simulation program for green roof

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Dear Colleagues,

Would you tell me, please, which simulation program can simulate performance of green roofs.I would be gratefulif you
could kindly guide me by offering any information . I am planning to simulate performance of one the building in terms of
energy and acoustic through green roof.

Thanks in advance for any help and advice

Shahryar Habibi, architect

PhD candidate in Architectural Technology
University of Ferrara, Department of Architecture

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EnergyPlus has a model for green roofs.

I'm not sure it handles acoustics, but it will simulate energy and water.

Fred Betz PhD., LEED AP (r)BD&C
Senior Sustainable
Systems Analyst

AEI | AFFILIATED ENGINEERS, INC.
5802 Research Park Blvd. | Madison, WI 53719

P: 608.236.1175 | F: 608.238.2614
fbetz at aeieng.com | www.aeieng.com

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Yes I've modelled green roofs through designbuilder which is a graphical interface to energy plus. Worked well for me.

Dr. Apeksha Gupta
Senior Project Manager for Educated Environments
BREEAM international assessor
Certified Passivhaus designer,
Sustainability consultant

Sent from my iPhone

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Dear colleagues,

Thank you so much for all your help I really appreciate it.

Yours sincerely,

Shahryar Habibi, architect

PhD candidate in Architectural Technology
University of Ferrara, Department of Architecture

Yes I've modelled green roofs through designbuilder which is a graphical interface to energy plus. Worked well for me.

Dr. Apeksha Gupta
Senior Project Manager for Educated Environments
BREEAM international assessor
Certified Passivhaus designer,
Sustainability consultant

Sent from my iPhone

EnergyPlus has a model for green roofs.

I?m not sure it handles acoustics, but it will simulate energy and water.

Fred Betz PhD., LEED AP ?BD&C
Senior Sustainable
Systems Analyst AEI| AFFILIATED ENGINEERS, INC.
5802 Research Park Blvd. | Madison, WI 53719

P: 608.236.1175 | F: 608.238.2614
fbetz at aeieng.com | www.aeieng.com

From:shahryar habibi [mailto:shahryar_habibi at yahoo.com]
Sent: Thursday, September 25, 2014 9:00 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] simulation program for green roof

Dear Colleagues,

Would you tell me, please, which simulation program can simulate performance of green roofs.I would be grateful if you
could kindly guide me by offering any information . I am planning to simulate performance of one the building in terms of
energy and acoustic through green roof.

Thanks in advance for any help and advice

Shahryar Habibi, architect
PhD candidate in Architectural Technology
University of Ferrara, Department of Architecture

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Hi Shahryar
EnergyPlus can model thermal performance of green roofs via Material:roofVegetation object developed by Portland University, see i/o ref for more info.
Unfortunately I can't give you any suggestion about acoustic performance simulation program.
Best
Alessandro Gober

________________________________
Da: "bldg-sim-request at lists.onebuilding.org"
A: bldg-sim at lists.onebuilding.org
Inviato: Gioved? 25 Settembre 2014 22:10
Oggetto: Bldg-sim Digest, Vol 82, Issue 21

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Today's Topics:

1. simulation program for green roof (shahryar habibi)
2. Re: General query - impact of location on energy demand
(Jeetendra Kumar)
3. 90.1-2010 Baseline lighting power allowance calculation
(Jones, Christopher)
4. Re: General query - impact of location on energy demand
(Javed Iqbal)
5. Re: 90.1-2010 Baseline lighting power allowance calculation
(Cheney)
6. Re: General query - impact of location on energy demand
(Jim Dirkes)

Dear Colleagues,

Would you tell me, please, which simulation program can simulate performance of green roofs.I would be grateful if you
could kindly guide me by offering any information . I am planning to simulate performance of one the building in terms of
energy and acoustic through green roof.

Thanks in advance for any help and advice

Shahryar Habibi, architect

PhD candidate in Architectural Technology
University of Ferrara, Department of Architecture

Hi All,

Thank you for the responses.

Brian: your reply shows a comparison which I was looking for, although the data you shared seems different from what's available from EIA and Eurostat.

Jim: Thanks for pointing out the "comfort expectations" aspect. This adds a dimension that seems difficult to analyze - gap analysis for different locations. Please share if you can suggest any source for comfort benchmarks.

Shanta: for conciseness, I'd skipped what you pointed out, but sure this has to be accounted for. Thanks for pointing this out. Also, for suggesting the ASHRAE tables and the link.

Jeremiah: didn't know about the link. Thanks. Shall try checking that soon.

Well, I would like to ask you the following question(the reason for my earlier questions):

Do you think our understanding of the impact of location on energy and emissions, esp due to natural factors, can be used for planning where should we build cities in future, to fight global warming?

For now, just a no/yes is fine.

Looking forward to your views.

Sincerely,

Jeetendra.

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?
But do all of these programs account fro the impact on the roof micro
climate? None to my knowledge do. When you get a large roof surface
the above roof air temperature bias can be 2-5DegC between a cool roof
(or green roof) and more historical roof (higher absoprtance). These
second order effects become essential to account for if you have
mechanical equipmnt on the roof as ventilation air and condesning
temperatures are impacted. We have been doing some research into this
area in Australia.?Think about the urban heat island effect at a
micro scale, becomes very important with big box retail, shopping
centres, industrial facilities, airports, maybe hospitals etc. for
shopping centres in Australia with AHUs on the roof, E+, DOE-2.2 and
IES only account for 20-25% of the cool roof benefits via th first
order effects. The second order effects due to the micro climate bias
are 3-4 times what is accounetd for within these programs ...

We haven't been able to get software developers to bring attention to
this so if others can shake the tree it would be good as the
workarounds while?possible are quite involved with a high degree of
uncertainty. There is a paper I wrote for IBPSA BS 2011 I can forward
when I get back from leave in a few weeks for those interested.

Graham Carter

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Link to the paper referred to below:
http://www.ibpsa.org/proceedings/BS2011/P_1927.pdf

Christopher Jones, P.Eng.
Tel: 416.644.4226 ? Toll Free: 1.888.425.7255 x 527

Chris Jones

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Dear Shahryar,

DesignBuilder is a graphical interface to EnergyPlus that can model the thermal performance of a green roof but is not able to model the acoustics. You can easily find more information about DesignBuilder via your favourite search engine or the link in my contact details below.

Regards,

Dave

David Cocking
DesignBuilder Software Limited
+44 (0) 1453 755500
www.designbuilder.co.uk

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Thanks for providing this link to the paper, which I've read with interest. However, I'm
puzzled because my primary concern with respect to modeling green roofs is whether and
how evapotranspiration has been handled and, unless I missed it in my quick read, I don't
see that mentioned in the paper.

In brief, evapotranspiration is the process by which vegetation sheds excessive heat gain
through transpiration, a process akin to sweating in animals for the same reason. When I
had worked with the Urban Heat Island Group at LBNL (before the group got formalized), my
main interest was the effect of vegetation on counteracting the urban heat island, and
very quickly I got enmeshed with evapotranspiration models both at the individual tree
level (too detailed) or at the macro urban level (which I ended up applying in this 1987
paper
(http://journals.ametsoc.org/doi/abs/10.1175/1520-0450%281987%29026%3C1103%3ATPOVIR%3E2.0.CO%3B2
).

In another project that I was then doing on modeling foundation heat flows, I worked with
another researcher at the Univ. of Minnesota who had a foundation model including the heat
balance of the surrounding soil, who told me that he could get any ground surface
temperature he wanted simply by playing around with the evapotranspiration rate (which is
really just the conversion of incoming solar radiation to latent heat).

Since a green roof is basically a shallow slice of ground with vegetation, wouldn't it
make sense to add evapotranspiration to the model (if it doesn't handle it already) before
looking for other explanations why measured and modeled results differ? In my view,
attributing these differences to the urban heat island effect is unsatisfying for these
reasons: (1) it doesn't explain the cause and effect (although i would suspect that it's
precisely the latent cooling of evapotranspiration), (2) it confounds a building-level
strategy with a neighborhood-level phenomenon, i.e., you can be in an urban heat island
(or oasis) without a green roof, as well as having a green roof somewhere with no urban
heat island, (3) I am skeptical that a single green roof would have an appreciable effect
on reducing the air temperature above the roof, unless the air is completely still (see
http://heatisland.lbl.gov/publications/effects-roof-reflectance-air-temperat ).

Joe

White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"

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Reposted with better subject line.

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Hi Joe,

A lot to think about below. In short I hadn't considered evapo
transpiration as we were trying to explain what was being observed for
a change in solar absportance on a metal deck roof?- a cool roof with
a solar absportance of about 0.15 to 0.2 relaive to a more
conventional metal deck roof with probably SA>0.5 allowing for ageing.
A vegetated roof certainly would introduce the issues you refere to
below.

There has been some further research since the 2011 paper which has a
bit more academic rigor (my paper was based on empirical observations
and rough calculations to make a point) and it shows that the bias can
be fairly significant even with a 3-5 m/s wind. The University of
Wollongong had carried out some advanced 3D CFD studies (sponsored by
two companies) to show the bias in above roof temperatures?and roof
surface temperatures (biased by the air temperature above being
higher) can be significant under many conditions.?The bias occurs on
any roof, but for small roofs it is insignificant compared to other
fcators so we ignore it but it acumulates / aggregates to create an
urban heat island. However for larger shopping centre airport, and
industrial roofs the impact can become quite significant (2-5DegC). It
is on roofs such as these that AC energy savings for cool roofs have
been measured to be significant - 4-5 times higher than what typically
gets simulated with a modern energy simulation engine.

With truly green roofs, I agree with you that the benefits are
significant. There is an interesting debate emerging in Australia
whether it is better to cover roofs in photovoltaics or make them
green. I saw something late last year that I think Art Rosenfeld
around whether it was better to make roofs white or green. I didn't
get a chance to revisit it so can't really comment on the artricle /
paper here.

I will try to remember to loop back on this forum / thread when the
research gets into the public realm.

Regards,

Graham

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