Systems
Systems in HVAKR represent the HVAC equipment that conditions your building. Each system includes central equipment and serves one or more zones.
System Concepts
Section titled “System Concepts”What is a System?
Section titled “What is a System?”A system includes:
- Central unit - AHU, RTU, or other central equipment
- Terminal units - VAV boxes, fan coils, etc.
- Ductwork - Air distribution network
- Zones - The spaces being served
System Types
Section titled “System Types”Common system configurations:
- Single-zone - One thermostat controls the entire system
- Multi-zone - Multiple zones with terminal units
- VAV - Variable air volume with zone control
- VRF - Variable refrigerant flow
Creating Systems
Section titled “Creating Systems”New System
Section titled “New System”- Navigate to Building Model > Systems
- Click New System
- Select a system type template
- Configure system properties
- Assign zones to the system
System Type Selection
Section titled “System Type Selection”Choose the system type that matches your design:
- See System Types for configuration options
- Templates provide typical configurations
- Customize as needed for your project
Assigning Zones
Section titled “Assigning Zones”Zone Assignment
Section titled “Zone Assignment”Assign zones to systems:
- Select a system
- Click Add Zones
- Select zones from the list
- Zones appear under the system
Zone Requirements
Section titled “Zone Requirements”When zones are assigned:
- Airflow is calculated based on zone loads
- Terminal units are sized
- Ventilation is distributed to zones
System Capacity
Section titled “System Capacity”The system calculates total capacity based on:
- Sum of zone peak loads (with diversity)
- Ventilation requirements
- Safety factors
System Properties
Section titled “System Properties”Central Unit
Section titled “Central Unit”Configure the main air handling equipment:
- Capacity - Cooling and heating capacity
- Airflow - Supply air CFM
- Supply temperature - Leaving air temperature
- Outdoor air - Ventilation and economizer
Terminal Units
Section titled “Terminal Units”For multi-zone systems:
- Terminal unit type (VAV, fan coil, etc.)
- Sizing method
- Minimum airflow settings
Ductwork
Section titled “Ductwork”Duct system parameters:
- Duct type and material
- Sizing method
- Friction rate or velocity
System Calculations
Section titled “System Calculations”Load Aggregation
Section titled “Load Aggregation”System load combines zone loads:
- Sensible cooling load
- Latent cooling load
- Heating load
- Ventilation load
Airflow Calculation
Section titled “Airflow Calculation”Supply airflow based on:
- Peak sensible load
- Supply air temperature
- Minimum ventilation
Equipment Sizing
Section titled “Equipment Sizing”Size central equipment for:
- Peak system load
- Coincident outdoor air
- Part-load performance
Multiple Systems
Section titled “Multiple Systems”System Per Floor
Section titled “System Per Floor”Common approach:
- Separate AHU for each floor
- Easier maintenance access
- Simpler duct routing
System Per Exposure
Section titled “System Per Exposure”Alternative approach:
- Interior system (cooling only)
- Perimeter systems (heating and cooling)
- Better load matching
Central Plant
Section titled “Central Plant”For large buildings:
- Central chiller plant
- Central boiler plant
- Systems connect to plant loops
Best Practices
Section titled “Best Practices”- Match system to building - Use appropriate system types
- Consider maintenance - Accessible equipment locations
- Plan for future - Size systems with growth capacity
- Check diversity - System capacity vs. sum of zones
- Verify ventilation - Adequate outdoor air for all zones