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Features

openstudio-standards is intended for four main use-cases in mind:

  1. Provide higher level methods to help BEM users and developers to create OpenStudio models from existing geometry, or programmatically generated geometry
  2. Create typical building models in OpenStudio format
  3. Create a code baseline model from a proposed model
  4. Check a model against a code/standard

openstudio-standards previously supported making the DOE/PNNL prototype buildings in OpenStudio format. This has since been deprecated, as the DOE/PNNL prototypes are intended for specific code comparisons under the Energy Policy Act and are not intended to accurately represent typical existing or new buildings. While openstudio-standards still creates typical buildings, these are not the same as the DOE/PNNL prototypes.

The four main use-cases are all highly related, and share many common subtasks. For example, typical buildings tend to follow minimally code-compliant DX coil efficiencies at the time of construction. Code baseline modeling also requires setting DX coil efficiencies. And checking a model against a code or standard also requires looking up DX coil efficiencies. These methods require access to the information about the minimum efficiencies, u-values, etc. that are defined in the /data/standards directory.

The code has been structured such that several higher level methods may all call the same lower level method. For example, both of the methods below eventually call space_type_add_loads. Rather than having two copies of this code inside of the two top level methods, there is one method.

model_create_prototype_building('Small Office, '90.1-2010', 'ASHRAE 169-2013-5A')
	model_add_schedules
		space_type_add_schedules
	model_apply_standard
		space_type_add_loads(people = true, lights = true, plug_loads = true)

model_create_prm_baseline_building('Small Office', '90.1-2010', 'ASHRAE 169-2013-5A', 'Xcel Energy CO EDA', Dir.pwd, false)
	model_add_baseline_hvac_systems
	model_apply_standard
		space_type_add_loads(people = true, lights = true, plug_loads = false)

Where a method needs to operate slightly differently in two different situations, instead of duplicating the code, we make an input argument to tell that method what to do. In the example above, space_type_add_loads is called with plug_loads = true when creating the prototype building, but plug_loads = false when creating the baseline model, since plug loads stay the same as the proposed model in Appendix G.

Where a method needs to operate very differently in two different situations, it should be broken out into a separate method.

Outline of the main methods

model_create_prototype_model()**

  • load_geometry() Loads an .osm containing the geomety (including Spaces and SpaceTypes with types assigned) of the model.
  • model_add_loads() For each SpaceType in the model:
    • space_type_apply_internal_loads() Looks up internal loads from the OpenStudio_Standards_space_types.json and sets them
    • space_type_apply_internal_load_schedules() Looks up internal load schedules from the OpenStudio_Standards_space_types.json and sets them
  • model_apply_infiltration_standard() For each Space in the model:
    • space_apply_infiltration_rate() Sets the infiltration rate for this Space based on its exterior surface area.
  • model_modify_infiltration_coefficients() Sets the terrain and infiltration velocity coefficients.
  • model_modify_surface_convection_algorithm() Sets the correct simulation settings for surface convection.
  • model_add_constructions() Creates some generic constructions used by all Prototype models (interior walls, internal mass, etc.).
    • model_add_construction_set() Looks up the construction set for this building type from OpenStudio_Standards_construction_sets.json and adds all constructions in it to the model.
    • model_add_construction_set() Looks up the construction set for each SpaceType from OpenStudio_Standards_construction_sets.json and adds all constructions in it to the model. SpaceTypes only have construction sets where they differ from the overall building construction set.
  • model_create_thermal_zones() Creates one ThermalZone with a ThermostatSetpointDualSetpoint for each Space in the model. Also sets zone multipliers if defined in /prototypes/Prototype.large_office.rb.
  • model_add_hvac()
    • model_define_hvac_system_map() Get a map of HVAC system types from /prototypes/Prototype.large_office.rb
    • For each system type listed in the map, create the system using methods like model_add_cw_loop() and model_add_psz_ac(). Note that these methods only create the basic system layout; component efficiencies and code-mandated controls are applied later. Some of the inputs, like which type of heating or cooling fuel to use for these methods are pulled from OpenStudio_Standards_prototype_inputs.json.
  • model_custom_hvac_tweaks() Some building types have unique HVAC system characteristics. Rather than putting lots of special conditions for each building type into methods like model_add_psz_ac, the changes are defined in isolation for each building type and are made after adding the systems.
  • model_add_swh() For each service water type (main, booster, laundry) listed in OpenStudio_Standards_prototype_inputs.json. NOTE: this method is complex because of the inconsistencies in the way water use equipment is specified between different building types. There is opportunity here to streamline the approach
    • model_add_swh_loop() Adds a hot water loop
    • model_add_swh_end_uses() Adds WaterUseEquipment as specified in OpenStudio_Standards_prototype_inputs.json.
    • model_add_swh_end_uses_by_space() Adds WaterUseEquipment on a space-by-space basis based on the information in OpenStudio_Standards_space_types.json
  • model_add_exterior_lights() Adds Exteriorlights to the model as specified in OpenStudio_Standards_prototype_inputs.json.
  • model_add_occupancy_sensors() Adds lighting power reductions on a space-by-space basis based on SpaceType. NOTE: This method requires pre-computed assumptions about how much of each SpaceType exists in some models. It would be better to make this more generic.
  • model_add_design_days_and_weather_file() Adds design days and weather file for the specified climate zone.
  • model_apply_sizing_parameters() Sets the heating and cooling sizing factors. NOTE: These are not consistent between building types. Why?
  • model_run_sizing_run() Runs the first sizing run. Equipment sizes (mainly flow rates) are necessary for some of the subsequent steps.
  • model_apply_multizone_vav_outdoor_air_sizing() Reset damper positions on VAV systems to achieve a 60% ventilation effectiveness based on the 62.1 multizone calculations.
  • model_apply_prototype_hvac_assumptions() Apply Prototype-building-specific assumptions. These are things not governed by the Standard.
    • fan_apply_prototype_fan_pressure_rise() For each Fan (all types) set the pressure rise.
    • fan_apply_prototype_fan_efficiency() For each Fan (all types) set the fan efficiency.
    • air_loop_hvac_economizer_required?() Determine if an economizer is required. If it is, apply the type specified by the Prototype.
  • model_apply_hvac_efficiency_standard() Apply the HVAC efficiency standard
    • air_loop_hvac_apply_standard_controls() For each AirLoopHVAC apply the standard-mandated controls
      • air_loop_hvac_energy_recovery_ventilator_required?() Checks if ERV is required.
        • air_loop_hvac_apply_energy_recovery_ventilator() Applies ERV.
      • air_loop_hvac_apply_economizer_limits() Sets the economizer limits based on previously-assigned type.
      • air_loop_hvac_apply_economizer_integration() Sets economizer as integrated or non-integrated.
      • air_loop_hvac_multizone_vav_system?() For multizone VAV systems:
        • air_loop_hvac_apply_vav_damper_action() Sets damper action
        • air_loop_hvac_multizone_vav_optimization_required?() Checks if multizone VAV optimization is required.
          • air_loop_hvac_enable_multizone_vav_optimization() Enables multizone VAV optimization.
        • air_loop_hvac_static_pressure_reset_required?() Checks if static pressure reset is required.
          • fan_set_control_type() Applies static pressure reset to the fan.
      • air_loop_hvac_apply_single_zone_controls() Applies single-zone system controls.
      • air_loop_hvac_demand_control_ventilation_required?() Checks if DCV is required.
        • air_loop_hvac_enable_demand_control_ventilation() Applies DCV.
      • air_loop_hvac_supply_air_temperature_reset_required?() Checks if SAT reset is required.
        • air_loop_hvac_enable_supply_air_temperature_reset_warmest_zone() Enables worst-case zone based SAT reset. NOTE: PRM RM requires this method, but Prototypes use OAT-base reset. Why?
      • air_loop_hvac_unoccupied_fan_shutoff_required?() Checks if unoccupied hours fan shutoff is required.
        • air_loop_hvac_enable_unoccupied_fan_shutoff() Shuts off fan during unoccupied hours, otherwise set to Always-On.
      • air_loop_hvac_motorized_oa_damper_required?() Checks if motorized OA damper is required.
        • air_loop_hvac_add_motorized_oa_damper() Adds motorized OA damper.
    • fan_apply_standard_minimum_motor_efficiency() Sets fan motor efficiencies from OpenStudio_Standards_motors.json.
    • pump_apply_standard_minimum_motor_efficiency() Sets pump motor efficiencies from OpenStudio_Standards_motors.json.
    • coil_cooling_dx_two_speed_apply_efficiency_and_curves() Sets efficiencies and curves from OpenStudio_Standards_unitary_acs.json.
    • coil_cooling_dx_single_speed_apply_efficiency_and_curves() Sets efficiencies and curves from OpenStudio_Standards_unitary_acs.json.
    • coil_heating_dx_single_speed_.apply_efficiency_and_curves() Sets efficiencies and curves from OpenStudio_Standards_heat_pumps_heating.json.
    • chiller_electric_eir_apply_efficiency_and_curves() Sets efficiencies and curves from OpenStudio_Standards_chillers.json.
    • boiler_hot_water_apply_efficiency_and_curves() Sets efficiencies and curves from OpenStudio_Standards_boilers.json.
    • water_heater_mixed_apply_efficiency() Sets efficiencies and curves.
    • cooling_tower_single_speeapply_efficiency_and_curves() Sets efficiencies and curves.
    • cooling_tower_two_speed_apply_efficiency_and_curves() Sets efficiencies and curves.
    • cooling_tower_variable_speed_apply_efficiency_and_curves() Sets efficiencies and curves.
  • model_custom_swh_tweaks() Some building types have even more unique SWH characteristics. This approach keeps them isolated, which makes the already-complex methods model_add_swh() as simple as possible.
  • model_custom_geometry_tweaks() Some building types have even more unique geometry characteristics. This approach keeps them isolated.
  • model_add_daylighting_controls() Adds daylighting controls to the model. NOTE: This should probably be moved before the first sizing run.

model_create_prm_baseline_building()**

  • model_getBuilding.setName() Sets the name of the building to let you know what standard was applied.
  • model_remove_external_shading_devices() Removes external shading devices.
  • model_apply_performance_rating_method_baseline_window_to_wall_ratio() Reduces WWR, if necessary.
  • model_apply_performance_rating_method_baseline_skylight_to_roof_ratio() Reduces SRR, if necessary.
  • model_assign_spaces_to_stories() If the user has not grouped their Spaces by BuildingStory, infer stories based on Z-height of Space floor surfaces. Stories are necessary for baseline system addition.
  • 'space_type_apply_internal_loads()** For each SpaceType, modify the lighting loads, keeping all other user-defined loads. For this to work, the user must set the standardsBuildingTypeandstandardsSpaceTypeproperties for allSpaceTypes` in their model.
  • model_apply_performance_rating_method_construction_types() For each Construction, apply the standard construction types (e.g. IEAD, SteelFramed, WoodFramed) based on the types of Surfaces it is used on.
  • model_apply_standard_constructions() For each Construction, look up the construction properties from OpenStudio_Standards_construction_properties.json, create constructions representing these properties, and assign to the appropriate Surfaces.
  • model_performance_rating_method_baseline_system_groups() Group the zones based on fuel type and occupancy type.
  • model_remove_performance_rating_method_hvac() Remove the HVAC from the model. Don't remove SWH loops.
  • water_heater_mixed_apply_performance_rating_method_baseline_fuel_type() For each 'water_heater_mixed_' set the fuel type.
  • model_performance_rating_method_baseline_system_type() For each Group of zones, determine the baseline system type.
    • model_add_performance_rating_method_baseline_system() For each Group of zones, add the baseline HVAC system.
      • 'model_add_hw_loop(), model_add_pvav_pfp_boxes(), etcThere is a method for each type of system. These are also used by themodel_create_prototype_building()`**.
  • ThermalZone.apply_performance_rating_method_baseline_supply_temperatures() For each ThermalZone, set the zone sizing SAT based on the thermosat setpoints.
  • air_loop_hvac_apply_performance_rating_method_baseline_controls() For each AirLoopHVAC, apply the controls specified in the baseline model that are not mandated by the standard.
    • air_loop_hvac_performance_rating_method_baseline_economizer_required?() Check if PRM requires an economizer.
      • **air_loop_hvac_apply_performance_rating_method_baseline_economizer(template, climate_zone) Apply the economizer.
    • air_loop_hvac_supply_air_temperature_reset_required?() Checks if SAT reset is required.
      • air_loop_hvac_enable_supply_air_temperature_reset_warmest_zone() Enables worst-case zone based SAT reset.
    • air_loop_hvac_self.enable_unoccupied_fan_shutoff() Schedule fans off when not occupied.
  • air_loop_hvac_apply_minimum_vav_damper_positions() For each AirLoopHVAC, apply the minimum damper positions, assuming no DDC control of VAV terminals
  • plant_loop_apply_performance_rating_method_baseline_temperatures() For each PlantLoop, apply the baseline system setpoint temperatures.
  • model_run_sizing_run() Runs the first sizing run. Equipment sizes (mainly flow rates) are necessary for some of the subsequent steps.
  • model_apply_multizone_vav_outdoor_air_sizing() Reset damper positions on VAV systems to achieve a 60% ventilation effectiveness based on the 62.1 multizone calculations.
  • air_loop_hvac_apply_performance_rating_method_baseline_fan_power() For each AirLoopHVAC, set the baseline fan power.
  • plant_loop_apply_performance_rating_method_number_of_boilers() For each PlantLoop, set the number of boilers.
  • plant_loop_apply_performance_rating_method_number_of_chillers() For each PlantLoop, set the number of chillers.
  • plant_loop_apply_performance_rating_method_number_of_cooling_towers() For each PlantLoop, set the number of cooling towers.
  • model_run_sizing_run() Runs the second sizing run with new chillers, boilers, and cooling towers to determine capacities.
  • plant_loop_apply_performance_rating_method_baseline_pump_power() For each PlantLoop, set the pumping power.
  • plant_loop_apply_performance_rating_method_baseline_pumping_type() For each PlantLoop, set the pumping control type.
  • model_apply_hvac_efficiency_standard() Apply the HVAC efficiency standard
    • air_loop_hvac_apply_standard_controls() For each AirLoopHVAC apply the standard-mandated controls
      • air_loop_hvac_energy_recovery_ventilator_required?() Checks if ERV is required.
        • air_loop_hvac_apply_energy_recovery_ventilator() Applies ERV.
      • air_loop_hvac_apply_economizer_limits() Sets the economizer limits based on previously-assigned type.
      • air_loop_hvac_apply_economizer_integration() Sets economizer as integrated or non-integrated.
      • air_loop_hvac_multizone_vav_system?() For multizone VAV systems:
        • air_loop_hvac_apply_vav_damper_action() Sets damper action
        • air_loop_hvac_multizone_vav_optimization_required?() Checks if multizone VAV optimization is required.
          • air_loop_hvac_enable_multizone_vav_optimization() Enables multizone VAV optimization.
        • air_loop_hvac_static_pressure_reset_required?() Checks if static pressure reset is required.
          • fan_set_control_type() Applies static pressure reset to the fan.
      • air_loop_hvac_apply_single_zone_controls() Applies single-zone system controls.
      • air_loop_hvac_demand_control_ventilation_required?() Checks if DCV is required.
        • air_loop_hvac_enable_demand_control_ventilation() Applies DCV.
      • air_loop_hvac_supply_air_temperature_reset_required?() Checks if SAT reset is required.
        • air_loop_hvac_enable_supply_air_temperature_reset_warmest_zone() Enables worst-case zone based SAT reset. NOTE: PRM RM requires this method, but Prototypes use OAT-base reset. Why?
      • air_loop_hvac_unoccupied_fan_shutoff_required?() Checks if unoccupied hours fan shutoff is required.
        • air_loop_hvac_enable_unoccupied_fan_shutoff() Shuts off fan during unoccupied hours, otherwise set to Always-On.
      • air_loop_hvac_motorized_oa_damper_required?() Checks if motorized OA damper is required.
        • air_loop_hvac_add_motorized_oa_damper() Adds motorized OA damper.
    • fan_apply_standard_minimum_motor_efficiency() Sets fan motor efficiencies from OpenStudio_Standards_motors.json.
    • pump_apply_standard_minimum_motor_efficiency() Sets pump motor efficiencies from OpenStudio_Standards_motors.json.
    • coil_cooling_dx_two_speed_apply_efficiency_and_curves() Sets efficiencies and curves from OpenStudio_Standards_unitary_acs.json.
    • coil_cooling_dx_single_speed_apply_efficiency_and_curves() Sets efficiencies and curves from OpenStudio_Standards_unitary_acs.json.
    • coil_heating_dx_single_speed_.apply_efficiency_and_curves() Sets efficiencies and curves from OpenStudio_Standards_heat_pumps_heating.json.
    • chiller_electric_eir_apply_efficiency_and_curves() Sets efficiencies and curves from OpenStudio_Standards_chillers.json.
    • boiler_hot_water_apply_efficiency_and_curves() Sets efficiencies and curves from OpenStudio_Standards_boilers.json.
    • water_heater_mixed_apply_efficiency() Sets efficiencies and curves.
    • cooling_tower_single_speed_apply_efficiency_and_curves() Sets efficiencies and curves.
    • cooling_tower_two_speed_apply_efficiency_and_curves() Sets efficiencies and curves.
    • cooling_tower_variable_speed_apply_efficiency_and_curves() Sets efficiencies and curves.
  • model_add_daylighting_controls() Adds daylighting controls to the model. NOTE: This should probably be moved before the first sizing run.