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2016-04-12 18:07:44 -0500 | marked best answer | Chiller connection to condenser loop for ASHRAE 90.1 System 8 in OpenStudio Dear all, I am wondering how I can add an additional chiller to the chilled water loop that connects to a condenser loop. According to Table G3.1.3.7 in ASHRAE 90.1-2007 I need to have "2 water-cooled screw chillers sized equally". I read from another post that one way of adding a chiller which has a condenser loop is to use "VAV with Reheat" in OpenStudio and then modify the components. However, if I need 2 chillers how can I model it in OpenStudio? When I try to drag a "Chiller Electric EIR" component to the system it doesn't come with a condenser loop. Is there a way to add one to it? Thanks in Advance, Daniel |
2016-04-12 18:02:07 -0500 | marked best answer | VRF system with huge no. of unmet hours only during heating Dear all, I am in a battle with all these unmet hours in my VRF system and I desperately need some help (OpenStudio). It is a pretty straight forward system configuration with 1 outdoor unit linking to several indoor units. The zones served by the system have different orientations, internal loads and ventilation requirements. Fresh air is provided by the mixers in the VRF terminals. I am using dual setpoint for the thermostat, i.e. temperature setpoints are 22C for heating mode and 26C for cooling. The peculiar thing is that unmet hours happen nearly exclusively during heating mode. There are at least two symptoms that I observed:
Any pointers would be highly appreciated. Thanks in advance, Daniel |
2015-11-08 20:50:58 -0500 | asked a question | Monthly Electricity Energy Consumption Dear all, I am interested in looking at the proportion of different end-uses in different months. Does anyone know if it is possible to generate the "EnergyConsumptionElectricityNaturalGasMonthly" summary in OpenStudio? This can easily be called in EnergyPlus but if I can do it in OpenStudio I can save the conversion. p.s. This table used to be available in the result tab in OS 1.8. Not sure where I can find it in OS 1.9. Thanks in advance, Daniel |
2015-10-16 02:51:22 -0500 | asked a question | construction conflicts between surfaces '1', and '1' Dear all, This warning pops up at the end of a simulation: [openstudio.model.ConstructionBase] <1> Could not resolve matched surface construction conflicts between surfaces '1', and '1', area calculation may be incorrect I am not sure what it means as there are no surfaces "1" in the model. I am using the default settings in OpenStudio for ASHARE 90.1-2010 Office in Climate zone 3 and have the ideal load set to ON. It doesn't seem to be having an effect on the result of the simulation but it would like to confirm that this is really the case and it would be even better if it can be resolved. Thanks in advance, Daniel |
2015-08-25 03:35:21 -0500 | commented answer | VRF with variable fresh air supply Supplementary info: All zones switch between cooling and heating by a schedule. There is an hour of buffer time so morning start-up doesn't seem to be a problem. |
2015-08-23 22:05:25 -0500 | commented answer | VRF with variable fresh air supply I have uploaded the ESO snap shots of the before-and-after room temperature. |
2015-08-21 03:29:01 -0500 | commented answer | VRF with variable fresh air supply I have tried adding an extra air loop in OpenStudio to represent the system but the zone temperatures went completely out of control. I believe that's because I couldn't specify the simulation "priority" in the OpenStudio (at least I don't know where I can set it) so the terminal units were not aware of a separate fresh air supply and fresh air load was not taken care properly by the terminal units. |
2015-08-21 03:22:51 -0500 | commented answer | VRF with variable fresh air supply Thank you both for the input. I have modelled the system using "OutdoorAirUnit" as suggested and it worked OK. The temperature control was a bit unstable with a +/-1.5C fluctuation around the temperature set point compared with +/-0.5 when using a simple VRF system. I am already quite happy with the result but is there a way to improve the control? |
2015-08-20 05:13:55 -0500 | asked a question | VRF with variable fresh air supply Dear all, I am trying to model a VRF system with variable flow fresh air fans (in red). As shown in the figure below. In EnergyPlus (OpenStudio) the is only one fan in each system and it is constant speed (i.e. no red fans). Is there a way I can model the actual design in EnergyPlus or OpenStudio? Furthermore, when I enter the "Pressure Rise" for the system, should I use the pressure rise for the whole air path, fresh air+internal+exhaust? I believer that might result in an overestimated fan energy consumption because fresh air only makes up a fraction of the supply air. Any advice on that? Thanks in Advances, Daniel After implementing the ZoneHVAC:OutdoorAirUnit approach the problem is basically solved but the zone temperature is less stable. (Set point = 26C) This is the zone temperature before This is the zone temperature after |
2015-08-16 20:27:24 -0500 | commented answer | VRF system shows very low COP in heating mode Thanks for your comment, the performance curves did seem to be doing something odd. I have changed the curves to the default ones in EnergyPlus and immediately the whole system behaved a lot closer to what I expected. I am still going through the material and may use it to fine-tune the curves. |
2015-08-14 02:14:53 -0500 | asked a question | VRF system shows very low COP in heating mode Dear all, I am modelling a VRF system for a typical office building in Japan (Climate zone 3A). The result indicates that a large proportion of energy goes to heating which is generally not the case in reality. I exported the Openstudio file to Energyplus and called the hourly COP. I found that the COP for heating is constantly a lot lower (1-1.5) than the rated COP which I have inputted (3.5) The COP also appears to reach a max. at around 3. I am using the default performance curves in Openstudio. Any ideas what can be done? Regards, Daniel |
2015-08-11 04:29:02 -0500 | asked a question | Openstudio: Sensible Heat Gain Summary vs. Electricity Consumption I am currently modelling an office building using VRF heat pumps for both heating and cooling. What I find very puzzling is that in the "Sensible heat gain summary" the: HVAC Input sensible air heating = 165,853 kWh HVAC Input sensible air cooling = 562,794 kWh However, the "Electricity consumption" table shows: Heating = 335,025 kWh Cooling = 197,461 kWh Given that the COP in both the cooling and heating mode are around 3, the electricity consumption for heating should be less than the input sensible air heating but it is not!! Does anyone know why this is the case? |
2015-08-11 04:26:21 -0500 | asked a question | Openstudio Report: Sensible heat gain summary vs. Electricity consumption Dear all, I am currently modelling an office building using VRF heat pumps for both heating and cooling. What I find very puzzling is that in the "Sensible heat gain summary" the: HVAC Input sensible air heating = 165,853 kWh HVAC Input sensible air cooling = 562,794 kWh However, the "Electricity consumption" table shows: Heating = 335,025 kWh Cooling = 197,461 kWh Given that the COP in both the cooling and heating mode are around 3, the electricity consumption for heating should be less than the input sensible air heating but it is not!! Does anyone know why this is the case? Thanks in advance, Daniel |
2015-07-09 19:46:51 -0500 | commented answer | Is it possible to meter different "Fan" annual electricity consumptions separately in OS? Thank for the reply, I will check it out later. |
2015-07-09 19:44:46 -0500 | received badge | ● Commentator |
2015-07-09 19:44:46 -0500 | commented answer | Is it possible to meter different "Fan" annual electricity consumptions separately in OS? Dear Matthew thanks for the answer |
2015-07-09 04:59:52 -0500 | asked a question | Is it possible to meter different "Fan" annual electricity consumptions separately in OS? Dear all, As a requirement in the LEED submission, I need to report the exhaust fan energy consumption for the car park separately. It seems that there is only one item in the "Energy Meters" section of the OpenStudio report which is "Fan:Electricity". Is there a way to break this down into different fans so I can extract the information for a particular fan only? Regards, Daniel |
2015-05-26 19:45:24 -0500 | received badge | ● Supporter (source) |
2015-05-18 21:25:55 -0500 | asked a question | What kind of energy consumptions are included in "water systems" in Openstudio and EnergyPlus Dear all, I am trying to model a hot water system in Openstudio in which the water flowrate of the proposed case is 23% lower than the baseline. From the results, the energy consumption under "pumps" was 23% lower in the proposed case which sounded fair. However,the energy consumption under "water systems" of the proposed case was 50% lower than the baseline. I am not sure what are included in the "water system" such that a 23% drop in flowrate resulted in a proportionally higher energy saving as all other input parameters in the two models were exactly the same. I am therefore wondering if that is normal or if I have made a mistake somewhere in the inputs. Daniel |
2015-05-17 19:53:31 -0500 | commented question | OpenStudio Crashes with the error "bad cast" and "Access violation - no RTTI data!" Dear Kyle, thank you for fixing the file. As for the changes I had made before something went wrong, I removed a few thermal zones (the IT rooms) from the main chilled water loop and created a VRF system for them. I had also done other minor modifications to the model like adjusting schedules and loads but I don't think they caused the file to corrupt. I might have mis-clicked something which I was not aware of. |