Systems

Systems in HVAKR represent the HVAC equipment that conditions your building. Each system includes central equipment and serves one or more zones.

Views

Switch between three views with the view icons next to Systems in the left sidebar:

• Canvas (default) - Draw system boundaries and assign zones visually
• Table - Edit systems in a sortable table docked beside the canvas; expand it to fill the pane, or collapse it back
• Kanban - Zone cards sit in columns by system, including an Unassigned column; drag a card to a different column to reassign its system. See Kanban View

HVAKR remembers the last view you used for this page.

Kanban View

Each system column header lists the system’s Zones count, Spaces count, Levels, Total Area, Peak Time, and Total Peak Cooling. The column footer lists the space Types in the system. The Unassigned column has no summary.

If the project has no systems, the view shows No Systems. Click Create Systems to return to the Canvas view.

Click a zone card to open its detail panel at the bottom of the pane. Click the card again or close the panel to dismiss it. Drag the top edge of the panel to resize it. The panel header shows the zone name and, for an assigned zone, a tag with its system name. The panel has three sections:

• Cooling Load Profile - The zone’s hourly cooling loads for one month, with a line at the month’s peak. The month selector opens on the peak month. Without calculated loads, the chart reads No Cooling Loads
• Cooling - Peak Cooling, Peak Time, Sensible Heat Ratio, Load Distribution (area per unit of peak cooling), and Peak Heating. For a zone in a system, the list adds the system’s peak time (System name Peak Time), Load at Group Peak (the zone’s cooling load at that hour), and Coincidence (that load as a percentage of the zone’s own peak)
• Space & Airflow - Area, Occupancy, Cooling Setpoint, Supply Airflow, Supply Density, Outside Airflow, Wall Area, Window Area, and Roof Area

Use the coincidence values to decide if a zone peaks with the rest of its system.

System Concepts

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

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

Automatic System Creation

HVAKR can automatically create systems from unassigned zones:

1. Navigate to Building Model > Systems
2. Click Auto Group Zones (the sparkles icon) in the toolbar
3. HVAKR creates systems and groups unassigned zones into them immediately (there is no strategy dialog). The Project jobs list in the toolbar shows how many systems were created and zones grouped, or No zones were grouped. Only zones without a system are grouped.
4. Review the results on the canvas and adjust zone assignment as needed

Create a System

1. Navigate to Building Model > Systems
2. In the Systems panel, click Create System (or press N)
3. A new system named New System is added and selected, and zone assignment starts right away: the hint bar reads Click a zone to toggle system assignment
4. Click zones on the canvas to assign them (see Assigning Zones), then click Done
5. Rename the system and set its color in the System Data panel

A new system comes with a default central unit already configured. It carries all six components, but only three start enabled: Outside Air (Sum of Spaces method) and a Cooling Coil in Cooling mode, with a Heating Coil enabled instead in Heating mode. ERV, Return Air, and Fan Heat are present and disabled. There is no system-type template to pick at creation, but you can replace the whole arrangement afterwards with Apply System Preset. Review and adjust the central unit, coils, and outdoor air in the System Design > Configuration pane.

Assigning Zones

Assign Zones to a System

1. Select a system in the Systems panel
2. In the System Data panel, click Assign Zones
3. Click zones on the canvas to toggle their assignment: the hint bar reads Click a zone to toggle system assignment. Drag a box to assign every zone inside it; a box never removes a zone
4. Assigned zones appear in the system’s Zones list; remove one with the ✕ button
5. Click Done (or press Enter) when finished. Esc or a click on an empty part of the canvas also ends assignment

Each change applies as you make it. While you assign, each zone shows in its system’s color (or its gradient color, when a loads or airflow gradient is on in the canvas View menu), zones with no system are gray, and the zones in the system you are editing show as selected. If the system is deleted during assignment (for example by undo or a collaborator), assignment stops.

A zone can only belong to one system. Clicking a zone that belongs to another system moves it to this one.

Unassigned Zones

Outside assignment, the Systems canvas still draws zones that have no system, in muted gray under a No system assigned label, so you can see what is left to assign.

Zone Requirements

When zones are assigned:

• Airflow is calculated based on zone loads
• Terminal units are sized
• Ventilation is distributed to zones

System Capacity

The system calculates total capacity based on:

• Sum of zone peak loads (with diversity)
• Ventilation requirements

System Data

Select a system in the Systems panel to edit it in the System Data panel:

• Name - Rename the system
• Total Area - Combined floor area of the system’s spaces (read-only)
• Color - Display color for the system on the canvas
• Zones - The zones assigned to the system (see Assigning Zones); click a zone to open it
• Occupancy Diversity, Lighting Diversity, Equipment Diversity, and Miscellaneous Load Diversity - Diversity factors applied to the system’s occupancy, lighting, per-area (plug) equipment, and miscellaneous loads when aggregating zone loads. A value of N% keeps N% of the undiversified total; it is not a reduction by N%. An empty factor is 100%. Equipment Diversity applies only to the per-area equipment load. Miscellaneous Load Diversity applies only to the space miscellaneous sensible, latent, and heating loads, including itemized miscellaneous equipment. Space and zone loads are not diversified. Hover the info icon next to each factor for a summary. Occupancy Diversity also scales the people component of the system’s outdoor airflow requirement. See Occupancy Diversity in the Rollup
• Preview Loads - Show the system’s aggregated load summary
• Delete - Remove the system

The System Data header carries Locate (or press L), which switches to the system’s level and fits the canvas around its spaces. A system that spans levels keeps the current level when one of its spaces is on it, and drops to the lowest level it occupies when none is. Copy System Properties and Paste System Properties sit next to it.

The central unit, terminal units, coils, outdoor air, and duct parameters are not set here. Configure them in the System Design > Configuration pane, using the project’s duct types for duct sizing.

System Calculations

Load Aggregation

System load combines zone loads:

• Sensible cooling load
• Latent cooling load
• Heating load
• Ventilation load

Airflow Calculation

Supply airflow based on:

• Peak sensible load
• Supply air temperature
• Minimum ventilation

Equipment Sizing

Size central equipment for:

• Peak system load
• Coincident outdoor air
• Part-load performance

Multiple Systems

System Per Floor

Common approach:

• Separate AHU for each floor
• Easier maintenance access
• Simpler duct routing

System Per Exposure

Alternative approach:

• Interior system (cooling only)
• Perimeter systems (heating and cooling)
• Better load matching

Central Plant

For large buildings:

• Central chiller plant
• Central boiler plant
• Systems connect to plant loops

Best Practices

1. Match system to building - Use appropriate system types
2. Consider maintenance - Accessible equipment locations
3. Plan for future - Size systems with growth capacity
4. Check diversity - System capacity vs. sum of zones
5. Verify ventilation - Adequate outdoor air for all zones