Department of Interior and Native Plants on Green Roofs, Guidance for Historic Structures

I am proud the U.S Park Service, Department of the Interior's (DOI) headquarter building has a green roof.  This fact alone is an amazing statement towards the Department's commitment to sustainability.

On the other hand I am amused with their choice of plants, non-native species.

In defense of non-native landscape plants, many such as Sedum are extremely well behaved and proven to survive in harsh conditions.  Sedum is beautiful and Sedum is economically important to many green roof plant growers.

I am not bashing Sedum, lets get that out of the way up front.  Once this discussion gets started,  Sedum proponents immediately change the conversation from "Sedum is not a native" to "Sedum is not invasive and has been used for years".

The underlying issue here lies not even in the fact that the U.S. National Park Department of Interior's main headquarters building in our Capital possesses a green roof with a non-U.S. native (though there are a few native Sedum species in the U.S. they are not used on the roof) plant selection.

National Park Service, Dept. of Interior Headquarters Green Roof

Sedum is native to Europe and Asia.  We have exotic European landscape plants on top of our National Park Service's headquarters, so what?

The real point here is the photo of of the DOI's green roof is used on a publication entitled "Illustrated Guidelines on Sustainability for Rehabilitating Historic Structures".  These guidelines are what every local Preservation Appropriateness Review Committee use as a standard for renovation projects.

The document states very plainly under the Recommended approach column, "Selecting sustainable native plants that are drought resistant and will not require excessive watering of a green roof".

The document then goes on to post several photographs portraying the Sedum as U.S. native plant species.

Illustrated Guidelines on Sustainability for Rehabilitating Historic Structures

 The material as presented is not accurate.

I am working on a project now proposing to incorporate a green roof onto a non-original additional to a structure in a Preservation District and every reviewer is looking to the Illustrated Guidelines on Sustainability for Rehabilitating Historic Structures for guidance.

We have been extremely careful during plant design phase to use only low growing native plant species, those found growing not just in the U.S. but those plants native to the specific area where the green roof is being proposed.

How then does our government publish guidelines and not abide by them themselves?  I suspect the U.S. Park Service and Department of Interior really do want to encourage the use of native plants and their efforts are visible with all the references to wildflowers and native plant research they support, making this issue all the more confusing.

DOI should then start by being the example everyone looks too.

I would suggest either replacing the non-native rooftop plants with drought tolerant natives on the DOI green roof or change the language in the Illustrated Guidelines on Sustainability for Rehabilitating Historic Structures to allow for use of exotic, foreign plants.

Two levels of standards, one for the government and one for us regulated is not equitable or fair.

The question is really about native plants and exotic plants.

The question is not really about exotic invasive plants.

Yet there is another even more bizarre twist to the situation.

Exotic invasive plants are typically those plants non-native to an area AND exhibiting tendencies to displace native wildflowers and plants.

Certainly there are levels of invasivity.  Sedum and kudzu cannot be fairly compared as to damage caused.

Interestingly though, the Sedum shown on the DOI's green roof in the above photographs appear to be S. acre, and other Sedum species now listed on many U.S. and worldwide invasive species lists.

I did confirm the plants shown in the photograph on the DOI building are in fact Sedum, through a project description located on the manufacturer's website.

Included below is a brief excerpt from a previous post concerning invasive species issues on green roofs:

Here in the US there are many red flags and concerns now being raised concerning Sedum use and the potential for invasive activity.

For example;

• The City of Indianapolis cautions against the use of both S. sarmentosum and S. hispanico in the Indianapolis Stormwater Green Roof Technical Design Manual
• The Invasive Plant Association of Wisconsin lists S. acre and S. purpureum as having invasive qualities
• Missouri's Exotic Pest Plant list includes S. sarmentosum as a category B exotic present in Missouri
• Virginia's Department of Conservation and Recreation ranks S. sarmentosum as an invasive species
• Massachusetts suggests it is necessary to gather additional data on the S. telephium as part of the Managing Invasive Plants program.
• The Great Lakes Indian Fish and Wildlife Commission list Sedum spp. as a terrestrial  invasive
• Wyoming's Natural Diversity Database report lists S. acre as a noxious weed plant located across F.E. Warren Air Force Base
• New York's state Early Detection Invasive Plant Program lists both S. sarmentosum and S. telephium species
• U.S. Fish and Wildlife Service list S. telephium on their invasive plant list
• S. acre, S. albo-roseum, S. purpureum, S. ruprestre and S. sarmentosum are listed as Alien Plants by Illinois' State Museum site
• USDA Forest Services, Non-Native Invasive Plant List lists S. telephinum/ S. purpureum on their Invasive Plant list
• US Natural Resource Conservation Service maps naturalized and escaped non-natives, including Sedum.  Their database of non-native Sedum species occurrences is informative.  They suggest "These plants are introduced to some part of the PLANTS Floristic Area, though they may be native in other parts. While many are harmless or beneficial, others that are not already invasive or noxious have a high potential to become so in all or part of their range. In general, introduced plants are likely to invade or become noxious since they lack co-evolved competitors and natural enemies to control their populations."  Sedum species listed include;
• S. acre
• S. aizoon
• S. album
• S. dasyphyllum
• S. dendroideum
• S. hispanicum
• S. hybridum
• S. kamtschaticum
• S. linare
• S. mexicanum
• S. ochroleucum
• S. praealtum
• S. refluxeum
• S. sarmentosum
• S. sexangulare
• S. spurium
• S. stoloniferum, and 
• S. ternatum

Other Countries too, view Sedum species as an invasive plant, including;

• Poland, New Zealand, Switzerland
• Czech Republic
• Japan - see above
• New South Wales
• British Columbia
• Ontario Society for Ecological Restoration
• Canadian Wildlife Service
• Mediterranean regions
• and many others

Many Not-For-Profit organizations and preserves also consider Sedum to be potentially invasive. A few include;

• Nature Conservancy of Canada - Garry Oaks Ecosystems lists S. acre as an established invasive species
• Wisconsin Botanical Information System tracks county by county where the many different Sedum species have escaped and become naturalized
• Washington State University Extension Blog has a comment " My plant peeve right now is sedum. It's used and promoted extensively for green roofs and rooftop garden use, because it grows so well in extreme conditions -- which makes it also quite willing to grow in not-so-extreme conditions. I planted a handful that a neighbor had given me, and it now has spread through one garden bed, along the base of a rock outcrop on the other side of the yard (I took a snippet and parked it from the bed onto the outcrop, not knowing how it would spread and spread), and now is moving into the lawn. It's easy to pull out, but a tiny piece will root, so composting is out, and vigilant disposal is necessary. I have yet to see sedum on an invasive species list, but predict that it will show up on a bunch of them in the next few years, as pieces make their way off of rooftops and into the on-the-ground landscape. "
• Mid-Atlantic Gardener's Guide says 'Many smaller sedums are invasive..."
• Grassroots websites suggest Illinois' Draft Invasive Plant documents list both S. sarmentosum and S. telephium are invasive
• The New York Botanical Garden's notes S. sexangulare has been newly noted in the Torrey Range as an exotic species

Truly there may be places for Sedum use.

Yet to confuse potential project applicants with photos and guidance language speaking to the use of native plants yet portraying and using a plant native not to America when referring to historic structures does not seem logical.

In fact, it is lack of consistency in guidance and procedure that can lead to expensive and time consuming litigation.

Thee is an easy solution.  Either recommend native plants and use native plants or don't recommend native plants if DOI wishes to continue to use exotic landscape plants on their green roofs.

All the Department of Interior had to do was consult with their own plant experts.  A monoculture of only a few genera never is optimum for biodiversity support.

On the other hand, a green roof filled with many different native wildflower families, genera and species could make a powerful statement about America's heritage at the headquarters of the Department of Interior.

Green Roofs and Historic Structures

We are involved in a small green roof project now in a historic neighborhood and on an addition to a historic structure.

U.S. Department of Interior's Guidance for Rehabilitation of Historic Structures

What could be moe historic than plants used in the same manner as those in the Hanging gardens of Babylon or any other number of historic structures?  Apparently the U.S. Department of interior has reservations concerning Green Roofs.

And green roofs and rooftop gardens may be an issue for concern to local ro municipal regulators when reviewing a project for compliance to code, typically due to the infrequency of green roof installations on historic structures.

The latest guidance to renovation of historic structures issued by the U.S. Secretary of Interior can be downloaded here.  Interestingly, the cover page to the document has a photo of a green roof planted with sedum.

Sedum certainly is an appropriate historical plant for some areas of the world and history has shown us of her use in portions of Europe.  Because certain species of sedum may now be added to watch lists for aggressive and invasive species lists, I think a green roof depicting native wildflowers would have been more appropriate.

After reviewing the document I offer the following comments;

• The document recommends against the use of non-natives that may displace native species yet the document has a photo of a roof with, unless I am mistaken, Sedum acre being used.  Sedum acre is listed across Canada and in some U.S. jurisdictions as potentially invasive, including listings by the U.S. National Park Service. Though I do believe Sedum is appropriate for select green roof projects, monoculture type projects with oen or two genus should not grace the cover of our Nation's Park Service stewards (epic fail).  You can read more of my Sedum rantings here from previous posts.
• Under the guidance round ugly satellite dishes are easier to approve on historic buildings than green roofs.
• Green roofs are not afforded the same treatment as window boxes.  The guidance recommends a green roof be not visible from the street.
• and more...

Download the document and keep for future reference!

I'll be doing a post once we complete the historic building review process to share what we learn.

Green Roofs over Sloped Metal Roofs

Green and Vegetated Mat Roof systems can easily be adapted to metal standing seam roofs.

Because vegetated mats are monolithic - an integral unit - and not comprised of individualized smaller modules, the system offers considerable "uni-body type" strength.

There are many systems such as these available on the market today.  There are many beautiful pictures of sedum mats and other vegetated mats published across the web, those capable of use on a sloped roof.

Vegetated mat systems are attached to the standing seam metal roof with roofing screws and washers but can also be cantilevered over the peak of a sloped roof depending upon the architect's or engineer's design requirements.

MetroVerde Vegetated Mat Design for Standing Metal Seam Roof

Included here is a typical design sheet for a standing seam metal roof with a vegetated mat overlay component - designed for Florida's 5 H's - Hurricanes, High Humidity, heat, Hard Freezes and High Winds!

A membrane/liner is used to separate the vegetated roof system from the standing seam roof panels.

Low VOC adhesives are used when necessary and the standing seam roof ridge-cap and end trim cover any loose mat ends.

With advances in sealant and adhesive technologies sloped green roof systems and vertical living wall systems can be installed across the Urban Core.

Finally, as the plants grow - the plant root systems criss-cross through the mat, interweaving themselves into the mat and with other roots, creating a strong panel of plants and locked into place soil.

Green Roof Weeds, Maintenance and Taking Care of Plants on the Roof

This is an update of a post I wrote about two years ago.

I was asked to contribute towards a new municipality green roof regulatory policy, one where there was considerable incentive given developers towards site entitlements if the project would include a green/vegetated roof.

One of the committee members also invited was an accomplished technical/construction specialist - one with multiple graduate degrees in technical and mechanical fields.  But she did not understand plants.

Her past green roof projects had been designed around available landscape plants.  Choose the typical on-the-ground landscape plant and design irrigation and fertilizer and other accessory design criteria to support the landscape plants - was the motto.

Whenever we'd discuss native species or volunteer species showing up on the roof, she'd immediately try to quash the discussion by shouting 'WEEDS!  NO ONE WANTS WEEDS ON THE ROOF!'

I think it was because she felt uncomfortable trying to work with the organic, dynamic complexities of nature.  Obviously she wanted no part of having native wildflowers or grasses on the roof.  Moreover, I've seen some of her 'landscaped' green roofs and they quickly revert back to natives, or as she calls them 'weeds'.  I am sure the selective herbicides are used quite often.

We must stop seeing masses of green and train ourselves to look at the plant.  There are few if any true weeds in nature and on green roofs.

Each plant has its own beauty and purpose, even those obnoxious ones.

I've often quoted Lydia Cabrera in saying "there are more spirits in the plants/forests than in the sky'.

The vegetated roof in Sanford I toured this week was full and vibrant due to volunteer plants.

There are no weeds.

I learned this from my daughter, today.  Though I knew it long ago.

She showed me her photos of one of the most obnoxious plants in my book - Bidens alba (Hairy Beggar's-tick).  Just try walking through a mass of Bidens and wait till you come out the other end of the patch....

I love their masses of white flowers but distrust their desire to bestow me with masses of aggravating seeds.

I almost at this time of the year agreed with the self-centered technocrat who probably couldn't tell bamboo from horsetail or coral honeysuckle from trumpet vine.  I almost shouted WEEDS!

But Jincy showed me her pictures from today.  Ones she and Ruairi took out back.  The Bidens are growing on the roof too.

And Lydia Cabrera is right about more spirits in plants.  And I am right about 'there really are no weeds'....

No need to weed green roofs.  Just step back and admire the Bidens.

Green Roof Beauty - Not Weeds - Bidens alba providing habitat and foraging

Green Roof Wonders - Not weeds, Bidens alba provides nectar

Happy Green Roofing!

Kevin

Green Roof Plant, Sesbania herbacea, Danglepod

Danglepod is a great native green roof plant for many reasons, including habitat, forage, food for Lepidoptera, nectar provider, nitrogen fixer, shade producer, wind break plant, native species and so much more.

Sesbania herbacea, Danglepod flowers ont he Green Roof

Sure to catch anyone's attention Danglepod is also known by its scientific name Sesbania herbacea.  Danglepod grows wild across Florida and many of you may remember seeing broad patches alongside road and highways blooming during the summer.

Sesbania herbacea growing on the Breaking Ground Contracting Green Roof

I like Danglepod as a green roof plant for a number of reasons, including all of those listed above.  Very resilient to wind Danglepod makes a great permaculture type windbreak and provides shade, so though welcome anywhere on the green roof I especially like to see the plant grow around the perimeter.

Danglepod is a summer annual, however the hot tropical desiccating winds are what I most like to protect against.

Moreover, Danglepod is a fertilizer plant for green roofs.  A member of the Fabaceae family, Danglepod fixes nitrogen into the soil and has been listed in many permaculture and biodiversity online databases, including international sites such as EcoCrop.  The USDA NRCS plant website refers to Danglepod as being native across the southern US.

Danglepod's Seeds

Research is presently being conducted across the world on the economic and ecological potential of the plant, including fiber utilization and biofuel production.  The Atlas of Florida Vascular Plants has several great photos of Danglepod along with considerable botanical data.

Danglepod and other Sesbania are used by numerous Lepidoptera for food sources.  The Orange Sulfur,  Gray Hairstreak, Zarucco Duskywing and others use the plant as larval food.

The plant reseeds itself prolifically and is considered a 'weed' by many.  In fact, many herbicide companies and 'weed' organizations recommend applying chemicals to this plant to kill it (along with the butterflies and pollinators using the species).

Being a native weed I consider Danglepod a wildflower with benefits and the plant is welcome on all green roofs I work on.  If too many appear it is easy to pull a few up.

As to the free nitrogen, shade, wind protection and wildlife habitat, Danglepod packs a powerful and beneficial punch!

Green Roofs Teach Us About Plants

We are always very focused on learning about how plants do on the ground and then using compiled data to determine what plants works best on green roofs.


Yet the reverse is true also!  We can take what we learn from green roofs and apply to ground level landscapes with stunning results!


Really cool when we learn from the Green Roof experiences about those plants who do well without irrigation and in extreme heat & desiccating winds.  Roofs are magnitudes more hostile than ground level planting areas.

Native Plants provide beautiful non-irrigated landscape

Species who have proved themselves on the roof are solid choices for most ground level landscapes.

And there are cost savings too!  Here this planting is non-irrigated (the city approved zero irrigation) yet we have a tropical, lush look from two great native plants, Adam's needle and Little Bluestem. The soil prep was special and heavy pine straw mulch applied. Very green in many ways!  For more on this native plant install click here.


Understanding Green Roofs and Green Roof plants pays many dividends.

Brown Green Roofs, Green Roof Forensics

Any green roof designer has had plants die from time to time.  Roofs are one of the most harshest places to grow across and good green roof design involves much more than basic landscaping.

Here in the tropics an understanding of environmental factors is crucial to ensuring green roof survival, beginning with a solid knowledge of plant selection. Importantly, long-tern survival depends not only on appropriate underlying green roof support systems, but soil media and 'Right Plant Right Place' issues also.

The tropics, for instance possess finicky climates with wild temperature swings, horrendous humidity, extreme temperatures, desiccating winds, salt spray, stealth-like killer fungi, hurricanes and more.

This doesn't mean green roofs do not work in the tropics, they do!

Unfortunately, the attached photos depict what can go wrong with a green roof here.

Struggling Green Roof

Sedum is not generally considered a plant suitable for the tropics.  Note I say generally as I am sure there may be exceptions.  Southern Blight fungus and hot, sticky humidity overwhelm sedum during the hot summer months.  The same applies to many Delosperma also.  

Rainfall quantity distribution here is unusual.  In many places receiving 150 cm rainfall each year the majority of that amount may come in only a series of heavy downpours.  Green roof system drainage must be designed to handle extreme water flows, otherwise failure may occur.  Apparently some of the soil media here has ended up in the swimming pool below.

The example shown here did not possess additional irrigation.  Instead as the plants withered, a rotary sprinkler was pulled up to the roof in a futile attempt to save the plants.  Im not sure how long the sprinkler ran, but it did run long enough to erode grooves in the soil media.

Irrigation erosion from sprinkler

A green roof system without irrigation is a environmentally friendly approach, and can work.   However other factors, including appropriate plant selection must be considered.

Soil media must reflect site specific drainage requirements.  Soil media high in fines may blind geosynthetic fabrics which comprise portions of the green roof drainage system, restricting vertical permeability and causing soil media to wash off the roof.

In this case it appears a lack of vertical drainage has caused rainfall to rush across the sloped roof soil media surface, scouring the grit and producing serious erosion.  It is entirely possible that during a tropical storm, such as TS Fay in 2008 where 600mm+ rainfall dropped in some places, the soil media here would end up in the gutters or on the ground unless appropriately stabilized.  Moreover, damp water retention pads and even the smallest of pooled water depressions can lead to hoards of pesky mosquitos.

Green Roof design involves much more than planting inexpensive fertilizer pumped up plants on a roof platform.

Appropriate green roof design takes into account wind, light levels, available daylight intensities, temperatures, invasive aspects, native plant considerations, nutrients, air quality including NOx levels, pests, adjacent potential allelopathic influences, air water vapor and much more.

Investing in a Green Roof Professional's time up front will save significant costs in the long-term.

Green Roof Irrigation Opportunities, Exploring Water Vapor

Fortunately, there are many ways green roof plants can be provided irrigation water.  First we should utilize native rainfall amounts, second water vapor in the form of dew, fog and air humidity.   Air conditioning condensate can provide a significant amount of irrigation as well.  Finally, rainfall captured in rain barrels or underground storage and cistern systems may be utilized to support plant water requirements.  Grey water too may be used if local or state regulations permit.

I've always been amazed at how much water the air holds.

Several of our past blog posts have addressed dew, fog and water vapor (biomimicry).

This morning as I inspected a recent green roof project, I was awestruck at just how much water was rolling off the solar panels, dripping to the single ply roofing, running across the roof to the drip edge and into the gutters.  Alot of water!

Dew Stream Dripping from Solar Panels

So when we think of green roof design we need to visualize the advantages elevated vegetated plantings have over ground level plants from water laden air exposure.

Nature has provided many plants with fine hairs, such as one of my favorite green roof plants, Yucca filamentosa, a physiological attribute allowing for water collection.

Before we immediately specify irrigation systems with potable water for either primary or backup supply,  lets seriously look at what nature provides.

We may be surprised at just how much water nature is making available.

Green Roof at Dawn

This morning's photo of the Breaking Ground Green Roof at dawn.  What a way to start the day!

MetroVerde Green Roof at Breaking Ground Contracting, Jacksonville, FL

Prostrate Rosemary on BGC Green Roof

Green Roof Rosemary

Yellowing of prostrate rosemary can be caused by three factors we've found on green roofs.  First is water stress, second is Iron deficiency and the third is Nitrogen deficiency.  In a highly inorganic material you should check the pH.  Calciferous soils with higher pH will bind iron and promote the yellowing.  We add dry pine needles and oak leaves as a mulch around the root ball before we plant and then add the same to the soil around the plants.  The organic matter provides micronutrients in ways, we've seen, industrially manufactured fertilizers can't.  In fact, smart leaf compost application has allowed us to create thriving rosemary plantings.

The attached photo is of prostrate rosemary growing on a green roof in 50mm of a soil media with sharp sand for drainage and heavy leaf usage.  Once the plant becomes established the leaf requirements diminish.  I prefer to only plant rosemary where it can 'cascade' over the side of a sidewall or edging.

Finally, cow peas interspersed with the rosemary really helps from a NH4 availability perspective.

Growing Food on Roofs - Rooftop Permaculture Can Help Feed the Urban Core

Green Roof Mat with Swale Pads For Food Growing - Roof Permaculture

Growing food on the roof makes sense.  With hundreds of thousands of acres of otherwise wasted space available for planting in the Urban Core, city dwellers are now more than ever planting their rooftop spaces to help offset high food prices.

The rooftop permaculture systems we work with generally employ some type of three dimensional weave to allow plant roofs the chance for anchoring.  These are the same systems we just successfully tested in the hurricane simulators - where, once installed the plants and soils stay embedded in the mats under 120 mph winds.

Soil embedded three dimensional netting, though not essential, is important in sub tropical climates influenced each summer by cyclones and hurricanes, helping hold both soil and plants in place.  The weave also allows for steeply sloped rooftop areas to be taken advantage of for agricultural purposes.

Green Roof Mat & Soil Added For Food Growing - Roof Permaculture

Low cost and organic alternatives to the polypropylene weave include hemp and burlap fabric, fowl or hail netting, twine weave and any other system allowing inter-connectivity of plant roots to underlying roofing systems.

Importantly, growing food on the roof creates economic opportunity.  Many small cafes and restaurants will purchase locally grown organic produce.  Moreover, rooftop gardens  reduce heat island effect, produce oxygen and sequester carbon, provide habitat and offer many other benefits.

One of the first suggestions a friend offered was to take the multi-dimensional mat and fold it under in certain areas, creating a swale-like structure - a technique successfully used in permaculture practices, one with a focus on water efficiency maximization.

Judy's Spring Mix Ready for Green Roof Planting

The folds were added after the fact because the mat had already been installed.

A lightweight roof soil mix was added to the mat and seedlings Judy had grown - a spring mix - were planted.

Growing food on roofs and walls in the Urban Core opens many economic, ecological and social doors.  Elimination of food transportation costs can even help reduce our dependence on foreign oil.

Green Roof Food Garden - Roof Permaculture

Green 'Green Roof' with Fertilizer from the Air - Floating Wetland Secrets & Companion Fertilizer Legumes

Science has shown us the most common component of air is Nitrogen, typically making up about 80-82% of the earth's atmosphere.

Green Roof plants, as well as every other living organism on the face of the earth must take this nitrogen and build protein, amino acids, nucleic acids, DNA and other life-giving substances.

Green Roof Legumes companion planted

However most of the atmospheric nitrogen exists in a form that cannot be used unless converted into ammonia.  Ammonia is formed from one nitrogen and four hydrogen atoms.  Ammonia is the substance living organisms use to process nitrogen into life.

On a rooftop or in a garden, available ammonia nitrogen amounts are usually discernible by shades of green across leaves.  Darker green typically represents strong availability of ammonia nitrogen whereas light green or yellow leaves may indicate a serious lack of available ammonia nitrogen.

One school of thought concerning ammonia nitrogen availability focuses on use of industrially processed ammonia compounds in the form of liquid or more commonly, pelletized fertilizers.  However with the world's waterbodies, lakes, rivers and springs quickly eutrophying with runoff carrying excess ammonia and phosphorous, industrial fertilizers are coming under frequent criticism.

Adding industrial fertilizers to green roofs may compound existing pollution problems.

Another perspective for providing green roof with adequate supplies of ammonia fertilizers is an approach incorporating nitrogen fixing plants into green roof plantings.

Nitrogen fixing plants are commonly represented by the well-know legume families such as clover, beans and other 'green manure' plants where the nitrogen in the form of nitrogen gas, N2, is converted to ammonia, NH4, by bacterial processes.  The NH4 is then released to the soil and plants when either the bacteria die or the bacteria live in close association with plants.

Planting nitrogen fixing plants on a green roof can reduce or eliminate all together the necessity of additional industrial fertilizers.

The opportunity to use nitrogen fixing plants to provide ammonia really caught my attention over the last year as we worked with floating wetland technology.

Hoping floating wetland plants would clean stormwater through uptake of nutrients, the research conducted ultimately pointed towards a very interesting conclusion with green roof fertilizer implications.

In waterbodies with low nitrogen concentrations (very clean lakes, streams and rivers) the water under and around the floating wetlands had higher than normal nitrogen concentrations.

At first these findings were a big surprise yet as we looked at the systems from a more global perspective and noticed the presence of certain nitrogen fixing plant and bacteria species the results began to make sense.

Nature knows when ammonia fertilizers are needed and provides the biological process to accomplish such.

In a time of severe water pollution and excess nutrients we should be looking to nitrogen fixing plants for green roof fertilizers.

Especially in Urban Core areas where NOx and SOx smog is bad, plants not only make fertilizers available but clean the air in the process.

Many of the plants in the Fabaceae family fix nitrogen.  Wikipedia offers some interesting perspectives on the topic also.

Studies have shown nitrogen fixing plants can add up to seventy five pounds of nitrogen to the soil per acre in natural ecosystems and up to several hundred pounds per acre in cropping systems.

Nature can teach us (biomimicry) about important agricultural and green roof considerations.  There are many web resources available for more information on nitrogen fixing plant types and their biological processes.

Next time you consider applying industrial fertilizers, try using nitrogen fixing plants .  You'll be helping keep our waterbodies free from algae blooms, cleaning the air, providing your plants with needed nitrogen and much more.

DIY Solar Hot Water Heater we Built & Use for Under $200 with a Green Roof twist

Sits right next to the small Cubanelle pepper Green Roof on a southerly exposure sloped roof and the DIY solar hot water panel works very well.  Photos below but first a photo of the Green Roof Cherry Tomatoes growing adjacent to the Rooftop Solar hot Water Heater :)

Rooftop Permaculture - Cherry Tomatoes

I will be clear up front I have alot to do before It is truly complete.  I know there are many unorthodox approaches here and I am sure a mechanical designer could list many reasons why this is an inefficient design and why a much more expensive system would be capture and retain with higher efficiencies.  Importantly, I didn't want to use CPVC or Copper in the collection coils because of photodegradation.

But the point here is simple.  I have disconnected the circuit breaker to the electric hot water heater and we still have plenty of hot water for a family of four, including two shower loving teenagers.

So I understand that the system is inefficient.

But I am not paying for hot water now.  And I am not using coal or petroleum generated electrical power.  What I am doing is using the sun's energy, reducing my electrical bill and affording us here on the Jax Urban Farm another step towards true independence.  Once we get our electric bill I'll do a follow up post.

DIY Solar Hot Water Directions.

1. Find your most sun exposed roof surface.
2. I used a old tin planter boxes for the frames however 3" edging could be used to create the side walls.  You really dont need a bottom to the box.
3. Once you decide the length and width you want - I used 1 meter x 2 meters, cut a piece of used plastic, preferably a EDPM or PVC material - something like a Coy Pond Liner (you can find these on Craigslist for almost nothing).
4. Make sure the roof is clean and spot adhere the waterproofing liner to the asphalt shingles using a tube of roofing adhesive from your home improvement store.
5. Attach the box or frame (I'd recommend a 1 M x 2 M rectangular frame made from 3" edging without a bottom) to the roof above the liner.  Use 1 1/4 or 1 1/2" metal roofing screws with sealant washers.
6. Uncoil a roll of 1" PPE 150PSI Black Irrigation Tubing (see photo below) and place inside frame/box)
7. Drill entry/exit holes in frame or box for tubing.
8. Run 3/4 CPVC pipe from existing hot water heater inlet to tubing in solar box and attach with standard adapter and band.
9. Add drain valve to system for draining during very cold weather.
10. Cover all pipe with standard pipe insulation.
11. Let glue dry.
12. Enjoy free hot water.

I am going to add a piece of clear fiberglass or plexiglass over the box as a top at some point but haven't yet.

The system heats the water going into my hot water heater.  Once in the hot water heater the water stays warm because the tank is insulated.

We've noticed of course the water is hotter during the afternoon than it is in the morning yet there is still plenty of hot water to go around.

What I do plan to do is add another coil of 1" insulation tubing to increase capacity, add a clear cover.

We are considering adding a green roof soil media around the coils and plant some small plants as an experiment.  We have found on our many green roofs that our speciality soil media serves as a heat sink, allowing for the storage of heat.  Will update the post as we implement the green roof component.

There have been no leaks.  The systems has experienced 150-170F , 65C to 75C during the day dropping to 70F,  20C at night so there has been plenty of thermal expansion going on.

Yes, many different ways to cost-effectively (the key here is inexpensive) improve this system and I'd love to hear your comments.  We have worked for years in designing living wall and green roof systems for low cost applications in slums and intense Urban Core permaculture situations and what I cannot incorporate are expensive, custom components.

Disclaimers important, I will say your should check with all the appropriate regulatory authorities for code, permit and blah, blah, blah requirements.  Insurance companies also have their own blah, blah, blah requirements.

However, if you want free hot water you can have free hot water and for less than US $200 and a weekend of your time.

Please leave your thoughts on fine tuning and I'll consider incorporating them!

MATERIALS

1. Tube of adhesive $4
2. Pond Liner or plastic $5
3. Roofing Screws $7
4.  6 M ( 20') 3" vinyl or aluminum edging (for sidewall frame) $15
5.  50' roll black 1" 150 PSI irrigation tubing $60
6.  3/4 CPVC to 1" tubing adapters (2) $4
7. Misc 90's ells and couplings 3/4" CPVC & CPVC Glue $15
8. 3/4" CPVC pipe $24
9. 3/4" drain valve $4
10. Standard pipe insulation $10

Total Approximate Cost $ 138

Installed $200 Solar Hot Water Heater

Tubing to CPVC Connection

1" 150 PSI Irrigation Tubing serves as Coils

CPVC supply lines to Hot Water Heater

Green Roof for Landscape and Parking Lots - cleaning and storing stormwater

Green roof concepts are not just limited to the top of a structure.  They can be adapted almost anywhere plants, water and a platform can be integrated.  

Referring to the term 'volumetric green' in the Urban Core - green roof technology can be adapted to provide habitat, clean stormwater, sequester carbon, produce oxygen and create beauty across the cityscape.

Ultimately, to be cost-effective, a best management practice must bring cost effectiveness to the table.

Maximizing site development potential by combining stormwater, green space and other site functions allows for green practices to be more readily implemented.

Below is a diagram of what we've done with the lessons learned from building lightweight green roofs however the 'roof' is actually a landscape cover for stormwater storage and recycling.

"Green Roof" over Rainwater storage, cleaning and recycling system

One of the aspects about plants we have come to realize is plants are efficient with uptaking nutrients - nutrients otherwise contributing to algae blooms and dead waterbodies. 

As site development becomes more constrained with respect to available space, stormwater and wastewater treatment can turn to green roof inspired, plant based systems as a method of sequestering nitrogen, phosphorus, zinc, copper and other contaminants. 

Once sequestered, these pollutants may be removed through biomass harvesting and composted on-site for reuse in the landscape. 

Removing nutrients from the water cycle is the most efficient way of cleaning our water supply. 

Green roof technology applied to stormwater storage and recycling has many benefits.  Stored rainwater may be used for irrigation, flushing of toilets and more.

Combining landscape and rainwater recycling through green roof technology

Green Roof Technology applied to Stormwater Capture and Storage