Dynamic model compliance analysis results

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I made model using eQuest 3.65 and after simulation, baseline building
generation and results compliance I see 55 % percent improvement in
proposed design against the baseline design.
This model is just schematic for CS precertification but the envelope is
modeled with most probably final design that will be built. The envelope
is kind of a modular system with overall U factor 0,14BTU
/ft2/hr*F per modul (it
means both glass a wall parts).

My question - is it possible to get 55 % improvement against the
baseline with this U factor? I checked, that LEED requirements is Umax
0,513, so our value is very good compared to this requirements. However
compared to our local norms (Czech republic) it is not anything extra,
so the 55 % percent improvement surprised me.
In HVAC system I used everywhere standard efficiencies of motorts, pumps
etc. and VSD regulation, but this I think doesn?t have as large impact
on the result as the envelope - or does it have?

Thanks a lot for all thoughs and answers.


Frantisek Bartos's picture
Joined: 2013-11-14
Reputation: 4


I think you are wise to question your result and investigate whether or not
it is reasonable or even possible to save 55% based primarily on envelope
measures. I'll describe the type of 'sanity check' process I might follow
in assessing whether or not the results make sense:

One way to look at this is to consider how the whole building baseline
energy consumption breaks down by end use. What percentage is due to
lights, plug loads, heating, cooling, fans, etc. I would assign a
percentage to each of these end uses based on your baseline model results.
Then consider which end uses can be affected by the envelope, and which
cannot. Without more information, I might assume that lighting energy, plug
load energy, process load energy, and service hot water would be completely
unaffected by envelope characteristics. This means that your whole building
savings would be coming only from HVAC energy. Now consider that the
heating and cooling of ventilation air is completely unaffected by the
envelope as well, so only a portion of the HVAC usage can be conserved
through envelope measures. Next I would compare the percentage of whole
building energy allocated to HVAC with the percent savings you are seeing,
and evaluate for yourself whether or not everything looks reasonable.

For example, if your whole building energy from HVAC is, say, 50% of your
whole building baseline energy consumption, then it would be impossible to
save 55% of whole building energy from HVAC savings, even if you completely
removed the HVAC systems from the building.

The take away is that in order for envelope improvements to save 55% of
whole building energy, the building would need to consume very little
lighting, plug load, process, and SHW energy relative to heating and cooling
energy, and would have to be minimally ventilated. The only building types
I can think of that could potentially fit this bill are conditioned storage
buildings or possibly a residence. 55% savings for a typical office
building due to envelope measures alone seems highly unlikely.

One more note: Whether you are looking at energy savings or dollar savings
can make a significant difference, depending on fuel sources and prices for

I'm not sure this fully addresses your question, but hopefully it is a
little helpful.


Christian Kaltreider, LEED AP 

Christian Kaltreider's picture
Joined: 2011-09-30
Reputation: 1