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Air System Load and Sizing Results
Air System Load and Sizing Results

Air System Results, AHU sizing, peak airflow, block loads, coincident loads, HVAC sizing

Akshay Padwal avatar
Written by Akshay Padwal
Updated over a week ago

Air Systems are a collection of Zones served by common, central components such as heating coils, cooling coils, and fans. They are often the largest single piece of equipment on a project along with one of the highest cost items of the mechanical package. Finally, they have a large impact on energy consumption over the life of a building. Given their importance in size, cost, and energy sizing Air Systems correctly is of critical importance to sustainable building design.

How are Air Systems sized on the platform?

Air Systems are sized via the EnergyPlus engine as the coincident peak of all zone and system-level loads. Coincident, or block load is the simultaneous load on the system at a specific (peak) time. The coincident load is an actual peak for the system or building taking into account the dynamic nature of individual zone loads that make up the total. The alternative to coincident load is a simplified peak load that ignores the time individual loads occur, resulting in a higher total value which is purely theoretical. To promote the right sizing of equipment all results for Air Systems, Mechanical Plants, and whole buildings are provided as coincident loads on the platform.

Note that Air System results are produced for Central Air Systems only. For Local Systems all the equipment results can be found with the Zone Results.

Detailed Air System Load Results (online view)

Right-click and open a new tab for a larger view

Results for air systems are found on a dedicated tab on the platforms results page. Each Air System in the project can be selected to view the detailed results, including airflow, coincident loads, coil sizing, ancillary equipment loads, and checks. Selecting the cooling and heating loads will open a graphic breakdown of end uses.

Spreadsheet Export

All results can also be downloaded as a spreadsheet by clicking the Export Spreadsheet button under the Air System Results List. The Spreadsheet will have 2 sheets - Air Systems Results Summary and Air Systems Results All. The Summary sheet provides the key sizing information for that system, including peak loads and airflow. The All sheet provides all the detailed information calculated for the systems, including the end-use breakdown, safety factors, checks, etc.

Air System Check Summary Report

Results can be downloaded to a standard pdf Check Summary Report which provides all the key data for each Air System. To generate this report simply click the Export pdf report button found under the Air System Result List header. The report includes the same information as the online view and is formatted to allow quick inspection of important results such as the auto-calculated checks.

Result Variable Definitions

Full descriptions of each result variable is available here.

Using the Results

  • Sizing reports for the air system can be used for equipment selections by sharing with manufacturer reps

  • The online view allows for easy access to the results to your entire team. Use the Internal Chat Feature to invite teammates to the project so they can collaborate.

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