Module: OpenstudioStandards::Infiltration

Defined in:
lib/openstudio-standards/infiltration/infiltration.rb,
lib/openstudio-standards/infiltration/nist_infiltration.rb

Overview

The Infiltration module provides methods create, modify, and get information about model infiltration

Calculations collapse

Surface collapse

SubSurface collapse

NIST Infiltration collapse

Class Method Details

.adjust_infiltration_to_new_pressure(infiltration_rate, initial_pressure: 75.0, final_pressure: 4.0, infiltration_coefficient: 0.65) ⇒ Double

Convert an infiltration rate at a given pressure to another pressure (typically lower) Method from Gowri, Krishnan, Winiarski, David W, and Jarnagin, Ronald E. Infiltration modeling guidelines for commercial building energy analysis. United States: N. p., 2009. Web. doi:10.2172/968203.

Parameters:

  • infiltration_rate (Double) —

    initial infiltration rate

  • initial_pressure (Double) (defaults to: 75.0) —

    pressure difference at which initial infiltration rate was determined, typically 75 Pa

  • final_pressure (Double) (defaults to: 4.0) —

    desired pressure difference to adjust infiltration rate, typically 4 Pa

  • infiltration_coefficient (Double) (defaults to: 0.65) —

    infiltration coeffiecient

Returns:

  • (Double) —

    adjusted infiltration rate in the same units as infiltration_rate



14
15
16
17
18
19
20
21
 
# File 'lib/openstudio-standards/infiltration/infiltration.rb', line 14

def self.adjust_infiltration_to_new_pressure(infiltration_rate,
                                             initial_pressure: 75.0,
                                             final_pressure: 4.0,
                                             infiltration_coefficient: 0.65)
  adjusted_infiltration_rate = infiltration_rate * ((final_pressure / initial_pressure)**infiltration_coefficient)

  return adjusted_infiltration_rate
end

.adjust_infiltration_to_prototype_building_conditions(infiltration_rate, initial_pressure: 75.0) ⇒ Double

Convert the infiltration rate to the pressures and conditions assumed in the PNNL prototype buildings Details described in Gowri, Krishnan, Winiarski, David W, and Jarnagin, Ronald E. Infiltration modeling guidelines for commercial building energy analysis. United States: N. p., 2009. Web. doi:10.2172/968203.

Parameters:

  • infiltration_rate (Double) —

    initial infiltration rate

  • initial_pressure (Double) (defaults to: 75.0) —

    pressure difference at which initial infiltration rate was determined in Pa, default 75 Pa

Returns:

  • (Double) —

    adjusted infiltration rate in the same units as infiltration_rate



29
30
31
32
33
34
35
36
37
38
39
40
41
 
# File 'lib/openstudio-standards/infiltration/infiltration.rb', line 29

def self.adjust_infiltration_to_prototype_building_conditions(infiltration_rate, initial_pressure: 75.0)
  alpha = 0.22 # terrain adjustment factor for an urban environment, unitless
  uh = 4.47 # wind speed, m/s
  rho = 1.18 # air density, kg/m^3
  cs = 0.1617 # positive surface pressure coefficient, unitless
  n = 0.65 # infiltration coefficient, unitless

  # Calculate the typical pressure - same for all building types
  final_pressure_pa = 0.5 * cs * rho * (uh**2)
  adjusted_infiltration_rate = (1.0 + alpha) * infiltration_rate * ((final_pressure_pa / initial_pressure)**n)

  return adjusted_infiltration_rate
end

.model_infer_nist_building_type(model) ⇒ OpenStudio::Model::Schedule

Infer the building type to use for NIST correlations, as only a subset of building types are available.

Parameters:

  • model (OpenStudio::Model::Model) —

    OpenStudio model object

Returns:

  • (OpenStudio::Model::Schedule) —

    OpenStudio Schedule object



30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
 
# File 'lib/openstudio-standards/infiltration/nist_infiltration.rb', line 30

def self.model_infer_nist_building_type(model)
  if model.getBuilding.standardsBuildingType.is_initialized
    model_building_type = model.getBuilding.standardsBuildingType.get
  else
    model_building_type = ''
  end

  case model_building_type
  when 'Office'
    # map office building type to small medium or large
    floor_area = model.getBuilding.floorArea
    if floor_area < 2750.0
      nist_building_type = 'SmallOffice'
    else
      nist_building_type = 'MediumOffice'
    end
  when 'LargeOffice', 'Outpatient', 'OfL'
    nist_building_type = 'MediumOffice'
  when 'Retail'
    # map retal building type to RetailStripmall or RetailStandalone based on building name
    building_name = model.getBuilding.name.get
    if building_name.include? 'RetailStandalone'
      nist_building_type = 'RetailStandalone'
    else
      nist_building_type = 'RetailStripmall'
    end
  when 'StripMall', 'Warehouse', 'QuickServiceRestaurant', 'FullServiceRestaurant', 'RtS', 'RSD', 'RFF', 'SCn', 'SUn', 'WRf'
    nist_building_type = 'RetailStripmall'
  when 'SuperMarket', 'RtL'
    nist_building_type = 'RetailStandalone'
  when 'EPr'
    nist_building_type = 'PrimarySchool'
  when 'ESe'
    nist_building_type = 'SecondarySchool'
  when 'Mtl'
    nist_building_type = 'SmallHotel'
  when 'Htl'
    nist_building_type = 'LargeHotel'
  when 'Hsp'
    nist_building_type = 'Hospital'
  when 'OfS'
    nist_building_type = 'SmallOffice'
  else
    nist_building_type = model_building_type
  end

  OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Infiltration', "Using building type #{nist_building_type} for model building type #{model_building_type}.")

  return nist_building_type
end

.model_set_nist_infiltration(model, airtightness_value: 13.8, airtightness_pressure: 75.0, airtightness_area_covered: '5-sided', air_barrier: false, hvac_schedule_name: nil, nist_building_type: nil) ⇒ Boolean

This method applies infiltration to a model that varies with weather and HVAC operation, and takes into account building geometry (height, above-ground exterior surface area, and volume). It is based on work published by Ng et al. (2018) <a href=‘doi.org/10.1016/j.buildenv.2017.10.029’>‘Weather correlations to calculate infiltration rates for U.S. commercial building energy models’</a> and Ng et al. (2021) <a href=‘doi.org/10.1016/j.buildenv.2021.107783’>‘Evaluating potential benefits of air barriers in commercial buildings using NIST infiltration correlations in EnergyPlus’</a>. This method of calculating infiltration was developed using eleven of the DOE commercial prototype building models (<a href=‘www.energycodes.gov/development/commercial/prototype_models’>Goel et al. 2014</a>) and TMY3 weather files for eight climate zones (CZ). Guidance on implementing the infiltration correlations are explained in the NIST technical report <a href=‘doi.org/10.6028/NIST.TN.2221’>‘Implementing NIST Infiltration Correlations’</a>. Ng et al. (2018) shows that when analyzing the benefits of building envelope airtightening, greater HVAC energy savings were predicted using the infiltration inputs included in this method compared with using the default inputs that are included in the prototype building models. This method will remove any existing infiltration objects (OS:SpaceInfiltration:DesignFlowRate and OS:SpaceInfiltration:EffectiveLeakageArea). Every zone will then get two OS:SpaceInfiltration:DesignFlowRate objects that add infiltration using the ‘Flow per Exterior Surface Area’ input option, one infiltration object when the HVAC system is on and one object when the HVAC system is off. The method assumes that HVAC operation is set by a schedule, though it may not reflect actual simulation/operation when fan operation may depend on internal loads and temperature setpoints. By default, interior zones will receive no infiltration. The user may enter a design building envelope airtightness at a specific design pressure, and whether the design value represents a 4-sided, 5-sided, or 6-sided normalization. By default, the method assumes an airtightness design value of 13.8 (m^3/h-m^2) at 75 Pa. The method assumes that infiltration is evenly distributed across the entire building envelope, including the roof. The user may select the HVAC system operating schedule in the model, or infer it based on the availability schedule of the air loop that serves the largest amount of floor area. The method will make a copy of the HVAC operating schedule, ‘Infiltration HVAC On Schedule’, which is used with the HVAC on infiltration correlations. The method will also make an ‘Infiltration HVAC Off Schedule’ with inverse operation, used with the HVAC off infiltration correlations. OS:SpaceInfiltration:DesignFlowRate object coefficients (A, B, C, and D) come from Ng et al. (2018). The user may select the Building Type and Climate Zone, or the method will infer them from the model.

Parameters:

  • model (OpenStudio::Model::Model) —

    OpenStudio model object

  • airtightness_value (Double) (defaults to: 13.8) —

    Airtightness design value (m^3/h-m^2). The airtightness design value from a building pressurization test. Use 5.0 (m^3/h-m^2) as a default for buildings with air barriers. Convert (cfm/ft^2) to (m^3/h-m^2) by multiplying by 18.288 (m-min/ft-hr). (0.3048 m/ft)*(60 min/hr) = 18.288 (m-min/ft-hr).‘

  • airtightness_pressure (Double) (defaults to: 75.0) —

    Airtightness design pressure (Pa). The corresponding pressure for the airtightness design value, typically 75 Pa for commercial buildings and 50 Pa for residential buildings.

  • airtightness_area_covered (String) (defaults to: '5-sided') —

    Airtightness exterior surface area scope. Airtightness measurements are weighted by exterior surface area. 4-sided values divide infiltration by exterior wall area. 5-sided values additionally include roof area. 6-sided values additionally include floor and ground area.

  • air_barrier (Boolean) (defaults to: false) —

    Does the building have an air barrier? Buildings with air barriers use a different set of coefficients.

  • hvac_schedule_name (String) (defaults to: nil) —

    HVAC Operating Schedule. Default will look up from model.

  • nist_building_type (String) (defaults to: nil) —

    NIST building type. If the building type is not available, pick the one with the most similar geometry and exhaust fan flow rates. Default will lookup from model.

Returns:

  • (Boolean) —

    returns true if successful, false if not

Author:



97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
 
# File 'lib/openstudio-standards/infiltration/nist_infiltration.rb', line 97

def self.model_set_nist_infiltration(model,
                                     airtightness_value: 13.8,
                                     airtightness_pressure: 75.0,
                                     airtightness_area_covered: '5-sided',
                                     air_barrier: false,
                                     hvac_schedule_name: nil,
                                     nist_building_type: nil)
  # validate airtightness value and pressure
  if airtightness_value < 0.0
    OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Infiltration', 'Airtightness value must be postive.')
    return false
  end

  if airtightness_pressure < 0.0
    OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Infiltration', 'Airtightness pressure must be postive.')
    return false
  end

  # calculate infiltration design value at 4 Pa
  airtightness_value_4pa_per_hr = airtightness_value * ((4.0 / airtightness_pressure)**0.65)
  OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Infiltration', "User-inputed airtightness design value #{airtightness_value} (m^3/h-m^2) at #{airtightness_pressure} Pa converts to #{airtightness_value_4pa_per_hr.round(7)} (m^3/h-m^2) at 4 Pa")

  # convert to m^3/s-m^2
  airtightness_value_4pa_per_s = airtightness_value_4pa_per_hr / 3600.0

  # get 4-sided, 5-sided, and 6-sided areas
  exterior_wall_area = 0.0
  exterior_roof_area = 0.0
  exterior_floor_area = 0.0
  ground_wall_area = 0.0
  ground_roof_area = 0.0
  ground_floor_area = 0.0
  model.getSurfaces.each do |surface|
    bc = surface.outsideBoundaryCondition
    type = surface.surfaceType
    area = surface.grossArea
    exterior_wall_area += area if bc == 'Outdoors' && type == 'Wall'
    exterior_roof_area += area if bc == 'Outdoors' && type == 'RoofCeiling'
    exterior_floor_area += area if bc == 'Outdoors' && type == 'Floor'
    ground_wall_area += area if bc == 'Ground' && type == 'Wall'
    ground_roof_area += area if bc == 'Ground' && type == 'RoofCeiling'
    ground_floor_area += area if bc == 'Ground' && type == 'Floor'
  end
  four_sided_area = exterior_wall_area + ground_wall_area
  five_sided_area = exterior_wall_area + ground_wall_area + exterior_roof_area + ground_roof_area
  six_sided_area = exterior_wall_area + ground_wall_area + exterior_roof_area + ground_roof_area + exterior_floor_area + ground_floor_area
  energy_plus_area = exterior_wall_area + exterior_roof_area
  OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Infiltration', "4-sided area = #{four_sided_area.round(2)} m^2, 5-sided area = #{five_sided_area.round(2)} m^2, 6-sided area = #{six_sided_area.round(2)} m^2.")

  # The SpaceInfiltrationDesignFlowRate object FlowperExteriorSurfaceArea method only counts surfaces with the 'Outdoors' boundary conditions towards exterior surface area, not surfaces with the 'Ground' boundary conditions.  That means all values need to be normalized to exterior wall and roof area.
  case airtightness_area_covered
  when '4-sided'
    design_infiltration_4pa = airtightness_value_4pa_per_s * (four_sided_area / energy_plus_area)
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Infiltration', "#{airtightness_area_covered} infiltration design value #{airtightness_value_4pa_per_s.round(7)} (m^3/s-m^2) converted to #{design_infiltration_4pa.round(7)} (m^3/s-m^2) based on 4-sided area #{four_sided_area.round(2)} m^2 and 5-sided area #{energy_plus_area.round(2)} m^2 excluding ground boundary surfaces for energyplus.")
  when '5-sided'
    design_infiltration_4pa = airtightness_value_4pa_per_s * (five_sided_area / energy_plus_area)
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Infiltration', "#{airtightness_area_covered} infiltration design value #{airtightness_value_4pa_per_s.round(7)} (m^3/s-m^2) converted to #{design_infiltration_4pa.round(7)} (m^3/s-m^2) based on 5-sided area #{five_sided_area.round(2)} m^2 and 5-sided area #{energy_plus_area.round(2)} m^2 excluding ground boundary surfaces for energyplus.")
  when '6-sided'
    design_infiltration_4pa = airtightness_value_4pa_per_s * (six_sided_area / energy_plus_area)
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Infiltration', "#{airtightness_area_covered} infiltration design value #{airtightness_value_4pa_per_s.round(7)} (m^3/s-m^2) converted to #{design_infiltration_4pa.round(7)} (m^3/s-m^2) based on 6-sided area #{six_sided_area.round(2)} m^2 and 5-sided area #{energy_plus_area.round(2)} m^2 excluding ground boundary surfaces for energyplus.")
  end

  # validate hvac schedule
  if hvac_schedule_name.nil?
    hvac_schedule = OpenstudioStandards::Schedules.model_get_hvac_schedule(model)
  else
    hvac_schedule = model.getScheduleByName(hvac_schedule_name)
    unless hvac_schedule.is_initialized
      OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Infiltration', "HVAC schedule argument #{hvac_schedule} not found in the model. It may have been removed by another measure.")
      return false
    end
    hvac_schedule = hvac_schedule.get
    if hvac_schedule.to_ScheduleRuleset.is_initialized
      hvac_schedule = hvac_schedule.to_ScheduleRuleset.get
    elsif hvac_schedule.to_ScheduleConstant.is_initialized
      hvac_schedule = hvac_schedule.to_ScheduleConstant.get
    else
      OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Infiltration', "HVAC schedule argument #{hvac_schedule} is not a Schedule Constant or Schedule Ruleset object.")
      return false
    end

    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Infiltration', "Using HVAC schedule #{hvac_schedule.name} from user arguments to determine infiltration on/off schedule.")
  end

  # creating infiltration schedules based on hvac schedule
  if hvac_schedule.nil?
    OpenStudio.logFree(OpenStudio::Warn, 'openstudio.standards.Infiltration', 'Unable to determine the building HVAC schedule. Treating the building as if there is no HVAC system with outdoor air. This may be appropriate for design sizing, particularly heating design sizing. If this is not the case, input a schedule argument, or assign one to an air loop in the model.')
    on_schedule = OpenStudio::Model::ScheduleConstant.new(model)
    on_schedule.setName('Infiltration HVAC On Schedule')
    on_schedule.setValue(0.0)
    off_schedule = OpenStudio::Model::ScheduleConstant.new(model)
    off_schedule.setName('Infiltration HVAC Off Schedule')
    off_schedule.setValue(1.0)
  elsif hvac_schedule.to_ScheduleConstant.is_initialized
    hvac_schedule = hvac_schedule.to_ScheduleConstant.get
    on_schedule = OpenStudio::Model::ScheduleConstant.new(model)
    on_schedule.setName('Infiltration HVAC On Schedule')
    on_schedule.setValue(hvac_schedule.value)
    off_schedule = OpenStudio::Model::ScheduleConstant.new(model)
    off_schedule.setName('Infiltration HVAC Off Schedule')
    if hvac_schedule.value > 0
      off_schedule.setValue(0.0)
    else
      off_schedule.setValue(1.0)
    end
  elsif hvac_schedule.to_ScheduleRuleset.is_initialized
    hvac_schedule = hvac_schedule.to_ScheduleRuleset.get
    on_schedule = hvac_schedule.clone.to_ScheduleRuleset.get
    on_schedule.setName('Infiltration HVAC On Schedule')
    off_schedule = OpenstudioStandards::Schedules.create_inverted_schedule_ruleset(hvac_schedule, schedule_name: 'Infiltration HVAC Off Schedule')
  end

  # get climate zone number
  climate_zone_number = OpenstudioStandards::Weather.model_get_ashrae_climate_zone_number(model)

  # get nist building type
  if nist_building_type.nil?
    nist_building_type = model_infer_nist_building_type(model)
  end

  # check that model building type is supported
  unless nist_building_types.include? nist_building_type
    OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Infiltration', "NIST coefficients are not available for model building type #{nist_building_type}.")
    return false
  end

  # remove existing infiltration objects
  OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Infiltration', "The modeled started with #{model.getSpaceInfiltrationDesignFlowRates.size} infiltration objects and #{model.getSpaceInfiltrationEffectiveLeakageAreas.size} effective leakage area objects.")
  model.getSpaceInfiltrationDesignFlowRates.each(&:remove)
  model.getSpaceInfiltrationEffectiveLeakageAreas.each(&:remove)

  # load NIST infiltration correlations file and convert to hash table
  nist_infiltration_correlations_csv = "#{__dir__}/data/NISTInfiltrationCorrelations.csv"
  unless File.exist?(nist_infiltration_correlations_csv)
    OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Infiltration', "Unable to find file: #{nist_infiltration_correlations_csv}")
    return false
  end
  coefficients_tbl = CSV.table(nist_infiltration_correlations_csv)
  coefficients_hsh = coefficients_tbl.map(&:to_hash)

  # select down to building type and climate zone
  coefficients = coefficients_hsh.select { |r| (r[:building_type] == nist_building_type) && (r[:climate_zone] == climate_zone_number) }

  # filter by air barrier
  if air_barrier
    coefficients = coefficients.select { |r| r[:air_barrier] == 'yes' }
  else
    coefficients = coefficients.select { |r| r[:air_barrier] == 'no' }
  end

  # determine coefficients
  # if no off coefficients are defined, use 0 for a and the on coefficients for b and d
  on_coefficients = coefficients.select { |r| r[:hvac_status] == 'on' }
  off_coefficients = coefficients.select { |r| r[:hvac_status] == 'off' }
  a_on = on_coefficients[0][:a]
  b_on = on_coefficients[0][:b]
  d_on = on_coefficients[0][:d]
  a_off = off_coefficients[0][:a].nil? ? on_coefficients[0][:a] : off_coefficients[0][:a]
  b_off = off_coefficients[0][:b].nil? ? on_coefficients[0][:b] : off_coefficients[0][:b]
  d_off = off_coefficients[0][:d].nil? ? on_coefficients[0][:d] : off_coefficients[0][:d]

  # add new infiltration objects
  # define infiltration as flow per exterior area
  model.getSpaces.each do |space|
    next unless space.exteriorArea > 0.0

    hvac_on_infiltration = OpenStudio::Model::SpaceInfiltrationDesignFlowRate.new(model)
    hvac_on_infiltration.setName("#{space.name.get} HVAC On Infiltration")
    hvac_on_infiltration.setFlowperExteriorSurfaceArea(design_infiltration_4pa)
    hvac_on_infiltration.setConstantTermCoefficient(a_on)
    hvac_on_infiltration.setTemperatureTermCoefficient(b_on)
    hvac_on_infiltration.setVelocityTermCoefficient(0.0)
    hvac_on_infiltration.setVelocitySquaredTermCoefficient(d_on)
    hvac_on_infiltration.setSpace(space)
    hvac_on_infiltration.setSchedule(on_schedule)

    hvac_off_infiltration = OpenStudio::Model::SpaceInfiltrationDesignFlowRate.new(model)
    hvac_off_infiltration.setName("#{space.name.get} HVAC Off Infiltration")
    hvac_off_infiltration.setFlowperExteriorSurfaceArea(design_infiltration_4pa)
    hvac_off_infiltration.setConstantTermCoefficient(a_off)
    hvac_off_infiltration.setTemperatureTermCoefficient(b_off)
    hvac_off_infiltration.setVelocityTermCoefficient(0.0)
    hvac_off_infiltration.setVelocitySquaredTermCoefficient(d_off)
    hvac_off_infiltration.setSpace(space)
    hvac_off_infiltration.setSchedule(off_schedule)
  end

  OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Infiltration', "The modeled finished with #{model.getSpaceInfiltrationDesignFlowRates.size} infiltration objects.")

  return true
end

.model_set_nist_infiltration_schedules(model, hvac_schedule: nil) ⇒ Boolean

Loops through SpaceInfiltrationDesignFlowRate objects and adjusts the infiltration schedules to account building HVAC operation

Parameters:

  • model (OpenStudio::Model::Model) —

    OpenStudio model object

  • hvac_schedule (OpenStudio::Model::Schedule) (defaults to: nil) —

    OpenStudio Schedule object for the HVAC Operating Schedule. Default will look up from model.

Returns:

  • (Boolean) —

    returns true if successful, false if not



294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
 
# File 'lib/openstudio-standards/infiltration/nist_infiltration.rb', line 294

def self.model_set_nist_infiltration_schedules(model, hvac_schedule: nil)
  # delete existing schedules if present
  on_schedule = model.getScheduleByName('Infiltration HVAC On Schedule')
  on_schedule.get.remove if on_schedule.is_initialized
  off_schedule = model.getScheduleByName('Infiltration HVAC Off Schedule')
  off_schedule.get.remove if off_schedule.is_initialized

  # validate hvac schedule
  if hvac_schedule.nil?
    hvac_schedule = OpenstudioStandards::Schedules.model_get_hvac_schedule(model)
  else
    unless hvac_schedule.to_Schedule.is_initialized
      OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Infiltration', "HVAC schedule argument #{hvac_schedule} not found in the model or is not a Schedule object. It may have been removed by another measure.")
      return false
    end
    hvac_schedule = hvac_schedule.to_Schedule.get
    if hvac_schedule.to_ScheduleRuleset.is_initialized
      hvac_schedule = hvac_schedule.to_ScheduleRuleset.get
    elsif hvac_schedule.to_ScheduleConstant.is_initialized
      hvac_schedule = hvac_schedule.to_ScheduleConstant.get
    else
      OpenStudio.logFree(OpenStudio::Error, 'openstudio.standards.Infiltration', "HVAC schedule argument #{hvac_schedule} is not a Schedule Constant or Schedule Ruleset object.")
      return false
    end

    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Infiltration', "Using HVAC schedule #{hvac_schedule.name} from user arguments to determine infiltration on/off schedule.")
  end

  # creating infiltration schedules based on hvac schedule
  if hvac_schedule.nil?
    OpenStudio.logFree(OpenStudio::Warn, 'openstudio.standards.Infiltration', 'Unable to determine the HVAC schedule. Treating the building as if there is no HVAC system with outdoor air.  If this is not the case, input a schedule argument, or assign one to an air loop in the model.')
    on_schedule = OpenStudio::Model::ScheduleConstant.new(model)
    on_schedule.setName('Infiltration HVAC On Schedule')
    on_schedule.setValue(0.0)
    off_schedule = OpenStudio::Model::ScheduleConstant.new(model)
    off_schedule.setName('Infiltration HVAC Off Schedule')
    off_schedule.setValue(1.0)
  elsif hvac_schedule.to_ScheduleConstant.is_initialized
    hvac_schedule = hvac_schedule.to_ScheduleConstant.get
    on_schedule = OpenStudio::Model::ScheduleConstant.new(model)
    on_schedule.setName('Infiltration HVAC On Schedule')
    on_schedule.setValue(hvac_schedule.value)
    off_schedule = OpenStudio::Model::ScheduleConstant.new(model)
    off_schedule.setName('Infiltration HVAC Off Schedule')
    if hvac_schedule.value > 0
      off_schedule.setValue(0.0)
    else
      off_schedule.setValue(1.0)
    end
  elsif hvac_schedule.to_ScheduleRuleset.is_initialized
    hvac_schedule = hvac_schedule.to_ScheduleRuleset.get
    on_schedule = hvac_schedule.clone.to_ScheduleRuleset.get
    on_schedule.setName('Infiltration HVAC On Schedule')
    off_schedule = OpenstudioStandards::Schedules.create_inverted_schedule_ruleset(hvac_schedule, schedule_name: 'Infiltration HVAC Off Schedule')
  end


  model.getSpaceInfiltrationDesignFlowRates.each do |infil|
    if infil.name.get.include?('HVAC On Infiltration')
      infil.setSchedule(on_schedule)
    end

    if infil.name.get.include?('HVAC Off Infiltration')
      infil.setSchedule(off_schedule)
    end
  end

  return true
end

.nist_building_types ⇒ OpenStudio::StringVector

DOE prototype buildings for which there are NIST infiltration coefficients.

Returns:

  • (OpenStudio::StringVector) —

    vector of strings of valid building types



9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
 
# File 'lib/openstudio-standards/infiltration/nist_infiltration.rb', line 9

def self.nist_building_types
  building_types = OpenStudio::StringVector.new
  building_types << 'SecondarySchool'
  building_types << 'PrimarySchool'
  building_types << 'SmallOffice'
  building_types << 'MediumOffice'
  building_types << 'SmallHotel'
  building_types << 'LargeHotel'
  building_types << 'RetailStandalone'
  building_types << 'RetailStripmall'
  building_types << 'Hospital'
  building_types << 'MidriseApartment'
  building_types << 'HighriseApartment'

  return building_types
end

.sub_surface_component_infiltration_rate(sub_surface, type: 'baseline') ⇒ Double

Determine the component infiltration rate for a sub surface Details described in Table 5.7 of Thornton, Brian A, Rosenberg, Michael I, Richman, Eric E, Wang, Weimin, Xie, YuLong, Zhang, Jian, Cho, Heejin, Mendon, Vrushali V, Athalye, Rahul A, and Liu, Bing. Achieving the 30% Goal: Energy and Cost Savings Analysis of ASHRAE Standard 90.1-2010. United States: N. p., 2011. Web. doi:10.2172/1015277.

Parameters:

  • sub_surface (OpenStudio::Model::SubSurface) —

    OpenStudio SubSurface object

  • type (String) (defaults to: 'baseline') —

    choices are ‘baseline’ and ‘advanced’

Returns:

  • (Double) —

    component infiltration rate in m^3/s



124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
 
# File 'lib/openstudio-standards/infiltration/infiltration.rb', line 124

def self.sub_surface_component_infiltration_rate(sub_surface, type: 'baseline')
  # Define the envelope component infiltration rates
  component_infil_rates_cfm_per_ft2 = {
    'baseline' => {
      'opaque_door' => 0.40,
      'loading_dock_door' => 0.40,
      'swinging_or_revolving_glass_door' => 1.0,
      'vestibule' => 1.0,
      'sliding_glass_door' => 0.40,
      'window' => 0.40,
      'skylight' => 0.40
    },
    'advanced' => {
      'opaque_door' => 0.20,
      'loading_dock_door' => 0.20,
      'swinging_or_revolving_glass_door' => 1.0,
      'vestibule' => 1.0,
      'sliding_glass_door' => 0.20,
      'window' => 0.20,
      'skylight' => 0.20
    }
  }

  # Skip non-outdoor surfaces
  unless sub_surface.outsideBoundaryCondition == 'Outdoors'
    return 0.0
  end

  # Per area infiltration rate for this sub surface
  case sub_surface.subSurfaceType
  when 'Door'
    infil_rate_cfm_per_ft2 = component_infil_rates_cfm_per_ft2[type]['opaque_door']
  when 'OverheadDoor'
    infil_rate_cfm_per_ft2 = component_infil_rates_cfm_per_ft2[type]['loading_dock_door']
  when 'GlassDoor'
    OpenStudio.logFree(OpenStudio::Info, 'openstudio.standards.Infiltration', "Assuming swinging_or_revolving_glass_door for #{sub_surface.name} for component infiltration rate.")
    infil_rate_cfm_per_ft2 = component_infil_rates_cfm_per_ft2[type]['swinging_or_revolving_glass_door']
  when 'FixedWindow', 'OperableWindow'
    infil_rate_cfm_per_ft2 = component_infil_rates_cfm_per_ft2[type]['window']
  when 'Skylight', 'TubularDaylightDome', 'TubularDaylightDiffuser'
    infil_rate_cfm_per_ft2 = component_infil_rates_cfm_per_ft2[type]['skylight']
  else
    OpenStudio.logFree(OpenStudio::Warn, 'openstudio.standards.Infiltration', "Could not determine infiltration sub surface type for #{sub_surface.name}, defaulting to 0 component infiltration rate.")
    return 0.0
  end

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

  # Rate for this sub 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

  return comp_infil_rate_m3_per_s
end

.surface_component_infiltration_rate(surface, type: 'baseline') ⇒ Double

Determine the component infiltration rate for a surface Details described in Table 5.7 of Thornton, Brian A, Rosenberg, Michael I, Richman, Eric E, Wang, Weimin, Xie, YuLong, Zhang, Jian, Cho, Heejin, Mendon, Vrushali V, Athalye, Rahul A, and Liu, Bing. Achieving the 30% Goal: Energy and Cost Savings Analysis of ASHRAE Standard 90.1-2010. United States: N. p., 2011. Web. doi:10.2172/1015277.

Parameters:

  • surface (OpenStudio::Model::Surface) —

    OpenStudio Surface object

  • type (String) (defaults to: 'baseline') —

    choices are ‘baseline’ and ‘advanced’

Returns:

  • (Double) —

    component infiltration rate in m^3/s



53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
 
# File 'lib/openstudio-standards/infiltration/infiltration.rb', line 53

def self.surface_component_infiltration_rate(surface, type: 'baseline')
  # 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
    }
  }

  # Skip non-outdoor surfaces
  boundary_condition = surface.outsideBoundaryCondition
  unless boundary_condition == 'Outdoors' || boundary_condition == 'Ground'
    return 0.0
  end

  # Per area infiltration rate for this surface
  surface_type = surface.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']
    when 'Floor'
      infil_rate_cfm_per_ft2 = component_infil_rates_cfm_per_ft2[type]['floor_over_unconditioned']
    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
  else
    OpenStudio.logFree(OpenStudio::Warn, 'openstudio.standards.Infiltration', "Could not determine infiltration surface type for #{surface.name}, defaulting to 0 component infiltration rate.")
    return 0.0
  end

  # Area of the surface
  area_m2 = surface.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

  return comp_infil_rate_m3_per_s
end