Building Safety: The bas And Beyond
To help mitigate occupants' fears, building owners are taking a harder look at the safety of their buildings. Granted, nothing could have been done at the building level as far as the airplane attacks were concerned. But the latest scare of biological and chemical weapons has made building owners wonder whether or not something can be done to prevent such an attack at the building level.
As such, they're starting to secure their perimeters, give occupants badges for entry, and also look at the building automation system (bas) and other hvac equipment for help in preventing bioterrorist activities. While the security measures and occupancy fluctuations can certainly be tied into a bas, it's unclear whether or not the system could truly be of help in case a contaminant were placed directly into the hvac system.
As many experts note, there is no silver bullet available to make buildings safer. It takes diligence on the part of the management team and also the expertise of engineers to keep building occupants safe.
For The Most Part, Buildings Are SafeWhile it's easy to panic over building safety, it is important to note that for the most part, American buildings are a good place to be. The World Trade Center Towers were comprehensively engineered and ended up standing more than an hour after the airplanes hit. In addition, WTC building owners had prepared more thorough evacuation plans after the 1993 bomb went off in the basement of one of the towers. The combination of the two allowed the majority of occupants to flee safely.
Even the scare of anthrax hasn't extended much beyond the postal service and the direct recipients of the mailed spores. Granted, several buildings have had to be decontaminated, but there has been no report of a biological or chemical agent being introduced directly into a building via the ventilation system, which was a much publicized concern for a while.
Unfortunately, what's good about American buildings got lost in all the media coverage after the terrorist attacks. "It's too bad that message is getting out there, that all of a sudden we have to do all these things to take care of the terrorists, when in fact we've done an awful lot and buildings are performing very well today," says James E. Woods, Ph.D., P.E., director and president, HP Woods Research Institute (Herndon, VA).
Woods has been tapped by ASHRAE to chair a presidential study group entitled Health and Safety Under Extraordinary Incidents. The group will study incidents such as attack from high-impact explosives; incendiary missiles; internal incendiary devices; and chemical, biological, and radiological contamination.
The group will address all aspects of health and safety, except structural integrity and security protection. These include materials; egress; chemical, biological, and radiological protection; fire extinguishing; smoke removal or purging; filtration; maintenance of comfort and air quality; entrance paths for contaminants; building envelopes, and water supplies.
At the time of the interview, Woods could not divulge too many specifics as far as what group members were discussing. That's because a final report was scheduled to be presented at ASHRAE's 2002 Winter Meeting in January in Atlantic City. What he could say, however, was the group is focusing on three basic questions:
- What can be done to ensure that the building is doing what it can to meet the extraordinary instances that might occur, with no additional capital or time?
- What can be done in a retrofit situation?
- What should be done when designing a new building?
Based on meetings so far, the group has recommended that management should first make sure the building is performing the way it was intended to by design. Then it's important to not make any changes unless it's understood what the consequences of those changes might be. Finally, there has to be some knowledge about those issues on the part of the facility manager who's responding.
"That leads to a whole set of questions of whether or not the facility manager is competent and the building is performing okay, and if either of those doesn't come into consideration, then what do you do?" asks Woods. Obviously, there are no easy answers.
Woods did stress, however, that when making changes to a system, it's important to be sure those changes are not counterproductive; for example, shutting off the outside air in a tall building, which could lead to occupants becoming sick. "Then people will think they've been poisoned for sure," notes Woods. "What we need to do is think very carefully about how the building is supposed to perform and then provide some assurances that it is doing that."
Can The bas Help?With regard to the bas, Woods notes that if it is doing what it is supposed to do, it certainly will not cause any harm as far as extraordinary events are concerned unless people use it for purposes other than for what it was intended. And there's the possibility that could happen. "People might try to rig the building automation system to do things that it's not intended to do, and they need to understand the consequences of that," says Woods.
Len Damiano, vice president - sales and marketing, Ebtron Inc. (Loris, SC), notes that a bas may be programmed to automatically respond to a range of other life safety threats, so it could be programmed to respond to bioterrorism attacks as well. "One of the greatest threats is using the ventilation system to distribute an aerosolized chemical agent, airborne infectious bacteria, or virus. A 'panic button' approach that would shut down fans and all operable dampers would be our first consideration," notes Damiano.
But just how fast a bas could shut down a system may be a concern. "Frankly, at this time we don't see a controls solution to this at all," says Thomas Hartman, P.E., The Hartman Company (Marysville, WA). "What we have done on some projects is to put quick-acting dampers in, if some kind of warning is given, then the outside air dampers would close very quickly. The idea of sensing [anthrax] is very difficult to do and even if you sense it, the idea of being able to react somehow to close the system down before such an agent travels into the system is just not reasonable."
Hartman notes that right now, there are no dampers available that could respond almost instantaneously to an outside threat anyway. He'd like to see research start on some type of mechanism that would provide an instant close on the dampers and that could be simply implemented as part of a system. "At this point in time, the building controls' response is very crude. All we can really do is try to shut down the system as quickly as possible, and we can try to start up the pressurization systems that would normally be used for smoke control as an emergency response while we evacuate the building."
Damiano also adds that more sophisticated responses, above and beyond the 'panic button' approach, would require complicated control scenarios and tend not to be as reliable. However, "Using sensitive and accurate sensors to prove airflow velocity and direction will allow the controls to create areas of refuge or protected avenues of egress - very similar to smoke control systems, but requiring instrumentation to provide the control input and not visual cues (e.g., smoke) or responses from 'dumb' smoke detectors," says Damiano.
Hartman remains skeptical. "At this point in time, once you sense a biological element in the system, all you've done is figured out that you've lost. By the time you got people out of the building, it's very likely a great deal of damage would be done. I think at this point in time, a realistic scenario is well-integrated security, building shutdown, and evacuation."
Areas Of ConcernSecurity is definitely more prevalent in many buildings these days. Mechanical rooms are being locked up, and occupants are being monitored as they enter and exit the building. But there is still a huge problem in many buildings, and that is the air intakes are often located at ground level. "I know buildings where they have inlet ducts right down on the ground level and there's no restricted access. It's a dangerous situation," says Hartman.
The approach that Hartman has used in international building designs is to keep air intakes at high levels and install a security perimeter some distance from them. A signal would come from the security system to the bas that if security is ever breached for any reason at all, the hvac system would immediately close down.
For many buildings, full-time security around a ground-level air intake is not possible. In these cases, the only "safe" answer is to move the intake. That can be an expensive proposition, though, that many building owners may not like.
Moving ground-level intakes can be especially difficult for buildings that have full air-side economizers, because the ductwork is so large. It may be that such a building will no longer be able to operate on a full air-side economizer in any practical sense. Fortunately, the development of other technologies makes it increasingly economical to provide mechanical cooling at low outdoor ambient conditions for a very low cost, according to Hartman.
"When you think the fans may not have to run so fast, you may actually be able to provide sufficient cooling at low ambient conditions for the same cost that you did with an air-side economizer," notes Hartman. "So it doesn't have to be costly in terms of operation if you apply a well-thought-out package as to how you're going to improve this building."
Hartman also adds that there is some time for building owners to react. "We need to understand that we may be moving into a new era, and I think it's very prudent to provide a plan for the natural improvement of buildings that accommodates these new realities."
An Engineered ResponseThe question will be what types of products, system designs, or responses will be needed to improve buildings. Manufacturers of UV lighting products and high-efficiency filtration have sent out press releases discussing how their equipment can help in the case of a bioterrorist attack. Whether or not these products or systems work remains to be seen.
"There needs to be considerable testing and research performed before effective solutions to these threats can be offered," notes Jack Probolus, vice president, AirQual Corp. (Canton, MA). "There is no 'one size fits all' approach to potential problems. Effective treatment will involve a detailed assessment of the facility and potential exposures. Once this assessment is made, effective alternatives and treatments can be evaluated and a system deployed."
And there won't even be a 'final decision,' because every building owner will react differently. Most building owners will base their decisions on a cost-benefit analysis; basically, what degree of risk that they want to control against vs. how much money that's going to cost. More high-risk, high-profile buildings will probably spend considerably more on their "fixes" than a low-profile building with unknown tenants.
Woods believes that the answers will reside in engineered solutions. "There probably is not going to be a silver bullet. The new equipment and systems and components that will be available, if they're used wisely, are probably going to enhance control, but will they enhance control just under extraordinary conditions, or will they enhance control generally? If they are to be economically justified, then we have to think about the more universal application of what's going on," he notes.
While many believe we're entering a new era as far as building safety is concerned, Woods' feeling is that if people accept their positions of responsibility and accountability, then there's nothing really new. Many are now looking for simple answers to a complex issue, but they're not going to find it.
What building owners will be looking for, however, is the expertise of engineers, and it will likely be the engineers who will learn what can be done better at a building level and ultimately enhance building performance. But people are going to have to give a little more thought to it, and systems will probably have to be engineered to a greater degree.
"One of the real problems that we've got in a lot of buildings right now is they're not thought through from an engineering standpoint to the extent they should be," says Woods. "What happens is we get a lot of catalog engineering, and good systems analysis is not performed. One of the areas that I think will come out of this is demand by the general public that better accountability of engineered performances becomes available."
That probably scares a few engineers out there, as liability and accountability are already huge concerns in the industry. And for those who were already worried about those issues, Woods has some final words of advice, "As a professional engineer, your prime responsibility is to look out for the general health and welfare of the society, based on the decisions that you're making. In a sense, licensed professional engineers are officers of the state in that regard, so they carry a public responsibility, and if they're not willing to do that, they maybe shouldn't be in the business." ES