Go ahead, click the Calculate button.
After the simulation is completed, you are directed to the Heating And Cooling Loads report, as shown in Figure 8.17. Depending on the level of report detail you selected prior to running the simulation, the tabulated results will be shown, broken into an overall project summary, a building summary, building-level summaries, individual zone data, and individual space data.
The Project Summary area lists the project information (name, address, location), as well as calculated design date and time, Summer Dry Bulb and Wet Bulb temperatures, the Winter Dry Bulb temperatures, and the Mean Daily Range—values that should match the inputs you have entered with the weather data. The Building Summary area includes the global building type
and its total analytical area and volume, as well as the overall calculated performance of the building—peak cooling loads, peak heating loads, airflows, and building checksums.
The Level Summary area includes the analytical area and volume of each level of the design building, if applicable, as well as each level′s individual performance values, similar to the Building Summary. The Zone Summary lists each analyzed zone along with its inputs, psychrometrics, and the calculated performance results. It also breaks down the various cooling and
heating components and displays a list of the spaces that make up the zone along with a brief summary of the space performance. The Space Summary displays the space analytical areas and space volume, load inputs, and space type, as well as the calculated results for the space. It also contains a breakdown of the individual space components and how they contribute to the cooling and heating loads.
Revit MEP allows you to run a heating and cooling load analysis, make changes, and run subsequent analysis all while retaining the reports run for each analysis. Load reports are individually time stamped and can be accessed in the Project Browser under Reports. This enables
you to easily flip to a previous report and quantify the changes in your design, without resorting to printing out each report as it is generated. Each report can grow to several hundred pages, depending on the size of your job and the detail level selected.
Now is a good time to set up and run a sample HVAC load analysis in Revit. Here′s how:
1. Open the file CHAPTER 8 HVAC.rvtavailable at www.sybex.com/go/
2. Download and link in the Architectural model file Chapter8SampleBuilding.rvt, which can be found on the same web page. Use Origin To Origin placement when linking the file.
3. Set the property of the linked file to Room Bounding by selecting the link, editing its Type Parameters, and selecting the Room Bounding check box. Click OK.
4. Place your spaces. Click the Analyze tab, and select Spaces to begin placing your spaces in the view. Either select the rooms you want to model, or click Place Spaces Automatically. Confirm the number of spaces created.
5. Create a working Space Properties schedule to manage space data. Click the Schedule/Quantities button.
6. Select Spaces as the category, and use New Construction as the phase. Click OK.
7. From the available fields, select the appropriate categories to match the Space Properties schedule shown earlier in Figure 8.4.
8. Adjust the Name and Number fields to match the architectural link, either by manually entering the values or by using a space-naming utility. Sort the rows in descending numerical order.
9. Notice that all the space types are set to <Building>, and the condition type is Heated And Cooled. If you examine the building type, you should see that it is set to Office.
Choose Manage Project Information Energy Settings to confirm. Click OK twice.
10. In the Space Properties schedule, select the space type cell associated with Office 102. Open the Space Type Settings dialog box by clicking the ellipsis in that cell.
11. Set the Space Type to Office – Enclosed. Notice the changes in the space parameter values.
Verify that the Occupancy Schedule is set to Common Office Occupancy – 8 AM to 5 PM and that the Lighting and Power Schedules are set to Office Lighting – 6 AM to 11 PM.
12. Notice that the Number Of People value for Office 102 has changed. This reflects the
different Area Per Person parameter value for the Space Type – Office vs. the Building
Type – Office.
13. Set the remaining space type values appropriately.
14. Notice that the number of people in each space is taken out to six decimal places. Set the field format for this column to use fixed units with a rounding to 0 decimal places. Switch back to the 1 – Mech floor-plan view.
15. Click the Heating And Cooling Loads button on the Analyze tab. Switch the view to Details, and expand the Default tree.
16. Each space has a warning symbol attached to it. Select a space. As you click the Warning button, you will see that the space is not upper-bounded by a roof, ceiling, or floor element. You need to set the upper limits of each space to ensure accurate building analysis.
Click OK and then Cancel.
17. In the 1 – Mech floor plan, select all the spaces. In the Properties palette, set the upper limits of each space to Level 2, with a 0˝-0≤offset.
18. Open the Heating And Cooling Loads window, and verify that all the warnings have been cleared from the spaces.
19. Click Calculate.
20. View the building performance report that has been generated.
21. Switch back to the 1 – Mech floor plan and click the Zone button on the Analysis tab.
22. Create zones in the 1 – Mech floor plan. Group the spaces as shown in Figure 8.18, and name the zones per the sample schedule.
23. Select Zone 05 in the floor plan. Verify that the service type is VAV – Terminal Reheat and that the Cooling and Heating Information settings are both Default.
24. Click Edit for the Outdoor Air Information and, for this zone, enter 5 CFM per person, and 0.06 CFM/SF in the appropriate boxes. Set the space occupancies equal to 1 person.
25. Run another building analysis.
26. As you view the Zone Summary report for Zone 05, you should see that the Peak Ventilation Airflow is 20 CFM. The Ventilation Density value equals 0.06 CFM/SF—the value you entered. The Ventilation/Person value, however, equals 7 CFM/person, which is not what was entered. Remember, Revit MEP takes the largestventilation load, notthe required combined ventilation load, when calculating the building performance.
27. To get the ASHRAE-required ventilation, do the following:
a. Calculate the required ventilation from area.
b. Calculate the required ventilation from occupants.
c. Add the two values, and divide by the total area.
d. Enter this value in the Outdoor Air Information window for Zone 05.
28. Run the analysis again, and observe that the Zone 05 Ventilation Airflow has changed to the airflow calculated in the previous step.
29. Using the Space Properties schedule, zone properties, and the Heating And Cooling Loads window, adjust various parameters and rerun the heating and cooling analysis.
30. Use the different reports generated to compare the effects of your changes to the building.
31. Close the file