against it because it didn’t sound too kosher (green). Re: solar panels, My husband took a course on it a few years ago, thinking he would install them on our house, but decided it wasn’t worth it because we would still have to rely on the grid. This was about 4 years ago, so maybe it’s gotten better. Don’t ask me what we’ve decided to use for the deck, because we kind of put that project aside.