A GI.* formula pulls a single live number from your Giraffe project into a cell, the same way SUM pulls a total from a range. Use it to pin a hard cost rate, a total gross area or a unit count into a pro forma without retyping it every time the model changes.
Write a Gi formula
Type =GI. into any cell. Autocomplete lists this project's own fields, not a generic function list, so you pick from what your project actually has.
A few common ones:
=GI.TOTAL("grossArea"): every section's gross area, added up.=GI.TOTAL("grossArea", "usage=Residential"): the same total, filtered to one usage.=GI.COUNT("levels>3"): how many geometries have more than 3 levels.=GI.WEIGHTEDAVG("salePrice"): the area-weighted mean sale price. It is a mean, not a sum.
Spreadsheet ships with roughly 45 functions in total, the set a development pro forma, an area schedule and a unit mix actually need, rather than every function a full spreadsheet program has. Click Help in the toolbar for the full list, or see Function List in Spreadsheet.
Point at cells instead of typing addresses
Type = and then point at cells instead of typing their addresses, the same as in Excel:
Arrow keys pick a cell on the sheet instead of moving your text cursor, and
Shift+arrow extends the pick to a range.Clicking a cell inserts its reference. Dragging inserts a range.
Typing anything else ends the pick, and the reference stays as text.
Mid-formula, click a different sheet tab and then a cell there to reference across sheets, for example =Usages!C8. Pressing Enter brings the formula back to the cell where you started typing it.
Worked examples
These are the calculations a development pro forma almost always needs. Each one combines a GI.* function with ordinary spreadsheet functions.
Plot ratio (FAR)
Divide total gross area by the site area:
=GI.TOTAL("grossArea") / GI.SITEAREA()
Use GI.SITEAREA(), not GI.FOOTPRINT(). The footprint is the ground your geometries actually cover, so a plot ratio built on it instead of the site reads higher than the true number.
Net-to-gross efficiency
Divide net area by gross area, filtered to the usage you care about:
=GI.TOTAL("netArea", "usage=Residential") / GI.TOTAL("grossArea", "usage=Residential")
This is the same number Spreadsheet's efficiency field already carries as a weighted average, so =GI.WEIGHTEDAVG("efficiency", "usage=Residential") gets there in one step when the project already has that field.
Blended sale revenue
Multiplying a total area by an average sale price overstates or understates revenue on any scheme with mixed pricing. Work the arithmetic out per geometry instead:
=GI.SUMEACH("saleableArea * salePrice", "usage=Residential")
See Per-Geometry Calculations in Spreadsheet for why GI.SUMEACH gives a different, more accurate answer than a total times an average.
Unit mix percentages
The dwelling mix arrives as one field per bed type, such as dwelling-2BED-Count. Divide each bed type by the total to get its share:
=GI.TOTAL("dwelling-2BED-Count") / GI.TOTAL("dwellingTotalCount")
Format the result as a percentage from the toolbar's number format dropdown. Click Examples ▾ and choose Dwelling counts to stamp every bed type as its own column in one step, then add a percentage row underneath.
Residual land value
A residual appraisal is revenue, minus costs, minus a required profit margin, leaving what the land itself is worth:
Revenue:
=GI.SUMEACH("saleableArea * salePrice"), by usage.Hard and soft costs:
=GI.SUMEACH("grossArea * hardCost"), and a soft cost percentage applied to that.Profit: a percentage of revenue or of total cost, entered as an ordinary assumption cell.
Residual land value: revenue, minus costs, minus profit.
Click File ▾ → Residual appraisal for a full worked version of this schedule against your own project. See Example Workbooks in Spreadsheet.
Monthly cashflow: NPV and IRR
Lay a draw schedule down a column of monthly dates, with cash out (costs) and cash in (sales) beside each date, then read the return with NPV and IRR:
=NPV(discount_rate/12, cashflow_range) + initial_outlay
=IRR(cashflow_range)
Build the month column with EOMONTH so it advances by calendar month rather than a fixed number of days:
=EOMONTH(A2, 1)
Click File ▾ → Monthly cashflow for a full worked 24-month draw with NPV and IRR already built. See Column Types in Spreadsheet for continuing a date series with the fill handle, and Charts in Spreadsheet for turning this into a chart. For a full walkthrough, see Create a Pro Forma and Cashflow in Spreadsheet.