sh Thermal Unit Per Hour, Cost per Watt
Density: Kilograms per Cubic Centimeter
Diffusivity: Square Feet per Second, Square Meters per Second
Distance, Length, Stationing, Stationing Interval: US Survey Feet
Flow per Power: Cubic Feet per Minute per British Thermal Unit Per Hour, Cubic Meters per Watt Second
Force Scale, Linear Moment Scale: Feet per Kip, Meters per Kilonewton
Friction: Meters of Water Column per Meter, Millimeters of Water Column per Meter
Isothermal Moisture Capacity: Cubic Feet per Pound Mass, Cubic Meters per Kilogram
Luminance: Candelas Per Square Foot
Mass per Time: Kilograms per Hour, Kilograms per Minute, Kilograms per Second, Pounds Mass per Hour, Pounds Mass per Minute, Pounds Mass per Second
Moment Scale: Inverse Kilonewtons, Inverse Kips
Power: Thousand British Thermal Units per Hour
Power per Flow: Watts per Cubic Foot per Minute, Watts per Cubic Meter per Second
Power per Length: Watts per Foot, Watts per Meter
Pressure: Meters of Water Column, Millimeters of Water Column
Rotation Angle: Multiples of Pi
Thermal Gradient Coefficient for Moisture Capacity: Kilograms per Kilogram Kelvin, Pounds Mass per Pound Degree Fahrenheit
Viscosity: Kilograms per Meter Hour, Kilograms per Meter Second, Newton Seconds per Square Meter, Pound Force Seconds per Square Foot
User Interface Improvements
Revit 2021.1 includes a number of user interface improvements to make working easier.
System Browser interaction in a panel schedule view: When you select an element in the System Browser while in a panel schedule view, the Properties palette displays the properties of the selected element, similar to the behavior in plans, sections, and 3D views.
Level Offset for System-Zones: The value displayed for the Level Offset parameter for the selected System-Zone displays and is editable in the Properties palette.
Shared Parameters Dialog: Resize the shared parameters dialog to make it easier to work with shared parameters in your models.
User Profile Improvements: The disciplines and job roles you select during installation are more clearly defined to match how you work.
Active View Tab Switching: Set view tab switching keyboard shortcut based on your preferences. Switch view tabs based on tab position, or history order.
Acquire Shared Coordinates Notification
When you acquire shared coordinates from a linked file, you now receive a confirmation message. The message tells you the process completed successfully and the GIS coordinate system that was acquired if the linked file contains one.
Dynamo Updates
Ninety new Dynamo nodes are available in several categories, allowing you to easily manipulate Revit element functions.
Set Points for Systems Analysis
New parameters for set points for heating, cooling, humidification, and dehumidification have been added to the building types and space types for use with Systems Analysis.

Enhancements

API
Deprecated two properties DocumentSavingAsEventArgs.IsSavingAsMasterFile and DocumentSavingAsEventArgs.IsSavingAsMasterFile and added two properties DocumentSavingAsEventArgs.IsSavingAsCentralFile and DocumentSavedAsEventArgs.IsSavingAsCentralFile.
In the API, replaced the Enum value ConnectorType.MasterSurface with a new value ConnectorType.MainSurface (no rebuild of existing applications referencing the replaced value is required).
Alignments
Added support for alignments to Revit transferred from a future version of InfraWorks as a part of the InfraWorks bridge model. Alignments support alignment station annotations to be added to an imported alignment individually or as "sets" to meet documentation requirements.
Dynamo for Revit
Updated Dynamo for Revit version to 2.6 in Revit 2021.1.
Provided new Dynamo for Revit nodes for Path of Travel function including getting/adding/setting and removing waypoints, calculate the shortest way to multiples destinations.
Added 90 new Dynamo Revit nodes related to Revit platform functions such as selection, documentation, view, etc.
Electrical Panel Schedule
Added support so users can modify elements in a circuit using the properties palette while in a panel schedule view by selecting the desired element(s) in the System Browser.
Export DGN
Renamed the property used for selecting the working units during DGN export through the API to WorkingUnits.
Import/Export/Link SAT/SKP
Added support for importing SketchUp 2020 files.
MEP Analytical Systems
Improved System-Zones by reporting the Level Offset and making it editable in the Properties palette.
MEP Miscellaneous
Added support for P&ID Modeler to access Plant 3D Collaboration projects on a Europe data center.
Reinforcement
Added the ability to identify the rebar host for any selected rebar set, area or path reinforcement.
Shared Coordinates
Provided informational messages when attempting to acquire coordinates from a link.
Shared View
Provided an easy way to share 3D views in Revit.
Units
Added 50 new units of measurement, spanning across all disciplines. Please see What's New for a complete list. link.
User Interface
Refined disciplines and job roles in the user profile.
Updated the following dialogs to be resizable: Parameter Properties (Family Editor), Manage Project Units, Manage Project Parameters, Project Parameter Properties, New Shared Parameter, Shared Parameter Properties, Edit Tooltip.
Refined a link message in the Default Family Template File Invalid dialog.
Added the option to switch view tabs by history order (starting from last active/working view) using CTRL+(SHIFT)+TAB.
Autodesk Revit 软件功能：
-简单的用户界面，可以快速学习
-同时设计和绘制二维和三维施工图
-能够在建筑平面图，结构和2之间建立联系并在它们之间建立协调
-能够作为一个小组使用，并在一个项目