Hello!

There is a good reason people don't use spreadsheet analyses very much
anymore for building modeling. I used bin models for many years to
estimate HVAC energy use and kept improving my technique until I arrived at
what was dubbed the Osama bin Model approach. In the end, I ditched this
to learn how to do things right in eQuest.

What was the big lesson? Bin models at best are big sloppy averaging
exercises that use first principals (read: "easy math") to determine
operation at any one point in time. This is cool for ventilation
calculations where the loads are instantaneous and related directly to
ambient conditions, but definitely not a good way to model the impacts of
anything that has time lags/delayed responses. How do you estimate the
benefit of commercial building envelope upgrades? Most savings arise
during unoccupied periods, primarily from reduced cycling of fans, pumps,
cooling systems, and boilers. Sure there are reduced heating/cooling
loads, but how do you estimate the heat loss when you can't estimate what
the average interior temperature is going to be?

Yeah, spreadsheet calcs definitely have their place and I still do use
them. I have found that eQuest is a whole lot faster and more accurate
than the ol' Osama bin Model when doing whole-building analyses.

Eric Studer, PE

FROM: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] ON BEHALF OF Daniel
Croisant
SENT: Monday, February 22, 2010 4:50 PM
TO: bldg-sim at lists.onebuilding.org
SUBJECT: [Bldg-sim] Estimating Energy Consumption Using Spreadsheets

Hello,

I?ve ?grown-up? in the time when energy modeling programs always existed.
I?m curious if anyone that has been in the business for awhile has any
experience using spreadsheets to estimate a building?s energy consumption,
and if so, would you be so kind as to share them with me? I?m not looking
to use it on any projects and would not try to hold anyone liable for any
results. I?m just curious as to how people tackled the issue of estimating
energy usage, other than degree days, before the popularization of DOE and
other energy modeling programs. Plus I think it would just be fun to play
around with what other people have used.

Thank you in advance,

DAN CROISANT