Hagerman & Company, Inc. Technology Bulletin

Heating and Cooling Loads

by Barry Howard
AEC Solutions Engineer

Autodesk^®Revit^® MEP integrates a heating and cooling load analysis tool to let you quickly evaluate loads. This tool opens the Heating and Cooling Loads dialog, allowing you to perform an energy analysis and produce reports showing heating and cooling loads for a project. After you examine the building model and specify the appropriate construction parameters, you can click the Calculate button to run load calculations. A time-stamped report is placed in the Reports folder in the Project Browser, and the results display as a Heating and Cooling Load Report in the drawing area.

The left side of this dialog lets you view a building model, scrolling, zooming and spinning the model to examine every space.

(View Selector) lets you display the building model as wireframe or with shading.

(Dynamic View) opens the Dynamic View dialog that allows you to scroll, pan, and spin the building model.

The right side of the dialog contains a Building tab and Rooms tab where you can specify the overall construction and location parameters for the building and customize the construction parameters to selected rooms.

The Calculate button runs load calculations and creates the heating and cooling loads report for the building model.

The <Virtual Environment> button opens IES <Virtual Environment> which is installed on your system. IES <VE> lets you create an analytical model from the current building model. You can then use the expanded features of IES <VE> to calculate loads, create reports and import the results back into Revit MEP.

Building Tab
This tab lets you specify construction parameters that are applied to the overall building model. However, when parameters have been applied to individual rooms within the model, the room parameters take precedence.

Rooms tab
This tab lets you specify construction parameters that are applied to individual rooms within the building model.

	(Highlight) lets you highlight selected rooms.
	(Isolate) displays only the selected rooms.

Heating and Cooling Loads Calculation
The room volumes in the building model are computed as an analytical volume and an inner volume. The analytical volume is bounded by the center plane of walls and the top plane of floors and roofs. You use the analytical volume to verify that there are no gaps in the building model. Inner volume is bounded by the interior surfaces of walls, floors and roofs. Inner volumes are computed when the loads calculation is started.

Heating and Cooling Loads Calculation is based on:

Heat conduction and storage

Convection heat transfer

Heat transfer by air movement

Long-wave radiation heat transfer

Solar radiation

Casual (internal) gains

Thermo-physical properties of air

Room plant and control

Room and building heat balance

Loads Report
The resulting loads report consists of a summary section for the project and detailed sections showing information for each of the rooms in the project. It is placed in the Reports folder in the Project Browser. Each time you run the analysis, a time-stamped report is saved under Reports, so you can view the impact of any design changes you have made.

Loads Report Summary

Loads Report Detailed