FrontierAssoc104's profile - activity

I saw that, and my only concern there is I have no documentation to validate what the Fan Rated Electric Power [W] really represents. If it is simply the rated power of the motor powering the fan, then it should be trivial enough to get a savings value for each fan to get what I need.

I appreciate the feedback. I understand that the Fan Total Efficiency is what really is read by the model for energy usage purposes, but I was wondering if there was another way to change the motor size rather than simply the efficiency of the system. The method you described Archmage is exactly what I was thinking I would have to do, but I wasn't sure if there was something I would be missing to take me from changing efficiency to savings per horsepower. Chris, your line of thought is correct, you would have to change fan total efficiency to see a difference.

Right now I am deciding between writing a hand calculation (for which sources are readily available) to calculate energy savings for replacing a supply fan electric motor with one of higher efficiency and of the same size. The energy savings would need to be general enough to have energy/demand savings for motor replacements of varying rated powers. Currently, I do not see any motor sizing functionality in Energy Plus, so I do not believe this could be done via modeling (since power-efficiency curves are not an available object for supply fan motors or motor sizing cannot be specified). Energy savings per horsepower would be a desirable outcome from the modeling effort, and if anyone could let me know if this is possible, that would be great. Additionally, if someone has a compelling argument to go with the hand calculation method as an alternative to the modeling approach, that would be equally beneficial.

Really I am looking for load factor, not power factor.

I am wondering if EnergyPlus has the capability to model digital economizer controls to estimate energy savings for a more efficient economizer controller. I see there is a separate toggle for DCV under the Controller:MechanicalVentilation, but that is not what I am looking for. Alternatively, would there simply be a way to change the availability schedule for the economizer controller?

The power factor is essentially what I'm after, because I was going to use (average fan speed/rated fan speed)^3 to estimate the power factor. Alternatively, the fan Rated electric power is an output seen via the HTML file produced by an energy plus simulation, and the hourly fan electric power output (specific to each fan) could be averaged over the year and normalized by the fan's rated electric power. I'm just not sure if this is a valid method of collecting the fan motor power factor.

The question is two fold. Is Energy+ capable of outputting the hourly fan speed? Also is there a roundabout way of finding the load factor from the fan motor via the hourly fan energy usage?

I am trying to calculate energy savings for implementing a VFD and premium efficiency motor as an RTU retrofit. I am thinking to use the Variable Air Volume object to model the VFD, and changing the fan efficiency since it is a product of motor and fan efficiency. My question comes in to the Load Factor and % full rated speed of the fan air flow rate. Since I am going to make a lump system energy savings due to the interactive energy savings between the VFD and efficient motor, I need the % full rated speed (cubed) due to the fan affinity laws. Additionally I would need the motor load factor. I know that there is a design max air flow field in the variable air volume fan class, but I have not seen an output for hourly air flow rate to get the average % flow rate. Additionally I'm not sure about the load factor on the motor, although I may just assume the same load factor for both baseline and proposed cases. Any feedback on my line of thought or about the air volume fraction would be greatly appreciated.

I have a follow up question from this earlier thread. I'm not sure where the default coefficient values in the fan power curve come from? If anyone could point me in the right direction, that would be greatly appreciated.

Okay, this gives me a few follow up questions. First, I'm assuming changing to a VFD controlled fan would change the fan efficiency component of the total fan efficiency (not the motor efficiency since this is a nameplate value?). Secondly, the pressure rise would also potentially change, in a manner that is not immediately obvious to me. Additionally, the fan power curve coefficients that are in the variable volume fan class that are not in the constant volume fan class could be set at default values, or would they need to be modified? If the coefficients would need to be modified, how and wh

Okay, this gives me a few follow up questions. First, I'm assuming changing to a VFD controlled fan would change the fan efficiency component of the total fan efficiency (not the motor efficiency since this is a nameplate value?). Secondly, the pressure rise would also potentially change, in a manner that is not immediately obvious to me. Additionally, the fan power curve coefficients that are in the variable volume fan class that are not in the constant volume fan class could be set at default values, or would they need to be modified? If the coefficients would need to be modified, how and what values would be required?

I'm trying to make base and change cases for energy efficiency comparisons for HVAC optimization. One measure I plan to implement is premium efficiency motors on HVAC fans. The only thing I see that ties into this would come from the fan efficiency field. Can anyone explain what goes into the fan efficiency, and how I would be able to directly change the motor efficiency of the fan in Open Studio or energy plus?

I need the standard rating values for COP and Cooling Capacity for chillers for some post processing of model simulations. DX Cooling Coils have these output parameters defined, but are not always output in the HTML file produced from the E+ simulation. However, I was able to find formulas to calculate these values for Single and Two Speed DX Cooling Coils. For DX Cooling Coils, the formulas for these were explicitly stated in the Engineering Reference PDF v8.4 in the energy plus documentation. However, for chillers, no such formulas are provided, and it is not produced in the HTML file generated from an E+ simulation. Only Nominal values for Cooling Capacity and COP for chillers are output. If anyone could point me towards formulas or share why there would not be such an output, I would be greatly appreciative. For example, I was using Equations 217 and 220 in section 16.2.6.6 Standard Ratings of the Engineering Reference PDF v8.4 to calculate the Standard Rating Net Cooling Capacity and Standard Rating EER, respectively.

I am looking to extract hourly energy usage data in the form that EnergyPlus ouputs the METER data in excel compatible format. When a simulation is preformed in EnergyPlus, this is automatically created. However, in Open Studio, a .mtr file that is similarly disorganized to a .ESO file is created. I am wondering if there is a way to organize the .mtr file into a readable hourly energy usage file for the whole year, just like the EnergyPlus created METER data. It seems like something similar to ReadVarsESO would work, however .mtr is not .eso . I am using Open Studio version 1.8 for reference. The motivation behind organizing the .mtr file is that when I export my Open Studio Model to an IDF to be run in EnergyPlus 8.3 to automatically create the METER data, I do not get the same annual end uses. Thank you for any insight.

I'm wondering how variable air volume fans are controlled in Open Studio. End use, I am trying to model VFDs on HVAC fans (not exhaust fans) and I am wondering how a VFD on a CAV fan would operate differently/similarly to a VAV fan?

In my previous experience (early August) that measure was not complete and did not lead to replication of the DOE Reference Buildings to OSM format. Using this measure was our first idea, but it did not pan out and seemed to be a work in progress.

I am working on modifying DOE reference buildings with new types of HVAC, but first am attempting to replicate the results of the METER output data from the DOE IDF within Open Studio. I am not seeing the item AirLoopHVAC:UnitaryHeatCool in Open Studio 8.3, but am currently using AirLoopHVAC:UnitarySystem instead. I am not getting matching results for the cooling electricity usage even when setting the electric reheat for this system to zero. Still using Fan:OnOff, DX CoolingCoil Single Speed, and gas heat. Can anyone explain the differences between AirLoopHVAC:UnitarySystem and AirLoopHVAC:UnitaryHeatCool so that I can better find a solution for my problem?

I am having issues adding Clothing Insulation and Air Velocity Schedules in Open Studio (under the people object in E+ 8.3). In OS, under the people load the boxes are greyed out. Is there a way to make these boxes available to edit?

Currently working with DOE commercial reference buildings as a starting point to do high level HVAC analysis, swapping out HVAC systems. I am fairly confident I have rebuilt the HVAC equipment and plant loops in OpenStudio after importing the commercial reference building IDF from SketchUp, but the output results are very different, as much as 3 times higher cooling electric consumption from Open Studio simulation with rebuilt HVAC than from original run within Energy+. Are there any other known constructions/schedules/materials that do not transfer into Open Studio when importing an IDF?

Thank you Joe! I had suspected it was mainly based upon empirical data and first hand experience from the authors, so I appreciate the confirmation.

I can tell that the DOE reference buildings were created with data from 2003 CBECS. I am wondering how the individual space types were assigned. For example, the reference building for secondary school uses an air cooled chiller and packaged single zone units. I do not understand what rationale the modelers had for placing each HVAC type where? Why are certain space types cooled by the chiller, but others by the single zone units? How would I find this information? I am interested because I have to interchange HVAC equipment from these reference buildings, and would like some reference for where to put what types of HVAC in a building on a space type level of detail.

This is helpful, but more general than what I was looking for. Ideally, and I'm not sure there is something comprehensive like this, there would be a similar chart for only Heat Pumps or Chilled Water Systems to breakdown how often specific types of each (e.g. air-source heat pump, water-source heat pump, etc.) would be used per building type. Something on the next level of specificity.

I am looking to switch out several HVAC system types from DOE commercial reference buildings with 'typical' HVAC systems specific to that buidling type. For example, The reference building for a Warehouse utilizes packaged AC as default (coded into the original IDFs), but I would like to separately model a Warehouse using a heat pump system. How would I find out what a typical heat pump system in a Warehouse is comprised of? Is there a good reference for various building type - HVAC type combinations? I realize this probably varies with climate zone.

I am looking through DOE reference building IDFs. Using the Notepad++ comparison tool, I am finding differences between reference building HVAC equipment characteristics (e.g. DX coil Rated COP or Package Fan Efficiency). I know that simulations preform a sizing run first and then the actual simulation, so I am wondering why these parameters may differ? I am comparing the same building types but for different climate zones, so it may be solely weather based. However, I am wondering if there could be another rationale. Why would these parameters differ before the sizing run occurs?

I am going to analyze energy savings for several DOE reference buildings in various climate zones. I have a feeling that the same HVAC type (e.g. heat pump or chilled water system) would be sized differently for each climate zone based on humidity and temperature. If I am making measures for each building type in different climate zones, would I need a separate measure for each climate zone? If not, how would the sizing be taken care of? I should mention, I am planning to use the Parametric Analysis Tool in Open Studio for the simulations to show optimization results to determine best practice for various building types.

I am having a little trouble with the Slab program. First, I can't find anywhere an example of the GroundHeatTransfer:Slab:Control object and what it should look like. I see in the input-output reference that it needs: Field:Name and Field:Run Slab Preprocessor, but I'm not sure what the format looks like. Additionally, I am wondering where the Slab objects and GroundHeatTransfer:Slab:Control object are positioned in the IDF file. Do they necessarily need to be placed in a specific place (before or after any object)?

I am using DOE Reference Building files (.idf), but modifying them with information from Representative City data from another state (Las Vegas -> El Paso). One part of replacing the weather data is the Site:GroundTemperature:BuildingSurface information. I cannot find this in the .stat, .epw, or .ddy files from El Paso. Is this a calculated value, and if so, how is it calculated?

I was wondering what versions of EnergyPlus are compatible with TMY3 weather data. Namely, using EnergyPlus 7.2 would be ideal since that is what the DOE reference buildings were made in.