[Bldg-sim] [Spam:*****] Energy needs at an early design stage

Dennis Knight dknight at wholebuildingsystems.com
Fri Oct 25 06:57:50 PDT 2013


Jens,
Target Finder and Portfolio manager are great tools with a rich set of data
behind them.  Bear in mind that they are based on statistical analysis of
2003 CBECS reference data and are going to return total annual numbers -
not something like monthly consumption and peak demand. Those tools do not
make assumptions about occupancy, schedules, equipment, etc.  They also do
not make any assumptions about the activities that may be present in your
design or proposed building.  The tools normalize the data from their
reference database based on your design inputs to generate a median EUI and
either a score or target EUI for your building or proposed design.  We've
done some modeling of about half of the DOE reference buildings in all 16
climate zones to see if a model can be tuned/calibrated to mimic the output
from Target Finder and Portfolio Manager for a median building.  Since
occupancy, schedule, activity, fuel mix, climate zone, ventilation,
envelope characteristics all have an impact you can chase your tail for a
long time trying to get a precise match.  We've also done some sensitivity
analysis on those variables across climate zones. Depending on climate
zone, any one of those variable can swing the numbers significantly off the
median.  Then there is the issue of site versus source EUI's.  In some of
our analysis the numbers for some buildings and climate zones correlate
closely with site numbers and in others with the source EUI numbers.  If
you are wanting to provide your client with at least high level decision
making information on total energy annual consumption and maximum peak
demand for all your fuel sources I think you still need a baseline model.
 That model can be as simple as four walls, a roof, some basic schedules
and setpoints.  Most of the tools allow you to set that up fairly quickly.
 The difficulty I've noted on a previous post to this question is that
often this early stage model is not able to evolve into a design phase
model without significant modification and it is often just as easy to
create a new design level model.
Dennis



On Thu, Oct 24, 2013 at 12:53 PM, Samuelson, Holly Wasilowski <
hsamuelson at gsd.harvard.edu> wrote:

>  Dear Jens,
> Another idea may be to use benchmark data rather than simulation if you
> can find an appropriate database.  There is the Energy Star Target finder
>
> http://www.energystar.gov/buildings/service-providers/design/step-step-process/evaluate-target/epa%E2%80%99s-target-finder-calculator
>
> and the DOE Building Performance Database
> https://bpd.lbl.gov/
>
> These are US-based, so I'm not sure if they would be appropriate for your
> building in the Netherlands.
> Best,
> Holly
>
> Holly W. Samuelson
>  DDes | Registered Architect | LEED AP+
> Assistant Professor Harvard Graduate School of Design
>    ------------------------------
> *From:* Wagemakers, Jens (2034464) [2034464wagemakers at zuyd.nl]
> *Sent:* Wednesday, October 23, 2013 6:23 AM
> *To:* bldg-sim at lists.onebuilding.org
> *Subject:* [Bldg-sim] [Spam:*****] Energy needs at an early design stage
>
>   Dear all,
>
> Does anyone of you know a software program which I can use to calculate
> the energy needs of a building (installed power) at an early stage
> (design). With the usual programs like EnergyPlus or Trnsys you need to
> insert a lot of parameters to get the information, parameters which  just
> aren’t allways available in the design stage.
> The calculations don’t have to be very precise, I’m looking for a tool
> which can give an acceptable result, so we can give our customer an idea of
> how much power is needed for a certain building.
>
>
>
> Greatfully,
>
> Jens Wagemakers (The Netherlands)
>
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-- 
M. Dennis Knight, P.E., FASHRAE
Founder & CEO
*W*hole *B*uilding *S*ystems, LLC
P.O. Box 1845
Mt. Pleasant, SC 29465
Phone: 843-437-3647
Email: dknight at wholebuildingsystems.com
Website: www.wholebuildingsystems.com
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