Pump power and control

Code requirements

G3.1.3.5: Hot-water pumps The baseline building design hot-water pump power shall be 19 W/gpm. The pumping system shall be modeled as primary-only with continuous variable flow and a minimum of 25% of the design flow rate. Hot-water systems serving 120,000 ft2 or more shall be modeled with variable-speed drives, and systems serving less than 120,000 ft2 shall be modeled as riding the pump curve.

Exception to G3.1.3.5: The pump power for systems using purchased heat shall be 14 W/gpm.

G3.1.3.10 Chilled-Water Pumps (System 7, 8, 11, 12 and 13) Chilled-water systems shall be modeled as primary/secondary systems with constant-flow primary loop and variable-flow secondary loop. For systems with cooling capacity of 300 tons or more, the secondary pump shall be modeled with variable-speed drives and a minimum flow of 25% of the design flow rate. For systems with less than 300 tons cooling capacity, the secondary pump shall be modeled as riding the pump curve. The baseline building constant-volume primary pump power shall be modeled as 9 W/gpm, and the variable-flow secondary pump power shall be modeled as 13 W/gpm at design conditions. For computer room systems using System 11 with an integrated fluid economizer, the baseline building design primary chilled-water pump power shall be increased by 3 W/gpm for flow associated with the fluid economizer.

Exception to G3.1.3.10 For systems using purchased chilled water, the building distribution pump shall be modeled with variable-speed drive, a minimum flow of 25% of the design flow rate, and a pump power of 16 W/gpm.

G3.1.3.11 Heat Rejection (Systems 7, 8, 11, 12 and 13) The baseline building design condenser-water pump power shall be 19 W/gpm and modeled as constant volume. For computer room systems using System 11 with an integrated fluid economizer, the baseline building design condenser-water-pump power shall be increased by 3 W/gpm for flow associated with the fluid economizer. Each chiller shall be modeled with separate condenser-water and chilled-water pumps interlocked to operate with the associated chiller.

key functions

ashrae_90_1_prm.PlantLoop.rb: plant_loop_apply_prm_baseline_pump_power Standards.PlantLoop.rb: plant_loop_apply_prm_baseline_pumping_type - Sub-function: plant_loop_apply_prm_baseline_hot_water_pumping_type - Sub-function: plant_loop_apply_prm_baseline_chilled_water_pumping_type - Sub-function: plant_loop_apply_prm_baseline_condenser_water_pumping_type

Parameters:

Pump power constants set in PlantLoop class:

HOT_WATER_PUMP_POWER = 19 # W/gpm
HOT_WATER_DISTRICT_PUMP_POWER = 14 # W/gpm
CHILLED_WATER_PRIMARY_PUMP_POWER = 9 # W/gpm
CHILLED_WATER_SECONDARY_PUMP_POWER = 13 # W/gpm
CHILLED_WATER_DISTRICT_PUMP_POWER = 16 # W/gpm
CONDENSER_WATER_PUMP_POWER = 19 # W/gpm

Pump curve coefficients used to defining the pump type

when 'Riding Curve'
  coeff_a = 0.0
  coeff_b = 3.2485
  coeff_c = -4.7443
  coeff_d = 2.5294
when 'VSD No Reset'
  coeff_a = 0.0
  coeff_b = 0.5726
  coeff_c = -0.301
  coeff_d = 0.7347

Limitations

PRM-RM