Sunday, January 11, 2009

Making Green Make Cents with BIM

Last Friday and Saturday I had two separate conversations with BIM (Revit) masters. Friday's conversation was with Jay Dougherty, Microsol Resources and Saturday's conversation was with a fellow Twitterer (whom I just met Saturday also), Gregory Arkin, Cadd Centers. BIM for those who don't know, stands for Building Information Modeling, and the main program 'doing' this is Revit, by AutoDesk. I have a bit of experience with it, i.e.: tip of the iceberg experience, having been trained at the basic level two years ago. I do recognize the power of the program however, and always have (even if I admit I kicked and screamed a bit at first -learning a new program can be painful). The potential it has is unparalleled, because when working with it, you are literally and figuratively building the building in 3-d; any other computer drafting program is really now nothing more than 2-d lines on paper.

BIM Will Revolutonize Green Design
My conversations with both Jay and Gregory opened my eyes to just how incredibly powerful this program is. Revit can do more than just building your building in 3-d. And it can do more than do precise take-offs for cost-estimating the building (which it does, so no more rule of thumb bids -you can price a building to the penny). It can also model the building -and I am talking way more than the pretty picture modeling architects like. Revit, in concert with a few key plug-in programs (IES and Ecotec) can perform detailed building science modeling, such as energy use (electric, HVAC), carbon footprint analysis, natural daylight analysis, sun and shading analysis per building orientation, thermal envelope analysis of floor/wall/roof system, water use, and modeling far beyond this I am sure.

Currently, we can do this kind of modeling, but it's all a different program and done by someone else; i.e.: we have several separate models, pretty much all disconnected and not necessarily playing well with other programs. And to boot, generally all this kind of modeling isn't done. Why? It usually requires a different consultant for each model, which means additional services, which means more money and etc. etc. etc. So valuable information which could be gleaned isn't, and instead it is building as usual, rules of thumb and so forth; we're still living in flat world.

Now, think about having all this information -energy/resource use, daylighting levels, building envelope thermal attributes and etc., contained in one model, accessible by all consultants. Everyone can access the same model and everyone can have the same information at their fingertips and everyone, everyone, knows how the building works, breathes, lives. You can also have various design models to compare within the one model. Do we want this kind of insulation and this kind of window system with this HVAC system or that HVAC system? Model it. Analyze it. Find out your payback. Just click a button. Okay, maybe a few buttons. But it completely shifts each consultant's connection to the building design -it is now true integrated design; now we're living in round world.

Making Cents
Does Revit and the add-on programs mentioned cost more than the basic computer drafting programs in use today? Yes. But note the key word -drafting. The other programs out there today, such as AutoCAD, do not possess the power BIM does. They are in comparison, drafting programs, literally, drawing with pencil on vellum. You have little clue about how the building -a living, breathing entity, works with a drafting program. But when you consider the information contained in the one Revit model, the modeling capabilities and the fact that we will be designing more efficiently and more integratively, it doesn't make cents not to go with BIM. With BIM, we will be making green make cents.

Monday, January 5, 2009

“Demand Dims for Energy-Efficient Homes”

“As fuel prices fall, buyers reluctant to pay for green extras”

This title and sub-title are direct from a Friday, January 2nd Philadelphia Inquirer article. Upon reading the article, I discovered –to no surprise, that it was the higher cost of add-ons, such as solar panels and other “eco-friendly enhancements,” which had reduced demand. In essence, prospective buyers just don’t want to pay the associated increased first cost, according to the article, especially in these more challenged economic times.

The eco-friendly enhancements listed, aside from solar panels, were dual-pane windows, high-performing insulation and low-leakage ductwork. Reading this list, you might think that typically, single-pane windows, low to non-performing insulation and high-leakage ductwork are installed in a conventional home. I say this in jest of course, but still, it makes one wonder.

Just say no to add-ons –for now

Energy-efficiency doesn’t start with add-ons though. And you can build an energy-efficient home with conventional-performing insulation, like fiberglass batts, (and believe it or not, even single-pane windows). The key is first eliminating all air leakage through the building envelope (walls, floor and roof). This requires properly installed insulation –whether batt or spray-foam, sealing at various joints and junctures –like wall to roof and around window and door rough openings, to name a few methods. Second is to ensure a high/recommended R-value –and make sure you have eliminated thermal conductivity at studs (studs have a) low R-value to begin with and b) cold/hot air is easily transmitted through a stud into a building, it’s basic physics; click here for an excellent white paper/primer on thermal bridging). This is actually simple, and can easily be accomplished by installing 3/4-inch thick rigid insulation over top the exterior wall sheathing. Once you have a tight envelope, you have a more efficient heating and cooling system by default, simply because without air leakage, it will need to work less hard to keep the occupants comfortable. Working less hard means less money in utilities.

Making cents

Do these two measures require a bit more work on the part of the sub-contractor? Yes. Does a tighter building envelope require a ventilation system for proper air exchange? Yes. But I also believe these measures can be easily implemented by any homebuilder without having to change the basic design of the house, and with very little cost increase when compared to more costly add-ons. And taking into account that most homebuilders have each home down to a science, i.e.: they know the design, the material list, the sub-contractors, the profit and etc., I think this first step makes some green cents, for the homebuilder as well as the occupant.

Of course, I’d like to see homebuilders move far beyond these simple measures. In fact, I believe it’s imperative (check out the 100k house as a great example of energy/resource efficiency on a low budget). But it’s a start, and sometimes, even I’ll admit that baby steps can sometimes lead to giant leaps faster than we think. We also need to focus way more attention on our existing residential housing stock, making it more energy and resource efficient. Without that, we’ll have hardly made a dent (and on that front, click here for an e-book on my house –a circa 1920 brick twin, to see what I'm doing to increase its efficiency).

image is of thames & kosmos power house, a toy for ages 12+