diff --git a/.github/workflows/merge-and-run.yaml b/.github/workflows/merge-and-run.yaml
index 5ae2d7b2..2f44b7ff 100644
--- a/.github/workflows/merge-and-run.yaml
+++ b/.github/workflows/merge-and-run.yaml
@@ -26,6 +26,13 @@ jobs:
           lfs: ${{ inputs.lfs }}
           fetch-depth: 0  # fetches the whole history in order to be able to merge with the base branch
 
+      - name: Setup DotNet Environment
+        uses: actions/setup-dotnet@v1
+        with:
+          dotnet-version: |
+            6.0.x
+            8.0.x
+
       - name: Setup Git VIM Robot User Info
         run: |
           git config --global user.email "vim-robot@email.com"
diff --git a/src/cs/vim/Vim.Format.Tests/RoomServiceTests.cs b/src/cs/vim/Vim.Format.Tests/RoomServiceTests.cs
new file mode 100644
index 00000000..8359ca8e
--- /dev/null
+++ b/src/cs/vim/Vim.Format.Tests/RoomServiceTests.cs
@@ -0,0 +1,67 @@
+using NUnit.Framework;
+using System.IO;
+using System.Linq;
+using Vim.Format.Merge;
+using Vim.Format.ObjectModel;
+using Vim.Format.SceneBuilder;
+using Vim.Math3d;
+using Vim.Util.Tests;
+
+namespace Vim.Format.Tests;
+
+[TestFixture]
+public static class RoomServiceTests
+{
+    /// <summary>
+    /// Merges two unrelated VIM files and then calculates the inclusion of elements
+    /// coming from the first VIM file (containing no rooms) in the rooms of the second VIM file.
+    /// </summary>
+    [Test]
+    public static void TestRoomService_ComputeElementsInRoom()
+    {
+        var ctx = new CallerTestContext();
+        var dir = ctx.PrepareDirectory();
+
+        // Merge the VIM files.
+        var vim1 = Path.Combine(VimFormatRepoPaths.DataDir, "Wolford_Residence.r2023.om_v5.0.0.vim");
+        var vim2 = Path.Combine(VimFormatRepoPaths.DataDir, "RoomTest.vim");
+        var mergedFilePath = Path.Combine(dir, "merged.vim");
+
+        var mergeFiles = new MergeConfigFiles(new[]
+        {
+            (vim1, Matrix4x4.Identity),
+            (vim2, Matrix4x4.Identity)
+        }, mergedFilePath);
+
+        var mergeOptions = new MergeConfigOptions()
+        {
+            GeneratorString = nameof(TestRoomService_ComputeElementsInRoom),
+            VersionString = "0.0.0",
+        };
+
+        MergeService.MergeVimFiles(mergeFiles, mergeOptions);
+
+        var mergedVim = VimScene.LoadVim(mergedFilePath);
+        Assert.DoesNotThrow(() => mergedVim.Validate());
+
+        var dm = mergedVim.DocumentModel;
+
+        var elementInfos =
+            Enumerable.Range(0, mergedVim.DocumentModel.NumElement)
+                .AsParallel()
+                .Select(elementIndex => dm.GetElementInfo(elementIndex))
+                .ToArray();
+
+        var wolfordFamilyInstances = elementInfos
+            .Where(ei => ei.BimDocumentFileName.Contains("Wolford") && ei.IsFamilyInstance)
+            .ToArray();
+        var wolfordFamilyInstanceElementIndices = wolfordFamilyInstances.Select(ei => ei.ElementIndex).ToHashSet();
+
+        // Compute the element association in each room.
+        var familyInstancesInRooms = RoomService.ComputeElementsInRoom(
+            mergedVim,
+            ei => wolfordFamilyInstanceElementIndices.Contains(ei.ElementIndex));
+
+        Assert.IsNotEmpty(familyInstancesInRooms);
+    }
+}
diff --git a/src/cs/vim/Vim.Format/ObjectModel/ElementInfo.cs b/src/cs/vim/Vim.Format/ObjectModel/ElementInfo.cs
index f8f40bac..ad545f29 100644
--- a/src/cs/vim/Vim.Format/ObjectModel/ElementInfo.cs
+++ b/src/cs/vim/Vim.Format/ObjectModel/ElementInfo.cs
@@ -86,6 +86,8 @@ public bool IsSystem
         public int CategoryIndex => DocumentModel.GetElementCategoryIndex(ElementIndex);
         public int LevelIndex => DocumentModel.GetElementLevelIndex(ElementIndex);
         public int LevelElementIndex => DocumentModel.GetLevelElementIndex(LevelIndex);
+        public int RoomIndex => DocumentModel.GetElementRoomIndex(ElementIndex);
+        public int RoomElementIndex => DocumentModel.GetRoomElementIndex(RoomIndex);
         public int BimDocumentIndex => DocumentModel.GetElementBimDocumentIndex(ElementIndex);
         public int WorksetIndex => DocumentModel.GetElementWorksetIndex(ElementIndex);
         public int FamilyInstanceElementIndex => DocumentModel.GetFamilyInstanceElementIndex(FamilyInstanceIndex);
@@ -100,6 +102,7 @@ public bool IsSystem
         public Element Element => DocumentModel.ElementList.ElementAtOrDefault(ElementIndex);
         public Category Category => DocumentModel.CategoryList.ElementAtOrDefault(CategoryIndex);
         public Level Level => DocumentModel.LevelList.ElementAtOrDefault(LevelIndex);
+        public Room Room => DocumentModel.RoomList.ElementAtOrDefault(RoomIndex);
         public BimDocument BimDocument => DocumentModel.BimDocumentList.ElementAtOrDefault(BimDocumentIndex);
         public Workset Workset => DocumentModel.WorksetList.ElementAtOrDefault(WorksetIndex);
         public FamilyInstance FamilyInstance => DocumentModel.FamilyInstanceList.ElementAtOrDefault(FamilyInstanceIndex);
@@ -164,6 +167,7 @@ public string ElementUniqueIdWithBimScopedElementIdFallback
 
         public string ElementName => DocumentModel.GetElementName(ElementIndex);
         public string CategoryName => DocumentModel.GetCategoryName(CategoryIndex);
+        public string CategoryBuiltInName => DocumentModel.GetCategoryBuiltInCategory(CategoryIndex);
         public string LevelName => DocumentModel.GetElementName(LevelElementIndex);
         public string FamilyName => DocumentModel.GetElementName(FamilyElementIndex, DocumentModel.GetElementFamilyName(ElementIndex));
         public string FamilyTypeName => DocumentModel.GetElementName(FamilyTypeElementIndex);
diff --git a/src/cs/vim/Vim.Format/RoomService.cs b/src/cs/vim/Vim.Format/RoomService.cs
new file mode 100644
index 00000000..1ea67d13
--- /dev/null
+++ b/src/cs/vim/Vim.Format/RoomService.cs
@@ -0,0 +1,145 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Vim.Format.Geometry;
+using Vim.Format.ObjectModel;
+using Vim.LinqArray;
+using Vim.Math3d;
+
+namespace Vim.Format
+{
+    public class ElementInRoom
+    {
+        public int ElementIndex { get; }
+        public int RoomIndex { get; }
+
+        public ElementInRoom(int elementIndex, int roomIndex)
+        {
+            ElementIndex = elementIndex;
+            RoomIndex = roomIndex;
+        }
+    }
+
+    public static class RoomService
+    {
+        public delegate bool GeometricElementInfoFilter(ElementInfo elementInfo);
+
+        public static ElementInRoom[] ComputeElementsInRoom(VimScene vim, GeometricElementInfoFilter geometricElementInfoFilter)
+        {
+            var dm = vim.DocumentModel;
+
+            var roomElementIndices = new HashSet<int>(dm.RoomElementIndex.ToEnumerable());
+            if (roomElementIndices.Count == 0)
+                return Array.Empty<ElementInRoom>(); // no rooms found.
+
+            // Collect the bounding boxes of geometric elements
+            var geometricNodesGroupedByElementIndex = vim.VimNodes
+                .Where(n => n.HasMesh)
+                .GroupBy(n => n.ElementIndex)
+                .ToArray();
+
+            var roomGeometryCollection = geometricNodesGroupedByElementIndex
+                .AsParallel()
+                .Where(g =>
+                {
+                    var elementIndex = g.Key;
+                    return roomElementIndices.Contains(elementIndex);
+                })
+                .Select(g =>
+                {
+                    // ASSUMPTION: Rooms are typically represented by a single geometric node, so take the first item in the group.
+                    var worldSpaceMesh = g.First().TransformedMesh();
+                    var roomElementIndex = g.Key;
+
+                    var roomIndexFound = dm.ElementIndexMaps.RoomIndexFromElementIndex.TryGetValue(roomElementIndex, out var roomIndex);
+                    roomIndex = roomIndexFound ? roomIndex : -1;
+
+                    return new RoomGeometry(roomIndex, worldSpaceMesh.Vertices.ToArray(), worldSpaceMesh.Indices.ToArray());
+                })
+                .ToArray();
+
+            if (roomGeometryCollection.Length == 0)
+                return Array.Empty<ElementInRoom>(); // no rooms with geometry found.
+
+            var filteredElementGeometricNodes = geometricNodesGroupedByElementIndex
+                .AsParallel()
+                .Where(g =>
+                {
+                    // Filter the elements
+                    var elementInfo = g.First();
+                    if (!geometricElementInfoFilter(elementInfo))
+                        return false;
+
+                    // Ignore room elements.
+                    if (roomElementIndices.Contains(elementInfo.ElementIndex))
+                        return false;
+
+                    return true;
+                }).Select(g =>
+                {
+                    var elementIndex = g.Key;
+
+                    // Determine whether the element geometry's bounding box center is contained in one of the rooms.
+                    var boundingBox = g.Select(n => n.TransformedBoundingBox()).Aggregate((acc, cur) => acc.Merge(cur));
+                    var boxCenter = boundingBox.Center;
+
+                    foreach (var roomGeometry in roomGeometryCollection)
+                    {
+                        // Broad-phase bounding box check.
+                        var containmentType = roomGeometry.AABox.Contains(boundingBox);
+                        if (containmentType == ContainmentType.Disjoint)
+                            continue;
+
+                        // Refined point-in-mesh check
+                        if (roomGeometry.ContainsPoint(boxCenter))
+                            return new ElementInRoom(elementIndex, roomGeometry.RoomIndex); // early return on the first room which contains the bottom center of the box.
+                    }
+
+                    return null;
+                }).Where(eir => eir != null)
+                .ToArray();
+
+            return filteredElementGeometricNodes;
+        }
+
+        private class RoomGeometry
+        {
+            private readonly Vector3[] _vertices;
+            private readonly int[] _indices;
+
+            public int RoomIndex { get; }
+            public AABox AABox { get; }
+
+            public RoomGeometry(int roomIndex, Vector3[] vertices, int[] indices)
+            {
+                RoomIndex = roomIndex;
+                _vertices = vertices;
+                _indices = indices;
+                AABox = AABox.Create(vertices);
+            }
+
+            public bool ContainsPoint(Vector3 point)
+            {
+                var intersections = 0;
+
+                var ray = new Ray(point, Vector3.UnitZ);
+
+                for (var i = 0; i < _indices.Length; i += 3)
+                {
+                    var v0 = _vertices[_indices[i]];
+                    var v1 = _vertices[_indices[i + 1]];
+                    var v2 = _vertices[_indices[i + 2]];
+
+                    var triangle = new Triangle(v0, v1, v2);
+
+                    if (ray.Intersects(triangle) != null)
+                    {
+                        intersections++;
+                    }
+                }
+
+                return intersections % 2 == 1; // Inside if odd intersections
+            }
+        }
+    }
+}