330kV x 20mA = 6600W Those used by dentist is only about 600W.
My comment was general, and did not occurred to me that X-ray equipment needed a special treatment for heating load.
==========================
Now that I understand that you were just thinking aloud, the topics raised are relevant in simulation, but are not what can be discussed in detail in this forum as one topic.
You are right that new and old buildings may require different approach in simulation.
For energy saving research, they are the same. Type of HVAC equipment used is not an issue.
====================
By the way all those users who are worrying about un-met setpoints do not realize that they themselves generated these warnings.
In the 5 zone example, the five VAV dampersare individually controlled by five zone thermostat, and one AHU ref. set point, how do you expect all the five zones to be in sync with the 5 zone thermostat values, while the damps are moving.
I kept saying that such a system does not exist in general, and all beginners are using them without reheat.
The old master slave zones theremostat simulation do not care about these small differences in temperature values.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Date: Mon, 7 Nov 2011 17:38:55 -0500
Subject: RE: [EnergyPlus_Support] Energy Models for existing buildings
Expanding a bit on my earlier post:
I know it can be done (model an existing building) with most currently available software. I have prepared energy models for existing buildings using EnergyPlus that matched the utility bills within 1% for annual consumption and with >80% R-squared correlation for the month-to-month energy.
That was not easy, however, and I spent way too much time getting those results! I spent a lot of time detailing certain aspects that I later decided were not important enough to merit that time. It also required a different perspective than is common for new building modeling; you can make a lot of assumptions for a new building model that will be completely wrong for an existing building.
There is precious little on the Web / Google about the ?big picture? process of modeling an existing building. I suspect that this is because 95% of energy modeler?s attention in recent years has been directed to new buildings for LEED certification.
Nonetheless, I know many of you modelers have worked on existing buildings for energy audits and have developed a plan and procedures for doing this efficiently in a manner that assures reliable estimates of savings for your clients who are spending real dollars based on your predictions.
Still hoping to hear from more of you!
p.s., to Dr. Li, I used an Xray machine as an example of a non-typical, potentially high energy using equipment that does not fit typical power usage profiles.
The Building Performance Team
James V. Dirkes II, P.E., BEMP , LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of YuanLu Li
Sent: Monday, November 07, 2011 4:39 PM
To: EnergyPlus_Support
Subject: RE: [EnergyPlus_Support] Energy Models for existing buildings
Employ someone to do it for you. Using any software. Wish you the best.
======================
All can be done using EPlus, as far as I know. If an item is not available, a module can be written to cover your need.
===================
X-ray? No problem. I have worked with X-ray equipment up to 330KV. How do you want to simulate it? Direct viewing, with intensifier? film? CCD camera? or for tissue burning? Not kidding. or just kidding?
====================
Past papers? Ask Google.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Date: Mon, 7 Nov 2011 15:48:43 +0000
Subject: [EnergyPlus_Support] Energy Models for existing buildings
Dear Forum,
I am soliciting input from you regarding your experience in using full, 8760 hour energy models for energy audits of existing buildings. I have used EnergyPlus for a few of these and am starting to get an opinon about what is important for an existing building energy model. I am convinced that the rules are different than for a new building, but would like to know what your experience has been.
My primary interest is the "big picture" factors, not so much the fine details. I have made an outline of factors and considerations below and will appreciate your feedback and comments as you are able!
p.s., I suspect that I am not the first to ask this question! If you are aware of past conferences or papers, please point me in the right direction.
Energy Audits Which Utilize an Energy Model
Factors which imply the need for an energy model
? Multi-use (different schedules for portions of the building)
? Radically different construction types in different portions of the building
o e.g., lightweight construction added to massive construction, high % glazing added to low % glazing
? Multiple air handlers of different types
o E.g., RTUs for one portion, baseboard heating only for another portion
? Anticipation of changing to one of the above
? Other???
What is the minimum data needed for a defensible / reliable energy model?
? Correct total wall area plus window area by elevation?
o With low regard for a perfect match to actual geometry
? Schedules of operation?
? Motor power for fans, pumps?
? Air and water flow for fans and pumps?
? Special uses?
o Pool
o Assembly
o Specialized equipment such as servers, X-ray
? Plug loads?
? Outdoor air flow?
? Lighting loads in W/sq.f.t? W / zone or room?
? Exterior lighting?
? Temperature / humidity setpoints?
? Air handler control setpoints?
o Which ones?
? Shading elements?
What method should be used for evaluating hard-to-measure data such as actual lighting and plug load use, outdoor air flow, heating / cooling system efficiency at part loads, infiltration, insulation (especially for old buildings with no construction drawings), process power
? Trial & error? Using user-imposed restraints?
? Benchmark or past project data?
? ???
How closely must the energy model match past energy use?
? Match annual consumption +-10%? >75% R2 month-by-month?
? Is actual weather data important? (vs. TMY / "typical")
? ???
How carefully must the energy model match define ECMs?
? Annual? Peak? Efficiency of new components
? Generic or manufacturer-specific performance data?
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