diff --git a/src/blenderbim/blenderbim/bim/module/drawing/decoration.py b/src/blenderbim/blenderbim/bim/module/drawing/decoration.py
index 6b21e95bee..ebff8b188d 100644
--- a/src/blenderbim/blenderbim/bim/module/drawing/decoration.py
+++ b/src/blenderbim/blenderbim/bim/module/drawing/decoration.py
@@ -1926,7 +1926,7 @@ class DecorationsHandler:
         if cls.installed:
             cls.uninstall()
         handler = cls()
-        # NOTE: we USE POST_PIXEL here so that we can draw use both 3D_POLYLINE_UNIFORM_COLOR
+        # NOTE: we USE POST_PIXEL here so that we can use both 3D_POLYLINE_UNIFORM_COLOR
         # and drawing text in the same handler. BUT this means that we supply coordinates in WINSPACE
         cls.installed = SpaceView3D.draw_handler_add(handler, (context,), "WINDOW", "POST_PIXEL")
 
@@ -1944,6 +1944,7 @@ class DecorationsHandler:
             self.decorators[object_type] = self.decorators["FALL"]
 
     def get_objects_and_decorators(self, collection):
+        # TODO: do it in data instead of the handler for performance?
         results = []
 
         for obj in collection.all_objects:
diff --git a/src/blenderbim/blenderbim/bim/module/system/__init__.py b/src/blenderbim/blenderbim/bim/module/system/__init__.py
index a57b7fb5a8..ea95b8965e 100644
--- a/src/blenderbim/blenderbim/bim/module/system/__init__.py
+++ b/src/blenderbim/blenderbim/bim/module/system/__init__.py
@@ -17,7 +17,7 @@
 # along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
 
 import bpy
-from . import ui, prop, operator
+from . import ui, prop, operator, decorator
 
 classes = (
     operator.AddPort,
@@ -51,7 +51,9 @@ classes = (
 
 def register():
     bpy.types.Scene.BIMSystemProperties = bpy.props.PointerProperty(type=prop.BIMSystemProperties)
+    bpy.app.handlers.load_post.append(decorator.toggle_decorations_on_load)
 
 
 def unregister():
     del bpy.types.Scene.BIMSystemProperties
+    bpy.app.handlers.load_post.remove(decorator.toggle_decorations_on_load)
diff --git a/src/blenderbim/blenderbim/bim/module/system/data.py b/src/blenderbim/blenderbim/bim/module/system/data.py
index 6c71e88dc9..9dd348fe13 100644
--- a/src/blenderbim/blenderbim/bim/module/system/data.py
+++ b/src/blenderbim/blenderbim/bim/module/system/data.py
@@ -27,6 +27,7 @@ def refresh():
     SystemData.is_loaded = False
     ObjectSystemData.is_loaded = False
     PortData.is_loaded = False
+    SystemDecorationData.is_loaded = False
 
 
 class SystemData:
@@ -140,3 +141,19 @@ class PortData:
 
             data.append((port, port_obj, connected_element))
         return data
+
+
+class SystemDecorationData:
+    data = {}
+    is_loaded = False
+
+    @classmethod
+    def load(cls):
+        cls.data = {
+            "decoration_data": cls.decoration_data(),
+        }
+        cls.is_loaded = True
+
+    @classmethod
+    def decoration_data(cls):
+        return tool.System.get_decoration_data()
diff --git a/src/blenderbim/blenderbim/bim/module/system/decorator.py b/src/blenderbim/blenderbim/bim/module/system/decorator.py
new file mode 100644
index 0000000000..244c8d9a5f
--- /dev/null
+++ b/src/blenderbim/blenderbim/bim/module/system/decorator.py
@@ -0,0 +1,145 @@
+# BlenderBIM Add-on - OpenBIM Blender Add-on
+# Copyright (C) 2023 Dion Moult <dion@thinkmoult.com>, @Andrej730
+#
+# This file is part of BlenderBIM Add-on.
+#
+# BlenderBIM Add-on is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# BlenderBIM Add-on is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with BlenderBIM Add-on.  If not, see <http://www.gnu.org/licenses/>.
+
+import bpy
+import gpu
+import bmesh
+import blenderbim.tool as tool
+from math import sin, cos, radians
+from bpy.types import SpaceView3D
+from mathutils import Vector, Matrix
+from gpu_extras.batch import batch_for_shader
+import ifcopenshell
+from blenderbim.bim.module.system.data import SystemDecorationData
+from bpy.app.handlers import persistent
+
+
+ERROR_ELEMENTS_COLOR = (1, 0.2, 0.322, 1)  # RED
+UNSPECIAL_ELEMENT_COLOR = (0.2, 0.2, 0.2, 1)  # GREY
+
+
+def transparent_color(color, alpha=0.1):
+    color = [i for i in color]
+    color[3] = alpha
+    return color
+
+
+@persistent
+def toggle_decorations_on_load(*args):
+    if bpy.context.scene.BIMSystemProperties.should_draw_decorations:
+        SystemDecorator.install(bpy.context)
+    else:
+        SystemDecorator.uninstall()
+
+
+class SystemDecorator:
+    installed = None
+
+    @classmethod
+    def install(cls, context, get_custom_bmesh=None, draw_faces=False, exit_edit_mode_callback=None):
+        """Note that operators that change mesh in `exit_edit_mode_callback` can freeze blender.
+        The workaround is to move their code to function and use it for callback.
+
+        Example: https://devtalk.blender.org/t/calling-operator-that-saves-bmesh-freezes-blender-forever/28595"""
+        if cls.installed:
+            cls.uninstall()
+        handler = cls()
+        cls.installed = SpaceView3D.draw_handler_add(
+            handler, (context, get_custom_bmesh, draw_faces, exit_edit_mode_callback), "WINDOW", "POST_VIEW"
+        )
+
+    @classmethod
+    def uninstall(cls):
+        try:
+            SpaceView3D.draw_handler_remove(cls.installed, "WINDOW")
+        except ValueError:
+            pass
+        cls.installed = None
+
+    def draw_batch(self, shader_type, content_pos, color, indices=None):
+        shader = self.line_shader if shader_type == "LINES" else self.shader
+        batch = batch_for_shader(shader, shader_type, {"pos": content_pos}, indices=indices)
+        shader.uniform_float("color", color)
+        batch.draw(shader)
+
+    def draw_faces(self, bm, vertices_coords):
+        """mutates original bm (triangulates it)
+        so the triangulation edges will be shown too
+        """
+        traingulated_bm = bm
+        bmesh.ops.triangulate(traingulated_bm, faces=traingulated_bm.faces)
+
+        face_indices = [[v.index for v in f.verts] for f in traingulated_bm.faces]
+        faces_color = transparent_color(self.addon_prefs.decorator_color_special)
+        self.draw_batch("TRIS", vertices_coords, faces_color, face_indices)
+
+    def __call__(self, context, get_custom_bmesh=None, draw_faces=False, exit_edit_mode_callback=None):
+        self.addon_prefs = context.preferences.addons["blenderbim"].preferences
+        selected_elements_color = self.addon_prefs.decorator_color_selected
+        unselected_elements_color = self.addon_prefs.decorator_color_unselected
+        special_elements_color = self.addon_prefs.decorator_color_special
+
+        gpu.state.point_size_set(6)
+        gpu.state.blend_set("ALPHA")
+
+        ### Actually drawing
+        all_vertices = []
+        error_vertices = []
+        selected_vertices = []
+        unselected_vertices = []
+        # special = associated with arcs/circles
+        special_vertices = []
+        special_vertex_indices = {}
+        selected_edges = []
+        unselected_edges = []
+        arc_edges = []
+        roof_angle_edges = []
+        preview_edges = []
+
+        if not SystemDecorationData.is_loaded:
+            SystemDecorationData.load()
+
+        decoration_data = SystemDecorationData.data["decoration_data"]
+        all_vertices = decoration_data["all_vertices"]
+        preview_edges = decoration_data["preview_edges"]
+        special_vertices = decoration_data["special_vertices"]
+        selected_edges = decoration_data["selected_edges"]
+        selected_vertices = decoration_data["selected_vertices"]
+
+        ### Actually drawing
+        # 3D_POLYLINE_UNIFORM_COLOR is good for smoothed lines since `bgl.enable(GL_LINE_SMOOTH)` is deprecated
+        self.line_shader = gpu.shader.from_builtin("3D_POLYLINE_UNIFORM_COLOR")
+        self.line_shader.bind()
+        # POLYLINE_UNIFORM_COLOR specific uniforms
+        self.line_shader.uniform_float("viewportSize", (context.region.width, context.region.height))
+        self.line_shader.uniform_float("lineWidth", 2.0)
+
+        # general shader
+        self.shader = gpu.shader.from_builtin("3D_UNIFORM_COLOR")
+        self.shader.bind()
+
+        self.draw_batch("LINES", all_vertices, transparent_color(unselected_elements_color), unselected_edges)
+        self.draw_batch("LINES", all_vertices, selected_elements_color, selected_edges)
+        self.draw_batch("LINES", all_vertices, UNSPECIAL_ELEMENT_COLOR, arc_edges)
+        self.draw_batch("LINES", all_vertices, special_elements_color, preview_edges)
+        self.draw_batch("LINES", all_vertices, special_elements_color, roof_angle_edges)
+
+        self.draw_batch("POINTS", unselected_vertices, transparent_color(unselected_elements_color, 0.5))
+        self.draw_batch("POINTS", error_vertices, ERROR_ELEMENTS_COLOR)
+        self.draw_batch("POINTS", special_vertices, special_elements_color)
+        self.draw_batch("POINTS", selected_vertices, selected_elements_color)
diff --git a/src/blenderbim/blenderbim/bim/module/system/prop.py b/src/blenderbim/blenderbim/bim/module/system/prop.py
index 3d31414ffd..f1ffa3263c 100644
--- a/src/blenderbim/blenderbim/bim/module/system/prop.py
+++ b/src/blenderbim/blenderbim/bim/module/system/prop.py
@@ -18,6 +18,7 @@
 
 import bpy
 from blenderbim.bim.module.system.data import SystemData
+import blenderbim.bim.module.system.decorator as decorator
 from blenderbim.bim.prop import StrProperty, Attribute
 from bpy.types import PropertyGroup
 from bpy.props import (
@@ -44,6 +45,14 @@ class System(PropertyGroup):
     ifc_definition_id: IntProperty(name="IFC Definition ID")
 
 
+def toggle_decorations(self, context):
+    toggle = self.should_draw_decorations
+    if toggle:
+        decorator.SystemDecorator.install(context)
+    else:
+        decorator.SystemDecorator.uninstall()
+
+
 class BIMSystemProperties(PropertyGroup):
     system_attributes: CollectionProperty(name="System Attributes", type=Attribute)
     is_editing: BoolProperty(name="Is Editing", default=False)
@@ -52,3 +61,6 @@ class BIMSystemProperties(PropertyGroup):
     active_system_index: IntProperty(name="Active System Index")
     active_system_id: IntProperty(name="Active System Id")
     system_class: EnumProperty(items=get_system_class, name="Class")
+    should_draw_decorations: BoolProperty(
+        name="Should Draw Decorations", description="Toggle system decorations", update=toggle_decorations
+    )
diff --git a/src/blenderbim/blenderbim/bim/module/system/ui.py b/src/blenderbim/blenderbim/bim/module/system/ui.py
index 5b60c151e7..d8e6b764c6 100644
--- a/src/blenderbim/blenderbim/bim/module/system/ui.py
+++ b/src/blenderbim/blenderbim/bim/module/system/ui.py
@@ -101,6 +101,10 @@ class BIM_PT_object_systems(Panel):
         if not ObjectSystemData.is_loaded:
             ObjectSystemData.load()
         self.props = context.scene.BIMSystemProperties
+
+        row = self.layout.row(align=True)
+        row.prop(self.props, "should_draw_decorations")
+
         if self.props.is_editing:
             row = self.layout.row()
             row.alignment = "RIGHT"
diff --git a/src/blenderbim/blenderbim/tool/system.py b/src/blenderbim/blenderbim/tool/system.py
index 13e25cf6af..87bdcc1a65 100644
--- a/src/blenderbim/blenderbim/tool/system.py
+++ b/src/blenderbim/blenderbim/tool/system.py
@@ -182,3 +182,80 @@ class System(blenderbim.core.tool.System):
     @classmethod
     def set_active_system(cls, system):
         bpy.context.scene.BIMSystemProperties.active_system_id = system.id()
+
+    @classmethod
+    def get_decoration_data(cls):
+        all_vertices = []
+        preview_edges = []
+        special_vertices = []
+        selected_edges = []
+        selected_vertices = []
+
+        si_conversion = ifcopenshell.util.unit.calculate_unit_scale(tool.Ifc.get())
+        start_vert_i = 0
+
+        if bpy.context.active_object and (active_element := tool.Ifc.get_entity(bpy.context.active_object)):
+            selected_elements = cls.get_connected_elements(active_element)
+        else:
+            selected_elements = set()
+
+        # TODO: get only objects visible in viewport
+        objects = set(bpy.data.objects) - set(bpy.data.collections["Types"].objects)
+        for obj in objects:
+            start_vert_i = len(all_vertices)
+            if obj.hide_get():
+                continue
+
+            if not isinstance(obj.data, bpy.types.Mesh):
+                continue
+
+            element = tool.Ifc.get_entity(obj)
+            if not element:
+                continue
+
+            if not cls.is_mep_element(element):
+                continue
+
+            ports = tool.System.get_ports(element)
+
+            for port in ports:
+                position = tool.Model.get_element_matrix(port).translation * si_conversion
+                all_vertices.append(position)
+
+            verts = range(start_vert_i, start_vert_i + len(ports))
+            edges = [(i, i + 1) for i in range(start_vert_i, start_vert_i + len(ports) - 1)]
+            if element in selected_elements:
+                selected_vertices.extend(verts)
+                selected_edges.extend(edges)
+            else:
+                special_vertices.extend(verts)
+                preview_edges.extend(edges)
+
+        decoration_data = {
+            "all_vertices": all_vertices,
+            "preview_edges": preview_edges,
+            "special_vertices": [all_vertices[i] for i in special_vertices],
+            "selected_edges": selected_edges,
+            "selected_vertices": [all_vertices[i] for i in selected_vertices],
+        }
+        return decoration_data
+
+    @classmethod
+    def get_connected_elements(cls, element, elements=None):
+        if elements is None:
+            elements = set((element,))
+
+        connected_elements = ifcopenshell.util.system.get_connected_from(element)
+        connected_elements += ifcopenshell.util.system.get_connected_to(element)
+
+        for element in connected_elements:
+            if element in elements:
+                continue
+            elements.add(element)
+            cls.get_connected_elements(element, elements)
+
+        return elements
+
+    @classmethod
+    def is_mep_element(cls, element):
+        return element.is_a("IfcFlowSegment") or element.is_a("IfcFlowFitting")