[Bldg-sim] Right sizing of equipment aka sleeping giant

[Glen Anderson]

Taking this discussion back to energy simulation and its impact on
design.  Over-sizing systematically occurs but from an energy
perspective it is not always bad.  One of our jobs as energy modelers is
to identify the impacts of over-sizing and to drive the design to
maximum annual efficiency.   So if the designer is going to oversize the
pump, we need to try and quantify the savings potential of including a
VFD for balancing instead of using throttling valves.  If the designer
is going to oversize the boiler, we need to justify to the owner the
incremental costs for purchasing the most efficient boiler setup, which
could be a boiler with a high turndown ratio and oxygen trim controls or
multiple smaller boilers.

 

Also, we may want equipment/systems to be oversized in some situations.
Our job as modelers is to quantify the energy impacts of design
decisions, which may include over-sizing.  And what does over-sizing
always mean?  Should pipes be sized for 1, 2 or 3ft loss/100 ft, should
ducts be sized for , .1, .2, or .3 ft loss/100 ft, should air handler
coils be sized for 200 fpm or 400 fpm?  

 

Yes over-sizing costs money to the owner up front, but when designed,
installed, and operated correctly - in some situations over-sizing can
be the most efficient design with the most attractive life cycle cost. 

 

Glen R Anderson, PE

(801) 278-1927

Cell (801) 244-7654

1997 S 1100 E Suite 201

Salt Lake City, UT 84106

 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Acker, Brad
Sent: Tuesday, May 25, 2010 2:26 PM
To: eQUEST Users List; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Right sizing of equipment aka sleeping giant

 

I think this is a wonderful time to be in the HVAC industry. New tools
are changing the outdated, over simplified tools and methods used in the
past (and present). I would like to make one comment on the below
message. The sentence "Building occupants are intolerant of too hot and
too cold."  This is one good example of the changing attitudes in the
building industry. Resent research suggest that this sentence should
really read " Building occupants with no control over their environment
are intolerant to too hot or too cold".  When occupants know they can
control their environment (maybe with a window) they will dress
accordingly and expand their comfort zone. 

On a "right sizing" note, I do believe if owners would like to get
aggressive and truly right size equipment they will also need to
shoulder the possible risks, i.e. 10 or 20 hours out of the year you may
not be able to keep  your cooling set point. Its energy modeling that
will quantity these risks and size these systems, not a side ruler and a
design day (hour).

 

This exchange has been a nice change of pace from locating weather
files. It's very interesting to learn other current points of view in
our industry,

 

Best Regards,

 

Brad Acker, P.E.

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Carol
Gardner
Sent: Monday, May 24, 2010 12:07 PM
To: eQUEST Users List; bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Right sizing of equipment aka sleeping giant

 

All,

Should always be the goal but it is soooo hard to define. I have worked
on tiny commercial buildings as well as huge commercial buildings. All
types. Right sizing is always my goal and as far as I know is always the
goal of the ME's. It was mine when I did HVAC design work. Building
occupants are intolerant of too hot and too cold. And, in a building of
any size with more than one person in it you will find disagreement
about whether it is too hot or too cold at least some of the time. So
what do you do? Especially if you are just the hapless, overworked,
under paid energy modeler? You can see my project list if you want to.
If you listen closely you will hear whatever opinion you want to hear
about me and my work. Thank god for VFDs, VRVs and EC motors, eh?

-- 
Carol Gardner PE

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