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Re: [EnergyPlus_Support] Transient simulation of building structure and indoor air
I don't know about the weather file utility program problem.
You probably can't get the detailed wall information that you are seeking with Energy+ because the code uses transfer equations for the wall assembly rather than a full wall section simulation program such as WUFI 3.3
I am also sometimes more interested in the detailed dynamics of the wall systems. I have considered modeling buildings with Energy+ to generate boundary conditions for input into WUFI analysis of the wall systems. Energy+ probably does a reasonable job of estimating actual interior air conditions, but I also believe that you would have to trust that the code for moisture absorption of interior and exterior walls is accurate. The problem is that the interior conditions are affected by the dynamic of the moisture storage of the wall assemblies. So we have Energy+ analysis that attempts to account for these dynamics in predicting air conditions while not detailing wall response and WUFI 3.3 that tells us in detail what happens in the wall with no ability to interact with boundary conditions. The WUFI creators are considering a next generation WUFI program that reacts with interior climate, but I don't expect it to be any time soon or to be as flexible at modeling mechanical system dynamics as Energy+.
There are some free down loads available for WUFI, but you will have to buy a professional version in order to manipulate the input filles fully enough to try using Energy+ output as WUFI input.
I am also not sure that detailed wall analysis will give you what you are looking for. I suspect that you looking at the temperature swings or detailed energy use will be the yardstick to use. Try something simple like a massive wall with insulation outboard in on case and insulation inboard in another or the same insulation and no mass. The differences you see in interior temperatures or energy use are reflective of the wall construction differences.
Please note a common mistake I find in the field practice, setback temperatures and large thermal mass buildings. If you want consistent comfort in large mass buildings, simple setback temperature control is not likely to get you there. Such designs are often heating or cooling against the mass and unable to provide proper comfort during much of the occupancy period. There is probably real energy savings with setbacks in low mass or high loss construction. Also be aware that ventilation air is usually the bigger energy user in commercial construction
Ned Lyon
Senior Staff Engineer
Simpson Gumpertz & Heger Inc.
41 Seyon Street
Building #1, Suite 500
Waltham, MA 02453
Phone: 781-907-9000
Fax: 781-907-9009
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