Class: NRELZNEReady2017

Inherits:
ASHRAE901 show all
Includes:
NRELZNEReady2017CoolingTower
Defined in:
lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.rb,
lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.Space.rb,
lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirLoopHVAC.rb,
lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.ThermalZone.rb,
lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.FanVariableVolume.rb,
lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.CoolingTowerTwoSpeed.rb,
lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.HeatExchangerSensLat.rb,
lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.CoolingTowerSingleSpeed.rb,
lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.CoolingTowerVariableSpeed.rb,
lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirTerminalSingleDuctVAVReheat.rb,
lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.Model.rb,
lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.FanOnOff.rb,
lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.hvac_systems.rb,
lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.Model.elevators.rb,
lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.FanConstantVolume.rb,
lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.FanVariableVolume.rb,
lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.AirTerminalSingleDuctVAVReheat.rb

Overview

This class holds methods that apply the “standard” assumptions for ZNE-Ready buildings, as defined by NREL in 2017, to a given model.

Technical References:

Constant Summary collapse

@@template =

rubocop:disable Style/ClassVars

'NREL ZNE Ready 2017'

Instance Attribute Summary collapse

Space collapse

AirLoopHVAC collapse

ThermalZone collapse

FanVariableVolume collapse

HeatExchangerSensLat collapse

AirTerminalSingleDuctVAVReheat collapse

Model collapse

FanOnOff collapse

hvac_systems collapse

elevators collapse

FanConstantVolume collapse

CoolingTower collapse

Instance Method Summary collapse

Constructor Details

#initializeNRELZNEReady2017

Returns a new instance of NRELZNEReady2017.


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.rb', line 9

def initialize
  super()
  @template = @@template
  load_standards_database
end

Instance Attribute Details

#templateObject (readonly)

Returns the value of attribute template


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.rb', line 7

def template
  @template
end

Instance Method Details

#air_loop_hvac_apply_multizone_vav_outdoor_air_sizing(air_loop_hvac) ⇒ Object

TODO:

move building-type-specific code to Prototype classes

Apply multizone vav outdoor air method and adjust multizone VAV damper positions to achieve a system minimum ventilation effectiveness of 0.6 per PNNL. Hard-size the resulting min OA into the sizing:system object.

return [Bool] returns true if successful, false if not


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirLoopHVAC.rb', line 12

def air_loop_hvac_apply_multizone_vav_outdoor_air_sizing(air_loop_hvac)
  # First time adjustment:
  # Only applies to multi-zone vav systems
  # exclusion: for Outpatient: (1) both AHU1 and AHU2 in 'DOE Ref Pre-1980' and 'DOE Ref 1980-2004'
  # (2) AHU1 in 2004-2013
  # TODO refactor: move building-type-specific code to Prototype classes
  if air_loop_hvac_multizone_vav_system?(air_loop_hvac) && !(air_loop_hvac.name.to_s.include? 'Outpatient F1')
    air_loop_hvac_adjust_minimum_vav_damper_positions(air_loop_hvac)
  end

  # Second time adjustment:
  # Only apply to 2010 and 2013 Outpatient (both AHU1 and AHU2)
  # TODO maybe apply to hospital as well?
  # TODO refactor: move building-type-specific code to Prototype classes
  if air_loop_hvac.name.to_s.include? 'Outpatient'
    air_loop_hvac_adjust_minimum_vav_damper_positions_outpatient(air_loop_hvac)
  end

  return true
end

#air_loop_hvac_dcv_required_when_erv(air_loop_hvac) ⇒ Object

Determine if the standard has an exception for demand control ventilation when an energy recovery device is present. For NREL ZNE Ready 2017, DCV and an ERV may be used in conjunction.


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirLoopHVAC.rb', line 261

def air_loop_hvac_dcv_required_when_erv(air_loop_hvac)
  dcv_required_when_erv_present = true
  return dcv_required_when_erv_present
end

#air_loop_hvac_demand_control_ventilation_limits(air_loop_hvac) ⇒ Array<Double>

Determines the OA flow rates above which an economizer is required. Two separate rates, one for systems with an economizer and another for systems without. are zero for both types.

Returns:

  • (Array<Double>)
    min_oa_without_economizer_cfm, min_oa_with_economizer_cfm

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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirLoopHVAC.rb', line 252

def air_loop_hvac_demand_control_ventilation_limits(air_loop_hvac)
  min_oa_without_economizer_cfm = 1500 # half of 90.1-2013 req
  min_oa_with_economizer_cfm = 375 # half of 90.1-2013 req
  return [min_oa_without_economizer_cfm, min_oa_with_economizer_cfm]
end

#air_loop_hvac_economizer_limits(air_loop_hvac, climate_zone) ⇒ Array<Double>

Determine the limits for the type of economizer present on the AirLoopHVAC, if any.

Returns:

  • (Array<Double>)
    drybulb_limit_f, enthalpy_limit_btu_per_lb, dewpoint_limit_f

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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirLoopHVAC.rb', line 36

def air_loop_hvac_economizer_limits(air_loop_hvac, climate_zone)
  drybulb_limit_f = nil
  enthalpy_limit_btu_per_lb = nil
  dewpoint_limit_f = nil

  # Get the OA system and OA controller
  oa_sys = air_loop_hvac.airLoopHVACOutdoorAirSystem
  if oa_sys.is_initialized
    oa_sys = oa_sys.get
  else
    return [nil, nil, nil] # No OA system
  end
  oa_control = oa_sys.getControllerOutdoorAir
  economizer_type = oa_control.getEconomizerControlType

  case economizer_type
  when 'NoEconomizer'
    return [nil, nil, nil]
  when 'FixedDryBulb'
    case climate_zone
    when 'ASHRAE 169-2006-1B',
        'ASHRAE 169-2006-2B',
        'ASHRAE 169-2006-3B',
        'ASHRAE 169-2006-3C',
        'ASHRAE 169-2006-4B',
        'ASHRAE 169-2006-4C',
        'ASHRAE 169-2006-5B',
        'ASHRAE 169-2006-5C',
        'ASHRAE 169-2006-6B',
        'ASHRAE 169-2006-7A',
        'ASHRAE 169-2006-7B',
        'ASHRAE 169-2006-8A',
        'ASHRAE 169-2006-8B'
      drybulb_limit_f = 75
    when 'ASHRAE 169-2006-5A',
        'ASHRAE 169-2006-6A'
      drybulb_limit_f = 70
    end
  when 'FixedEnthalpy'
    enthalpy_limit_btu_per_lb = 28
  when 'FixedDewPointAndDryBulb'
    drybulb_limit_f = 75
    dewpoint_limit_f = 55
  end

  return [drybulb_limit_f, enthalpy_limit_btu_per_lb, dewpoint_limit_f]
end

#air_loop_hvac_economizer_type_allowable?(air_loop_hvac, climate_zone) ⇒ Bool

Check the economizer type currently specified in the ControllerOutdoorAir object on this air loop is acceptable per the standard.

Returns false if the economizer type is not allowable.

Returns:

  • (Bool)

    Returns true if allowable, if the system has no economizer or no OA system.


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirLoopHVAC.rb', line 97

def air_loop_hvac_economizer_type_allowable?(air_loop_hvac, climate_zone)
  # EnergyPlus economizer types
  # 'NoEconomizer'
  # 'FixedDryBulb'
  # 'FixedEnthalpy'
  # 'DifferentialDryBulb'
  # 'DifferentialEnthalpy'
  # 'FixedDewPointAndDryBulb'
  # 'ElectronicEnthalpy'
  # 'DifferentialDryBulbAndEnthalpy'

  # Get the OA system and OA controller
  oa_sys = air_loop_hvac.airLoopHVACOutdoorAirSystem
  if oa_sys.is_initialized
    oa_sys = oa_sys.get
  else
    return true # No OA system
  end
  oa_control = oa_sys.getControllerOutdoorAir
  economizer_type = oa_control.getEconomizerControlType

  # Return true if no economizer is present
  if economizer_type == 'NoEconomizer'
    return true
  end

  # Determine the prohibited types
  prohibited_types = []
  case climate_zone
  when 'ASHRAE 169-2006-1B',
      'ASHRAE 169-2006-2B',
      'ASHRAE 169-2006-3B',
      'ASHRAE 169-2006-3C',
      'ASHRAE 169-2006-4B',
      'ASHRAE 169-2006-4C',
      'ASHRAE 169-2006-5B',
      'ASHRAE 169-2006-6B',
      'ASHRAE 169-2006-7A',
      'ASHRAE 169-2006-7B',
      'ASHRAE 169-2006-8A',
      'ASHRAE 169-2006-8B'
    prohibited_types = ['FixedEnthalpy']
  when
    'ASHRAE 169-2006-1A',
      'ASHRAE 169-2006-2A',
      'ASHRAE 169-2006-3A',
      'ASHRAE 169-2006-4A'
    prohibited_types = ['FixedDryBulb', 'DifferentialDryBulb']
  when
    'ASHRAE 169-2006-5A',
      'ASHRAE 169-2006-6A',
      prohibited_types = []
  end

  # Check if the specified type is allowed
  economizer_type_allowed = true
  if prohibited_types.include?(economizer_type)
    economizer_type_allowed = false
  end

  return economizer_type_allowed
end

#air_loop_hvac_integrated_economizer_required?(air_loop_hvac, climate_zone) ⇒ Boolean

Determine if the system economizer must be integrated or not. All economizers must be integrated in NREL ZNE Ready 2017

Returns:

  • (Boolean)

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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirLoopHVAC.rb', line 86

def air_loop_hvac_integrated_economizer_required?(air_loop_hvac, climate_zone)
  integrated_economizer_required = true
  return integrated_economizer_required
end

#air_loop_hvac_motorized_oa_damper_limits(air_loop_hvac, climate_zone) ⇒ Array<Double>

Determine the air flow and number of story limits for whether motorized OA damper is required.

Returns:

  • (Array<Double>)
    minimum_oa_flow_cfm, maximum_stories

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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirLoopHVAC.rb', line 269

def air_loop_hvac_motorized_oa_damper_limits(air_loop_hvac, climate_zone)
  case climate_zone
  when 'ASHRAE 169-2006-1A',
      'ASHRAE 169-2006-1B',
      'ASHRAE 169-2006-2A',
      'ASHRAE 169-2006-2B',
      'ASHRAE 169-2006-3A',
      'ASHRAE 169-2006-3B',
      'ASHRAE 169-2006-3C',
    minimum_oa_flow_cfm = 300
    maximum_stories = 999 # Any number of stories
  else
    minimum_oa_flow_cfm = 300
    maximum_stories = 0
  end

  return [minimum_oa_flow_cfm, maximum_stories]
end

#air_loop_hvac_multizone_vav_optimization_required?(air_loop_hvac, climate_zone) ⇒ Bool

TODO:

Add exception logic for systems with AIA healthcare ventilation requirements dual duct systems

Determine if multizone vav optimization is required.

Returns:

  • (Bool)

    Returns true if required, false if not.


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirLoopHVAC.rb', line 167

def air_loop_hvac_multizone_vav_optimization_required?(air_loop_hvac, climate_zone)
  multizone_opt_required = false

  # Not required for systems with fan-powered terminals
  num_fan_powered_terminals = 0
  air_loop_hvac.demandComponents.each do |comp|
    if comp.to_AirTerminalSingleDuctParallelPIUReheat.is_initialized || comp.to_AirTerminalSingleDuctSeriesPIUReheat.is_initialized
      num_fan_powered_terminals += 1
    end
  end
  if num_fan_powered_terminals > 0
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.AirLoopHVAC', "For #{air_loop_hvac.name}, multizone vav optimization is not required because the system has #{num_fan_powered_terminals} fan-powered terminals.")
    return multizone_opt_required
  end

  # Not required for systems that require an ERV
  if air_loop_hvac_energy_recovery?(air_loop_hvac)
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.AirLoopHVAC', "For #{air_loop_hvac.name}: multizone vav optimization is not required because the system has Energy Recovery.")
    return multizone_opt_required
  end

  # Get the OA intake
  controller_oa = nil
  controller_mv = nil
  oa_system = nil
  if air_loop_hvac.airLoopHVACOutdoorAirSystem.is_initialized
    oa_system = air_loop_hvac.airLoopHVACOutdoorAirSystem.get
    controller_oa = oa_system.getControllerOutdoorAir
    controller_mv = controller_oa.controllerMechanicalVentilation
  else
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.AirLoopHVAC', "For #{air_loop_hvac.name}, multizone optimization is not applicable because system has no OA intake.")
    return multizone_opt_required
  end

  # Get the AHU design supply air flow rate
  dsn_flow_m3_per_s = nil
  if air_loop_hvac.designSupplyAirFlowRate.is_initialized
    dsn_flow_m3_per_s = air_loop_hvac.designSupplyAirFlowRate.get
  elsif air_loop_hvac.autosizedDesignSupplyAirFlowRate.is_initialized
    dsn_flow_m3_per_s = air_loop_hvac.autosizedDesignSupplyAirFlowRate.get
  else
    OpenStudio.logFree(OpenStudio::Warn, 'openstudio.standards.AirLoopHVAC', "For #{air_loop_hvac.name} design supply air flow rate is not available, cannot apply efficiency standard.")
    return multizone_opt_required
  end
  dsn_flow_cfm = OpenStudio.convert(dsn_flow_m3_per_s, 'm^3/s', 'cfm').get

  # Get the minimum OA flow rate
  min_oa_flow_m3_per_s = nil
  if controller_oa.minimumOutdoorAirFlowRate.is_initialized
    min_oa_flow_m3_per_s = controller_oa.minimumOutdoorAirFlowRate.get
  elsif controller_oa.autosizedMinimumOutdoorAirFlowRate.is_initialized
    min_oa_flow_m3_per_s = controller_oa.autosizedMinimumOutdoorAirFlowRate.get
  else
    OpenStudio.logFree(OpenStudio::Warn, 'openstudio.standards.AirLoopHVAC', "For #{controller_oa.name}: minimum OA flow rate is not available, cannot apply efficiency standard.")
    return multizone_opt_required
  end
  min_oa_flow_cfm = OpenStudio.convert(min_oa_flow_m3_per_s, 'm^3/s', 'cfm').get

  # Calculate the percent OA at design airflow
  pct_oa = min_oa_flow_m3_per_s / dsn_flow_m3_per_s

  # Not required for systems where
  # exhaust is more than 70% of the total OA intake.
  if pct_oa > 0.7
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.AirLoopHVAC', "For #{controller_oa.name}: multizone optimization is not applicable because system is more than 70% OA.")
    return multizone_opt_required
  end

  # TODO: Not required for dual-duct systems
  # if self.isDualDuct
  # OpenStudio::logFree(OpenStudio::Info, "openstudio.standards.AirLoopHVAC", "For #{controller_oa.name}: multizone optimization is not applicable because it is a dual duct system")
  # return multizone_opt_required
  # end

  # If here, multizone vav optimization is required
  multizone_opt_required = true

  return multizone_opt_required
end

#air_loop_hvac_single_zone_controls_num_stages(air_loop_hvac, climate_zone) ⇒ Integer

Determine the number of stages that should be used as controls for single zone DX systems. NREL ZNE Ready matches 90.1-2013, and depends on the cooling capacity of the system.

Returns:

  • (Integer)

    the number of stages: 0, 1, 2


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirLoopHVAC.rb', line 293

def air_loop_hvac_single_zone_controls_num_stages(air_loop_hvac, climate_zone)
  min_clg_cap_btu_per_hr = 65_000
  clg_cap_btu_per_hr = OpenStudio.convert(air_loop_hvac_total_cooling_capacity(air_loop_hvac), 'W', 'Btu/hr').get
  if clg_cap_btu_per_hr >= min_clg_cap_btu_per_hr
    num_stages = 2
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.AirLoopHVAC', "For #{air_loop_hvac.name}: two-stage control is required since cooling capacity of #{clg_cap_btu_per_hr.round} Btu/hr exceeds the minimum of #{min_clg_cap_btu_per_hr.round} Btu/hr .")
  else
    num_stages = 1
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.AirLoopHVAC', "For #{air_loop_hvac.name}: two-stage control is not required since cooling capacity of #{clg_cap_btu_per_hr.round} Btu/hr is less than the minimum of #{min_clg_cap_btu_per_hr.round} Btu/hr .")
  end

  return num_stages
end

#air_loop_hvac_supply_air_temperature_reset_required?(air_loop_hvac, climate_zone) ⇒ Bool

Determine if the system required supply air temperature (SAT) reset. For NREL ZNE Ready 2017, SAT reset requirements are based the same climate zone requirements as 90.1-2013.

Returns:

  • (Bool)

    Returns true if required, false if not.


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirLoopHVAC.rb', line 313

def air_loop_hvac_supply_air_temperature_reset_required?(air_loop_hvac, climate_zone)
  is_sat_reset_required = false

  # Only required for multizone VAV systems
  unless air_loop_hvac_multizone_vav_system?(air_loop_hvac)
    return is_sat_reset_required
  end

  case climate_zone
  when 'ASHRAE 169-2006-1A',
    'ASHRAE 169-2006-2A',
    'ASHRAE 169-2006-3A'
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.AirLoopHVAC', "For #{air_loop_hvac.name}: Supply air temperature reset is not required per 6.5.3.4 Exception 1, the system is located in climate zone #{climate_zone}.")
    return is_sat_reset_required
  when 'ASHRAE 169-2006-1B',
    'ASHRAE 169-2006-2B',
    'ASHRAE 169-2006-3B',
    'ASHRAE 169-2006-3C',
    'ASHRAE 169-2006-4A',
    'ASHRAE 169-2006-4B',
    'ASHRAE 169-2006-4C',
    'ASHRAE 169-2006-5A',
    'ASHRAE 169-2006-5B',
    'ASHRAE 169-2006-5C',
    'ASHRAE 169-2006-6A',
    'ASHRAE 169-2006-6B',
    'ASHRAE 169-2006-7A',
    'ASHRAE 169-2006-7B',
    'ASHRAE 169-2006-8A',
    'ASHRAE 169-2006-8B'
    is_sat_reset_required = true
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.AirLoopHVAC', "For #{air_loop_hvac.name}: Supply air temperature reset is required.")
    return is_sat_reset_required
  end
end

#air_terminal_single_duct_vav_reheat_apply_initial_prototype_damper_position(air_terminal_single_duct_vav_reheat, building_type, zone_oa_per_area) ⇒ Bool

Set the initial minimum damper position based on OA rate of the space and the template. Zones with low OA per area get lower initial guesses. Final position will be adjusted upward as necessary by Standards.AirLoopHVAC.apply_minimum_vav_damper_positions

Parameters:

  • zone_oa_per_area (Double)

    the zone outdoor air per area, m^3/s

Returns:

  • (Bool)

    returns true if successful, false if not


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# File 'lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.AirTerminalSingleDuctVAVReheat.rb', line 11

def air_terminal_single_duct_vav_reheat_apply_initial_prototype_damper_position(air_terminal_single_duct_vav_reheat, building_type, zone_oa_per_area)
  vav_name = air_terminal_single_duct_vav_reheat.name.get
  min_damper_position = case air_terminal_single_duct_vav_reheat_reheat_type(air_terminal_single_duct_vav_reheat)
                        when 'HotWater'
                          0.2
                        when 'Electricity', 'NaturalGas'
                          0.3
                        end

  # High OA zones
  # Determine whether or not to use the high minimum guess.
  # Cutoff was determined by correlating apparent minimum guesses
  # to OA rates in prototypes since not well documented in papers.
  if zone_oa_per_area > 0.001 # 0.001 m^3/s*m^2 = .196 cfm/ft2
    if building_type == 'Outpatient'
      min_damper_position = 1.0
    elsif building_type == 'Hospital'
      if vav_name.include? 'PatRoom'
        min_damper_position = 0.5
      else
        min_damper_position = 1.0
        min_damper_position = 1.0
      end
    else
      min_damper_position = 0.7
    end
  end

  # Set the minimum flow fraction
  air_terminal_single_duct_vav_reheat.setConstantMinimumAirFlowFraction(min_damper_position)

  return true
end

#air_terminal_single_duct_vav_reheat_minimum_damper_position(air_terminal_single_duct_vav_reheat, has_ddc = false) ⇒ Object

Specifies the minimum damper position for VAV dampers. For terminals with hot water heat and DDC, the minimum is 20%, otherwise the minimum is 30%.

Parameters:

  • has_ddc (Bool) (defaults to: false)

    whether or not there is DDC control of the VAV terminal in question


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.AirTerminalSingleDuctVAVReheat.rb', line 9

def air_terminal_single_duct_vav_reheat_minimum_damper_position(air_terminal_single_duct_vav_reheat, has_ddc = false)
  min_damper_position = nil
  case air_terminal_single_duct_vav_reheat_reheat_type(air_terminal_single_duct_vav_reheat)
  when 'HotWater'
    min_damper_position = if has_ddc
                            0.2
                          else
                            0.3
                          end
  when 'Electricity', 'NaturalGas'
    min_damper_position = 0.3
  end

  return min_damper_position
end

#cooling_tower_apply_minimum_power_per_flow_gpm_limit(cooling_tower) ⇒ Double Originally defined in module NRELZNEReady2017CoolingTower

Above this point, centrifugal fan cooling towers must meet the limits of propeller or axial cooling towers instead. 90.1 6.5.5.3 Limit on Centrifugal Fan Open Circuit Cooling Towers. is 1,100 gallons per minute.

OpenStudio::Model::CoolingTowerTwoSpeed, OpenStudio::Model::CoolingTowerVariableSpeed] the cooling tower

Parameters:

  • cooling_tower (OpenStudio::Model::CoolingTowerSingleSpeed, )

    ooling_tower [OpenStudio::Model::CoolingTowerSingleSpeed,

Returns:

  • (Double)

    the limit, in gallons per minute. Return nil for no limit.

#cooling_tower_variable_speed_apply_efficiency_and_curves(cooling_tower_variable_speed) ⇒ Object

Apply the efficiency, plus Multicell heat rejection with VSD per 90.1-2013 6.5.2.2

Parameters:

  • cooling_tower_variable_speed (OpenStudio::Model::CoolingTowerVariableSpeed)

    the cooling tower


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.CoolingTowerVariableSpeed.rb', line 9

def cooling_tower_variable_speed_apply_efficiency_and_curves(cooling_tower_variable_speed)
  cooling_tower_apply_minimum_power_per_flow(cooling_tower_variable_speed)

  cooling_tower_variable_speed.setCellControl('MaximalCell')

  return true
end

#fan_constant_volume_airloop_fan_pressure_rise(fan_constant_volume) ⇒ Double

Determine the prototype fan pressure rise for a constant volume fan on an AirLoopHVAC based on the airflow of the system. to the logic from ASHRAE 90.1-2004 prototypes.

Returns:

  • (Double)

    the pressure rise (in H2O). Defaults


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# File 'lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.FanConstantVolume.rb', line 8

def fan_constant_volume_airloop_fan_pressure_rise(fan_constant_volume)
  # Get the max flow rate from the fan.
  maximum_flow_rate_m3_per_s = nil
  if fan_constant_volume.maximumFlowRate.is_initialized
    maximum_flow_rate_m3_per_s = fan_constant_volume.maximumFlowRate.get
  elsif fan_constant_volume.autosizedMaximumFlowRate.is_initialized
    maximum_flow_rate_m3_per_s = fan_constant_volume.autosizedMaximumFlowRate.get
  else
    OpenStudio.logFree(OpenStudio::Warn, 'openstudio.prototype.FanConstantVolume', "For #{fan_constant_volume.name} max flow rate is not available, cannot apply prototype assumptions.")
    return false
  end

  # Convert max flow rate to cfm
  maximum_flow_rate_cfm = OpenStudio.convert(maximum_flow_rate_m3_per_s, 'm^3/s', 'cfm').get

  # Determine the pressure rise
  pressure_rise_in_h2o = if maximum_flow_rate_cfm < 7437
                           2.5
                         else # Over 7,437 cfm
                           4.09
                         end

  return pressure_rise_in_h2o
end

#fan_on_off_airloop_or_unitary_fan_pressure_rise(fan_on_off) ⇒ Double

Determine the prototype fan pressure rise for an on off fan on an AirLoopHVAC or inside a unitary system based on the airflow of the system. to the logic from ASHRAE 90.1-2004 prototypes.

Returns:

  • (Double)

    the pressure rise (in H2O). Defaults


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# File 'lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.FanOnOff.rb', line 9

def fan_on_off_airloop_or_unitary_fan_pressure_rise(fan_on_off)
  # Get the max flow rate from the fan.
  maximum_flow_rate_m3_per_s = nil
  if fan_on_off.maximumFlowRate.is_initialized
    maximum_flow_rate_m3_per_s = fan_on_off.maximumFlowRate.get
  elsif fan_on_off.autosizedMaximumFlowRate.is_initialized
    maximum_flow_rate_m3_per_s = fan_on_off.autosizedMaximumFlowRate.get
  else
    OpenStudio.logFree(OpenStudio::Warn, 'openstudio.prototype.FanOnOff', "For #{fan_on_off.name} max flow rate is not available, cannot apply prototype assumptions.")
    return false
  end

  # Convert max flow rate to cfm
  maximum_flow_rate_cfm = OpenStudio.convert(maximum_flow_rate_m3_per_s, 'm^3/s', 'cfm').get

  # Determine the pressure rise
  pressure_rise_in_h2o = if maximum_flow_rate_cfm < 7437
                           2.5
                         else # Over 7,437 cfm
                           4.09
                         end

  return pressure_rise_in_h2o
end

#fan_variable_volume_airloop_fan_pressure_rise(fan_variable_volume) ⇒ Double

Determine the prototype fan pressure rise for a variable volume fan on an AirLoopHVAC based on the airflow of the system. to the logic from ASHRAE 90.1-2004 prototypes.

Returns:

  • (Double)

    the pressure rise (in H2O). Defaults


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# File 'lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.FanVariableVolume.rb', line 8

def fan_variable_volume_airloop_fan_pressure_rise(fan_variable_volume)
  # Get the max flow rate from the fan.
  maximum_flow_rate_m3_per_s = nil
  if fan_variable_volume.maximumFlowRate.is_initialized
    maximum_flow_rate_m3_per_s = fan_variable_volume.maximumFlowRate.get
  elsif fan_variable_volume.autosizedMaximumFlowRate.is_initialized
    maximum_flow_rate_m3_per_s = fan_variable_volume.autosizedMaximumFlowRate.get
  else
    OpenStudio.logFree(OpenStudio::Warn, 'openstudio.prototype.FanVariableVolume', "For #{fan_variable_volume.name} max flow rate is not available, cannot apply prototype assumptions.")
    return false
  end

  # Convert max flow rate to cfm
  maximum_flow_rate_cfm = OpenStudio.convert(maximum_flow_rate_m3_per_s, 'm^3/s', 'cfm').get

  # Determine the pressure rise
  pressure_rise_in_h2o = if maximum_flow_rate_cfm < 4648
                           4.0
                         else # Over 7,437 cfm
                           5.58
                         end

  return pressure_rise_in_h2o
end

#fan_variable_volume_part_load_fan_power_limitation_capacity_limit(fan_variable_volume) ⇒ Double

The threhold capacity below which part load control is not required. Per 90.1-2013, table 6.5.3.2.1: the cooling capacity threshold is 75000 instead of 110000 as of 1/1/2014

Parameters:

  • fan_variable_volume (OpenStudio::Model::FanVariableVolume)

    the fan

Returns:

  • (Double)

    the limit, in Btu/hr. Return nil for no limit by default.


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.FanVariableVolume.rb', line 29

def fan_variable_volume_part_load_fan_power_limitation_capacity_limit(fan_variable_volume)
  cap_limit_btu_per_hr = case fan_variable_volume_cooling_system_type(fan_variable_volume)
                         when 'dx'
                           110_000
                         end

  return cap_limit_btu_per_hr
end

#fan_variable_volume_part_load_fan_power_limitation_hp_limit(fan_variable_volume) ⇒ Double

The threhold horsepower below which part load control is not required. Per 90.1-2013, table 6.5.3.2.1: the fan motor size for chiller-water and evaporative cooling is 0.25 hp as of 1/1/2014 instead of 5 hp

Parameters:

  • fan_variable_volume (OpenStudio::Model::FanVariableVolume)

    the fan

Returns:

  • (Double)

    the limit, in horsepower. Return nil for no limit by default.


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.FanVariableVolume.rb', line 10

def fan_variable_volume_part_load_fan_power_limitation_hp_limit(fan_variable_volume)
  hp_limit = case fan_variable_volume_cooling_system_type(fan_variable_volume)
             when 'dx'
               0.0
             when 'chw'
               0.25
             when 'evap'
               0.25
             end

  return hp_limit
end

#heat_exchanger_air_to_air_sensible_and_latent_minimum_efficiency(heat_exchanger_air_to_air_sensible_and_latent) ⇒ Object

Defines the minimum sensible and latent effectiveness of the heat exchanger. Assumed to apply to sensible and latent effectiveness at all flow rates. For NREL ZNE Ready 2017, assume 70% effectiveness, as this is higher than the typical 90.1 minimum of 50%, and is easily achievable with an enthalpy wheel.

Parameters:

  • heat_exchanger_air_to_air_sensible_and_latent (OpenStudio::Model::HeatExchangerAirToAirSensibleAndLatent)

    the heat exchanger


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.HeatExchangerSensLat.rb', line 11

def heat_exchanger_air_to_air_sensible_and_latent_minimum_efficiency(heat_exchanger_air_to_air_sensible_and_latent)
  min_effct = 0.7
  return min_effct
end

#model_cw_loop_cooling_tower_fan_type(model) ⇒ String

Determine which type of fan the cooling tower will have. Variable Speed Fan for NREL ZNE Ready 2017.

Returns:

  • (String)

    the fan type: TwoSpeed Fan, Variable Speed Fan


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# File 'lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.hvac_systems.rb', line 7

def model_cw_loop_cooling_tower_fan_type(model)
  fan_type = 'Variable Speed Fan'
  return fan_type
end

#model_economizer_type(model, climate_zone) ⇒ String

Determine the prototypical economizer type for the model.

'NoEconomizer' 'FixedDryBulb' 'FixedEnthalpy' 'DifferentialDryBulb' 'DifferentialEnthalpy' 'FixedDewPointAndDryBulb' 'ElectronicEnthalpy' 'DifferentialDryBulbAndEnthalpy'

Parameters:

  • model (OpenStudio::Model::Model)

    the model

  • climate_zone (String)

    the climate zone

Returns:

  • (String)

    the economizer type. Possible values are:


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# File 'lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.Model.rb', line 17

def model_economizer_type(model, climate_zone)
  economizer_type = case climate_zone
                    when 'ASHRAE 169-2006-1A',
                        'ASHRAE 169-2006-2A',
                        'ASHRAE 169-2006-3A',
                        'ASHRAE 169-2006-4A'
                      'DifferentialEnthalpy'
                    else
                      'DifferentialDryBulb'
                    end
  return economizer_type
end

#model_elevator_fan_pwr(model, vent_rate_cfm) ⇒ Double

Determines the power of the elevator ventilation fan. Same as 90.1-2013, which has a requirement for ventilation fan efficiency.

Returns:

  • (Double)

    the ventilaton fan power (W)


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# File 'lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.Model.elevators.rb', line 17

def model_elevator_fan_pwr(model, vent_rate_cfm)
  vent_pwr_per_flow_w_per_cfm = 0.33
  vent_pwr_w = vent_pwr_per_flow_w_per_cfm * vent_rate_cfm  # addendum 90.1-2007 aj has requirement on efficiency

  vent_pwr_w = vent_pwr_w * 0.29 / 0.70

  return vent_pwr_w
end

#model_elevator_lighting_pct_incandescent(model) ⇒ Object

Determines the percentage of the elevator cab lighting that is incandescent. The remainder is assumed to be LED. Defaults to 0% incandescent (100% LED), representing newer elevators.


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# File 'lib/openstudio-standards/prototypes/ashrae_90_1/nrel_nze_ready_2017/nrel_zne_ready_2017.Model.elevators.rb', line 8

def model_elevator_lighting_pct_incandescent(model)
  pct_incandescent = 0.0 # 100% LED
  return pct_incandescent
end

#space_daylighted_area_window_width(space) ⇒ String

Determines the method used to extend the daylighted area horizontally next to a window. If the method is 'fixed', 2 ft is added to the width of each window. If the method is 'proportional', a distance equal to half of the head height of the window is added. If the method is 'none', no additional width is added.

Returns:

  • (String)

    returns 'fixed' or 'proportional'


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.Space.rb', line 11

def space_daylighted_area_window_width(space)
  method = 'proportional'
  return method
end

#space_daylighting_control_required?(space, areas) ⇒ Array<Bool>

Determine if the space requires daylighting controls for toplighting, primary sidelighting, and secondary sidelighting. Defaults to false for all types.

Parameters:

  • space (OpenStudio::Model::Space)

    the space in question

  • areas (Hash)

    a hash of daylighted areas

Returns:

  • (Array<Bool>)

    req_top_ctrl, req_pri_ctrl, req_sec_ctrl


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.Space.rb', line 23

def space_daylighting_control_required?(space, areas)
  req_top_ctrl = true
  req_pri_ctrl = true
  req_sec_ctrl = true

  # Get the LPD of the space
  space_lpd_w_per_m2 = space.lightingPowerPerFloorArea

  # Primary Sidelighting
  # Check if the primary sidelit area contains less than 150W of lighting
  if areas['primary_sidelighted_area'] == 0.0
    OpenStudio.logFree(OpenStudio::Debug, 'openstudio.model.Space', "For #{space.name}, primary sidelighting control not required because primary sidelighted area = 0ft2 per 9.4.1.1(e).")
    req_pri_ctrl = false
  elsif areas['primary_sidelighted_area'] * space_lpd_w_per_m2 < 150.0
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.model.Space', "For #{space.name}, primary sidelighting control not required because less than 150W of lighting are present in the primary daylighted area per 9.4.1.1(e).")
    req_pri_ctrl = false
  else
    # Check the size of the windows
    if areas['total_window_area'] < OpenStudio.convert(20.0, 'ft^2', 'm^2').get
      OpenStudio.logFree(OpenStudio::Info, 'openstudio.model.Space', "For #{space.name}, primary sidelighting control not required because there are less than 20ft2 of window per 9.4.1.1(e) Exception 2.")
      req_pri_ctrl = false
    end
  end

  # Secondary Sidelighting
  # Check if the primary and secondary sidelit areas contains less than 300W of lighting
  if areas['secondary_sidelighted_area'] == 0.0
    OpenStudio.logFree(OpenStudio::Debug, 'openstudio.model.Space', "For #{space.name}, secondary sidelighting control not required because secondary sidelighted area = 0ft2 per 9.4.1.1(e).")
    req_sec_ctrl = false
  elsif (areas['primary_sidelighted_area'] + areas['secondary_sidelighted_area']) * space_lpd_w_per_m2 < 300
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.model.Space', "For #{space.name}, secondary sidelighting control not required because less than 300W of lighting are present in the combined primary and secondary daylighted areas per 9.4.1.1(e).")
    req_sec_ctrl = false
  else
    # Check the size of the windows
    if areas['total_window_area'] < OpenStudio.convert(20.0, 'ft^2', 'm^2').get
      OpenStudio.logFree(OpenStudio::Info, 'openstudio.model.Space', "For #{space.name}, secondary sidelighting control not required because there are less than 20ft2 of window per 9.4.1.1(e) Exception 2.")
      req_sec_ctrl = false
    end
  end

  # Toplighting
  # Check if the toplit area contains less than 150W of lighting
  if areas['toplighted_area'] == 0.0
    OpenStudio.logFree(OpenStudio::Debug, 'openstudio.model.Space', "For #{space.name}, toplighting control not required because toplighted area = 0ft2 per 9.4.1.1(f).")
    req_top_ctrl = false
  elsif areas['toplighted_area'] * space_lpd_w_per_m2 < 150
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.model.Space', "For #{space.name}, toplighting control not required because less than 150W of lighting are present in the toplighted area per 9.4.1.1(f).")
    req_top_ctrl = false
  end

  return [req_top_ctrl, req_pri_ctrl, req_sec_ctrl]
end

#space_daylighting_fractions_and_windows(space, areas, sorted_windows, sorted_skylights, req_top_ctrl, req_pri_ctrl, req_sec_ctrl) ⇒ Object

Determine the fraction controlled by each sensor and which window each sensor should go near.

Parameters:

  • space (OpenStudio::Model::Space)

    the space with the daylighting

  • sorted_windows (Hash)

    a hash of windows, sorted by priority

  • sorted_skylights (Hash)

    a hash of skylights, sorted by priority

  • req_top_ctrl (Bool)

    if toplighting controls are required

  • req_pri_ctrl (Bool)

    if primary sidelighting controls are required

  • req_sec_ctrl (Bool)

    if secondary sidelighting controls are required


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.Space.rb', line 85

def space_daylighting_fractions_and_windows(space,
                                            areas,
                                            sorted_windows,
                                            sorted_skylights,
                                            req_top_ctrl,
                                            req_pri_ctrl,
                                            req_sec_ctrl)
  sensor_1_frac = 0.0
  sensor_2_frac = 0.0
  sensor_1_window = nil
  sensor_2_window = nil

  # Get the area of the space
  space_area_m2 = space.floorArea

  if req_top_ctrl && req_pri_ctrl && req_sec_ctrl    # Sensor 1 controls toplighted area

    sensor_1_frac = areas['toplighted_area'] / space_area_m2
    sensor_1_window = sorted_skylights[0]    # Sensor 2 controls primary + secondary area

    sensor_2_frac = (areas['primary_sidelighted_area'] + areas['secondary_sidelighted_area']) / space_area_m2
    sensor_2_window = sorted_windows[0]
  elsif !req_top_ctrl && req_pri_ctrl && req_sec_ctrl    # Sensor 1 controls primary area

    sensor_1_frac = areas['primary_sidelighted_area'] / space_area_m2
    sensor_1_window = sorted_windows[0]    # Sensor 2 controls secondary area

    sensor_2_frac = (areas['secondary_sidelighted_area'] / space_area_m2)
    sensor_2_window = sorted_windows[0]
  elsif req_top_ctrl && !req_pri_ctrl && req_sec_ctrl    # Sensor 1 controls toplighted area

    sensor_1_frac = areas['toplighted_area'] / space_area_m2
    sensor_1_window = sorted_skylights[0]    # Sensor 2 controls secondary area

    sensor_2_frac = (areas['secondary_sidelighted_area'] / space_area_m2)
    sensor_2_window = sorted_windows[0]
  elsif req_top_ctrl && !req_pri_ctrl && !req_sec_ctrl    # Sensor 1 controls toplighted area

    sensor_1_frac = areas['toplighted_area'] / space_area_m2
    sensor_1_window = sorted_skylights[0]
  elsif !req_top_ctrl && req_pri_ctrl && !req_sec_ctrl    # Sensor 1 controls primary area

    sensor_1_frac = areas['primary_sidelighted_area'] / space_area_m2
    sensor_1_window = sorted_windows[0]
  elsif !req_top_ctrl && !req_pri_ctrl && req_sec_ctrl    # Sensor 1 controls secondary area

    sensor_1_frac = areas['secondary_sidelighted_area'] / space_area_m2
    sensor_1_window = sorted_windows[0]
  end

  return [sensor_1_frac, sensor_2_frac, sensor_1_window, sensor_2_window]
end

#space_infiltration_rate_75_pa(space) ⇒ Double

Determine the base infiltration rate at 75 PA.

defaults to no infiltration.

Returns:

  • (Double)

    the baseline infiltration rate, in cfm/ft^2


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.Space.rb', line 142

def space_infiltration_rate_75_pa(space)
  basic_infil_rate_cfm_per_ft2 = 0.5 # Half of 90.1-2013
  return basic_infil_rate_cfm_per_ft2
end

#thermal_zone_demand_control_ventilation_limits(thermal_zone) ⇒ Array<Double>

Determine the area and occupancy level limits for demand control ventilation.

and the minimum occupancy density in m^2/person. Returns nil if there is no requirement.

Parameters:

  • thermal_zone (OpenStudio::Model::ThermalZone)

    the thermal zone

Returns:

  • (Array<Double>)

    the minimum area, in m^2


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# File 'lib/openstudio-standards/standards/ashrae_90_1/nrel_zne_ready_2017/nrel_zne_ready_2017.ThermalZone.rb', line 11

def thermal_zone_demand_control_ventilation_limits(thermal_zone)
  min_area_ft2 = 500
  min_occ_per_1000_ft2 = 12 # half of 90.1-2013

  # Convert to SI
  min_area_m2 = OpenStudio.convert(min_area_ft2, 'ft^2', 'm^2').get
  min_occ_per_ft2 = min_occ_per_1000_ft2 / 1000.0
  min_ft2_per_occ = 1.0 / min_occ_per_ft2
  min_m2_per_occ = OpenStudio.convert(min_ft2_per_occ, 'ft^2', 'm^2').get

  return [min_area_m2, min_m2_per_occ]
end