[Bldg-sim] Modelling 90.1 Baseline Envelope for Existing + Additions

Maria Karpman maria.karpman at karpmanconsulting.net
Tue Nov 5 06:45:51 PST 2013


Santiago,

 

I would reach out to the reviewer and argue that your original
interpretation is correct. Appendix G Table 3.1.5 f that you quoted below
clearly suggests that the baseline building design for renovation projects
shall reflect existing conditions prior to any revisions. The section covers
all aspects of envelope including thermal and solar properties, assembly
type, and surface area, so there is no indication that the "existing
conditions" mentioned in 3.1.5 f exclude fenestration / skylight area. I
don't see why this rule should be void for projects that include both
renovation and addition. Section G1.3 is also relevant: G1.3 Trade-Off
Limits. When the proposed modifications apply to less than the whole
building, only parameters related to the systems to be modified shall be
allowed to vary. Parameters relating to unmodified existing conditions or to
future building components shall be identical for determining both the
baseline building performance and the proposed building performance. Since
the window/skylight area is not modified, it should produce neither penalty
nor credit for the proposed design. 

 

Maria 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Santiago Velez
Sent: Monday, November 04, 2013 7:16 PM
To: Nick Caton
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Modelling 90.1 Baseline Envelope for Existing +
Additions

 

PS. : My interpretation was mostly based on Appendix G Table 3.1.5 f)
"Existing Buildings. For existing building envelopes, the baseline building
design shall reflect existing conditions prior to any revisions that are
part of the scope of work being evaluated."

 

 

 

2013/11/4 Santiago Velez <santiagogvelez at gmail.com>

Nick, thanks for the response. The answer is yes, I'am trying to make a case
for exceeding the 5% threshold for existing bit of the project, which is not
modified.

The project is a big existing conditioned warehouse, with lots of skylights
(18% of roof area), the new bit is an office building, with more skylights
(properly shaded this time!). I thought it would be fare to have a baseline
which maintains the existing bit exactly the same (18% skylights), and the
new addition according to Table G3.1.5 (5%). The global skylight area for
the whole project is 12%, and this was reviewed. 

The opposite happens for vertical fenestration, warehouse has almost no
windows, and the new office is fully glazed. With the same criteria,
existing stays the same, new is 40% max; then the proposed ends up with
global 32% WWR and baseline only 28%. This was reviewed as well.  Am I
explaining my self?

 

I thought this would be fair, and in fact it made so much sense I thought it
was the only possible interpretation... Its very good to remember one an be
very wrong.

 

So my approach should be: 

- For vertical fenestration, 32% both baseline and proposed. 

- For the skylights, I would multiple every skylight by  5/12 to get a
global 5% skylight. 

 

 Hmmm....energy savings are going to plummet. 

Thank you again Nick.

 

Santiago.

 

2013/11/4 Nick Caton <ncaton at smithboucher.com>

Proposed and Baseline areas/layouts matching works perfectly until you
exceed either 40% for vertical or 5% for skylights.  See Table G3.1.5,
baseline items c. and d.  This might be coincidence, but just to be cover
all bases: 28% + 12% = 40% is an incorrect reading - the skylight and
vertical fenestration thresholds are independent.

 

I think you are to leave the vertical fenestrations alone (being under the
40% threshold) and you need to proportionally lower the area of the
skylights in the baseline model to get back to 5%.  Proposed model needs to
match actual design so it's skylights remain the same.

 

I'm not certain how or if the project being a major renovation has any
bearing on the matter.  

 

Are you making the case that the existing skylights are envelope components
not being touched, and so should remain equal in area between the models
despite exceeding the 5% threshold?  Do you have additional new skylights
complicating the matter? 

 

~Nick

 

 

NICK CATON, P.E.

SENIOR ENGINEER

 

Smith & Boucher Engineers

25501 west valley parkway, suite 200

olathe, ks 66061

direct 913.344.0036

fax 913.345.0617

 <http://www.smithboucher.com> www.smithboucher.com 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Santiago Velez
Sent: Monday, November 04, 2013 3:20 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Modelling 90.1 Baseline Envelope for Existing +
Additions

 


Dear forum users, I have modelled a project following Appendix G. and have
received a review regarding my interpretation of % glazed area on the
baseline.


The project is a mayor renovations + Additions (existing conditioned
warehouse + New office building attached). There were no modification on %
area of vertical and horizontal glazing on the existing bit of the building.

My approach was to model existing envelope, shape and fenestration, exactly
the same in both proposed and baseline. The addition was modelled following
the "maximum 40% for vertical fenestration and 5% for skylight" rule. The
result of the whole building for baseline is, 28% vertically glazed and 12%
of skylights (the existing bit was very different than 40%, and 5%
respectively)
The reviewer states that the end result for the baseline should still be 40%
and 5%. It is not very clear to me how would I get there.. Do I have to make
the existing fenestration proportionally smaller, just like I would do for
the baseline of a completely new building?

Thanks in advance.

Santiago.

 

 

 

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