Land Matters: In Search of a Good, Cheap Green Roof

What will the future of green roofs look like? Will it be some variation on the “starchitect” green roof at the California Academy of Sciences (CAS), above, multiplied many times over?

Probably not. Sure, it’s stunning, but the CAS roof is also relatively high maintenance. Correct me if I’m wrong, but I always thought the point of green roofs was that they would be mostly self-sustaining—not needing any irrigation beyond plant establishment, nor weeding, mowing, or fertilizing. The CAS roof, however, has a pop-up sprinkler system that, given San Francisco’s dry seasons, will probably have to be used in perpetuity. And partly because of the plant choices, the roof must be frequently hand weeded and fertilized.

No question, green-roof “starchitecture” has its place in today’s building environment, because the green-roof movement is still just gaining a foothold in this country. Doubtless many Americans are unaware that such systems even exist. So it’s important that these early “demonstration” green roofs be eye-catching. But we should also understand that demonstration projects are mainly there to promote the genre, not to serve as prototypes for what will be built in the future.

Take the Chicago City Hall green roof as another famous example. I have personally visited it. It is stunning and inspiring—like a patch of Midwestern prairie perched above the city, abloom with wildflowers and buzzing with dragonflies and other insects amid the tall, waving grasses. The exposure it has garnered has done a great deal to bring attention to the genre, but its $2.5 million price tag disqualifies it, too, as a model to be emulated.

How can we progress beyond a few high-profile green roofs sprinkled here and there in a few of our cities? Scale is what will make green roofs work as an ecosystem service. If they are really to ameliorate stormwater runoff and the heat island effect, we need whole city blocks that are green roofed corner to corner. We need lots of multiacre green roofs on big-box stores on the urban fringe. What will it take for these to happen?

A few local governments are offering incentives for buildings with roofs that soak up rain and keep it from overloading the city sewer system. That’s part of the solution. We also need low-cost, foolproof systems put in by experienced installers who know green roofs because that is the core of their business. But if green roofs become a streamlined, mass-production enterprise dedicated to greening America’s rooftops, will designers then have a role?

Landscape architects who continue to have a role in the future will be those who have proved they are up to the job. With green roofs, a lot seems to fall through the cracks between the drawing board and the final product. Landscape architects who get serious about this project type will have to learn about the technology, test their products, and pay attention to what happens on the job site—and afterward. Do green roofs present enough of an opportunity for landscape architects to make that kind of learning curve worth the time and effort?

J. William “Bill” Thompson, FASLA
Editor, Landscape Architecture magazine

Send in your ideas. Use the comments to post examples of good, low-cost green roofs.

12 thoughts on “Land Matters: In Search of a Good, Cheap Green Roof

  1. Jason King 07/17/2009 / 9:56 am

    There are literally hundreds of green roofs projects that fit the criteria of ‘affordable’ around the country and world… in our region, this is somewhere in the $8-10 sf range for everything above the membrane, and depending on conditions – is totally attainable with good design. This seems to be the price point to have projects go forward versus dying due to VE and other project-related ills. With the $5/sf incentive from the City of Portland’s Grey to Green grant – essentially you get a half price system.

    There’s a ton of projects utilizing proprietary systems, trays, and vegetated mats that often lead to unnecessary cost escalation. Sometimes these are absolutely necessary elements due to certain project criteria. Other times they are merely an easy solution to avoid figuring things out. This ‘systems’ approach tends to come with a bigger price-tag than any sort of custom design.

    Also, Bill (purposely?) omitted another exorbitantly expensive green roof model – that one atop the ASLA headquarters… Just saying fair is fair if we’re pointing out examples… stunning yes, but 3000 sf @ +/- $1million or so isn’t a great affordable example either.

  2. poltrackt 07/17/2009 / 1:34 pm

    I can’t speak to Bill’s intentions, but I can add that part of the reason for the high pricetag for the ASLA green roof was the decision to make it a public demonstration project. Two-thirds of the cost went to refitting the building to add the staircase that grants access. And the design is purposely complex to test different conditions. Not your average green roof.

  3. Jason King 07/19/2009 / 11:33 pm

    Understood. I’m just saying that the singling out of ‘model’ projects needs to acknowledge our own overpriced example in the mix. The examples in the editorial are not your average green roof either, which was the thrust of the question. Better examples would have been projects that, with a landscape architect and qualified team, could have been realized for a lower price – but were for various other reasons either VE’d or installed at a higher price due to other factors.

    Not to belabor the point, because I think the ASLA roof is beautiful… but to spend that much on retrofits may have been a red flag for the clients and designers to choose a different building to use for a demonstration project. Not many projects would be allowed to disregard reality of cost-benefit to this degree, because it sets a bad precedent. The fact that we essentially had to ‘pass the hat’ to the members to fund the cost overruns was a bit comical as well – but a good story of the members stepping up.

    The whole point of a demonstration roof is to provide a viable example that can be adopted widely, no?. For it’s many benefits, that didn’t really happen, but rather it showed that if you have enough cash to make them work, green roofs are good – but are mostly cost-prohibitive (even beyond many of the reasons listed above).

    I’m just saying its time for us (the profession/ASLA) to acknowledge that the ASLA roof is not a good example for widescale adoption of the concept.

  4. R. Coffman 07/21/2009 / 3:10 pm

    Several excellent points are made in this piece. I appreciate the fuel and I will use it.

    I would argue that our discipline is obligated first to lead green roof innovation, but that comes with responsibility on our part. I would agree ‘starchitecture’ projects are whole hardly experimental and should be gleaned for advancements and avoidances, but unfortunately they are not perceived that way by many professionals and the public. One reason for this is that projects are not written about or discussed in an objective way, yet.

    Critique of green roof projects is absent from our literature. Balanced reviews of built work should assist us in providing a good cheap roof- if that is goal. Otherwise, Tom Liptan’s garage might suffice as model. (He was innovating.) Beneath the surface here is a deeper issue related to landscape architecture’s perception of sustainability and the conceptualization of these roofs. I find that very interesting.

    On similar note: For those of you who have not read Werthman’s book on the ASLA Headquarters then I recommend it. On first read it’s largely positivistic, but read it again and you find a very comprehensive piece filled with meaningful information. It is so open that what is not included becomes very interesting. Werthman deserves a medal for respecting the clients and consultants while delivering a very open and resourceful book. Plus, it has wonderful graphics.

  5. Janet Gillmar 07/22/2009 / 5:31 am

    I expect green roofs to become increasingly affordable, reliable and reasonable to maintain because accelerating climate change is making the use of any promising mitigation strategy necessary. So, just like plant materials, green roofs will become part of the vocabulary that we will need to know well enough to responsibly incorporate into our projects and to take advantage of its aesthetic and functional potential.

  6. Adrienne Bottoms 07/22/2009 / 9:17 am

    It is very encouraging to hear that there are more and more green roof and sustainable projects being built and creating an interest in society. Not only are these projects benefiting communities directly, but I think they also inspire all related professions to educate themselves with the new ideas and related technology. I do believe that green roofs are economically feasible, and the demand as everyone realizes the extreme benefits will make them even more viable.

    More than anything, it is inspiring to realize that green roofs, with all of their direct economic benefits for a building, also contribute greatly to the therapeutic aspects of a place as well. A space that was once a detriment to health in many ways, can become a retreat and connection to nature that not only comes from being able to make physical contact with the garden (if it is accessible) but also to others perceiving it from further away.

    Will green roofs become more affordable? If health and well being are as important today as they have been in the past, then I think the world will answer with a resounding “yes!” as we cover the world in shades of green.

  7. Matt Moore 07/22/2009 / 2:09 pm

    This is a good discussion. I like that many of you are open to the idea that not every green roof has to look like Butchart Gardens, Filoli Center or the Conservatory of Flowers. Benefit vs cost + basic functionality will be the driving force behind mass acceptance of green roofs for these other applications.

    Proper planning up front, researching local resources, paying attention to the actual planting soil and proper plant selection will go a long way to achieving the more practical, affordable, and yet very functional green roof.

    As a producer of lightweight soil mixes for more than forty years, I can assure you that there are certainly more cost-effective materials available than most of what we see specified. Materials like expanded shale, vermiculite, perlite, etc. require huge amounts of energy to produce and are often shipped great distances (overseas in many cases), adding to both the cost and carbon footprint of the project. We can produce soils with equal or better performance, utilizing more local resources for substantially less cost, but we often run into contractors, inspectors, construction managers or even architects who are unwilling to look at any alternatives. To many, the specifications are etched in stone. Again, this relates to prior planning and not being married to a “system” who’s manufacturer is busy promoting their own product at the expense of your project.

    I look forward to seeing a more practical approach evolve, allowing a broader use of green roofs with greater environmental impact.

  8. Ian Mac 07/22/2009 / 6:41 pm

    If I’m not mistaken one of the main ideas of green roofs is to suppress the amount of water run off into drainage systems which it seems to be wasted. I am a huge fan of the roofs and have installed several in the UK, having been in the USA for several weeks it seems to me that more thought and resources should be put into capturing the little water that does fall here in California, it really is not rocket science is it!!.
    1, build more balancing ponds.
    2, Get away from using so much concrete.(A must).
    3, Why cant houses harness the water of their roofs into underground water tanks? (it can be done then use the water for irrigation)

    You only have to look else where around the world to see how thinks are actually working, my partner is a senor landscape architect in san Jose for the city and she pulls here hair out everyday trying to get sustainable landscaping systems passed people don’t like change?.

  9. Leland Walmsley 07/23/2009 / 3:25 pm

    There is no mention here of the lifecycle cost savings due to green roofs. Green roofs do not stand alone but rather have an affect on a number of other initial construction costs and cost savings over time.

    Green roofs can last up to 50 years. The green roof on Derry & Toms Department store (London) has had the same green roof since 1938 and through WW2. A Canadian study showed summer heat gains were reduced by 95% and winter heat losses reduced by 26%. Due to their insulation value, I know of a building with a green roof that downsized its HVAC ducting and equipment by one third.
    That’s a sizable chunk of change.

    Buildings in Chicago with green roofs have higher property values than those without.
    Commercial buildings with green roofs have less tenant turn-over and lower vacancy rates. The commercial tenants in those buildings report less absenteeism, less sick employees means higher productivity, fewer worker’s compensation claims, and happier employees.

    Hotels with green roof views fetch a higher room rate. In Vancouver, the Fairmont Hotel saves $25-30k per year by growing their culinary herbs on the green roof.

    Even buildings adjacent to and looking upon a green roof have higher values.

    A German study showed that photovoltaic panels have 6% greater outputs when coupled with a green roof.

    Another German study showed that green roofs have a better fire rating than conventional roofs, and German insurance is cheaper if your building has a green roof.

    According to William McDonough, the Ford River Rouge truck plant had birds nesting atop the roof within a week of its construction. How do you put a price on creating environment?

    Portland, OR and San Diego, CA allow a greater FAR (Floor Area Ratio) if the building has a green roof. In Portland, a developer was allowed to build an additional 6 condo units, worth $1.5 million

    Hospitals report faster recovery times for patients with a view. That view could likely be a green roof. Hence, lower insurance bills for hospital stays.

    Seems the value of green roofs is much more involved than merely weighing the initial construction costs.

    Leland Walmsley – ASLA, LEED AP

  10. Larry Saint Germain 07/24/2009 / 10:56 am

    I have wanted to green up my existing garage roof and small addition to my own home in Chicago but did not want to do a tear off of relatively new roof. I finally found two good sources of green roof systems for existing roofs. These are not intensive systems but since my roofs are really not visible it is more functional than aesthetics. Both are in the $9-11/SF cost (not installed but for me it will be a DYI project) and could be removed if we move.

    Larry Saint Germain AIA, LEED AP

  11. Jason King 07/25/2009 / 11:28 am

    Leland… great points. The multiple benefits are well known and have some great selling points for many clients. For instance, long-term owners such as institutions and public agencies. For instance, Multnomah County did a life-cycle assessment of the roof on their County office building, and quantified many of these items. While energy, stormwater, and other items were plusses, the biggest cost-benefit came from roof longevity – which was realized as a long-term cost-savings for taxpayers. Easy sell. The FAR bonus is another tool that has specific financial benefits that can be immediately realized – not factored in on a 10-15 year payback.

    The challenge, even with the manifold benefits – is to find the sweet spot for making sure that projects move forward – because often what is considered beneficial (some of the externalities) isn’t specifically given a project value in the pro-forma, which unfortunately but realistically often drives decision-making. If we can offer and capture these myriad benefits – and do it at a price-tag that offers the opportunity for wide-scale adoption – we’ll achieve both ends.

    I think Larry mentions a great dilemma in the dialogue… there are many products out there that could be the right choice for many projects and meet specific goals, but the reliance (or even focus) on ‘systems’ more often than not leads to cost-escalation… the idea that these can be ‘designed’ rather than merely ‘specified’ offers many opportunities to LAs to meet client goals and achieve lower costs. I’d bet a custom-design would be cheaper in 9 out of 10 cases – even factoring in design costs. But products are much easier to market – and the industry as a whole has done a great job of making a higher price tag palatable for people versus the unknowns of design. The onus is on us as designers to make the case that our service is valuable not just for design, but for cost-effective solutions.

  12. Jorg Breuning 12/08/2009 / 1:05 am

    What will the future of green roofs look like?
    Look at the mature green roof market in Europe -especially Germany. Since the last 10 years the US market developed very paralel as the German market developed 30 years ago -at the beginning. However in the US I often wonder why things are getting reinvented and fall back to what works since decades in Europe. Just copying would be more effienct for the environment but obiously not for profit of certain companies. For example the modular systems might not the most cost effienct, environmental friendly and proffesionel solution. In Germany modules went of the market nearly 30 years ago and all come backs failed.
    Today green roofs are common knowledge (don’t need expensive consulting, planning and fancy ideas) and implemented on 100 million sft every year at $2-5$ per sft.
    Germnay is also the leader in combined technologies like PV on green roofs.

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