[Bldg-sim] Pitched / attic roof membrane

James V. Dirkes II P.E. jvd2pe at tds.net
Sun Sep 14 14:03:53 PDT 2008


Dear List folk,
I recall a post that might have occurred about two - four months ago, in
which someone mentioned a film or membrane that was applied to the pitched
portion of an attic roof.  The film had radiation blocking properties or
something like that (I wasn't interested at the time).
 
If my memory is correct, will someone point me toward that post or a source
which describes that product?
 
Thanks in advance.
 

The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

 

 

  _____  

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Julia Beabout
Sent: Wednesday, September 10, 2008 11:57 AM
To: Paul Riemer; Karen Walkerman; Eric Youngson
Cc: bldg-sim at lists.onebuilding.org; bldg-rate at lists.onebuilding.org
Subject: Re: [Bldg-sim] District Thermal System


Let me reiterate, that I have not submitted my model yet to LEED.  So, I
don't have any feedback from them regarding the validity of my take on
things. 
 
In aswer to your question: Yes and no. :)
 
The way I see things:
 
For Step 1, the DES document talks about using a "market" rate for the DES
utilities.  So, my take on that is that if there is a general prevailing
rate for these utilities in your area, that should be used in Step 1.  Where
as the intent for Step 2 seems to be to use info (i.e. a rate or other
method as discussed below) that reflects your plant's actual efficiency.  
 
In theory, for Step 1, the rate shouldn't matter since it's effect is
neutralized by using it in both the proposed and baseline models.  However,
I'm thinking there may be a situation where if you have a really stellar
(i.e. low CHW, steam, HW rate) or poor (i.e. high CHW, steam, or HW rate)
performing proposed central plant and you use that rate in Step 1 in both
the proposed and baseline models, it may impact your results in Step 1.
Although, again, in theory, it shouldn't matter.  But, as I do more models,
it seems that the relationship between $ saved and the % saved is not linear
- i.e. as you demonstrate more and more savings, it seems easier to get to
the next LEED increment with smaller amounts of deltas - and vice versa
(which to some degree makes sense since dividing by smaller numbers).  But,
I'm thinking this effect could impact your savings in Step 1 and thus your
ability to even get to Step 2.  But, maybe I'm off base here.  I'm
speculating at this point in that regard.
 
That being said, it does seem that the rate you used in Step 1 could be the
same rate used in Step 2 for your proposed building and thus, the
performance shown for the proposed building models on the LEED templates
could be the same in both Steps. 
 
Another idea  I had was that the DES rate could be used to back calculate
the overall COP/efficiency of your plant.  And then use those figures in
your proposed model for Step 2.  It may be easier to adjust those rates for
distribution losses etc.  All this assumes that your DES rate is based on
metered data and actual production costs.  It seems LEED may want some
demonstration of this.  
 
----- Original Message ----
From: Paul Riemer <Paul.Riemer at dunhameng.com>
To: Julia Beabout <juliabeabout at yahoo.com>; Karen Walkerman
<kwalkerman at gmail.com>; Eric Youngson <ericy at pae-engineers.com>
Cc: "bldg-sim at lists.onebuilding.org" <bldg-sim at lists.onebuilding.org>;
"bldg-rate at lists.onebuilding.org" <bldg-rate at lists.onebuilding.org>
Sent: Wednesday, September 10, 2008 11:07:16 AM
Subject: RE: [Bldg-sim] District Thermal System


Julia,
 
Thank you for your comments.  Please allow me to ask a bit more.
 
Are you stating that Table 1.8.2(b) at the bottom of your Step 2 EAc1
template will have an energy type line item of "hot water", "steam", or
"chilled water"?  If so, will the numeric energy use value (e.g. 1,234 MBtu)
be exactly the same as in Step 1's EAc1 template?  Meaning the only
differences between the proposed columns of the two submittal templates will
be the dollar costs of the DES energy stream and total costs?
 
Paul Riemer


  _____  

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Julia Beabout
Sent: Wednesday, September 10, 2008 9:32 AM
To: Karen Walkerman; Eric Youngson
Cc: bldg-sim at lists.onebuilding.org; bldg-rate at lists.onebuilding.org
Subject: Re: [Bldg-sim] District Thermal System


I just finished my first DES project (not submitted yet, though) and have a
couple more in the works.  
 
I agree with the interpretations below especially with respect to Step 2 and
the utilization of the DES purchased rates as an acceptable means of
reflecting the prposed/actual central plant's efficiency in the proposed
energy model.  Although, the DES purchased rates should reflect/be adjusted
for the items Karen mentions.  Additionally, I'd recommend confirming that
the DES rate includes all the central plant's bits and pieces.  The
maintenance costs should also be extracted from the DES rate if possible.
(The DES document seems to clarify that the maintenance costs do not need to
be included.  So, if those can be extracted that will be more of an apples
to apples comparison with the baseline model and work in your proposed
model's favor).  
 
In my estimation, the above method provides the most expedient, realistic
and accurate method of determining the central plant's efficiency.  The
trick is that that info is not always available - especially in a campus
situation.  So, in that case you may need to use one of the other methods of
modeling the central plant discussed in the DES document: other metering
data, modeling of the central plant equipment, etc.  However, sometimes even
this data can be hard to come by and/or is not within the project's ability
or budget to determine or model.  So, in that type of situation, the default
central plant efficiency values provided in the DES document could be used.

 
 
 

----- Original Message ----
From: Karen Walkerman <kwalkerman at gmail.com>
To: Eric Youngson <ericy at pae-engineers.com>
Cc: bldg-sim at lists.onebuilding.org; bldg-rate at lists.onebuilding.org
Sent: Tuesday, September 9, 2008 3:08:28 PM
Subject: Re: [Bldg-sim] District Thermal System


I am also in the middle of a DES project at the moment.  The way that I
interpreted Step 1 and 2 is as follows:

Step 1:

Baseline: all downstream (on-site) equipment, envelope components, etc, as
in Appendix G.  heating and cooling is purchased from a DES system.
Proposed: all downstream (on-site) equipment, envelope components, etc, as
designed.  Heating and cooling is purchased from a DES system.

Step 2:

Baseline: all equipment is modeled as on-site.  Boilers and Chillers are to
be modeled as designed in Appendix G.  Utility rates are to be local utility
rates
Proposed: building is to be modeled as built.  Heating and cooling is
purchased from a DES system, energy costs must take into account DES
production and transmission losses.

In my opinion, the vocabulary in Table 1 is confusing, but the guidelines on
pages 5 and 6 seem pretty clear.  Am I on the same page as everyone else
here?

Thanks,

--
Karen



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