If you've been reading Tom Glavinich’s Integrated Building Systems columns, you probably picked up a running theme. He introduced it in his January 2007 column:
“Concern over the environment and global warming grows, and the public becomes increasingly aware that residential and commercial buildings use a large portion of the U.S. energy supply and produce an equally large amount of greenhouse gases. Therefore, the drive to make buildings more energy efficient and environmentally neutral will increase.”
This concern is inspiring the development of new applications for technology that could slow down the growth of electrical energy consumption. A lot of that technology will mean increasing business for the electrical contractor (EC) that is willing to branch out beyond its traditional specialties.
Electrical work falls into four general areas: power, control, information processing and communication. Developments in all of these areas can contribute to the goal of making buildings more energy efficient and environmentally neutral. As an example, power can be generated and distributed in new ways. Instead of completely relying on energy generated at a central plant and then transmitted over power lines to feed a large area, power can be generated at a building or neighborhood level.
A few advantages come to mind. Energy losses due to power traveling over long transmission lines can be reduced. Local generation can come from a variety of sources, designed for what is most practical in a given area. For example, photovoltaics could be most effective in sunny areas. There also are fuel cells, which can be installed anywhere and are efficient and nonpolluting.
The significance for the electrical contractor is that there is much electrical work involved in this:
- Power: Local power sources must be coordinated with utility power. Energy requirements may vary over the course of a day, presenting the local source with peaks and valleys in load requirements. During a peak, the facility being served may receive power from the utility. During a valley, the local power source may have a surplus, which it can feed back onto the power grid—a process called net metering. This involves complex power wiring, including the installation of an automatic transfer switch (ATS) designed so if there is any disturbance to the utility during the transition between sources, the alternate source and the load will be either nonexistent or at least kept to a minimum.
- Control: The unusual power wiring for this arrangement type is just one part of the picture. It is necessary to have a control system that senses the amount of energy being drawn and decides whether there needs to be a switchover. This might incorporate a programmable logic controller (PLC) or a computer-based system with specialized software. The control system must be integrated with the automatic switch by any one of a variety of methods. How to interconnect the sensing and control circuits with the power switch leads the designer to consider a range of choices. For example, this can be viewed as an isolated system, independent of other systems in the facility. It then might be feasible to hard wire each system component, although even within the confines of an isolated system, the designer might choose a standard serial bus, such as RS-232 or Modbus, in order to reduce the quantity of wires that need to be run. However, it might be a good idea to coordinate this system with the other building systems as part of a building management system (BMS) or when implementing a green building system. That would impact the interconnection decision. Modbus or Ethernet or another control platform, for example, can be used to integrate and control most building systems, and the power source is the most basic of those systems.
- Information processing: The control system depends on the accumulation and analysis of data, such as instantaneous load requirements, condition of the local and utility power sources, level and stability of voltage and frequency, and anticipated requirements based on history, time and day of the week. A central computer, either on its own or with operator intervention, decides to override the preprogrammed transfer of power or to adjust building systems, such as HVAC and lighting, to optimize the balance between local and utility power.
- Communication: A critical system, such as the transition between local and grid-supplied power, requires good, real-time information. As the systems in a building become more complex, it becomes more important to constantly monitor the systems and to alert the staff of any problems. Building managers should always be aware of the status of their electrical power feed. This information also must be sent to the utility, so it can have a clear picture of conditions on the power grid.
In addition, Internet protocol (IP), which is being used in more applications, is a means of integrating control, data processing and communication and should be considered for new installations.
This is just one example of how the movement toward conserving energy will offer many challenges and opportunities to the electrical contracting community.
Finally, I want to thank Doug Sandberg of ASCO Services Inc., Florham Park, N.J., for a very helpful discussion of automatic transfer switch applications.
BROWN is an electrical engineer, technical writer and editor. He serves as managing editor for SECURITY + LIFE SAFETY SYSTEMS magazine. For many years, he designed high-power electronics systems for industry, research laboratories and government. Reach him at email@example.com.