I am the Chair of the conference committee for the ASHRAE 2012 Energy
Modeling Conference that will be held in Atlanta on October 1, 2 & 3 this
year (see link below). The conference is focused on bringing
practitioners, software developers, researchers and facility users together
for 3 days of in depth discussion on current modeling software capabilities
and current best practices in energy modeling. I have two questions that I
would like to pose to this group to get some feedback to help provider
richer content for the discussions planned at the conference;
1. Are the current energy modeling tools available to an energy modeling
practitioner reliable enough to allow the modeler to predict a building's
actual energy consumption with a high degree of confidence such that an
accurate energy target can be established and recommended to the building
owner for the new building or a renovation/retrofit?
2. Are the current best practices of the energy modeling community reliable
enough, and well understood by most practitioners, to allow the modeler to
predict a building's actual energy consumption with a high degree of
confidence such that an accurate energy target can be established and
recommended to the building owner for the new building or a
renovation/retrofit?

Background for the discussion:
These questions recently came up in a discussion among the conference
committee. It seems that one our colleagues from the UK indicated that in
the UK new schools have performed very poorly in comparison with their
predicted energy use.

Another comment that was made was as follows:
"Often a building's actual energy consumption is 1.5 to 2 times as much as
the results of an energy model that was used to make decisions during
design about the building's energy using systems. Is it the the energy
modeling tools or is it the processes used by energy modelers to describe
the systems and how they operate in the software? Should energy models be
used to "predict" a building's future energy performance or just be used to
inform better decisions during design?

I have reviewed a good many models and, almost without fail, I never see a
modeler start by writing a sequence of operation and I also never see the
sequence of operation used by the modeler make its way into a set of
construction documents.

Also, when I am the modeler and I am "calibrating" a model to an existing
building's actual energy consumption it is a very iterative process. I
know what things to manipulate in the model to effect demand and what
things to manipulate to effect consumption. I just keep going back and
forth until I have a model that you can almost lay its output on top of the
building's utility bill history. I also have a good understanding of how
the building is actually being operated and maintained - which I hope helps
make the model more accurate, but, does that process really give me a
better model to make decisions from?"

I invite everyone to please, tell us what you think.
Sincerely,

Link to conference webpage:
http://www.ashrae.org/membership--conferences/conferences/ashrae-conferences/emc2012

--
M. Dennis Knight, P.E.