Election 2004: Where the Candidates Stand on IAQ

Revised NADCA ACR Standard Nears Completion

Guidance for Renovations in Occupied Schools

Word on the Street

• A FEW GOOD SPEAKERS IN 2005
  The National Air Duct Cleaners Association has issued a call for papers for its 16th annual meeting and exposition, to be held March 9–10 in Las Vegas. The committee handling the meeting says it is looking for knowledgeable IAQ professionals who are interested in sharing their experience and expertise at Indoor Environments 2005, the HVAC hygiene industry's premier event. Topics will vary, but should be directly related to either residential or commercial HVAC system restoration. To submit a paper topic, you should include a 100-word description, the title of your presentation, and a personal biography or résumé. Incomplete submissions, and those received after Aug. 31, will not be considered. To receive a paper submittal form, or for further information, call NADCA headquarters at (202) 737-2926.
    
  The American Industrial Hygiene Association is also accepting presentation proposals for the 2005 American Industrial Hygiene Conference and Expo, which will be held May 21–26 in Anaheim, Calif. Submissions must be made electronically at www.aiha.org/abstract.htm by Oct. 5. AIHce 2005 is seeking potential presenters to provide fresh, dynamic solutions to today's challenges–new standards and regulations, technological innovations, international security issues and expanding practice areas. Presenters may choose from three presentation formats: 1.) podium abstracts, oral presentations limited to 20 minutes that may be accompanied by slides; 2.) poster abstracts, visual displays on fiberboard (poster sessions include a two-hour period when the author is in attendance to answer questions); and 3.) environmental health and safety crossover programs, 90-minute presentations sharing practical information on non-industrial-hygiene topics such as safety and environmental issues. For more information, contact Claire Davis by e-mail at cdavis@aiha.org or by phone at (703) 846-0753.

• SENATORS BACK GREEN MOVEMENT...
  The High-Performance Green Buildings Act of 2004 was introduced into Congress July 8 with eight Senators backing it. Introduced by Sen. Jim Jeffords (Ind.-Vt.), the act would provide green federal buildings and schools with $35 million in assistance over five years. “It's time for the federal government to catch up to the private sector and work together to reap the many benefits of high-performance buildings,” Jeffords said in a statement that also listed a number of benefits associated with green buildings, including energy efficiency, waste reduction, occupant health and financial savings.
   
  Among other things, the bill would “require the [national] comptroller general to review the federal budget process to identify and incorporate long-term savings that can accrue from the use of life-cycle costing in building construction,” according to Jeffordsʼ press release. The legislation would also establish a new office within the General Services Administration – the Office of High-Performance Green Buildings – and create an interagency steering committee that would “increase the coordination of all relevant agencies in their implementation of the multiple laws and executive orders.”
   
  “We are excited about the introduction of legislation establishing an office and a federal role for green buildings,” said Rick Fedrizzi, president of the U.S. Green Building Council. “Senators Jeffords and Lautenberg have been savvy and supportive leaders in the effort to transform the built environment and this legislation will advance the knowledge, tools and understanding of building green within the federal government. Building green is exploding in the marketplace and this legislation provides the mechanism for preserving a leadership role for the federal government as well as enhancing the existing partnership of the U.S. Green Building Council and the federal family.”

• ...AND EPA DIPS INTO GREEN TOO
  The U.S. Green Building Council was really making its rounds in Washington, D.C., in recent days. The U.S. Environmental Protection Agency announced at a meeting in the nation's capital last month that the Agency had recently facilitated the first meeting between its Green Building Workgroup and the USGBC. The EPA said the workgroup is seeking to develop a closer relationship with the USGBC, particularly to facilitate EPA input into the highly successful green building rating system, Leadership in Energy and Environmental Design, or LEED. The EPA said it would like to influence decisions including improving the quality of LEED credits and guidance on indoor air.

• MGM GRANDER
  Just in time for the upcoming combined annual meetings of the Indoor Air Quality Association and National Air Filtration Association, host hotel the MGM Grand has announced its 380,000-square-foot, state-of-the-art convention center facility has gone smoke-free. MGM Grand is the first and only conference center in Las Vegas to offer a completely smoke-free environment. “We want to provide a comfortable, enjoyable and productive environment that will meet the needs of our meeting attendees,” said Richard Harper, vice president of sales for MGM Grand. The IAQA-NAFA convention takes place Sept. 27–30.

• INESCAPABLE DANDER
  Cat and dog dander are “universally present” in homes across the United States, in many cases, at levels exceeding those previously established as the risk for causing allergy symptoms, according to a recent sampling study published in the Journal of Allergy and Clinical Immunology. Researchers in Research Triangle Park, N.C., detected both allergens in nearly every one of the 831 homes selected as representative of U.S. housing, regardless of whether dogs or cats lived there. A proposed sensitization level for the dog allergen was exceeded in more than a quarter of the homes that did not have dogs, and the corresponding sensitization level for the cat allergen was exceeded in more than half of the houses without cats. Asthma symptom-causing levels for each allergen were also exceeded in at least 9 percent of homes without the corresponding pets. In about 90 percent or more of homes with cats or dogs, sensitization levels were exceeded.

Election 2004: Where the Candidates Stand on IAQ

President Bush and Senator Kerry Give Exclusive Interviews to IEC
Among Sen. John Kerry’s campaign promises, he says: “I will direct the EPA to develop scientifically sound and protective indoor air quality standards and measurement
methods; establish a program to educate commercial building owners and homeowners on indoor air treatment and source elimination options; and identify sources of harmful manmade chemicals in indoor air and work with industry to reduce or eliminate their presence in building materials and furnishings.” Kerry also articulates that this federal program “will deal with mold as well as a variety of other indoor air quality problems.” He explains: “I anticipate that the development of scientifically sound and protective indoor air quality standards and measurement methods, as described above, will deal with the dampness problem as well as the other serious problems of indoor environmental quality.”

President George W. Bush focuses on his administration’s environmental achievements, for instance: “At the end of this year, my administration will announce new stringent air quality standards for particulate matter, which will provide substantive health benefits for all who suffer from respiratory illness.” He also makes a number of promises for the long term: “I am also a strong supporter of energy-efficiency programs for low-income Americans. The 2005 budget increases funding for the Weatherization Assistance Program by $1.4 billion over the next 10 years in order to cut the utility bills of 1.2 million low-income families while conserving energy.”
He also provided information on a series of books he says “will help school districts save
millions of dollars on annual utility bills by designing energy-efficient schools compatible with regional climates.”

IEC: The trend toward green buildings is rapidly gaining momentum. Would you support an initiative requiring all new school construction to be done according to LEED (Leadership in Energy and Environmental Design) specifications?

John Kerry: My wife, Teresa Heinz Kerry, has been a strong advocate of the trend toward greater consciousness of the quality of the indoor environment. The foundation she runs has been at the forefront of funding the studies that have focused attention on this issue. My administration will support the use of greater technology to make school buildings more energy-efficient and provide a healthier environment for our children. Energy is typically the second largest budget item for schools, and energy efficiency can help save money and allow our education dollars to be spent on other priorities.

George W. Bush: My proposed National Energy Policy specifically addresses expanding existing programs to encourage energy efficient buildings. The Environmental Protection Agency and the Department of Energy are following through on that recommendation.

Secretary of Energy Spencer Abraham recently announced the release of six books that complete Energy Design Guidelines for High Performance Schools, a series of publications that will help school districts save millions of dollars on annual utility bills by designing energy-efficient schools compatible with regional climates. With these guidelines, schools can lower their energy bills by 25 percent and spend the savings for books, computers, teachers, and other worthy programs that improve learning. These guidelines support my No Child Left Behind policy by creating better learning and teaching conditions through energy efficiency in schools across the country.

As part of energy efficiency grants totaling over $12 million, Secretary Abraham provided funding for the “Rebuild America Program,” which has already formed more than 450 voluntary community partnerships nationwide to improve the energy efficiency of existing buildings. Rebuild America partnerships are saving school districts, businesses, and public agencies up to 30 percent annually on energy bills. These savings can be put to work for local community priorities such as purchasing educational materials for schools or books for libraries. State energy offices will use these funds to improve the energy efficiency of schools, homes, and other buildings; promote energy-efficient industrial technologies; and support renewable energy sources such as solar, wind, geothermal, and biomass. Some projects will identify opportunities for distributed energy resources that generate electricity at or near the point of use.

To reduce pollution caused by energy use from commercial buildings, the EPA is expanding the Energy Star program to encourage design of energy-efficient commercial buildings (commercial buildings alone emit about 20 percent of the nation’s greenhouse gas emissions).

IEC: The rate of asthma among America’s youth continues to skyrocket. What would your administration do to address this problem?

Kerry: The American Lung Association estimates that air pollution from power plants alone triggers 600,000 asthma attacks and causes 30,000 premature deaths annually. George Bush’s so-called “Clear Skies” proposal will result in over 21 million tons more pollution than if he simply enforced the Clean Air Act. Compared to an alternate EPA plan rejected by the White House, the Bush plan will result in over 100,000 more premature deaths and millions of added cases of asthma and other serious illnesses.

I have pledged to create a national health tracking system for chronic diseases and environmental health hazards. The proposal calls for tracking asthma and other debilitating illnesses linked to environmental causes that are not now monitored in any comprehensive manner. And I will enforce the Clean Air Act the way it’s written now and will work to pass tough but reasonable Clean Air Act amendments that will reduce emissions and the harmful health benefits that come with them.

Bush: At the end of this year, my administration will announce new stringent air quality standards for particulate matter, which will provide substantive health benefits for all who suffer from respiratory illness.

My Clear Skies initiative is the most aggressive presidential initiative in history to reduce power plant emissions. Clear Skies cuts mercury, sulfur dioxide, and nitrogen oxides by 70 percent by 2018 and provides substantial health and environmental benefits. These new standards require states to come up with local plans to control pollution. I have taken several landmark actions to assist the states in this effort.

In April of this year, my administration announced new, more stringent health-based air quality standards to reduce ozone, which is associated with serious lung illnesses. As Congress has yet to act, I directed my EPA administrator to take similar regulatory action. The Clean Air Interstate Rule, which would reduce emissions of sulfur dioxide and nitrogen oxides by nearly 70 percent when fully implemented, was proposed in December 2003, and we will finalize it this year.

States and local communities will also benefit from the recently finalized Clean Air Nonroad Diesel Rule, which the Natural Resources Defense Council called the “most significant public health step in a generation since lead was removed from gasoline.” The rule requires stringent pollution controls on diesel engines used in industries such as construction, agriculture, and mining, and it will slash the sulfur content of diesel fuel.

The new standards will cut emissions from nonroad diesel engines by over 90 percent. Nonroad diesel equipment, as described in this rule, currently accounts for 47 percent of diesel particulate matter and 25 percent of nitrogen oxides from mobile sources nationwide.

Sulfur levels will be reduced in nonroad diesel fuel by 99 percent from current levels (from approximately 3,000 parts per million [ppm] now to 15 ppm in 2010). The lower sulfur fuel will provide immediate public health benefits by reducing PM from engines in existing nonroad equipment. The rule will be a major help nationwide in efforts to reach clean air goals and improve public health.

By establishing the Clean School Bus USA program and providing $65 million in my Fiscal Year 2005 budget, we are bringing together partners from business, education, transportation, and public health to work toward three goals: encouraging policies and practices to eliminate unnecessary public school bus idling; retrofitting buses that will remain in the fleet with better emission control technologies and/or fueling them with cleaner fuels; replacing the oldest buses in the fleet with new vehicles, which produce less pollution. These federal tools will help the entire country to meet the new ozone and particulate matter standards – a remarkable achievement.

IEC: Environmental Protection Agency officials say their Indoor Environments Division is woefully under-funded. Would your administration provide great funding to the division?

Kerry: The air that we breathe during much of the day is the air that circulates in our schools, hospitals, factories and offices. Unfortunately, many of us are spending our days breathing stale, and sometimes dangerous, indoor air – with harmful allergens, molds and chemicals. I will direct the EPA to develop scientifically sound and protective indoor air quality standards and measurement methods; establish a program to educate commercial building owners and homeowners on indoor air treatment and source elimination options; and identify sources of harmful man-made chemicals in indoor air and work with industry to reduce or eliminate their presence in building materials and furnishings.

Bush: The administration understands the importance of assessing the threat of indoor air problems and addressing them at the federal level when necessary. While it does not encompass all the work the federal government does regarding indoor air quality, the president’s FY 2005 Budget for the indoor air programs at EPA proposes a $3.5 million increase over FY 2004 from $36.858 million to $40.366 million.

IEC: A recent study sponsored by the Centers for Disease Control and Prevention characterizes indoor dampness as “a widespread problem” and recommends the federal government develop and disseminate consensus guidelines on building design, construction, operation and maintenance. Would your administration finance this project?

Kerry: I anticipate that the development of scientifically sound and protective indoor air quality standards and measurement methods, as described above, will deal with the dampness problem as well as the other serious problems of indoor environmental quality.

Bush: The EPA’s Indoor Environment Division already provides helpful guidelines and assistance to control moisture and mold in large buildings and schools. For example, the Indoor Air Quality Tools for Schools kit provides clear and easily applied guidance that will help prevent indoor air quality problems and resolve such problems promptly if they arise. It recommends practical actions that can be carried out by the school staff without the need for training, and is flexible enough to conform to the specific needs of a school.

In addition, EPA has a number of publications to assist building managers in combating mold and mildew and improving indoor air quality. In March 2001, EPA published a guidance document titled, “Mold Remediation in Schools and Buildings,” which included helpful steps to address mold remediation and cleanup.

IEC: Several states are in the process of establishing licensing requirements and standards for the inspection and remediation of mold, or have already done so. Would your administration support a federal program for these issues?

Kerry: The federal program described above [in response to the question about the EPA Indoor Environments Division will deal with mold as well as a variety of other indoor air quality problems.

Bush referred to his answer to the previous question.

IEC: There is a powerful call for energy efficiency in today’s world. What federal programs related to energy efficiency are important to you? What are practical renewable energy strategies to reduce American dependence on foreign oil?

Kerry: I will provide a tax credit to purchase equipment that meets energy-efficiency standards for heating and cooling in new buildings and to retrofit existing ones. I will also provide a 20 percent tax credit for the purchase of energy efficient building equipment, including electric heat pumps, hot water heaters and natural gas heat pumps. I believe that the easiest and most rapid gains in the movement toward energy independence will come from efficiencies in the current energy regime. I will also set a national goal that 20 percent of our electricity should be produced from renewable sources by 2020, and achieve that goal by emphasizing research and market incentives for wind, solar, biomass, etc. projects. I support important programs like FEMP [the Federal Energy Management Program] and will work to implement executive orders calling on the government to increase its energy efficiency.

Bush: I am a strong believer in energy efficiency and renewable energy. I have sought more funding for energy efficiency and renewable energy programs than Congress appropriated in any of the last 20 years. More than half of the 106 recommendations in my National Energy Policy report concern energy efficiency and renewable energy.

My 2005 budget includes $4.1 billion over the next five years to encourage consumer purchase of energy-efficient and renewable energy technologies.

I am also a strong supporter of energy-efficiency programs for low-income Americans. The 2005 budget increases funding for the Weatherization Assistance Program by $1.4 billion over the next 10 years in order to cut the utility bills of 1.2 million low-income families while conserving energy. The budget includes $291 million for this program, a $64 million (28 percent) increase over 2004 funding, which will improve the energy efficiency in the homes of an additional 119,000 low-income families.

In 2003, I announced the largest increase in CAFE [corporate average fuel economy] standards in 20 years for light trucks. This will result in savings of approximately 3.6 billion gallons of gasoline over the lifetime of these trucks. My CAFE plan is responsible and technologically feasible and will not jeopardize vehicle safety.

For renewables, I have called on Congress to reauthorize the production tax credit to expand the use of wind power and pass a renewable fuels standard, which would require using 5 billion gallons of domestically produced, cleaner burning ethanol in gasoline. These measures will make America less dependent on foreign sources of energy and create more jobs.

My long-term energy strategy is to transform America’s energy infrastructure to support a hydrogen-based economy and reduce our dependence of foreign oil. In my 2003 State of the Union Address, I committed $1.7 billion over 5 years for the Hydrogen Fuel Initiative, which will develop the pipelines and distribution systems to make a hydrogen economy possible; and FreedomCAR, a public-private partnership to create automobiles that run on clean-burning hydrogen.

IEC: The private sector has accused corporations and the Tennessee Valley Authority of violating the Clean Air Act. Would your administration support a program to ensure adherence to this act, and why or why not?

Kerry: Yes. Clean air is too important, and I do not believe that we have to choose between clean air and affordable energy. We can have both.

Bush: My administration is aggressively enforcing the Clean Air Act; when companies violate the law, we hold them accountable. Since January 2002, my administration has reached settlements with 17 different companies, including PSE&G, Alcoa, Dominion, and Wisconsin Electric. Recently, the Department of Justice served Eastern Kentucky Power Cooperative with a “notice of violation” for its failure to abide by New Source Review.

However, environmental progress does not come through litigation, but rather through good government, technology, innovation, and markets. I have put into place improvements to the Clean Air Act New Source Review program that clarify these regulations.

This program has long been the source of litigation and impediments to environmentally
beneficial plant upgrades. I have expanded the successful cap-and-trade acid rain program with my Clear Skies initiatives. The power of the marketplace and mandatory, clear, certain pollution caps mean power plants can reduce pollution cost-effectively and continue to supply reliable, stable electricity to American consumers.

The National Air Duct Cleaners Association distributed the latest draft of its comprehensive HVAC system-cleaning standard to its mem­bers and other reviewers earlier this year. The draft included extensive revisions to ACR 2002, “Assessment, Cleaning and Restoration of HVAC Systems.” Many of these revisions were designed to make the ACR standard compatible with new standards for mold remediation.

NADCA committee members reviewed scores of comments this spring, resulting in sev­eral improvements to the draft standard. ACR spent a month in editing and is now entering the final phases of association approval. NADCA expects to publish the updated standard, under the acronym ACR 2005, around the time of its fall technical seminars. The seminars will also serve as the launching point for industry education about the changes to the standard.

While NADCA intended to update and republish the ACR standard in a regular three-year cycle after its 2002 debut, the need to make revisions was more urgent following the December 2003 release of the Institute of Inspection, Cleaning and Restoration Certification’s S520, “Standard and Reference Guide for Professional Mold Remediation.”

IICRC S520 includes by reference all require­ments of the ACR standard on mold remedia­tion projects that include contaminated HVAC systems. NADCA members served on the S520 Committee, and immediately after the approval of S520, these volunteers turned their attention toward bringing the ACR standard into synch with S520.

The latest draft of ACR follows S520 by defining three “conditions” of fungal ecology for indoor environments. HVAC system-clean­ing requirements vary depending on the fungal ecology of both the space served by the system and the level of microbial growth found within the HVAC system itself.

While many of the revisions to ACR relate to mold contamination, other updated sections include those on assessing system cleanliness, cleaning fibrous glass system components, and use of antimicrobial agents and surface treatments.

IAQ professionals interested in being the first to learn about revisions to the NADCA standard directly from the association might want to consider attending a NADCA technical seminar during the organization’s fall education series. Events are planned Sept. 16–18 in Baltimore, Sept. 30–Oct. 2 in Las Vegas, and Oct. 21–23 in Houston. For more information or to register for the seminars, call (202) 737-2926 or visit www.nadca.com.

Your school is about to undergo a major renovation project in multiple phases. Parts of it will remain occupied, and other areas will have normal classes going on.

The best reference for principles on minimizing occupant exposure to construc¬tion dust or fumes is the Sheet Metal and Air Conditioning National Contracting Association's “IAQ Guidelines for Occupied Buildings Under Construction,” published in November 1995. Purchasing this guide is well worth the investment for the liability it may reduce.

There is a growing awareness among building managers that occupants of facilities can be impacted by potentially irritating products or odors that are generated during renovations and new construction. In order to prevent or minimize occupant exposures, emissions from activities must be prevented from entering the HVAC system or contaminating adjacent areas. The use of dust partitions alone will not stop the movement of either fine particle or gases to other locations.

To manage and contain the emissions effectively, you typically need to employ a combination of well-sealed dust partitions, manipulation of the HVAC system, and temporary exhaust fans.

Typical Construction Emissions
Likely construction emission materials will typically include:

• dusts, both coarse and fine, from demolition or other mechanical processes;

• odors of solvents in paints, adhesives and cleaning agents;

• combustion gases and fine particle from vehicle or machine exhaust; and

• visual and noise disturbances. The control of any air contaminant, such as odors or irritants generated during renovations, can typically be exercised by one of the five following basic options of control:

Source removal: The most efficient technique for preventing exposures is to switch to a less noxious material. Although this is sometimes achievable, many construction managers often need to deal with noxious materials that could be hazardous or irritating to occupants of the facility. This section therefore will focus on the control options.

Source modification, i.e., scheduling: Scheduling modification refers to the timing for the use of a particular noxious material. Generating the odors or irritants during off hours and making sure that the materials have been adequately flushed out of the facility before the occupants' return can be effective, as long as the irritants are not absorbed into the furniture and walls only to be reemitted. This type of approach is most frequently observed with spray on foams or other finish materials that will rapidly stop emitting odors as soon as they are cured.

Air cleaning: The construction zone can be equipped with multiple air scrubbers to clean the air to remove the contaminants from the renovation location and to return clean air to the occupied zones. This can be prohibitively expensive.

Increased dilution ventilation: Dilution ventilation refers to dilution of contaminated air with uncontaminated air in a general area, room or building for the purpose of health hazard or nuisance control, the American Conference of Governmental Industrial Hygienists said in 1984. Although increased dilution could dilute the odor to below the odor threshold, this technique is seldom successful as most irritants have such a low odor threshold. Additionally, most HVAC systems are extremely limited to how much outside air can be brought through the system and still maintain thermal or humidity control. Increased dilution is typically only possible during temperate weather with HVAC systems that incorporate air economizer features. Although it may decrease the magnitude of the occupant exposure, it alone cannot prevent exposures from occurring.

Containment via pressure control and local exhaust ventilation: The key method, this is known as the “push-pull method”: Put clean air in the clean areas, and pull dirty contaminated air from the construction zone. Containment via pressure control and the collection of air contaminants is the only management strategy that is likely to succeed in most cases. This approach is one of the basic principles of industrial hygiene, and it also minimizes the air volumes required and maximizes the collection efficiency. Local exhaust of a containment area also requires that quantities of make-up air equal in volume to that being exhausted, be supplied to the perimeter by infiltration or from a make-up air system that places clean air in the adjoining clean occupied space, outside of the containment zone. Yes, this is easy if the construction zone has walls and windows and doors, or temporary ones are installed.

Mid-renovation Containment
To achieve the desired goals, there are certain basic rules that need to be followed. The first requirement is the designation of the perimeter of the area to be contained. Existing or temporary walls, floors, ceilings and dust barriers can all be used to create a containment area. For the containment area to be effective, the perimeter barriers do not have to be tightly sealed, as long as the pressure inside the containment is maintained at less than the pressure outside the containment area by typically five to 10 pascals or 0.02–0.04 inches of water column. Pressures that are this low typically are measured with a digital micromanometer. The tighter the perimeter barrier, the less fan horsepower of exhaust necessary to keep the renovation area negative with respect to the occupied area. The HVAC system needs to be off and sealed in the construction area, or at least the return side of the HVAC system which serves the containment area needs to be sealed air tight with poly at each diffuser or grill. To be effective, contaminants must be effectively isolated from the rest of the recalculating air-handling system to prevent transport to other locations in the building.

Once the containment zone has been isolated, temporary exhaust through the use of a suitable number of negative-air machines (like those used for asbestos containment) can be established. Supply to the containment zone may need to be throttled or also sealed, depending upon the situation. The exhaust from the containment area should be discharged away from open windows, air intakes and pedestrians. This situation will achieve the maximum benefit of air contaminant removal for given quantities of airflow.

Large-scale Roof Decking Replacement
We encountered a challenging opportunity to apply these principles when asked to design repairs for a microbial contaminated roofing system in an occupied 40,000-square-foot building. Initial visual observations revealed that the extent of the microbial amplification within the plywood substrate had rendered most of the 4-year-old material structurally unsound. Results of pressure and air pathway evaluations, which were carried out using principles of the ACGIH's 1989 “Guidelines for the Assessment of Bioaerosols in the Indoor Environment,” determined that the microbial amplification activity was located within the building envelope. In order to minimize and control possible occupant exposures, it was determined that the vertically zoned HVAC equipment would need to be protected from contamination on the top floor via a combination of careful isolation of lower areas, containment of the materials that would need to be disturbed in the attic, and the top floor knee-wall areas. Materials and methods: Due to the structural failure of the plywood from the microbial amplification activity, it was determined that the failed roofing system would need to be completely removed and replaced with a new design that would incorporate a continuous vapor and air barrier. Additionally, in order to meet the previously noted SMACNA and ACGIH guidelines (with sections of the roof missing), it was determined that a creative containment strategy would be needed in order to be effective.

HVAC/building shell evaluation: In order to determine the ability to achieve positive pressure (isolation) in the occupied three lower level floors during construction, a careful review of the designed outside air and exhaust capacities for the facility was undertaken. In addition, intra-zonal pressure measurements between the three lower floors and upper floor, and knee-walls, were conducted. Results of the HVAC design and pressure evaluation revealed that the facility was zoned vertically with three floors served by the same air handlers and that the building was designed to operate under a significant overall negative pressure. With this design, any disturbances of the contaminated substrate that allowed materials to become airborne in the attic or on the fourth floor level were thus destined for distribution to the remainder of the facility by the HVAC system.

Containment design approach: The basic containment strategy was to provide positive pressurization of the lower two floors, and to use the third floor as a partial containment zone during the roof renovation. Because of scheduling space needs, it was determined that only half of the third floor could be isolated at a time, necessitating a two-phase approach to the renovation. We determined the amount of actual make-up air that would be needed to pressurize the facility positively through fan pressurization testing. Analysis of the collected flow versus pressure data allowed a permanent make-up air system to be designed and installed prior to the commencement of renovation activities. Once the make-up air system was permanently installed and confirmed to work as designed, a phased pressure control strategy was planned. A temporary barrier was constructed at the top of the stairwell to allow pressurization of the lower floors with respect to the upper floor and the outdoors.

Additionally, a temporary double wall vertical divider was installed on the third floor. This walled area allowed the top floor to be subdivided such that pressure control and containment zones could be maintained on half of the attic/knee-wall area for each of the two phases. During construction, partial suction was created on the attic and knee-wall areas with the combined use of two HEPA-filtered negative-air machines, manipulation of wall/ceiling leakage areas via openings, and manipulation of the supply and return volumes from the air-handling units that serve the spaces.

Results: Air pressure data was recorded between the containment zone and isolation zone throughout the three-month period via a dual channel strip chart recorder and data logger. Laser particle count data was logged via a portable computer for two size ranges, greater than 0.5 microns diameter and greater than 5.0 microns diameter. An electronic time-share device and custom-designed valves allowed the laser particle counter to collect data in two locations, the containment and control areas.

Results of three months of pressure monitoring in general revealed the desired pressure relationships: the occupied isolated space being kept most positive, and the contained construction areas being kept most negative, with a buffer zone in between. Results of the laser particle counting confirmed continuous delivery of clean air to the isolation areas, and also identified disruptions in the containment zone caused by local construction and furniture moving.

Continuous pressure containment to prevent intra-zonal transport of bioaerosols from the roof reconstruction area to the occupied floors below was successful and allowed the project to be completed on schedule and with little occupant risk of exposure from the large quantity of contaminated materials that were disturbed and removed. In recent years, we have successfully applied these principles in over 20 school renovation projects with great success for the owner, general contractor and construction manager.

William A. Turner, MS, PE, is president of Turner Building Science LLC. He has more than 25 years of experience in IAQ/HVAC evaluation and development of solutions for building system problems. Turner can be reached by e-mail at bturner@turnerbuildingscience.com or by phone at (207) 583-4571 ext. 11.

Steve M. Caulfield, PE, CIH, is vice president of Turner Building Science. Caulfield can be reached by e-mail at scaulfield@turnerbuildingscience.com or by phone at (207) 583-4571 ext. 14.
Frederick McKnight is senior project engineer and chief IAQ engineer at Turner Building Science. McKnight can be reached by e-mail at mcknight@turnerbuildingscience.com or by phone at (802) 684-2134.