Load calculation (text version) | Revit MEP

The built-in load calculation tool for Revit MEP is based on the US ASHRAE load calculation standard using thermal balance method (HB) and Radiation Time series (RTS) for load calculations. The tool can automatically identify the building model information, read the area of the building components, volume and other data and calculate.

1. Basic settings

1.1. Location

Location information is used to determine the latitude and longitude of the project location and local meteorological parameters.

In Revit MEP, you can edit the geographic location in two ways:

• Ribbon: Manage → location
• Ribbon: Manage → project info → instance properties → energy settings-edit → location

The meaning of the tabs in the location, climate, and Venues dialog box that opens:

• Location: Define where the project is located
• Weather: Set meteorological parameters for the appropriate location
• Venue: direction of the building

1.2. Construction/Space Type setting

Ribbon: Manage →MEP settings → building/space type settings

The building/Spatial Type Settings dialog box lists energy analysis parameters for different building types and spatial types, such as indoor heat dissipation, thermal dissipation of lighting equipment and parameters for simultaneous use of parameters, all of which refer to the U.S. ASHRAE standard for the default parameter values. When designing projects in different countries and regions, users can adjust them according to local design standards and project characteristics to ensure the correctness of load calculation results.

• Type of building

  Refers to buildings of different functions.

  The energy analysis parameters of the building type include the body heat dissipation, the amount of heat dissipated by the device, the heating of the equipment, the distribution of the light in the positive pressure supply system, the usage, the opening time, the closing time and the temperature setting point of the non-air conditioning area.

  Energy analysis parameters can be adjusted according to the domestic design codes and manuals.

• Space type

  A room with different functions, such as a hall, office, etc.

  The space type does not contain three parameters for development time, shutdown time, and unoccupied refrigeration set point, and other parameters correspond to the same energy analysis parameters as the building type.

2. Space

Revit MEP automatically obtains information about the different rooms in the building by defining "space" for the building model: perimeter, area, volume, orientation, area of doors and windows, etc. By setting the "Space" property, the heat transfer coefficient of building envelope and the energy consumption analysis parameters of room personnel load are defined.

2.1. Space placement

After identifying the building elements (such as walls, ceilings, floors, doors, windows, etc.) of a room in a building model, it is possible to assign "space" to the building model. Select the linked building model, click on the Ribbon in the Modify | RVT link → Type property, in the Type Properties dialog box, check room boundaries under constraints.

"Analysis" → "space": Move the mouse to the building model, will automatically capture the room boundaries, click the corresponding room, you can change the room to define as space.

For large spaces, you can separate a large space by two or more spaces by analyzing → space separators in the Ribbon.

• Spatial visibility Settings
• "Spatial tags" are used to label space information

After the space is placed, select all the entities in the current view, and if there is a problem with space placement, show related warnings appears in the ribbon panel, the problematic space is highlighted, and the message dialog box opens.

2.2. Space settings

After the space is placed, the energy analysis parameters of each space need to be set. There are two ways to set the energy analysis parameters of space:

• Spatial Properties: Ribbon, properties → energy analysis.
  • positive pressure system: when the non-air-conditioning space used as a static pressure box, check this item;
  • Space: If the space is an air-conditioned area, check this option;
  • condition Type:: If empty Air conditioning area, choose the appropriate air-conditioning mode. If the space is non-air-conditioned, select "Unconditional";
  • Space type: Click the space type's ... icon, open the Spatial Type Settings dialog box, select a space type, and set the corresponding energy analysis parameters;
  • Construction type: Defines the heat transfer performance of the building envelope;
  • people: Go to people → Edit to open the People dialog box. If the values for occupy and per capita hot increments are selected by default, the person load is calculated according to the per capita area of the space type setting in the Building/Spatial Type dialog box in the basic settings, the latent heat increment for each person, and the explicit heating increment;
  • electrical load: Enter "electrical load" → " Edit to open the Electrical Load dialog box, if the values for lighting and power are selected by default, the power and lighting load will be calculated according to the lighting load density, the power load density, and the positive pressure distribution of the air supply system in the "Building/Spatial Type" dialog box in the basic setup. "Specify" to enter custom values yourself;
  • calculates the thermal load and the calculated cold load: This is the load value calculated using the Load calculation tool built into Revit MEP, and the values of these two items are displayed as "not calculated" until the load calculation is performed;
  • Design thermal load and design cold load: This is a user-defined expected load value;
• Space schedule: You can count and edit spatial information. In the Ribbon, "analysis" → "schedule/Quantity", "category" → "Space", set up a space schedule.
  • field: Adds the parameters related to the available Fields Intermediate spatial attribute to the Schedule field.
  • sorted into groups: in sort by, select level and ascending, and the space schedule will first be arranged in ascending order of different levels of each layer, and in the second filter, select number and ascending, and the different spaces in each layer will be sorted in ascending order by space number.

When you have finished the two edits above, click OK to generate the space schedule. Use the space Schedule to edit spatial properties.

3. Partition

A partition is a collection of spaces. Spaces using the same air conditioning system or air conditioning systems using the same air handling equipment can refer to locating the same partition. The newly created space is automatically placed under the default partition, and the space in the default partition does not participate in load calculations. Therefore, you must specify a partition for the space before the load calculation.

3.1. Partition placement

In the Ribbon, "split" → "Partition" → "Add space", select "Space" and add "space" to the specified partition.

Use the color scheme feature to color-fill individual partitions based on their name, area, or calculated cold load, and visualize information about each partition.

In the Ribbon, "design" → "Legend", select "Air Conditioning area" as "Space type" and click the legend placement in the view.

When the Ribbon Edit Scheme command is activated, open the Edit Color Scheme dialog box, edit the schema definition, and customize the partition color scheme according to the different needs in the color drop-down menu.

3.2. Partition settings

Click Partitions in the current view to open the Properties dialog box in the Ribbon, and define the parameters for the partition's device type, cooling, heating, and fresh air information under energy analysis

• Device type: Select the type of air-conditioning device used by the partition
• Refrigeration information: including refrigeration set point, cold air temperature, temperature control, dehumidification set point four settings
• Heating information: Including the heating set point, heating air temperature, temperature control, humidity set point four settings
• Fresh air information: including the amount of fresh air per person, the amount of fresh air per region, three per hour ventilation set

4. Thermal load and cold load

After the building type, space, and partition settings are completed, load calculations can be carried out according to the building model.

4.1. General

Building Information data includes:

• Building type: Consistent with "building type" set in "Building/spatial type" in basic settings
• Location: Same as the location setting described in basic settings
• Construction Equipment: The main type of air conditioning system used in the building
• Building construction: Same as the "Construction type" setting for space in space
• Building Air permeability Rating: building tightness rating
• Report type: How detailed the load report is generated after the load calculation is completed
• Ground plane: The elevation of the ground plane reference of the building, the space of the ground plane reference standard is considered as the underground space
• Small gap space tolerance: it is necessary to form a complete boundary with a parallel room boundary member, such as return air shaft and wall groove. If the set value is greater than 300, then the corresponding small gap space load calculation will belong to the adjacent room space, and participate in load calculation; If the set value is less than 300, the small gap space is not placed "space", the load calculation, the small gap space will be considered as outdoor.

4.2 More information

Contains spatial information and analytical surface information.

• "Space" contains partition information and spatial information:
  • Partition information: The information contained in the section "Properties" dialog box "Energy Information" has been
  • Spatial information: Contains information consistent with the energy analysis information in the Spatial Properties dialog box
• The analytical surface contains zoning information, spatial information, and building envelopes:

  The partitioning information and spatial information are set in the same way as when space is selected. When you select Analyze surface, the left window in the thermal load and cold Load dialog box displays analytical surface models for components including facades, interior walls, ceilings, floors, and so on.

4.3 Load reporting

When the above settings are verified or edited, click Calculate to generate the load report. If you do not perform the calculation, you can save your changes by clicking Save Settings.

You can set the data format for the load report by modifying the project units.

Load calculation (text version) | Revit MEP