Update app/materials_library.py

app/materials_library.py

@@ -1391,13 +1391,13 @@ def display_materials_help():
     **Materials Tab:**
     
     * **Library Materials**: Pre-defined materials with standard thermal properties. Use 'Preview' to view details or 'Copy' to add to your project.
-    * **Project Materials**: Materials you have added to your project. Use 'Edit' to modify or 'Delete' to remove.
+    * **Project Materials**: Materials you've added to your project. Use 'Edit' to modify or 'Delete' to remove.
     * **Material Editor/Creator**: Create new materials or edit existing project materials. Library materials can only be previewed.
     
     **Fenestrations Tab:**
     
     * **Library Fenestrations**: Pre-defined windows, doors, and skylights. Use 'Preview' to view details or 'Copy' to add to your project.
-    * **Project Fenestrations**: Fenestrations you have added to your project. Use 'Edit' to modify or 'Delete' to remove.
+    * **Project Fenestrations**: Fenestrations you've added to your project. Use 'Edit' to modify or 'Delete' to remove.
     * **Fenestration Editor/Creator**: Create new fenestrations or edit existing project fenestrations. Library fenestrations can only be previewed.
     
     **Key Properties:**
@@ -1405,7 +1405,7 @@ def display_materials_help():
     * **Thermal Conductivity (W/m·K)**: Rate of heat transfer through a material. Lower values indicate better insulation.
     * **Density (kg/m³)**: Mass per unit volume.
     * **Specific Heat (J/kg·K)**: Energy required to raise the temperature of 1 kg by 1 K. Higher values indicate better thermal mass.
-    * **Thermal Mass**: Areal heat capacity, categorized as Low (<30,000 J/m²·K), Medium (30,000–90,000 J/m²·K), or High (>90,000 J/m²·K).
+    * **Thermal Mass (J/m²·K)**: Areal heat capacity (density × specific heat × thickness).
     * **U-Value (W/m²·K)**: Overall heat transfer coefficient, accounting for material and surface resistances. Lower values indicate better insulation.
     * **SHGC**: Solar Heat Gain Coefficient (0-1). Fraction of incident solar radiation that enters through a fenestration.
     * **Visible Transmittance**: Fraction of visible light that passes through a fenestration.