How should green builders prepare for smart grids?
Friday, September 25, 2009 at 09:08PM
Toby Considine in BIM, Design, Smart Grid

Brian Duggan from West Coast Green asked me at GridWeek what green builders and sustainable construction companies should do to prepare themselves for the smart grid. What new construction methods should they use? What new smart-grid aware control systems would they need to install. My answer—nothing.

My answer was that before a building can collaborate with a smart grid, it must know what it has and know what it can do. Knowing what you have begins with information technology (IT), and knowing what you are building, and that begins with design.

Sustainable builders should embrace the use of building models and of building information models (BIM). BIM produces designs that more effectively engage the owner, earlier in the process. This leads to fewer retrofits, fewer changes, and less waste. I cannot imagine how anyone can claim to be committed to sustainable construction if they do not use BIM.

Energy models, an important part of LEEDS and other sustainable business practices, often have little to do with the actual design. Even when they do, they are only rarely updated to reflect design changes or value engineering. An energy model can be created directly from a BIM. As the design is updated, the energy model can be regenerated. Instead of being a separate and largely irrelevant check off, with BIM, the energy model becomes a recursive method to commission the design.

BIM-based construction shares information with the design to do a better job. BIM-bidding uses reduces uncertainty and risk—and thereby cost. Because the collisions are resolved in advance in the three dimensional model, subsystems and components are built off-site in controlled conditions. Casework, fire control systems, plumbing, duct, really any component can be cut, fit, and assembled off-site to achieve higher quality with less waste in less time.

Duct for example, can be pre-assembled, sealed, and insulated in shop conditions rather than in the field, perhaps the street, as is often the case in traditional construction. Higher quality ductwork is quieter and saves energy throughout the life of the system. The resulting components are installed faster and with minimal interference with other trades.

BIM today has little to say about the critical control systems that manage and monitor energy using systems in the building. I think BIM-based designers should specify performance goals, Healthfulness, comfort, and performance should be specified. Subcontractor bids should warrant results not methods; this maximizes the incentive for innovation. These performance goals, along with the intrinsic energy model described above, become the platform for commissioning.

Too often, commissioning falls back to the old standard—no sparks. BuildingSmart, the consortia that promotes best practices in BIM, has defined the Common Operations Building Information Exchange (COBIE). COBIE defines the handover of information from the BIM to operations at the end of construction. COBIE catalogues building systems and formalizes commissioning records. When combined with the performance specification for each system as described above, COBIE will raise commissioning to a higher level.

Building owners and operates must understand how their buildings actually operate before they can understand how to collaborate with the smart grid. Such knowledge increases the value received from site-based generation and storage even before smart grid interactions are considered. A tenant who can see the services provided by his building, and understands how changes affect quality of service changes, rather than how systems operation changes, knows enough to negotiate with the grid.

It starts with knowing what is in the building, what services are provided by the building, and how changes affect quality of service. In new construction, that should begin with BIM.

Article originally appeared on New Daedalus (http://www.newdaedalus.com/).
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