Letters – 2004-04-01
Savings Not Quite There In the Specifier's Notebook "Sensing Savings," (CSE 02/04 p. 66) on automatic sensor controls for lighting, author Al Borden gives concise advice on selection and specification of occupancy sensors for automatic lighting control but leaves the reader with a misunderstanding of the way in which infrared sensors function.
Savings Not Quite There
In the Specifier’s Notebook “Sensing Savings,” ( CSE 02/04 p. 66 ) on automatic sensor controls for lighting, author Al Borden gives concise advice on selection and specification of occupancy sensors for automatic lighting control but leaves the reader with a misunderstanding of the way in which infrared sensors function. Most if not all infrared occupancy sensors available for commercial installation are passive infrared, or “PIR” devices. PIR occupancy sensors do not emit infrared light. Rather, they sense the heat emitted in the infrared spectrum by objects within their field of view. This is why they are called passive devices, as opposed to active devices that emit a signal and then look for a reflection of that signal. Ultrasonic occupancy sensors are active devices.
The article by Mr. Borden also failed to touch upon a significant impediment to specification of automatic lighting controls: first cost. A $4.00 switch is significantly cheaper than a $25 or $50 occupancy sensor. Where local or state energy codes do not dictate the use of automatic lighting controls, the owner must perceive the benefit of either improved function for building occupants, improved energy cost savings, or both. Automatic lighting controls can also fall victim to cost reduction or “value engineering” in the face of pressure to reduce or control project costs. The A/E design team must be an advocate for automatic lighting controls.
Finally, the implementation of automatic controls for fluorescent lighting must also take into consideration the ballasts to be furnished with the luminaires. Use of instant-start ballasts offers measurable energy savings over rapid-start ballasts. Frequent cycling of instant-start ballasts will result in a measurable reduction in lamp life. The resulting labor and material costs incurred from more frequent relamping will offset the savings in energy costs. Where occupancy sensors are specified for automatic lighting control, the specifier should consider the use of program-start ballasts. Program-start ballasts are typically more expensive than either rapid-start or instant-start, and will therefore also have an impact upon project first costs.
Jim Willcockson, P.E., Shah Smith & Assocs., Houston
Author Al Borden responds:
Mr. Willcockson’s clarification on the operation of the passive infrared sensor is appreciated. The description that I offered was perhaps too simplistic, but my intent was to describe the more focused nature of the infrared sensor. Infrared sensors use a virtual “line of sight” to detect motion, whereas the ultrasonic sensor is volumetric in its detection.
The owner’s participation in a decision to use sensors is, of course, critical to their application on a project. First cost is always a stumbling point. However, we have been quite successful getting sensors on projects by showing that the simple payback period is often less than one year. This provides a financial benefit that can even be attractive to a speculative developer.
Mr. Willcockson’s last point does not entirely reflect our experience. When we use instant-start ballasts and rapid-start T8 lamps on sensors, we have found that the loss in potential lamp operating hours, because of more frequent starts, is mostly negated by a reduction in actual operating hours. The lamps may be switched on two or three times a day, instead of once, but they are not operating at all for several hours. Program-start ballasts do remove the concern about lamp life, but as Mr. Willcockson noted, they also increase the first cost of the system.
The life-cycle costing article “Dollars & Sense” (CSE 02/04 p. 40) was marred by one omission: no reference to asset disposal cost. What’s disposal cost? Allow me two examples: A small Kansas town needed a new elevated water storage tank. The initial investigation revealed the cost exceeded budget constraints. A councilman, however, had read recently that a company in Kansas City was offering X dollars per ton for scrap steel. He therefore convinced the town to proceed. Imagine their surprise when they learned that the price quoted was only for scrap that would be delivered to the Kansas City facility some 100 miles away. Cost of demolition and transport, of course, exceeded the price paid for the scrapped metal!
Similarly, right now, Russia is realizing that the cost of disposing of their abandoned nuclear submarines is beyond the capability of their treasury.
I find it strange that this concept hasn’t filtered down to modern life-cycle cost enthusiasts. And don’t try to argue that disposal cost is a part of O&M costs; it is a separate entity. But of course, when I was a program manager, I was prohibited from trying to include it in calculations because it made the initial overall cost estimate look bad!
William L. Kincheloe, P.E.
Seeing the teaser for “Fire Protection: The Right Balance,” ( CSE 02/04 p. 23 ), I eagerly flipped to the story. As I began to read it, I had to look back at the title and see if there had been some sort of mistake.
Active and passive fire protection are constantly portrayed as having adversarial roles in construction. This problem dates back to pro-sprinkler lobbying efforts in the codes that sought to expand their use by creating exceptions to other safety features for structures where sprinklers were incorporated into the codes. In those days, the industry sought to buy the affection of facility owners and developers by trading construction dollars. If this had occurred with automobiles, air bags would have displaced seat belts. But just like airbags and seat belts, we can have both active and passive protection incorporated into modern structures. Sprinklers save lives, but we can and should consider seismic events that might trigger fires and disrupt water supplies. We should also look at the numbers and consider the percentages regarding situations where sprinkler systems do not suppress fires. But we should also consider how lucky we are regarding fires that haven’t happened in buildings theoretically protected by sprinkler heads that could be defective, particularly in the wake of some very notable product recalls.
However, it might be more meaningful to reconsider the codes. Efforts there tend to lean toward new construction, when everything in a building is at its best. But what happens 20 or 30 years from now, when today’s buildings become tomorrow’s low-rent housing? What will stop fires when active systems are no longer properly maintained? This is the unfortunate reality. Let’s also consider the possibility of a school dormitory fire in 20 years where there are no fire walls to stop the propagation of fire and no protected means of egress in the event a sprinkler does fail. How many will die, and how comforting will the percentages be then? The experience of the Seton Hall dormitory fire told us that those particular dormitories should have been sprinklered, but what would have been the net result if there had been no passive features to slow and contain the fire and provide time for so many students to get out?
As far as balance in this feature is concerned, how balanced is it that Mr. [Michael] Madden [of Gage Babcock] and [John] Haynes/[Tom]Prymak [of sprinkler manufacturer Tyco] discuss the reliability of passive protection schemes without any mention of the sprinkler recall issues? How fair is it to criticize the performance of fireproofing? They might all consider Sept. 11th. Passive building features couldn’t save the World Trade Center, but they did allow most people to escape before the building collapsed. We might also note that sprinklers didn’t stop the fires and didn’t augment the passive features. Did we mention that sprinklers also didn’t save adjacent structures that were not struck on that fateful day [but also fell]? We also should mention the water damage to one adjacent building that effectively destroyed it. Do all of these things mean that we should not have sprinklers? Of course not! But thank goodness for those annoying passive systems and the fact that these structures were built before we became enlightened enough to remove them!
I will admit to being an executive of a company that manufactures passive fire protection products. I will also admit to 30 years of fire testing experience. Finally, while I may be biased, I do feel that I am capable of actually exhibiting the balance which seems to have been noticeably absent in this feature.
Jim Stahl, Specified Technologies, Inc., Somerville, N.J.
Ah, short memories. We were lambasted by sprinkler proponents for recognizing, in the 12/03 issue, a building that employed excellent use of passive systems without sprinklers. This month we’re too pro-sprinkler. For the record, the sprinkler recall issue was addressed in a past M/E Roundtable (CSE 10/02 p. 23). Also included in the more recent discussion was a table from NFPA documenting sprinkler performance—good and bad. Unfortunately, a representative from the passive product side was unable to participate, and time constraints prohibited a replacement. However, a link to a pair of white papers by an officer from the International Firestop Council addressing passive strategies was included in the piece. Unquestionably, there is a need for balance. This was confirmed in a poll the magazine conducted as part of a webcast we recently presented on protecting older, non-sprinklered buildings. In that poll, 88% of our viewers indicated that a combination of active and passive elements are necessary for effective fire protection.
Those sentiments were echoed by our expert panel. However, many of the maintenance and age arguments made by Mr. Stahl apply equally to passive measures, even more so considering the amount of new penetrations made due to churn or other renovations. But don’t take our word for it. Log onto www.csemag.com and view the archived webcast for yourself.