Green Building Practices for Both Virtual and Real Worlds

Earth Day has arrived, and we will again hear about many "Green" ways to build our lives and homes. Recycled materials, fume-free furnishings, energy-efficient lights and appliances--All are part of what it means to build and live "Green" today. I'd like to take a different tack here, and suggest some "Green Construction Tips" for the millions of people around the world who build homes, stores, and offices in the virtual world known as "Second Life." Amazingly enough, these tips could also affect our real, non-virtual, lives.

Green Virtual Construction Tip #1:

Anyone who buys or sells Second Life ("SL") land, buildings, or property soon runs into something called "prim limits." Virtual land can be purchased in a range of sizes (usually, from 512 to 65,536 square virtual meters). It isn't necessary to buy virtual land to use Second Life, but a surprising number of new "residents" do set up housekeeping on small 512 plots while they're getting a feel for the place.

Imagine their consternation, then, when after spending real money to buy virtual land, automobiles, yachts, jets, space ships, furniture, clothes, jewelry, and landscaping plants, they finally find their Dream House...buy it..."rez" it into existence on their patch of virtual turf...and discover that they can't also rez their car, furniture, clothes, or plants! They've run up against their land's "prim limit."

If you Google the phrase "second life land prim limits" you'll find a bunch of sites and videos about this issue. Specifically, if I purchase a 512-square-meter plot, all of the objects I set down on it can't together contain more than 117 "prims." Prims (SL lingo for "primitives") are the basic shapes from which all Second Life objects are made. Spheres, cubes, cones, toruses, rings, etc. are turned into everything from necklaces and castles, to simulated solar systems. Even an ordinary table might take up 5 prims (for its top surface and four legs). And a virtual garden could easily gobble up my land's entire prim allotment.

But why have prim limits in a virtual world? It's because all of Second Life runs on real-world servers owned by Linden Labs (in San Francisco)... and on SL residents' PCs. And with 16 million residents (at last count), allocation of the Lindens' computer resources is a constant issue. One way to manage their servers' use (by the almost 80,000 residents who may be "in-world" at any one time) is to limit the "prims" that both Linden servers and user PCs must display and track.

Even a shopping-mall owner with enough virtual land to support 15,000 prims may prefer to save more of this allotment for their sellers' products than for the walls, ceiling, and floors around them. So, our first "Green Virtual Construction Tip" is to "use as few prims as possible" in one's virtual construction. The fewer prims in your house, the more you'll have for your "virtual lifestyle stuff."

Green Virtual Construction Tip #2:

This is similar to the first tip...and is important for similar reasons.

Within Second Life, a programming language called Linden Scripting Language (or "LSL") is used to make virtual objects perform actions or respond to events (like being touched). These scripts do everything from opening doors to helping avatars move and hold virtual cups of coffee. Without LSL programs ("scripts"), nothing would really happen in SL. And the millions of tiny script commands executing on Linden servers every second not only affect how well users experience Second Life and how easily their SL avatars move around in it... but also the computer resources that are devoted to running the scripts themselves.

So our second "Green Virtual Construction Tip" is to use scripts only as and when necessary. And even then, one should avoid using the more computationally demanding LSL commands. Especially taxing are the commands that "listen" for user instructions and scan and "sense" their virtual environment. In both cases, these can be especially resource-intensive when they are programmed to run constantly...even when the scripted object's owner isn't around.

Green Virtual Construction Tip #3:

Many other virtual building practices add their own loads to the servers and PCs that support Second Life. Without going into too much detail, they include:

• "Particles"--These can realistically create sparkling diamonds, flickering flames, explosions, ghosts, mists, sea spray...and thousands of other optical effects. They also may be used in SL "poofers," which emit clouds of any object you'd like. But if overused, they can squander a lot of computing power.
• Fine Jewelry--A friend once told me that her SL avatar had to quit wearing a spectacular virtual necklace she'd bought. It contained hundreds of tiny prim spheres, and glittered madly through a particle script. It looked amazing, but when her avatar wore it, the avatar couldn't walk. The CPU processing needed to support her bling brought her PC to its knees. So watch that bling!
• "Flexie Prims"--These are special objects that respond to virtual forces like gravity, wind, and motion. They respond by flexing on screen, but this requires a huge number of geometric computations at multiple flex points. And if too many "flexies" are brought together in one place (such as, to create realistic wind-blown hair), computers can slow to a crawl. I encountered this myself, when I once tried to simulate a raging firestorm using flexies. It wasn't pretty.
• Huge Textures--In SL, "textures" are image files (created with a program like Photoshop) that are applied to virtual objects to change their appearance. A prim can look like wood, water, stone, steel, grass, dirt, or anything else through texturing. You can cram a lot of visual detail into textures too, without making SL computers work any harder. But the size of a texture file (in pixels) does affect the computer power need to apply it. Most SL texture files should be no bigger than 512x512 pixels...and some can be as small as 16x16 or less. But too many 1024x1024 textures can affect how rapidly user screens will display and update.

Surprisingly, all of these "Green" building issues affect both Second Life and our real world! Second Life's population has more than doubled over the past two years (according to Linden Lab statistics available in-world). And the more prims these virtual residents rez on their virtual land, the more scripts they run, the more virtual bling they wear (and so on), the more server capacity Linden Labs must add and the more real power Second Life and its users consume.

So while none of these have yet become Green Issue #1 in the real world, they do (and will) increasingly affect our global power consumption and our need to use the power we generate more efficiently. This will become increasingly important if Second Life's virtual population continues to double every two years.