In the future, buildings will be engineered and documented exclusively using virtual modeling techniques. The near future.

The term 'model' is being used in two ways: To pretend to build, as with clay or Legos. To simulate using math, logic, and rules, as with climate modeling.

Carry this further, and we see that the virtual building model contains two types of information: Polygons, the stuff the building pretends to be made of, and descriptions, the words and numbers about the stuff the the building is made of in reality.

This is instantly recognizable as the ancient duality of architectural documentation: pictures and specifications. Show what it should look like, add descriptions for clarity and emphasis.

We model geometry, which ends up as drawings. We model information, which ends up as specifications.

The geometric, polygon model allows/forces us to check the consistency of the geometry. Things have to fit. It discourages pretending. You can move the polygons now, or the concrete later.

Working out the geometry is hard work. But it is the exact same work builders have always done, now orders of magnitude less expensive. The responsibility of designers to understand the geometry has not changed. The tools have made this understanding a hundred times more attainable.

With the geometry in place, the simulation model gives us for free the ability to maintain the integrity of the information.

Ideally, we would draw/describe every single thing in the project, and point to the drawings/descriptions from every conceivable point of view. In reality, the maintenance of describing every single thing in every conceivable context becomes prohibitive. Changes are incompletely deployed, and you have inconsistency as well as errors of commission, i.e., mistakes. This is worse than what you were trying to avoid: errors of omission, where things aren't called out enough.

The virtual building enforces consistency. It enforces it by moving one window and affecting multiple views. It enforces it by letting you draw a detail once and call it out indefinitely.

As you zoom in in scale, less information is modeled, and more is drawn and described. Details will be drawn for the foreseeable future. This does not mean they're 'not modeled' and therefore substandard. They are drawn within the system of the virtual building, drawn once and called out repeatedly. Drawn accurately, so their geometry is checked, even in 2D. In this way, they are part of the model as simulation.

The important thing is for the professional, you, as you 'draw', to maintain the integrity of the model, in the software and in your mind. It is permissible and necessary to draw, but you must know exactly how that drawing relates to the model, and be able connect the drawing to the model, and maintain the connection. It is the maintenance, again, that is expensive. When you 'just draw it', you are sacrificing integrity, risking error, and making your job harder.

Buildings are incredibly complicated. The paradigm of our time is to say of complicated things, "They contain a lot of information." Without a computer, managing a lot information requires a lot of energy, which means people and money. With a computer, managing a lot of information is only slightly more costly than managing a little.

Cars and airplanes, which are much more complicated than buildings, have been designed digitally for some time. This shows clearly that the slowness of adoption in the building industry is due to culture, not technology. People are coming to realize that a complete building simulation is an extremely valuable document. It helps everyone: Architects, clients, engineers, tradespeople, facilities managers.

The virtual building idea is nearing a tipping point, where suddenly the next day it will be everywhere, like the web, or cars, or airplanes. We are lucky to be in the forefront of this movement; the late-adopters will be looking for work. Technological revolutions have a way of putting the leaders in the middle of the pack. We must continue to push forward, because things are about to start moving very fast.

All the JAM8 windows have a parameter called 'Mode' which allows you to tell the object how to interpret your width and height dimensions. (Then there's schematic mode which draws a glass box. More of a bar stunt than a feature, but it does work.)

The default is for the windows to treat the height and width as the frame size, the outside measurement of the unit. I chose this behavior because it is the most objective overall measurement for a window, when you consider different manufacturers. The other option is 'Jamb', which treats the height and width as the inside dimension of the frame instead of the outside. When measuring an existing window, this is the measurement you'll have.

Both the frame and jamb modes place the window so that the INSIDE of the head is at the head height as given in the settings box, which is the sill added to the height parameter. That is, switching from frame to jamb DOES NOT move the window in Z. The head height in the settings box always reflects the finish head height (above the subfloor, of course).

Reread the preceding paragraph several times.

Window companies are notoriously idiosyncratic about sizes, dimensions, standards, and terminology, to the point that the statement, "I want a 2-8 double-hung" is almost meaningless. Weathershield, for example, refers to its frame size as 'Jamb-to-Jamb', where normal people would think that meant the inside jamb dimension. Not helpful.

You have to develop a knowledge of what the different manufacturers mean by their terms. The only way to do this is to study their details and find the relationships among the various size definitions.

One of my more ambitious goals for the next version of the windows is to teach them the technical differences among the manufacturers, but it might be more trouble than it's worth. In the meantime, as usual, there is no substitute for understanding what you're doing. You might have to put in counterintuitive values to get the windows to behave correctly in a given application. I do it all the time.