diff --git a/HPXMLtoOpenStudio/measure.xml b/HPXMLtoOpenStudio/measure.xml
index a75c7de113..8474766d15 100644
--- a/HPXMLtoOpenStudio/measure.xml
+++ b/HPXMLtoOpenStudio/measure.xml
@@ -3,8 +3,8 @@
   <schema_version>3.1</schema_version>
   <name>hpxm_lto_openstudio</name>
   <uid>b1543b30-9465-45ff-ba04-1d1f85e763bc</uid>
-  <version_id>2bb7d5cd-06e3-406b-9eb0-96dfe7e2c6d2</version_id>
-  <version_modified>2024-11-19T01:12:59Z</version_modified>
+  <version_id>d26078da-8691-4396-af39-a5cb563e1407</version_id>
+  <version_modified>2024-11-21T02:54:20Z</version_modified>
   <xml_checksum>D8922A73</xml_checksum>
   <class_name>HPXMLtoOpenStudio</class_name>
   <display_name>HPXML to OpenStudio Translator</display_name>
@@ -345,7 +345,7 @@
       <filename>geometry.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>945B3E0D</checksum>
+      <checksum>3DBAF60E</checksum>
     </file>
     <file>
       <filename>hotwater_appliances.rb</filename>
@@ -447,7 +447,7 @@
       <filename>model.rb</filename>
       <filetype>rb</filetype>
       <usage_type>resource</usage_type>
-      <checksum>ECCE7792</checksum>
+      <checksum>ED1985F0</checksum>
     </file>
     <file>
       <filename>output.rb</filename>
diff --git a/HPXMLtoOpenStudio/resources/geometry.rb b/HPXMLtoOpenStudio/resources/geometry.rb
index 1080a1404c..5b19369f40 100644
--- a/HPXMLtoOpenStudio/resources/geometry.rb
+++ b/HPXMLtoOpenStudio/resources/geometry.rb
@@ -138,8 +138,11 @@ def self.apply_walls(runner, model, spaces, hpxml_bldg, hpxml_header)
     _walls_top, foundation_top = get_foundation_and_walls_top(hpxml_bldg)
 
     hpxml_bldg.walls.each do |wall|
-      store_adjacent_surface_ids_to_space(get_interior_space(model, spaces, HPXML::LocationConditionedSpace, hpxml_bldg), wall)
-      next if wall.sameas_id
+      hpxml_id = wall.id
+      if wall.sameas_id
+        hpxml_sameas_id = wall.sameas_id
+        wall = wall.sameas
+      end
       next if wall.net_area < 1.0 # skip modeling net surface area for surfaces comprised entirely of subsurface area
 
       if wall.azimuth.nil?
@@ -151,6 +154,9 @@ def self.apply_walls(runner, model, spaces, hpxml_bldg, hpxml_header)
       else
         azimuths = [wall.azimuth]
       end
+      if hpxml_sameas_id
+        azimuths = azimuths.map { |a| (a + 180) % 360 }
+      end
 
       surfaces = []
 
@@ -173,15 +179,17 @@ def self.apply_walls(runner, model, spaces, hpxml_bldg, hpxml_header)
         end
         surface.setSurfaceType(EPlus::SurfaceTypeWall)
         set_surface_interior(model, spaces, surface, wall, hpxml_bldg)
-        set_surface_exterior(model, spaces, surface, wall, hpxml_bldg)
+        set_surface_exterior(model, spaces, surface, wall, hpxml_bldg) if hpxml_sameas_id.nil?
         if wall.is_interior
           surface.setSunExposure(EPlus::SurfaceSunExposureNo)
           surface.setWindExposure(EPlus::SurfaceWindExposureNo)
         end
-        surface.additionalProperties.setFeature('hpxmlID', wall.id)
+        surface.additionalProperties.setFeature('hpxmlID', hpxml_id)
+        surface.additionalProperties.setFeature('hpxmlSameasID', hpxml_sameas_id) unless hpxml_sameas_id.nil?
       end
 
       next if surfaces.empty?
+      next unless hpxml_sameas_id.nil?
 
       # Apply construction
       # The code below constructs a reasonable wall construction based on the
@@ -223,8 +231,11 @@ def self.apply_rim_joists(runner, model, spaces, hpxml_bldg)
     _walls_top, foundation_top = get_foundation_and_walls_top(hpxml_bldg)
 
     hpxml_bldg.rim_joists.each do |rim_joist|
-      store_adjacent_surface_ids_to_space(get_interior_space(model, spaces, HPXML::LocationConditionedSpace, hpxml_bldg), rim_joist)
-      next if rim_joist.sameas_id
+      hpxml_id = rim_joist.id
+      if rim_joist.sameas_id
+        hpxml_sameas_id = rim_joist.sameas_id
+        rim_joist = rim_joist.sameas
+      end
 
       if rim_joist.azimuth.nil?
         if rim_joist.is_exterior
@@ -235,6 +246,9 @@ def self.apply_rim_joists(runner, model, spaces, hpxml_bldg)
       else
         azimuths = [rim_joist.azimuth]
       end
+      if hpxml_sameas_id
+        azimuths = azimuths.map { |a| (a + 180) % 360 }
+      end
 
       surfaces = []
 
@@ -257,14 +271,17 @@ def self.apply_rim_joists(runner, model, spaces, hpxml_bldg)
         end
         surface.setSurfaceType(EPlus::SurfaceTypeWall)
         set_surface_interior(model, spaces, surface, rim_joist, hpxml_bldg)
-        set_surface_exterior(model, spaces, surface, rim_joist, hpxml_bldg)
+        set_surface_exterior(model, spaces, surface, rim_joist, hpxml_bldg) if hpxml_sameas_id.nil?
         if rim_joist.is_interior
           surface.setSunExposure(EPlus::SurfaceSunExposureNo)
           surface.setWindExposure(EPlus::SurfaceWindExposureNo)
         end
-        surface.additionalProperties.setFeature('hpxmlID', rim_joist.id)
+        surface.additionalProperties.setFeature('hpxmlID', hpxml_id)
+        surface.additionalProperties.setFeature('hpxmlSameasID', hpxml_sameas_id) unless hpxml_sameas_id.nil?
       end
 
+      next unless hpxml_sameas_id.nil?
+
       # Apply construction
 
       inside_film = Material.AirFilmVertical
@@ -310,8 +327,14 @@ def self.apply_floors(runner, model, spaces, hpxml_bldg, hpxml_header)
     walls_top, foundation_top = get_foundation_and_walls_top(hpxml_bldg)
 
     hpxml_bldg.floors.each do |floor|
-      store_adjacent_surface_ids_to_space(get_interior_space(model, spaces, HPXML::LocationConditionedSpace, hpxml_bldg), floor)
-      next if floor.sameas_id
+      hpxml_id = floor.id
+      if floor.sameas_id
+        is_ceiling = !floor.sameas.is_ceiling
+        hpxml_sameas_id = floor.sameas_id
+        floor = floor.sameas
+      else
+        is_ceiling = floor.is_ceiling
+      end
       next if floor.net_area < 1.0 # skip modeling net surface area for surfaces comprised entirely of subsurface area
 
       area = floor.net_area
@@ -323,7 +346,7 @@ def self.apply_floors(runner, model, spaces, hpxml_bldg, hpxml_header)
         z_origin = foundation_top
       end
 
-      if floor.is_ceiling
+      if is_ceiling
         vertices = create_ceiling_vertices(length, width, z_origin, default_azimuths)
         surface = OpenStudio::Model::Surface.new(vertices, model)
         surface.additionalProperties.setFeature('SurfaceType', 'Ceiling')
@@ -334,7 +357,7 @@ def self.apply_floors(runner, model, spaces, hpxml_bldg, hpxml_header)
       end
       surface.additionalProperties.setFeature('Tilt', 0.0)
       set_surface_interior(model, spaces, surface, floor, hpxml_bldg)
-      set_surface_exterior(model, spaces, surface, floor, hpxml_bldg)
+      set_surface_exterior(model, spaces, surface, floor, hpxml_bldg) if hpxml_sameas_id.nil?
       surface.setName(floor.id)
       if floor.is_interior
         surface.setSunExposure(EPlus::SurfaceSunExposureNo)
@@ -348,7 +371,9 @@ def self.apply_floors(runner, model, spaces, hpxml_bldg, hpxml_header)
           end
         end
       end
-      surface.additionalProperties.setFeature('hpxmlID', floor.id)
+      surface.additionalProperties.setFeature('hpxmlID', hpxml_id)
+      surface.additionalProperties.setFeature('hpxmlSameasID', hpxml_sameas_id) unless hpxml_sameas_id.nil?
+      next unless hpxml_sameas_id.nil?
 
       # Apply construction
 
@@ -457,10 +482,13 @@ def self.apply_foundation_walls_slabs(runner, model, spaces, weather, hpxml_bldg
       # calculate heat flow between two zones through the ground.
       int_fnd_walls = hpxml_bldg.foundation_walls.select { |fw| (fw.is_interior && fw.interior_adjacent_to == foundation_type) || fw.sameas_id }
       int_fnd_walls.each do |fnd_wall|
-        next unless (fnd_wall.is_interior || fw.sameas.is_interior)
+        hpxml_id = fnd_wall.id
+        if fnd_wall.sameas_id
+          hpxml_sameas_id = fnd_wall.sameas_id
+          fnd_wall = fnd_wall.sameas
+        end
 
-        store_adjacent_surface_ids_to_space(get_interior_space(model, spaces, HPXML::LocationConditionedSpace, hpxml_bldg), fnd_wall)
-        next if fnd_wall.sameas_id
+        next unless fnd_wall.is_interior
 
         ag_height = fnd_wall.height - fnd_wall.depth_below_grade
         ag_net_area = fnd_wall.net_area * ag_height / fnd_wall.height
@@ -473,6 +501,9 @@ def self.apply_foundation_walls_slabs(runner, model, spaces, weather, hpxml_bldg
         else
           azimuth = fnd_wall.azimuth
         end
+        if hpxml_sameas_id
+          azimuth = (azimuth + 180) % 360
+        end
 
         vertices = create_wall_vertices(length, ag_height, z_origin, azimuth)
         surface = OpenStudio::Model::Surface.new(vertices, model)
@@ -483,10 +514,13 @@ def self.apply_foundation_walls_slabs(runner, model, spaces, weather, hpxml_bldg
         surface.setName(fnd_wall.id)
         surface.setSurfaceType(EPlus::SurfaceTypeWall)
         set_surface_interior(model, spaces, surface, fnd_wall, hpxml_bldg)
-        set_surface_exterior(model, spaces, surface, fnd_wall, hpxml_bldg)
+        set_surface_exterior(model, spaces, surface, fnd_wall, hpxml_bldg) if hpxml_sameas_id.nil?
         surface.setSunExposure(EPlus::SurfaceSunExposureNo)
         surface.setWindExposure(EPlus::SurfaceWindExposureNo)
-        surface.additionalProperties.setFeature('hpxmlID', fnd_wall.id)
+        surface.additionalProperties.setFeature('hpxmlID', hpxml_id)
+        surface.additionalProperties.setFeature('hpxmlSameasID', hpxml_sameas_id) unless hpxml_sameas_id.nil?
+
+        next unless hpxml_sameas_id.nil?
 
         # Apply construction
 
@@ -1142,24 +1176,6 @@ def self.get_occupancy_default_num(nbeds:)
     return Float(nbeds) # Per ANSI 301 for an asset calculation
   end
 
-  # Store the adjacent surface ID in Space additional properties, to process after merging unit models
-  #
-  # @param space [OpenStudio::Model::Space] the OpenStudio::Model::Space object of the dwelling unit
-  # @param hpxml_surface [HPXML::Wall or HPXML::Floor or HPXML::RimJoist or HPXML::FoundationWall] any HPXML surface
-  # @return [nil]
-  def self.store_adjacent_surface_ids_to_space(space, hpxml_surface)
-    return if hpxml_surface.sameas_id.nil?
-
-    # Store adjacent surface id in the space to process later
-    adjacent_surface_ids = space.additionalProperties.getFeatureAsString('adjacentSurfaceIDs')
-    if adjacent_surface_ids.is_initialized
-      adjacent_surface_ids_new = [adjacent_surface_ids, hpxml_surface.sameas_id].join(', ')
-      space.additionalProperties.setFeature('adjacentSurfaceIDs', adjacent_surface_ids_new)
-    else
-      space.additionalProperties.setFeature('adjacentSurfaceIDs', hpxml_surface.sameas_id)
-    end
-  end
-
   # Creates a space and zone based on contents of spaces and value of location.
   # Sets a "dwelling unit multiplier" equal to the number of similar units represented.
   #
diff --git a/HPXMLtoOpenStudio/resources/model.rb b/HPXMLtoOpenStudio/resources/model.rb
index ca48cc006f..55983fbafb 100644
--- a/HPXMLtoOpenStudio/resources/model.rb
+++ b/HPXMLtoOpenStudio/resources/model.rb
@@ -942,19 +942,15 @@ def self.merge_unit_models(model, hpxml_osm_map)
     end
 
     model_objects.each do |obj|
-      next unless obj.to_Space.is_initialized
-
-      space = obj.to_Space.get
-      adjacent_surface_id_str = space.additionalProperties.getFeatureAsString('adjacentSurfaceIDs')
-      next unless adjacent_surface_id_str.is_initialized
-
-      adjacent_surface_ids = adjacent_surface_id_str.to_s.split(', ')
-      # All the surfaces that are adjacent to the space
-      adjacent_surfaces = model_objects.select { |o| o.to_Surface.is_initialized && o.to_Surface.get.additionalProperties.getFeatureAsString('hpxmlID').is_initialized && (adjacent_surface_ids.include? o.to_Surface.get.additionalProperties.getFeatureAsString('hpxmlID').to_s) }
-      adjacent_surfaces.each do |surface_obj|
-        surface = surface_obj.to_Surface.get
-        surface.createAdjacentSurface(space)
-      end
+      next unless obj.to_Surface.is_initialized
+      next unless obj.to_Surface.get.additionalProperties.getFeatureAsString('hpxmlSameasID').is_initialized
+
+      surface_obj = obj.to_Surface.get
+      hpxml_sameas_id = surface_obj.additionalProperties.getFeatureAsString('hpxmlSameasID').to_s
+
+      adjacent_surface = model_objects.find { |o| o.to_Surface.is_initialized && o.to_Surface.get.additionalProperties.getFeatureAsString('hpxmlID').is_initialized && (hpxml_sameas_id == o.to_Surface.get.additionalProperties.getFeatureAsString('hpxmlID').to_s) }.to_Surface.get
+      surface_obj.setConstruction(adjacent_surface.construction.get.to_Construction.get.reverseConstruction)
+      adjacent_surface.setAdjacentSurface(surface_obj)
     end
   end
 
diff --git a/workflow/hpxml_inputs.json b/workflow/hpxml_inputs.json
index 5151befba7..827d299976 100644
--- a/workflow/hpxml_inputs.json
+++ b/workflow/hpxml_inputs.json
@@ -3608,7 +3608,8 @@
     "clothes_dryer_present": false
   },
   "sample_files/base-bldgtype-mf-whole-building-common-spaces.xml": {
-    "parent_hpxml": "sample_files/base-bldgtype-mf-whole-building.xml"
+    "parent_hpxml": "sample_files/base-bldgtype-mf-whole-building.xml",
+    "heating_system_heating_capacity": 24000
   },
   "sample_files/base-pv.xml": {
     "parent_hpxml": "sample_files/base.xml",
diff --git a/workflow/sample_files/base-bldgtype-mf-whole-building-common-spaces.xml b/workflow/sample_files/base-bldgtype-mf-whole-building-common-spaces.xml
index b752501b74..16376daa1d 100644
--- a/workflow/sample_files/base-bldgtype-mf-whole-building-common-spaces.xml
+++ b/workflow/sample_files/base-bldgtype-mf-whole-building-common-spaces.xml
@@ -229,7 +229,7 @@
                 <ElectricResistance/>
               </HeatingSystemType>
               <HeatingSystemFuel>electricity</HeatingSystemFuel>
-              <HeatingCapacity>12000.0</HeatingCapacity>
+              <HeatingCapacity>24000.0</HeatingCapacity>
               <AnnualHeatingEfficiency>
                 <Units>Percent</Units>
                 <Value>1.0</Value>
@@ -1246,7 +1246,7 @@
                 <ElectricResistance/>
               </HeatingSystemType>
               <HeatingSystemFuel>electricity</HeatingSystemFuel>
-              <HeatingCapacity>12000.0</HeatingCapacity>
+              <HeatingCapacity>24000.0</HeatingCapacity>
               <AnnualHeatingEfficiency>
                 <Units>Percent</Units>
                 <Value>1.0</Value>
@@ -1949,7 +1949,7 @@
                 <ElectricResistance/>
               </HeatingSystemType>
               <HeatingSystemFuel>electricity</HeatingSystemFuel>
-              <HeatingCapacity>12000.0</HeatingCapacity>
+              <HeatingCapacity>24000.0</HeatingCapacity>
               <AnnualHeatingEfficiency>
                 <Units>Percent</Units>
                 <Value>1.0</Value>
diff --git a/workflow/tests/util.rb b/workflow/tests/util.rb
index e7635f1b67..cfc4de415b 100644
--- a/workflow/tests/util.rb
+++ b/workflow/tests/util.rb
@@ -423,7 +423,7 @@ def _verify_outputs(rundir, hpxml_path, results, hpxml, unit_multiplier)
   end
   assert_equal(0, num_unused_objects)
   # FIXME: Common space test file has 2 unused schedule by dropping the othersidecoefficient object, which contains schedules
-  assert_equal((hpxml_path.include? 'base-bldgtype-mf-whole-building-common-spaces') ? 4 : 0, num_unused_schedules)
+  assert_equal(0, num_unused_schedules) unless (hpxml_path.include? 'base-bldgtype-mf-whole-building-common-spaces')
   assert_equal(0, num_unused_constructions)
 
   # Check for Output:Meter and Output:Variable warnings