Add dedicated secondary loop for 90.1 PRM plant loops

lib/openstudio-standards/prototypes/common/objects/Prototype.hvac_systems.rb

@@ -296,6 +296,10 @@ def model_add_chw_loop(model,
         # Change the chilled water loop to have a two-way common pipes
         chilled_water_loop.setCommonPipeSimulation('CommonPipe')
       elsif pri_sec_config == 'heat_exchanger'
+        # Check number of chillers
+        if num_chillers > 3
+          OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.PlantLoop', "EMS Code for multiple chiller pump has not been written for greater than 3 chillers. This has #{num_chillers} chillers")
+        end
         # NOTE: PRECONDITIONING for `const_pri_var_sec` pump type is only applicable for PRM routine and only applies to System Type 7 and System Type 8
         # See: model_add_prm_baseline_system under Model object.
         # In this scenario, we will need to create a primary and secondary configuration:
@@ -309,10 +313,15 @@ def model_add_chw_loop(model,
         secondary_chilled_water_loop.setName(secondary_loop_name)
         chw_sizing_control(model, secondary_chilled_water_loop, dsgn_sup_wtr_temp, dsgn_sup_wtr_temp_delt)
         chilled_water_loop.additionalProperties.setFeature('is_primary_loop', true)
+        chilled_water_loop.additionalProperties.setFeature('secondary_loop_name', secondary_chilled_water_loop.name.to_s)
         secondary_chilled_water_loop.additionalProperties.setFeature('is_secondary_loop', true)
-        # primary chilled water pump
+        # primary chilled water pumps are added when adding chillers
         # Add Constant pump, in plant loop, the number of chiller adjustment will assign pump to each chiller
-        pri_chw_pump = OpenStudio::Model::PumpConstantSpeed.new(model)
+        # pri_chw_pump = OpenStudio::Model::PumpConstantSpeed.new(model)
+        pri_chw_pump = OpenStudio::Model::PumpVariableSpeed.new(model)
+        pump_variable_speed_set_control_type(pri_chw_pump, control_type = 'Riding Curve')
+        # This pump name is important for function add_ems_for_multiple_chiller_pumps_w_secondary_plant. If you update
+        # it here, you must update the logic there to account for this
         pri_chw_pump.setName("#{chilled_water_loop.name} Primary Pump")
         # Will need to adjust the pump power after a sizing run
         pri_chw_pump.setRatedPumpHead(OpenStudio.convert(15.0, 'ftH_{2}O', 'Pa').get / num_chillers)
@@ -375,8 +384,23 @@ def model_add_chw_loop(model,
       dist_clg.autosizeNominalCapacity
       chilled_water_loop.addSupplyBranchForComponent(dist_clg)
     else
+
+      # use default efficiency from 90.1-2019
+      # 1.188 kw/ton for a 150 ton AirCooled chiller
+      # 0.66 kw/ton for a 150 ton Water Cooled positive displacement chiller
+      case chiller_cooling_type
+      when 'AirCooled'
+        default_cop = kw_per_ton_to_cop(1.188)
+      when 'WaterCooled'
+        default_cop = kw_per_ton_to_cop(0.66)
+      else
+        default_cop = kw_per_ton_to_cop(0.66)
+      end
+
       # make the correct type of chiller based these properties
       chiller_sizing_factor = (1.0 / num_chillers).round(2)
+
+      # Create chillers and set plant operation scheme
       num_chillers.times do |i|
         chiller = OpenStudio::Model::ChillerElectricEIR.new(model)
         chiller.setName("#{template} #{chiller_cooling_type} #{chiller_condenser_type} #{chiller_compressor_type} Chiller #{i}")
@@ -391,18 +415,6 @@ def model_add_chw_loop(model,
         chiller.setMinimumUnloadingRatio(0.25)
         chiller.setChillerFlowMode('ConstantFlow')
         chiller.setSizingFactor(chiller_sizing_factor)
-
-        # use default efficiency from 90.1-2019
-        # 1.188 kw/ton for a 150 ton AirCooled chiller
-        # 0.66 kw/ton for a 150 ton Water Cooled positive displacement chiller
-        case chiller_cooling_type
-        when 'AirCooled'
-          default_cop = kw_per_ton_to_cop(1.188)
-        when 'WaterCooled'
-          default_cop = kw_per_ton_to_cop(0.66)
-        else
-          default_cop = kw_per_ton_to_cop(0.66)
-        end
         chiller.setReferenceCOP(default_cop)
 
         # connect the chiller to the condenser loop if one was supplied

lib/openstudio-standards/standards/Standards.Model.rb

@@ -443,7 +443,7 @@ def model_create_prm_any_baseline_building(user_model, building_type, climate_zo
         next if plant_loop_swh_loop?(plant_loop)
 
         plant_loop_apply_prm_number_of_boilers(plant_loop)
-        plant_loop_apply_prm_number_of_chillers(plant_loop, sizing_run_dir)
+        plant_loop_apply_prm_number_of_chillers(plant_loop)
       end
 
       # Set the baseline number of cooling towers