Estimation

Basis of Design (BOD)

From room dimensions to AC tonnage — calculated, not guessed

Room-by-room heat load calculator purpose-built for HVAC contractors. Input area, occupancy and exposure. Get suggested tonnage, select real equipment from your inventory, then push the entire calculation into a Customer BOQ in one click.

6 capabilitiesIncluded in every plan30-day free trial
What it does

Everything Basis of Design (BOD) handles

Organise calculations into circuits (floors, zones, buildings)

Per room: area dimensions, heat gain factor, occupancy → auto-suggest AC tonnage

Select actual tonnage and equipment from your inventory

Multiple rooms per circuit; circuits grouped per opportunity

One-click import of BOD rows into BOQ Customer line items

Saves manual re-entry and calculation errors across estimation

Feature deep-dive

How it works in practice

01

Room-by-room load calculation — organised by circuit and zone

Structure your calculation by circuit (floor, zone or building wing), then add rooms within each circuit. For every room, input area dimensions, heat gain factor and occupancy count. HVAC Flow calculates the heat load and suggests the AC tonnage required.

  • Circuits (floors, zones, buildings) organise rooms into logical groups
  • Per room: area dimensions, heat gain factor, occupancy → auto-calculated heat load
  • Suggested tonnage based on calculated load — starting point for equipment selection

Basis of Design (BOD)

Room-by-room load calculation — organised by circuit and zone

01 / 3
1

Circuits (floors, zones, buildings) organise rooms into logical groups

2

Per room: area dimensions, heat gain factor, occupancy → auto-calculated heat load

3

Suggested tonnage based on calculated load — starting point for equipment selection

02

Select real equipment from your inventory, not generic specs

Once the suggested tonnage is calculated, select the actual AC unit from your Product catalogue. If you stock 1.5TR and 2TR units, pick which one to specify for each room. The BOD records the actual equipment, not just a tonnage number.

  • Select actual equipment from your Inventory catalogue per room
  • Finalised tonnage and model number stored per room for accurate BOQ export
  • Multiple rooms per circuit — each selection tracked individually

Basis of Design (BOD)

Select real equipment from your inventory, not generic specs

02 / 3
1

Select actual equipment from your Inventory catalogue per room

2

Finalised tonnage and model number stored per room for accurate BOQ export

3

Multiple rooms per circuit — each selection tracked individually

03

One click to push the BOD into your Customer BOQ

When the calculation is complete, import it directly into a BOQ Customer. Each room's selected equipment becomes a line item — with quantity, model and tonnage. No re-entry, no copy-paste errors.

  • One-click import: BOD rows become BOQ Customer line items automatically
  • Quantities, model numbers and tonnage carry over exactly — zero re-entry
  • BOD and BOQ Customer remain linked — scope changes are traceable

Basis of Design (BOD)

One click to push the BOD into your Customer BOQ

03 / 3
1

One-click import: BOD rows become BOQ Customer line items automatically

2

Quantities, model numbers and tonnage carry over exactly — zero re-entry

3

BOD and BOQ Customer remain linked — scope changes are traceable

Basis of Design (BOD) FAQ

Common questions

The calculation uses room area (length × width), floor-to-ceiling height, heat gain factor (based on exposure — exterior walls, windows, floor/roof), and occupancy count. These are the primary drivers of cooling load in a manual calculation method suitable for most HVAC estimation scenarios.

Yes. Circuits are the grouping mechanism — create one circuit per floor, zone or building wing. Within each circuit, add as many rooms as needed. The BOD is linked to one Opportunity, so one project can have multiple circuits.

From the BOD record, click Import to BOQ Customer. Each room's selected equipment, quantity and tonnage becomes a line item. You can edit the BOQ after import to adjust pricing or add installation labour.

Each BOD is linked to one Opportunity. For a new project with a similar room configuration, create a new BOD from scratch. Copying a BOD for repeat building types is on the roadmap.

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