SELECTING EQUIPMENT

The final step in the design process is to use system design reports to select HVAC equipment. At the beginning of this example, nine equipment sizing objectives were listed. Data provided on the System Sizing Summary report (see Figure 3.19) and the Zone Sizing Summary report (see Figure 3.20) can be used to meet all nine of these objectives. The Air System Design Load Summary (see Figure 3.21) provides supplemental information about component loads. The table below lists the nine sizing

The System Sizing Summary report contains data used to select the rooftop unit. The Central Cooling Coil Sizing Data table lists the peak coil capacities, coil entering and leaving conditions and a number of useful check figures. The Preheat Coil Sizing Data table lists the peak load for this coil as well as entering and leaving conditions. The Supply Fan Sizing Data table provides the required airflow rates and motor data for the supply fan. The Outdoor Ventilation Air Data section lists the total outdoor air requirement for the system. Together this data can be used in the applied rooftop unit selection software offered by Carrier and other manufacturers to select a rooftop unit which meets the sizing requirements. The Zone Sizing Summary report contains data used to select terminal equipment. The Zone Sizing Data table lists the required airflow rate for each zone terminal. It also lists the minimum airflow rate which can be used to set minimum damper positions for the mixing boxes. The Zone Terminal Sizing Data table lists the required sizes for the parallel mixing box fans, the reheat coils and the zone heating unit coils. The Space Loads and Airflows table lists the required airflows for each space served by the system. Because 8 of the 9 zones contain a single space, space and zone airflows for these zones will match. For the Music Room zone which contains four spaces, the airflow rates can be used to size ductwork and supply diffusers for the four rooms in this zone. Together this data can be used in air terminal selection software offered by Carrier and other manufacturers to select terminal components which meet the sizing requirements. This data can also be used in duct design calculations to size ductwork for the system.

Table 3.2. Location of System Sizing Data on Design Reports

Objective: Table

Report: Air System Sizing Summary

1. Rooftop Cooling Capacities Central Cooling Coil Sizing Data 2. Rooftop Supply Fan Airflow Supply Fan Sizing Data

3. Rooftop Preheat Coil Capacity Preheat Coil Sizing Data 4. Rooftop Outdoor Airflow Rate Outdoor Ventilation Air Data

Report: Zone Sizing Summary

5. Supply Terminal Airflow Rate Zone Sizing Data (see “Design Air Flow”) 6. Supply Terminal Minimum Airflow Rates Zone Sizing Data (see “Minimum Air Flow”) 7. Supply Airflow Rates for Mixing Box Fans Zone Terminal Sizing Data

(see “Mixing Box Fan Airflow”) 8. Terminal Reheat Coil Capacities Zone Terminal Sizing Data

(see “Reheat Coil Load”)

Chapter 3

System Design Example Problem

Figure 3.2 Design Weather Parameters

Figure 3.3 Wall Construction Data

Chapter 3

System Design Example Problem

Figure 3.5 Schedule Input Data (Continued)

Chapter 3

System Design Example Problem

Chapter 3

System Design Example Problem

Chapter 3

System Design Example Problem

Chapter 3

System Design Example Problem

Chapter 3

System Design Example Problem

Chapter 3

System Design Example Problem

Chapter 3

System Design Example Problem

Chapter 3

System Design Example Problem

This chapter contains a simple example problem which demonstrates how to use HAP to estimate annual energy use and cost for a building. The example is suitable for the detailed design phase of a project. The example builds on concepts and procedures discussed in Chapters 1 and 2.

4.1 OVERVIEW FOR THE EXAMPLE PROBLEM

The procedure for conducting an energy analysis with HAP involves five steps previously discussed in Chapter 1:

1. Define the Problem. 2. Gather Data.

3. Enter Data Into HAP.

4. Use HAP to Generate Simulation Reports. 5. Evaluate the Results.

The example problem presented in this chapter will demonstrate the first four steps in this process. In the remainder of this chapter a separate section will deal with each step.

4.2 DEFINING THE PROBLEM

The objective of this example problem is to estimate annual energy use and energy cost for a building. Normally an energy analysis compares energy use and cost for two or more design scenarios. To make this example practical and efficient, the scope of the example will be limited to estimating energy use and cost for a single design scenario. This will demonstrate the key steps in the energy analysis process. In a real energy study, certain of the steps would be repeated to generate the additional design scenarios so the costs of multiple scenarios could be compared.

The example will analyze the classroom wing of the high school building used in the system design example problem discussed in Chapter 3. The floor plan for this wing of the school building is shown in Figure 4.1. It is comprised of six classrooms, a music room and its associated office, storage and practice rooms, plus two corridors for a total of 12 rooms.