[Greenbuilding] Growing Media Embodied Energy

[John Salmen]

I think the roof chips have to be thought of as just roof cover initially
not a growing medium. Moss could be established. If the roof is partly
intensive this could work well as the chips will compost over time and can
be encouraged to do so which then supplements the nutrient needs for the
soil mix for the intensive plants. In terms of landscaping maintenance it is
similar to on the ground - a woodchip path has to be scraped back
occasionally and renewed. The bottom layer is the composted soil material
which saves bringing in organic material.

 

You can play with depths - 3" will compost quicker and support more life
than 6".  I don't think weight will be an issue as you pretty well have to
design for a certain depth of saturated soils no matter what.

 

From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org]
On Behalf Of Gennaro Brooks-Church - Eco Brooklyn
Sent: October-12-13 8:18 AM
To: Green Building
Subject: Re: [Greenbuilding] Growing Media Embodied Energy

 

That is a good idea. I've actually been meaning to look into Black Locust
chips given that woods ability to not rot under ground. My current project
is semi intensive so my reservation is what will happen to the weight  over
time. The wood will decompose and shrink in depth, requiring the addition of
more. Each time you do that the weight increases. Is that a valid concern?

 

As an extensive sedum or moss cover then wood chips is a no brainer. 

On Saturday, October 12, 2013, John Salmen wrote:

I would seriously look at using ground up wood waste / wood chips. They can
hold their structure for years achieving a number of green roof goals
without the green initially. The end product is soil so you can look at it
as a green roof in process or simply an urban composting area. Wood chips
have been used in biofilters and support a diversity of life. 

 

From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org
<javascript:_e(%7b%7d,%20'cvml',%20'greenbuilding-bounces at lists.bioenergylis
ts.org');> ] On Behalf Of Gennaro Brooks-Church - Eco Brooklyn
Sent: October-12-13 4:40 AM
To: Green Building
Subject: Re: [Greenbuilding] Growing Media Embodied Energy

 

That's very helpful. Thanks John. I agree with your list of priorities. I
would add quality of life, for all biota, especially in the city. 

I'm really struggling to find a lower embodied energy light aggregate here
in NYC. 

It's turning out to be as easy as my other quest- to find a greener option
to sheet rock. 

On Friday, October 11, 2013, John Salmen wrote:

The ESCSI (lightweight aggregate institute put out numbers in 2012). For
manufactured materials like expanded shale or other lightweight aggregates
the number is same for all - 2.16MBtu/ton or 1.34 mbtu/cubic yard. Carbon
dioxide is 350.5 lbs/ton 218lbs/cy.

 

Sand is about 20,000 Btu per ton and Crushed stone about 30,000 Btu/ton. 

 

Those numbers don't get it to your building site though.

 

I'm doing another green roof now (extensive type) and I've switched from
varied sedum type mix to just a moss roof (they typically turn into a moss
roof anyway and its a more desirable material in my mind). Soil mix is
simpler and can be limited to local sandy soils or cement sands (different
particle sizes) with some aggregate - limited organics. Less saturated
weight. 

 

For me the main points of a green roof are 

-          To substitute a natural bulk material (soils primarily) for a
manufactured sacrificial material (roofing that can withstand the elements

-          To reduce concentrated peak water flows (preventing erosion,
etc.)

-          To potentially improve the quality of the water by isolating it
from typical roof contaminants that it would normally degrade and carry away

Plants are secondary but they can improve water quality (and air) and moss
can be extremely effective for that with a higher probability of not dying.

 

Water retention (and ultimate weight) is calculated by soil mix and holding
capacity. Weight is a huge issue as it puts tremendous loads on a building
that have to be provided for (can really upsize a building especially in a
seismic area). 

 

 

 

From:



-- 
Gennaro Brooks-Church, Director
Eco Brooklyn
347-244-3016
22 2nd St, BK NY 11231
Sent from Mobile

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