Class: OpenStudio::Model::Surface

Inherits:
Object
  • Object
show all
Defined in:
lib/openstudio-standards/standards/Standards.Surface.rb

Overview

open the class to add methods to apply HVAC efficiency standards

Instance Method Summary collapse

Instance Method Details

#component_infiltration_rate(type) ⇒ Double

TODO:

handle floors over unconditioned spaces

Determine the component infiltration rate for this surface

Parameters:

  • type (String) —

    choices are ‘baseline’ and ‘advanced’

Returns:

  • (Double) —

    infiltration rate @units cubic meters per second (m^3/s)



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# File 'lib/openstudio-standards/standards/Standards.Surface.rb', line 10

def component_infiltration_rate(type)
  comp_infil_rate_m3_per_s = 0.0

  # Define the envelope component infiltration rates
  component_infil_rates_cfm_per_ft2 = {
    'baseline' => {
      'roof' => 0.12,
      'exterior_wall' => 0.12,
      'below_grade_wall' => 0.12,
      'floor_over_unconditioned' => 0.12,
      'slab_on_grade' => 0.12
    },
    'advanced' => {
      'roof' => 0.04,
      'exterior_wall' => 0.04,
      'below_grade_wall' => 0.04,
      'floor_over_unconditioned' => 0.04,
      'slab_on_grade' => 0.04
    }
  }

  boundary_condition = outsideBoundaryCondition
  # Skip non-outdoor surfaces
  return comp_infil_rate_m3_per_s unless outsideBoundaryCondition == 'Outdoors' || outsideBoundaryCondition == 'Ground'

  # Per area infiltration rate for this surface
  surface_type = surfaceType
  infil_rate_cfm_per_ft2 = nil
  case boundary_condition
  when 'Outdoors'
    case surface_type
    when 'RoofCeiling'
      infil_rate_cfm_per_ft2 = component_infil_rates_cfm_per_ft2[type]['roof']
    when 'Wall'
      infil_rate_cfm_per_ft2 = component_infil_rates_cfm_per_ft2[type]['exterior_wall']
    end
  when 'Ground'
    case surface_type
    when 'Wall'
      infil_rate_cfm_per_ft2 = component_infil_rates_cfm_per_ft2[type]['below_grade_wall']
    when 'Floor'
      infil_rate_cfm_per_ft2 = component_infil_rates_cfm_per_ft2[type]['slab_on_grade']
    end
  when 'TODO Surface'
    case surface_type
    when 'Floor'
      infil_rate_cfm_per_ft2 = component_infil_rates_cfm_per_ft2[type]['floor_over_unconditioned']
    end
  end
  if infil_rate_cfm_per_ft2.nil?
    OpenStudio.logFree(OpenStudio::Warn, 'openstudio.Standards.Model', "For #{name}, could not determine surface type for infiltration, will not be included in calculation.")
    return comp_infil_rate_m3_per_s
  end

  # Area of the surface
  area_m2 = netArea
  area_ft2 = OpenStudio.convert(area_m2, 'm^2', 'ft^2').get

  # Rate for this surface
  comp_infil_rate_cfm = area_ft2 * infil_rate_cfm_per_ft2

  comp_infil_rate_m3_per_s = OpenStudio.convert(comp_infil_rate_cfm, 'cfm', 'm^3/s').get

  # OpenStudio::logFree(OpenStudio::Debug, "openstudio.Standards.Model", "...#{self.name}, infil = #{comp_infil_rate_cfm.round(2)} cfm @ rate = #{infil_rate_cfm_per_ft2} cfm/ft2, area = #{area_ft2.round} ft2.")

  return comp_infil_rate_m3_per_s
end