RChidwick's profile - activity

Hello everyone,

I am wondering how shading calculations are performed on a wide surface with PV. Specifically, if a shadow is cast over part of the surface, how does that affect the performance of that whole surface? I am simulating a row of panels with a single surface (to avoid having to draw 1000's of surfaces, it's a large system), but I am concerned that generation numbers are lower than they should be due to the whole surface being 'shaded' when only a part of it is.

I hope that was clear, please comment if I need to clarify.

Thank you

Thank you for your answer. I forgot about the I/O Reference document.

I completely forgot about that function in Excel. That solution works perfectly, and very quickly. Thank you very much

Shading calculations Hello everyone, I am wondering how shading calculations are performed on a wide surface with PV.

Thank you very much for your answer, it was a great help.

Hello,

I am interested in accurately modeling the affects of shading objects on pv power generation. I am wondering if shading surfaces can be used to simulate shading objects like trees and neighbouring houses, and if the shade cast on the pv panels will affect the power generated by those panels.

If the panels are modelled using shading surfaces, are all shading surfaces converted into panels? This could be a problem in trying to model the lost production due to shading. Would creating separate structures in the zone in Sketchup accomplish the same goal?

I know this questions is very similar to this question, but I am using OpenStudio and Sketchup Plugin instead of E+ directly.

I'm not sure what the best option is to model the pv panels and simulate shading in Sketchup and OpenStudio. Any thoughts on this as well would be greatly apreciated.

Thank you

Output variables in sequential order Hello everyone, I have created a large commercial PV simulation in SketchUp using

Is PV panel electricity generation affected by shading surfaces? Hello, I am interested in accurately modeling the affe

Thank you. I had no idea that multiple simulation programs could be connected. This is a great help.

I am trying to model ground temperatures in EnergyPlus by using the slab.exe program. I read about it on the Auxiliary Programs document online, and I followed the instructions as best as I could.

My problem is that EnergyPlus is crashing when I try to run the simulation. I added all of the 'GroundHeatTransfer:Slab:' objects and the 'GroundHeatTransfer:Control' object with the Run Slab Preprocessor field set to 'yes'.

I also read about using a command window to run the slab preprocessor but I did not understand how that works.

I am happy to use either method. In then end I would just like to have ground temperatures to add to my simulation, rather than using the suggested '2C less than average monthly indoor temperature' rule. My simulation is located in Southern Alberta, and due to the large seasonal temperature swings experienced there I'm not sure how accurate that rule would be.

I am using the Lethbridge weather file from the EnergyPlus website, but when I view the file in the Elements program I do not see a column for 'undisturbed' ground temperatures. Do I need another weather file?

Thank you.

I asked a similar question. See the answer here. Using the 'Water Heater Mixed' or 'Water Heater Stratified' objects in OpenStudio with the heater capacity set to zero. Also be sure to set the parasitic load to zero.

Hello,

I am trying to model a large fish tank (essentially a swimming pool - the size of these cylindrical tanks is 3m in diameter, and 2m high) in OpenStudio. I have several thoughts on how I could go about doing this and wanted to get some feedback from the community. Maybe some of you have better ideas. The goal is to account for every way in which the fish tank, in the real world, absorbs and releases thermal energy into the thermal zone, and account for the heating and cooling needs of that water as well.

1) Use the 'Thermal Storage: Chilled Water: Mixed' object. I could use this object in combination with a chilled water radiant floor or some other method of allowing the water to gain and lose energy to the thermal zone, and then use a chiller to cool the water. This idea would cover the thermal storage aspect of the fish tank, but not how the fish tank is actually open the air.

2) Create a 'Water Use Equipment Definition'. A flow rate can be described, along with sensible and latent heat fraction schedules, and a temperature schedule, but no volume.

3) Use the 'Internal Mass' object. I could define the internal mass using material definitions and constructions. This would indirectly be modelling the water's thermal mass properties, but I can no longer actively cool the water, which is an important part of my energy model.

The fish tank is located inside a thermal zone with no windows, just solid walls. The space is also conditioned (currently I just have a PRAC in that zone).

I look forward to hearing your thoughts or other suggestions.

Thank you.

I am trying to use the SolarCollector:FlatPlate object in EnergyPlus to reduce the load on the boiler to provide heat for my space and swimming pool. I'm unfamiliar with this object and I don't know how to set it up correctly. I have read through the E+ documentation on the object, and I have looked through the example file for the object but I am still getting the following warnings in my simulation.

** Warning ** GetSpecificHeatGlycol: Temperature is out of range (too high) for fluid [WATER] specific heat **
**   ~~~   ** ..Called From:UpdatePlantLoopInterface,Temperature=[198.57], supplied data range=[0.00,125.00]
**   ~~~   **  Environment=LETHBRIDGE ANN CLG .4% CONDNS DB=>MWB, at Simulation time=07/21 00:00 - 00:10
** Warning ** GetDensityGlycol: Temperature is out of range (too high) for fluid [WATER] density **
**   ~~~   ** ..Called From:PlantPumps:CalcPumps: ,Temperature=[198.50], supplied data range=[0.00,100.00]
**   ~~~   **  Environment=LETHBRIDGE ANN CLG .4% CONDNS DB=>MWB, at Simulation time=07/21 00:00 - 00:10
** Warning ** GetSpecificHeatGlycol: Temperature is out of range (too low) for fluid [WATER] specific heat supplied values **
**   ~~~   ** ..Called From:UpdateSolarCollector,Temperature=[-28.33], supplied data range=[0.00,125.00]
**   ~~~   **  Environment=LETHBRIDGE ANN HTG 99.6% CONDNS DB, at Simulation time=01/21 05:10 - 05:20

I can't figure out what is causing the the temperature to be too high or too low. I have tried raising and lowering the flow rate of the water through the plate, but that did not solve the problem.

I am grateful for any ideas.

Hello,

I have been looking around the forum trying to figure out how to set up hot water thermal storage. I am working on a simulation for a greenhouse that uses a hot water radiant floor. The hot water is supplied by a boiler. So I have currently put together a plant loop using a boiler, HW setpoint manager, low temp radiant var flow object, and a variable speed pump. This is very similar to what the actual system is.

However, the greenhouse also has a very large hot water storage tank. Hot water can be stored there in case not all of the hot water is required at a certain time to heat the greenhouse, or if the greenhouse operator wants to run the boiler to get CO2 off the stack and pump that into the greenhouse for the plants while the hot water gets stored in the tank for later use.

I am wonder how I would go about doing this. I see from the HVAC System Requests and Priorities spreadsheet that a Thermal Storage - Hot Water Storage object exists but I do not see it in OpenStudio. I am currently using OS 1.9.0.

So far I have tried using water heaters on the demand side of the loop with the boiler on the supply side but that hasn't worked.

I'm grateful for any suggestions and help. Does anyone know if maybe the Thermal Storage Hot Water Storage object has been developed but not yet released?

Thank you.

I am trying to convert a csv weather file I got from here, to an epw file using the EnergyPlus Weather Converter tool. I learned that I needed a def file, so I found a def file for converting csv to epw. I am currently getting several errors. I know my question is very similar to this question, but I thought it may be helpful if I post some of the errors that I am getting.

The procedure that resulted in the fewest number of errors was selecting the csv as the input weather file, then overriding the default type and selecting 'energyplus comma separated variable' format. I selected the output format as epw, and gave a file name for the converted file and then selected 'convert file'.I have attached a screenshot of the audit file to this question. C:\fakepath\Barons weather audit file.JPG

Let me know if the procedure above is clear. I have tried the suggested solutions mentioned in the comments on the question I linked above, but they have not worked.

Hello everyone,

I have been encountering a problem lately when I try to model a radiant floor in OpenStudio.

I am currently using the OpenStudio 1.9.0 plugin for SketchUp.

I have a two story building, one thermal zone per floor, with each floor having a radiant floor heating system. I have created an internal source for each floor and added it to the respective construction set for each floor. I also added a 'low temperature radiant variable flow' to the zone equipment for each thermal zone, along with a cooling schedule and heating schedule, and linked the equipment to the thermal zones. Then I created an empty plant loop and added a boiler, setpoint manager schedule (HW Temp), and a variable speed pump.

When I run the simulation I get the following errors: * Severe * IP: IDF line~524 Object=ZONEHVAC:LOWTEMPERATURERADIANT:SURFACEGROUP, name=LOW TEMP RADIANT VAR FLOWFLOORS, Required Field=[Surface 1 Name] was blank. * Severe * IP: IDF line~524 Object=ZONEHVAC:LOWTEMPERATURERADIANT:SURFACEGROUP, name=LOW TEMP RADIANT VAR FLOWFLOORS, Required Field=[Flow Fraction for Surface 1] was blank. * Severe * IP: IDF line~2331 Object=ZONEHVAC:LOWTEMPERATURERADIANT:SURFACEGROUP, name=LOW TEMP RADIANT VAR FLOW 1FLOORS, Required Field=[Surface 1 Name] was blank. * Severe * IP: IDF line~2331 Object=ZONEHVAC:LOWTEMPERATURERADIANT:SURFACEGROUP, name=LOW TEMP RADIANT VAR FLOW 1FLOORS, Required Field=[Flow Fraction for Surface 1] was blank. * Severe * IP: IDF line~5354 Error detected in Object=PLANTEQUIPMENTOPERATIONSCHEMES, name=PLANT LOOP 1 OPERATION SCHEMES * ~~~ * Field [Control Scheme 1 Schedule Name] is required but was blank

I've looked all through OpenStudio and cannot find a way to solve any of these errors. I can solve them in E+, but I'd like to be able to solve them in OpenStudio. Do I need to write a measure to solve these in OpenStudio?

Thank you for any help! Let me know if I need to post the IDF file, I'm new to posting on Unmet Hours and am not sure if that is standard procedure or not.

I am interested in using the flat plate solar collector object in my simulation to decrease the demand on the boiler to provide hot water for the facility. I read in the EnergyPlus documentation that the SolarCollector:FlatPlate:Water object could be used to model 'glazed, unglazed, and tubular (i.e. evacuated tube) collectors'. I am not sure how to tell the program which type of collector I want to simulate. I also read about the SolarCollectorPerformance:FlatPlate object, but I did not read anywhere how I could specify the type of collector. In the Engineering Reference document, under Solar Collectors it does say that flat plate, integral-collector storage, and unglazed transpired collectors are the only types currently available in EnergyPlus. If that is the case, then why mention that the SolarCollector:FlatPlate:Water object can be used to simulate other types of collectors?

Thank you.

I created a simulation of an existing building in OpenStudio 1.10.0. The heating in the simulation is provided by a hot water heating coil (which is supplied by a natural gas boiler). I have hourly gas data from the actual building which I am using to verify that my heating system is working correctly. The real building uses 'rail heating' - exposed pipes that sit about 6 inches off the floor. Hot water circulates through the pipes to provide radiant heating. I have tried to model this using the ZoneHVAC:LowTemperatureVariableFlow object in OpenStudio but the gas usage is way off, about 3 to 5 times greater than the usage from the actual building.

I thought I would try using the Coil:Heating:Water object in place of the ZoneHVAC:LowTemperatureVariableFlow object. I made an air loop with just a fan, the coil, an uncontrolled diffuser and the thermal zone that the coil is supplying. I used the SetpointManager:SingleZone:Reheat setpoint manager for the air loop. The gas usage profile shape was nearly an exact match to the profile from the actual building, but the values were several times less than the actual values (peak hourly usage from the simulation was 3.8 GJ vs 16 GJ for the actual data).

I'm wondering if it makes sense that the gas usage from the simulation using a heating coil is much less than the gas usage from the building which is essentially using a radiant floor?

Thank you.

I am trying to improve the performance of the solar collectors in my simple simulation where two collectors (one on the south facing roof, one on the south wall) supply a hot water heating coil for a small space. Regardless of how I set up the schedule for the fan availability for the air loop or the coil availability, the 'solar collector heat transfer energy' shows that while the fluid gains heat throughout the year, it also loses heat. Surprisingly the heat loss is greatest in the summer time. I have also noticed that the efficiency of the panels throughout the year varies from 0 to large negative numbers.

I know that solar collectors perform better than this in the real world. I looked through the solar collector data set and made a simulation comparing all of the evacuated tubes, from which I chose the Thermomax Industries Ltd collectors as they seemed to perform the best. However, using the efficiency equation coefficients and incidence angle modifier coefficients given in the data set for the Thermomax panel, the outlet temperature never got higher than 50 at any time of the year.

I am very confused as to why the panels in my simulation perform so differently from the real world. Has anyone else had this problem? If so how did you fix it? I used OpenStudio 1.10.0 for this simulation.

Thank you.