Unmet Hours - RSS feedhttps://unmethours.com/questions/Question-and-Answer Resource for the Building Energy Modeling CommunityenThu, 05 Aug 2021 10:28:09 -0500Can doe-2 weighting factors be output in hourly report?https://unmethours.com/question/58333/can-doe-2-weighting-factors-be-output-in-hourly-report/I'm using the custom weighting factor method for internal mass and I've assigned a different weighting factor to each space (Weighting Factor 1 to first floor, Weighting Factor 2 to second floor, etc.). Is there a way I can find out what these weighting factors are? For example, I have no idea what Weighting Factor 1 is/means.ebs8Thu, 05 Aug 2021 10:28:09 -0500https://unmethours.com/question/58333/Dynamic internal mass in warehouse with EnergyPlushttps://unmethours.com/question/42662/dynamic-internal-mass-in-warehouse-with-energyplus/Dear forum,
In the context of a warehouse simulation with EnergyPlus, I would like to take into account the flow of products (massive amounts of wood), which come in at the same temperature all year round, whereas the warehouse air temperature can vary widely (between ~5 and 25 °C). I am interested in air temperature, but also wood temperature. At present, wood is modeled as InternalMass.
- The first possibility that comes to my mind is to model the flow of wood as an internal heating or cooling load, as in [this topic](https://unmethours.com/question/22750/warehouse-incoming-mass-becomes-a-heating-cooling-load/), using OtherEquipment and some schedule or EMS script. However, the load would be provided directly to the zone, rather than to the wood.
- Would there be a way to model the effect for wood temperature more accurately?
- Could for instance Construction:InternalSource be used in combination with InternalMass?
- Would it be a viable approach to use a "zone in the zone" to model these wood products?
- Or do you have any other idea on how to model this?aubrWed, 05 Feb 2020 09:56:57 -0600https://unmethours.com/question/42662/Modeling zone internal air mass load in internal masshttps://unmethours.com/question/48996/modeling-zone-internal-air-mass-load-in-internal-mass/How do you model the load effects of a zones internal air mass? I would like the "Convection Heat Gain Rate" of the air mass within the zone. Is this done in the internal mass class like the physical internal mass objects?
To model furnishings and partitions in internal mass, you create an object in the internal mass class where the construction type is furnishings and partitions. How is this done for the air in the zone? mademarcWed, 18 Nov 2020 12:24:39 -0600https://unmethours.com/question/48996/estimating thermal mass with Hybrid Model?https://unmethours.com/question/43564/estimating-thermal-mass-with-hybrid-model/ Hello everybody,
I have added the Hybrid Model object in order to determine the temperature capacitance multiplier which would make my simulation results closer to my measured data. I needed to adjust thermal mass of my model without using the object ThermalMass. I entered the measured room temperature as a Schedule txt file, as required by the hybrid model, and after running the simulation the results look great but I wasn't able to find the temperature capacity multiplier determined by the hybrid model which would give me those results. Does anybody know where I can find this value in my output files/tables? I looked everywhere but I wasn't able to find it.
Thank you in advance for your help.
Cheers, JuanitaJuanita SolanoTue, 31 Mar 2020 05:19:22 -0500https://unmethours.com/question/43564/estimating thermal mass with Hybrid Modelhttps://unmethours.com/question/42915/estimating-thermal-mass-with-hybrid-model/ Hello everybody,
I have added the Hybrid Model object in order to determine the temperature capacitance multiplier which would make my simulation results closer to my measured data. I needed to adjust thermal mass of my model without using the object ThermalMass. I entered the measured room temperature as a Schedule txt file, as required by the hybrid model, and after running the simulation the results look great but I wasn't able to find the temperature capacity multiplier determined by the hybrid model which would give me those results. Does anybody know where I can find this value in my output files/tables? I looked everywhere but I wasn't able to find it.
Thank you in advance for your help.
Cheers,
Juanita Juanita SolanoWed, 19 Feb 2020 04:41:47 -0600https://unmethours.com/question/42915/energyplus source code outputhttps://unmethours.com/question/42479/energyplus-source-code-output/I tested example file [HybridZoneModel.idf](https://github.com/NREL/EnergyPlus/blob/develop/testfiles/HybridZoneModel.idf) and see that there is not available output for ***Calculate Zone Internal Thermal Mass*** option. Checking source code [ZoneTempPredictorCorrector.cc#L5900](https://github.com/NREL/EnergyPlus/blob/3b407c42c1dec0085df88db513884f14c79eaa48/src/EnergyPlus/ZoneTempPredictorCorrector.cc#L5900), I found time step output ***ZoneVolCapMultpSensHM*** [ZoneTempPredictorCorrector.cc#L5946](https://github.com/NREL/EnergyPlus/blob/3b407c42c1dec0085df88db513884f14c79eaa48/src/EnergyPlus/ZoneTempPredictorCorrector.cc#L5946) inside **InverseModelTemperature** function for **Internal Thermal Mass** option while ***HybridModel.unit.cc*** also test this properties for **Hybrid model internal thermal mass (free-floating)** testcase [HybridModel.unit.cc#L287](https://github.com/NREL/EnergyPlus/blob/3b407c42c1dec0085df88db513884f14c79eaa48/tst/EnergyPlus/unit/HybridModel.unit.cc#L287). I wonder if there is any way to get such output in output of EP run or I should build EP source code to get it for such case?
**Update: How about the plan of zone Hybrid object development ? - EP documentation seem not update-to-date for this object**ngkhanhSun, 26 Jan 2020 00:34:49 -0600https://unmethours.com/question/42479/Internal Mass - Surface Areahttps://unmethours.com/question/42257/internal-mass-surface-area/ Hi,
I am using e+ to model building energy use. One of the input parameters of "Internal Mass" is surface area. Since my research is at urban scale, I am dealing with hundreds of buildings so calculating the surface area of internal mass for each zone is very difficult. Does anyone know a simplified procedure to estimate surface area of the internal mass (floor wall, etc.)? Can e+ autocalculate surface area of walls, windows, and floors?
I really appreciate your help.
RezvanTue, 14 Jan 2020 16:29:22 -0600https://unmethours.com/question/42257/How does EnergyPlus parameterize internal mass?https://unmethours.com/question/40116/how-does-energyplus-parameterize-internal-mass/I would like to know how to parameterize internal mass in EnergyPlus. ie. the internal mass of furnishings, internal partitions, occupancy, etc.mademarcWed, 28 Aug 2019 10:51:18 -0500https://unmethours.com/question/40116/Indoor air to structure heat exchangehttps://unmethours.com/question/20954/indoor-air-to-structure-heat-exchange/I have been trying to find the link to online E+ directory explaining E+ calculations on structural mass energy interchange with the space, could anybody please point me to it? Trying to find the E+ algorithms/calculations on how on hot summer days higher internal air temperature is soaked up by cooler exposed concrete structure.MroyFri, 04 Nov 2016 05:13:13 -0500https://unmethours.com/question/20954/Thickness of internal mass materialhttps://unmethours.com/question/31158/thickness-of-internal-mass-material/ Hi everyone
I have a rather simple question, but I haven't been able find the right answer yet. I am doing some research on internal thermal mass and would be using the "InternalMass" section in EnergyPlus.
In the 'engineering reference' I found that for internal mass object that "if both faces are within the zone, this situation can be modeled either by creating another internal mass surface with the reverse construction, or, for symmetric constructions, simply doubling the area of the surface." (3.7 Adiabatic Boundary Conditions)
My question now is, which thickness do I use when such an object has its both faces within the zone? When doubling the area of the surface, do I use the full thickness or only half of the thickness? arnodielsSun, 29 Apr 2018 08:12:27 -0500https://unmethours.com/question/31158/Defining internal objects in EnergyPlushttps://unmethours.com/question/23174/defining-internal-objects-in-energyplus/ Dear All!
I intend to define an internal object (solid material) inside the building to evaluate the impact of thermal inertia for different materials, but Sketchup and EnergyPlus only allow me to define specific types of surfaces (roof, floor, wall) or subsurfaces (windows, doors, etc.). Would you please help me with that? Thanks a lot!
PouyaTue, 07 Mar 2017 10:31:47 -0600https://unmethours.com/question/23174/Warehouse incoming mass becomes a heating / cooling loadhttps://unmethours.com/question/22750/warehouse-incoming-mass-becomes-a-heating-cooling-load/Dear forum,
I've recently refined my approach to making an energy model reflect the HVAC loads caused by incoming products to a warehouse, and would love feedback regarding whether I have covered the key aspects. This is a topic which I have not seen addressed in forums or elsewhere, but it seems significant for certain buildings.
One the one hand, this took a while to figure out and create. On the other hand, I think it can be replicated very quickly and adds more depth to models which have lots of incoming material.
Background: Some warehouses receive tons of product each day from delivery vehicles like semi-trailers. The contents of the trailers are generally at the same temperature as the outdoors and so impose a heating load on the building in the winter and cooling load in the summer. I'm not always sure if the load is worth modeling, but wanted to make a fast way to include that load. Here's what I have done so far:
1. Find out or make assumptions about the rate at which material arrives, resulting in somethng like:
![image description](/upfiles/14870853315172847.png)
2. Quantify that as a peak load on a Winter DesignDay (lower right of the image below)
3. If the product moves from one zone to another, (e.g., receiving dock to storage), determine how long it stays in the first zone and assign a fraction of the total load to the time it spends in each zone. (the chart below uses a simple quadratic formula to portion the load to each hour)
![image description](/upfiles/14870853801702266.png)
4. Review the weather file to see monthly average temperature and apply a fraction for (monthly temp / peak temp) to each month. (I've made a TMY spreadsheet which figures out the average temp for 12 time periods in a year.)
![image description](/upfiles/14870855712337041.png)
5. Put those values in Schedule objects (one for heating, one for cooling, one of which is always =0)
![image description](/upfiles/14870857638998623.png)
6. Make the load a negative value in winter, positive in summer and run the model
![image description](/upfiles/14870858665846434.png)
I occasionally model a building in which a heating process (e.g., oven) adds energy to parts which then cool inside the zone. That situation can be modeled with a fairly simple adaptation of this approach.
p.s., I'm happy to share the tool if you agree with the process and are interested.Jim DirkesTue, 14 Feb 2017 09:31:18 -0600https://unmethours.com/question/22750/Internal mass for a warehousehttps://unmethours.com/question/18028/internal-mass-for-a-warehouse/ Dear forum,
I don't normally pay much attention to internal mass, but am modeling a warehouse which is relatively full of tall steel racking and products. These seem to represent a LOT of internal mass and should not be ignored.
I have made an estimate of total internal surface area (which appears to be in excess of 2 million square feet for a 100,000 sq.ft. warehouse), but am now thinking in more detail about the properties of the internal mass.
- Racking is steel and has high surface / mass ratio
- The products which are stored on the racks are unknown, but almost certainly will be a composite of steel, aluminum, plastic. wood, etc. These products will be inside packages (e.g., boxes) that reduce overall surface area of the product, so surface / mass ratio is probably lower than the racking.
Have some of you done research on this topic? Have you made reasoned assumptions? studied the impact and found it to be too small to worry about?
Thanks for your insights.
Jim DirkesMon, 06 Jun 2016 09:37:30 -0500https://unmethours.com/question/18028/OpenStudio merged surfaces inside a thermal zone to internalmasshttps://unmethours.com/question/10810/openstudio-merged-surfaces-inside-a-thermal-zone-to-internalmass/In OpenStudio when I assign multiple spaces into one thermal zone, in the exported IDF, the partition walls between these spaces gets merged into "InternalMass" in EnergyPlus. However, looks like the "SurfaceArea" of the InternalMass is only one wall area. Since EnergyPlus asks for the "total surface area exposed to the zone air" should that be two times the original wall area since both sides of the partition wall are exposed to the zone air?
TiejunWuMon, 31 Aug 2015 13:50:24 -0500https://unmethours.com/question/10810/Set People and Lights for Internal Masshttps://unmethours.com/question/9606/set-people-and-lights-for-internal-mass/ Hi when the matched surfaces like floor and roof ceiling are translated into Internal Mass in EnergyPlus, how to deal with the internal load?
I mean for light, equipment and people etc, ususally we set x watts per **Zone Floor Area**. But you know in this case, Internal Mass is not floor area anymore.
Thanks!EvaThu, 23 Jul 2015 21:39:11 -0500https://unmethours.com/question/9606/