Building Codes for the Smart Grid Ready Home
Friday, September 17, 2010 at 11:30AM
Toby Considine in BIM, Construction, Electric Cars, Microgrids and Distributed Systems, Smart Grid

Companies were looking to put standards into production at the Smart Grid Interoperability Panel (SGIP) Face to Face meeting in St Louis this week. The most interesting new question I heard was “Where are the model home building codes to support smart energy?” I don’t think there are any.

Smart grid-ready homes must go beyond smart thermostats. LEED and other models design for energy efficiency but do not manage actual use. Smart energy demands that homes respond to changing energy prices and changing requirements of their occupants. No existing code plans for new patterns of electrical use, ones that may change the wiring requirements of the home. Today’s codes do not plan for rapid changes of technology in the future.

Energy efficient design means little without monitoring. Tomorrow’s smart homes must monitor their actual energy use; they must know if they are delivering the performance promised. They should measure live or plug energy load just as they measure energy for the installed systems and sections of the house. Without the means to measure and verify energy use, efficient designs are not ready for smart energy.

In the home, the highest energy efficiency may actually hinder some interactions with smart grids. Smart energy supplies will be intermittent, in price if not in availability. Smart grid-ready homes must be able to store energy during abundance for use during scarcity. Storage will never be as efficient as instant use, so smart energy homes will be less than perfectly efficient.

Some energy based services achieve their effect right away; lights come on almost instantly. Some services require time; air conditioning and humidity control may require hours to show their effects. The most efficient systems have run constantly with just enough capacity; they do not have the excess capacity to respond on demand.

Smart grid-ready homes must anticipate their occupants’ needs, even as the price of energy changes over time. Smart energy homes must learn the schedules of their inhabitants and make plans to provide services at the right times while buying energy in response to markets.

Smart energy must support distributed energy generation and storage, both today and tomorrow. Smart grid-ready home designs will have places to site energy generation and storage systems. Home circuit panels must accept multiple energy inputs. These systems must be able to connect and disconnect, enabling the home owner to upgrade as new technologies come on the market. The smart grid ready home must be able to disconnect automatically from the grid, both for safety and to avoid power quality problems to and from the neighborhood distribution.

Distributed energy changes the wiring requirements for the home. Today’s wiring is undersized for its load, designed provide rated power for only a few minutes at a time. Energy storage and electric cars will require full power for hours at a time, causing cables to fail early. Internal wires to support, say, a 50 amp services for such uses must be larger than those for a 50 amp service today. Even the cable supplying the house must be larger to support the stresses of continuous outside, lest it to fail early.

Most energy use in our homes is, or could be, supported by Direct Current (DC). Traditional power coming from the grid is Alternating Current (AC). Batteries and many forms of distributed generation produce DC. Energy is lost when power is converted DC to AC for local distribution just as it is when converting AC to DC for point use. (This is what your wall-warts do.) Internal DC distribution and DC plug standards may be part of building codes for smart-grid ready homes.

Building a new smart grid ready neighborhood of smart grid ready homes requires care, attention, creativity, new technology, and planning for a steady stream of technology changes in the future. It probably starts with BIM-based construction to establish a known baseline building performance and capabilities. It will require standards for energy information exchange that are only now nearing completion. Each home will be filled with sensors to inform the systems of today, openly accessible to share with tomorrow’s systems that today we do not know. Each home must interact with the computers, PDAs, and smart phones that run the lives of its inhabitants. Above all, each home must be designed to allow for constant and regular upgrades.

We don’t have those building codes yet.

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