Mechanical and electrical engineering: Things that keep me up at night
There are several emerging mechanical and electrical engineering technical trends that are worrisome to this author.
By Paul Lutkevich, Parsons Brinckerhoff, Boston
When first asked the question, “What are the things you most worry about and keep you up at night?” the immediate response that came to mind was my kids, of course. And although I’m not sure I have nightmares over new technologies, there are several emerging technical trends that are worrisome. For example, we seem to have entered into a period where technologies and design methods are in rapid flux, causing design professionals to maintain a breakneck pace in the adoption, training, and validation of these new methods. The engineer’s inherent methodical approach and adoption of new design practices is being rushed by client demands and industry buzz about the next best thing. We question how to keep up, and sometimes more importantly whether we should keep up, with the adoption of certain technologies and practices. The basic questions—“is it safe,” “is it cost effective,” and “is it in the best interest of the client”—are sometimes difficult and time consuming to answer.
We all have our own lists of concerns, but here are a few of my top concerns along with some thoughts on how we can better cope with them.
Are we there yet?
It is very difficult for codes, standards, and research to keep ahead of rapidly advancing technology. With revision cycles of three to five years for most codes and recommended practices, a lot can happen between revisions. Some technologies specified by engineers are advancing so quickly that codes, standards, and application information are often not fully developed at the onset of the use of that technology and research. Let’s take the example of solid-state lighting devices.
Light-emitting diodes (LEDs) have been emerging quickly as a possible replacement for currently used sources such as fluorescent and high-intensity discharge (HID) lamps. The efficiency of LEDs in terms of lumens/Watt (LPW) is approaching and, in some cases, surpassing these sources. There are many control options, optical efficiency benefits, and opportunities for design optimization. There are also the myths that can emerge as with any new technology.
The impression most people have is that LEDs will save energy compared to anything else available on the market. Claims of retrofits saving 50%, 100%, or more are regularly touted and written about. The facts, however, are more selective:
- When comparing source efficacy, many fluorescent and high-pressure sodium lamps still produce more LPW than currently available LEDs. These sources have made advances in recent years, and claims of energy superiority often are based on retrofits of old technology lamps. LEDs do offer greater control than these sources, so in general a lot of that difference can be made up by getting a greater percentage of lumens on the surface that is intended to be illuminated. When selecting the most cost-effective new luminaire, sometimes LED is the best option and other times it will be just another lamp type.
- Claims are being made that sources rich in shorter wavelength spectral content (more blue/white in color) increase visibility in outdoor lighting applications. Essentially, this is based on the eye responding to a different spectrum of light at lower light levels because of the increased use of rod photoreceptors. There is very solid research that shows this is the case. However, there are other factors not fully addressed in this research, which should limit confidence in adopting the premise in exterior lighting designs. Things like vehicle headlights, eye scanning traits, glare sources, and more may limit this effect. More blue/white color sources will appear brighter, but it is not known if visual performance will definitively be improved in actual applications. Additional research is being performed to address these questions, which may be answered sometime in the near future.
- The belief that LEDs require little or no maintenance needs careful scrutiny. How long an LED will last (or how long until it reaches its L70 life, the time when the output has depreciated to 70% of the initial output) depends on several factors. The primary ones are the drive current at which the LEDs are operated and the junction temperature of the LEDs. These factors are luminaire dependent and need to be evaluated for every product an engineer is considering. General assumptions about conventional lamp technology relied on in the past can no longer be made with confidence. The same LED can perform differently depending on the quality of the fixture design. Consideration also must include the driver performance. Many drivers have a predicted life of about 50,000 hours, so even if the LEDs have a long life potential, some components will still require replacement on shorter maintenance cycles.
LEDs will undoubtedly be the source of the future (or possibly OLEDs or plasma technology, depending on how far ahead one cares to look). However, it is prudent to approach a new technology with care. Several new pieces of information are recently available or being developed. Some of the more notable are the Lighting Research Center (www.lrc.rpi.edu) report on lighting for collector roads, which takes an application-specific look at LED technology; new documents being developed by the Illuminating Engineering Society (IES) concerning solid-state devices; and their application documents. Recommendations on things like adaptive lighting (where exterior lighting systems can be dimmed based on pedestrian or vehicle volumes) are being considered which would allow an easily controllable source like LEDs to acquire additional energy and maintenance benefits. Also worth checking are IES position statements that attempt to address issues immediately instead of waiting for document revision cycles.
The best way to stay current on emerging technologies is to be involved with the research supporting the development of these technologies and be active in the standards and code committees that will guide their use. The investment of 1% to 2% of staff time, with associated expenses, to assist in these endeavors quickly pays back by identifying technologies that benefit clients. Firms that wait for information on new technologies will be far behind those firms that are actively engaged.
It’s not easy being green
The concepts of saving money and saving the environment are sometimes difficult to reconcile, but the green movement has required that the attempt be made. Most engineers will say their designs have always tried to be cost-effective in terms of installation, maintenance, and operational costs. Many of the energy-efficiency initiatives considered to be green were always the foundation of this good design practice. The recognition by owners of new sustainability possibilities, the advent of new conservation technologies, and the U.S. Green Building Council’s formalized LEED process have prompted engineers to push the design boundaries, or at least have reminded them of where those boundaries are. Sleepless nights can occur, at least for a mechanical and electrical (M+E) engineering manager, because of a few primary assumptions, including:
Designing green costs the same. Not really. Let’s start with design costs. To evaluate the feasibility and return on investment of a water reclamation system, green roof, space daylighting, geothermal, solar-electric, or wind renewable energy, and fully integrated environment and equipment controls, it will take more design effort. This time is well spent and will yield significant benefits, but it does indeed require more effort. One of the toughest tasks engineers face is to adequately explain the true value of spending more money in the design phase to save money on facility operations. Designers have the ability to show life-cycle cost differences in systems and approaches but rarely include the design cost differences that will arise.
Clients demand and architects design facilities that feature dramatic images and expansive windows. While aesthetically desirable, such facility designs may not meet prescriptive requirements of energy codes, so a dynamic model of the expected energy consumption must be developed. The energy model, which was once an option available to clients, has now become a necessity to comply with energy codes. It is but one example of the additional documentation required to obtain LEED certification. In addition to registration of the project, LEED certification requires that design professionals provide detailed documentation on the performance of each of the sustainable features of the facility—again, a worthwhile endeavor, but one that has implications on the overall cost of the design.
To fully understand the differences in design approaches and their benefits, clients need to be brought into the predesign process. In a LEED project, this is somewhat built in with the addition of a commissioning authority (CxA) and the preparation of the owner’s project requirements (OPR) and the design team basis of design (BOD). An often successful approach is to show that the additional design expenses established in the OPR will be paid back quickly in operational costs, in some cases within the first year. Some clients opt to design and construct their facilities to LEED criteria but choose not to obtain certification, thereby receiving the benefit of sustainable design without the associated cost of application for certification and documentation of the sustainable features.
Renewable power is free energy. Many people think that renewable power systems will quickly pay back the original investment. When including renewable sources as part of a facility or infrastructure project, it becomes obvious that this is not always the case. Given the right location and the needed combination of rebates and tax incentives, a renewable component can certainly provide a reasonable payback. And it seems true that the larger the scale of the project, the quicker it will pay for itself.
The problem generally occurs when trying to integrate a renewable power component into a smaller project. Photovoltaic cells can be integrated into many kinds of surfaces or on structures. Small microturbines or vertical axis wind turbines can be added to any roof or on top of many structures and will generate some level of power. While the likelihood of these systems producing a financial payback in a reasonable amount of time is pretty slim, they do offer an environmental return and are worth considering. Many projects are including some percentage of renewable power as a way to reduce their carbon footprint and be a responsible part of the community. From an engineering standpoint, opportunities must be sought to integrate renewable power options and advise clients of all of the benefits, financial and social.
Phased production of design work. Many projects are performed with the architect starting work, followed by structural design, and finally mechanical and electrical design. In order to live within shrinking budgets for design, the M+E system designer will often wait until the building design is well established before laying out equipment. As part of a green design team the M+E engineers have to be actively involved in the development of the architecture layouts, looking for opportunities to integrate daylighting, and assist with the selection of material properties and other considerations to add green technologies. The structural engineers need to be informed of the potential use of renewable technologies and their impact on the structural design.
So, the preferred approach to green technology can be summed up as more communication. This includes communication with the client to establish reasonable expectations, costs, and return on investment criteria (many times as part of the OPR and BOD); communication within the design team to coordinate design and production approach; and agreement by everyone involved that there is a significant though sometimes obscure benefit to sustainable design methods.
Remember the days of mylar drawings, Leroy lettering templates, and pin registry systems for overlaying drawings? Don’t admit it to anyone because you are showing your age. Expectations from clients now include 3-D models, computer visualizations, and virtual walkthroughs of proposed designs. These technologies are such powerful design tools that it’s a wonder how we lived without them. They are advancing as more external design computations are included and performed within the software and will eventually lead to more automated construction methods being a part of virtual design and construction. The advancement of these tools in the design environment does create some areas where the engineering community needs to take extra care.
In general, it seems that younger engineers are more comfortable and efficient in virtual environments than more experienced engineers. As these technologies make the design and production an integrated function, designs are being produced faster by design professionals who may have not “been around the block a few times.” Also, because the design environment is different than in the days of 2-D drawings, experienced engineers can’t always spot mistakes.
In a fully functional building information modeling (BIM) system, calculations for most systems are performed by the software. The need for voltage drop calculations, lighting calculations, distribution equipment sizing, and so on to be done separately from drawing production can potentially be greatly reduced. With the software’s sophistication, there is a tendency to assume that these calculations are correct; however, errors are often missed because of an engineer’s lack of experience. Although manufacturers of BIM software represent that it has the ability to perform such design calculations, experienced engineers often find that the relatively new BIM software lacks the details and flexibility to perform all the calculations necessary and that calculations must be duplicated using other software tools.
To implement these technologies successfully, they must be adopted throughout an organization, not just by a few techno-savvy experts. Engineers of all experience levels must be trained and familiar with BIM to maintain the required quality control. The cadre of very experienced engineers needs to accept it, and newer engineers need to question the results. (Remember the garbage in/garbage out mantra.) QA/QC programs specifically designed to maintain quality with a working BIM environment need to be adopted by engineering firms.
Speaking of validating results, there is room for improvement in BIM software for M+E design. Many engineers have noticed the advantages and limits in BIM design tools. The advancing requirements of energy-efficient, sustainable structures require the design tools to be equally advanced. The basic tools may be sufficient for simple design analysis, but engineers must work with the developers of BIM software to add the necessary components for more sophisticated designs. Another solution would be industry integration into BIM products of some of the more popular and solid calculation platforms currently available for things like lighting analysis, short circuit study, and others.
A final concern is that BIM not become a substitute for design coordination, and remain just a useful tool. With all of the building systems designed in BIM, coordination issues between disciplines should be quickly identifiable, with coordinating disciplines constantly aware of what others are doing.
Despite the concerns and additional development that is needed in BIM for M+E systems, the technology should be embraced. BIM calculation methodology is being validated, staff members are being trained in the use of BIM prior to the commencement of a BIM project, and engineers are working with developers of BIM systems on a host of software issues. Although this type of collaboration takes time, it ultimately benefits clients, business, and industry in the long run. Careful attention is also being paid to identifying the projects that are suitable for BIM and steering away from BIM for those projects not suitable for its application.
These are a few of the things I worry about. As noted, all of these issues require attention but they are clearly manageable. Frankly, when I think of where technology is heading—that in the future engineers will be designing carbon-neutral facilities with computer-based designs that are fully visualized and experienced by the end user before leaving the designer’s office, and possibly constructed directly from the model developed during the design—I am more likely to lose sleep because of excitement over the possibilities rather than any nightmares encountered in the development process.
- Lutkevich is vice president and manager of the Mechanical and Electrical National Technical Excellence Center at Parsons Brinckerhoff and the electrical technical director. He is involved in research with state and federal agencies in the evaluation of new technologies, highway safety and visibility, and advanced visualization techniques.
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