Type GH2 into the Rhino 9 BETA command line and a second Grasshopper opens next to the first one. It is not a reskin and it is not a plug-in. Japhy (McNeel) described it on 30 Jul 2026 as “a ground-up rewrite of the visual programming environment you already know — new solver, new data model, new interface — built to remove the limits we’ve been designing around in Grasshopper 1 for over fifteen years.” The same announcement also answers the question every Bürochef asks first: “GH1 and GH2 can be open at the same time — your GH1 workflow is not affected.”

That sentence is all the permission you need. A junior architect who has never wired a definition can start in GH2 without inheriting anyone’s canvas, and a senior who lives in GH1 gives up nothing. Nobody inherits spaghetti on day one. Enjoy it while it lasts.

What GH2 is, and why it is wired differently

Grasshopper is the environment David Rutten began building in 2007. For more than 15 years it has been the common language of parametric architecture, from façade grids to structural form-finding. With GH2, McNeel is rebuilding that foundation instead of patching it. Three ideas change how a façade definition gets wired:

• Metadata on every value. According to Japhy’s post, “data trees have been redesigned, and every item can now carry meta data — attach names, values, and tags to your data.” A louvre can carry its bay, its orientation and its fire zone with the geometry itself, so you no longer keep a parallel list and hope it stays aligned. David Rutten explained on 27 Oct 2025 that GH2 trees are immutable: “it would be very inefficient to build them one value at a time.” He describes the Garden class as “the central factory for these data types.” In practice you build the collection in one go and then pass it on.
• Shout / Listen. “Shout publishes a named value, and any parameter expression downstream can read it by name.” Listen matches names by pattern, and Japhy pointed out on the forum that it is “CaSe Sensitive.” One sun-altitude value can drive five bays without five wires crossing the canvas.
• A solver that uses the whole machine. “GH2 computes across your cores, and a running solution can be cancelled.” A cluster can also feed its output back into its input, and a Loop Repeats pin sets the number of iterations.

The trade-off is plain, and McNeel states it first: components are still being added, GH1 plugins do not load in GH2, and production work stays in GH1. Brian Gillespie (McNeel) announced on 23 Jun 2026 that the Rhino 9 BETA is “feature-complete,” with the team “fixing bugs, documenting, localizing, and helping third-party developers update their plugins.” The BETA is open to licensed Rhino 8 users and runs alongside Rhino 8. The open forum keeps pace with it. On 29 Jul 2026 a user reported a GH2 tooltip crash, David Rutten replied “I can repeat this on Windows,” and the same day he pointed to Rhino Beta 9.0.26210.00303 as the fix. Few software houses publish a bug and its fix inside the same day.

←TODAY: GH2 ships inside the Rhino 9 BETA beside GH1, with over 120 example definitions and a 300+ term glossary in the app.
→3012: The façade bay carries its own meaning, because every louvre knows which bay, which sun and which rule made it.
Fulcrum: Metadata written today is the documentation a stranger reads in fifty years.

The Tool: Grasshopper 2, McNeel’s visual programming environment, included in the Rhino 9 BETA. It is built by the team that answers on the McNeel forum: David Rutten, Japhy, and Ehsan Iran-Nejad on the script components. It is worth an afternoon for one reason: you can learn the new model on a clean canvas while the office’s GH1 work keeps running untouched. Japhy confirmed on 21 Sep 2026 that the “GH2b” beta label goes away with the Rhino 9 release, and that GH2 will keep its own release cadence after that. No release date has been announced.

Setup:

# 1. Download the Rhino 9 BETA (needs a Rhino 8 licence, runs beside Rhino 8)
#    https://www.rhino3d.com/download/rhino/beta/
# 2. Start the Rhino BETA and type in the command line:
GH2
# 3. On the GH2 canvas: double-click, then type
# python
# 4. Proof of life: paste into the new script component and run it
print('GH2 + Python 3 + RhinoCommon ready')

First steps (a 6 x 4 m façade bay whose louvres tilt with sun altitude):

1. Open the in-app Help and drag one of the example definitions onto the canvas, just to get used to the new zoomable UI. Japhy confirmed on 3 Aug 2026 that examples can be dragged in. Then clear the canvas.
2. Double-click the canvas and search for a numeric slider four times: bay width 6.0 m, bay height 4.0 m, louvre count 12, and sun altitude 0-90 degrees. Slider naming in GH2 may differ from GH1, so search rather than guess. Then double-click again and type # python, which is the method Ehsan Iran-Nejad published on 30 May 2025. Add the inputs w, h, n and alt with Item access, and one output, louvres. Paste the script below. Before you rely on it, check the editor’s template for how GH2 sets outputs.

import math
import Rhino.Geometry as rg

depth = 0.25                       # blade depth, m
tilt = math.radians(90 - alt)      # blade turns as the sun rises
louvres = []
for i in range(int(n)):
    z = (i + 0.5) * h / n
    pl = rg.Plane(rg.Point3d(0, 0, z), rg.Vector3d.ZAxis)
    pl.Rotate(tilt, pl.XAxis)
    rect = rg.Rectangle3d(pl, rg.Interval(0, w), rg.Interval(-depth / 2, depth / 2))
    louvres.append(rect.ToNurbsCurve())

3. Wire louvres into a native component that turns closed curves into surfaces or solids (search the canvas for “Boundary” or “Extrude”). Then follow the in-app Display Rules help to colour any blade steeper than 45 degrees, so you can read the result without baking.
4. Shout the altitude slider as SunAlt. Copy the bay, and let the copy Listen to Sun* with no wire, keeping the capital S. Bake only when you are happy with it, and save the GH2 file separately from any GH1 version.

Atelier: A 12-person studio in Zürich that tests summer sun protection on its façades (the SIA 180 conversation) usually keeps that logic in one person’s GH1 file, and the AI assistants creeping into the office cannot read it either. GH2’s metadata gives both the colleague and the machine a label to read. On Monday, make one rule: every new GH2 experiment names its key values with Shout, using one prefix per project.

Hack: Check, before you open any solar tool, from what sun angle your 12-blade bay starts blocking direct light. For flat blades on a south façade at noon, the sun’s profile angle equals its altitude. Full shading starts where the gap between blades (the pitch) is covered by the blade depth.

import math
h, n, depth = 4.0, 12, 0.25
pitch = h / n                                   # 0.333 m between blade centres
cutoff = math.degrees(math.atan(pitch / depth)) # 53.1 deg
print(f'pitch {pitch:.3f} m, full shade above {cutoff:.1f} deg')

Change depth to 0.33 m and the cutoff falls to about 45 degrees. Deeper blades shade sooner and also block more of the view. That ratio is the one to argue about in the design meeting.

Learn-it:

• Japhy (McNeel): Grasshopper 2 BETA, the announcement and its limits
• Ehsan Iran-Nejad: GH2 script components, inputs and access kinds
• David Rutten on immutable twigs, trees and the Garden class
• GH2 Shout/Listen thread: pattern matching and case sensitivity
• PAZ Rhino and Grasshopper add-ons. PAZ Academy, a Rhino centre in Switzerland, supplies Rhino 8 licences, which are also the key to the BETA.

From where I sit, decades on, the façades nobody could repair were the ones whose logic lived only in someone’s head. Write the intent into the values. Open the Rhino 9 BETA, type GH2, and build the louvre bay once, slider by slider, until you can explain every wire.