CLEANLINESS REQUIREMENTS FOR VENTILATION DUCTS IN THE NEW FINNISH LABELING SYSTEM: PRACTICAL CONSEQUENCES

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1 1 CLEANLINESS REQUIREMENTS FOR VENTILATION DUCTS IN THE NEW FINNISH LABELING SYSTEM: PRACTICAL CONSEQUENCES P. Pasanen (PhD), R. Holopainen, V. Asikainen, M. Björkroth, M. Tuomainen, J. Säteri, O. Seppänen, T. Raunemaa (PhD), P. Kalliokoski (PhD) 1. ABSTRACT The newest version of the Finnish Classification of Indoor Climate, Construction and Finishing Materials released in 2001 includes cleanliness requirements for ventilation components. The components fulfilling these requirements can be provided with M1 label. The use of M1 classified components and the consideration of the strictest cleanliness category P1 requirements for the design and installation of an air-handling system are important means to achieve the best indoor air quality class (S1). The limit value for surface dust in new HVAC components manufactured without oil lubrication is 0.5 g/m 2. The oil residue maximum is 50 mg/m 2 for new round spiral seamed duct components and 300 mg/m 2 for those new duct components which require oil lubrication during manufacture. The dust limit for new installed air supply ducts is 1 g/m 2. When new buildings have been investigated it has been shown that the P1 category ducts have been significantly cleaner than the P2 ducts. It has also been observed that the P1 criteria are realistic to achieve. However, this requires careful working practices. After completing the labelling system, man-made mineral fibers (MMMF) originating from ventilation systems have been suspected to cause irritation symptoms in several buildings. Even though the classification includes a criterion for MMMF released into air flow, 0.01 pc/cm 3, this is not a health based criterion but it is based more on practical determination limit and is difficult to test. Therefore, the number of fibers in surface dust is usually determined, and the results have been compared with the Danish recommendations. However, the results have often remained inconclusive. A typical case is given where moderately high numbers of MMMF were detected on a few locations in the ventilation system but the amounts of fibers remained low even on infrequently cleaned room surfaces. P.Pasanen is acting professor, Department of Environmental Sciences, University of Kuopio, Finland; R. Holopainen is researcher, Department of Mechanical Engineering, Helsinki University of Technology; V. Asikainen is researcher, Department of Environmental Sciences, University of Kuopio; M. Björkroth is assistant, Department of Mechanical Engineering, Helsinki University of Technology; M. Tuomainen is researcher, Department of Mechanical Engineering, Helsinki University of Technology; J. Säteri is director, Finnish Society of Indoor Air Quality and Climate; O. Seppänen is professor, Department of Mechanical Engineering, Helsinki University of Technology: T. Raunemaa is professor, Department of Environmental Sciences, University of Kuopio; P. Kalliokoski is professor, Department of Environmental Sciences, University of Kuopio

2 2 2. INTRODUCTION The Classification of Indoor Climate, Construction and Finishing Materials was released in Finland in The classification was well received by the construction industry branch, and it was expanded in 2000 to include cleanliness requirements for ventilation components. The new version was published in 2001 (FiSIAQ 2001). The goal of the classification is to achieve good indoor climate. There are target values for thermal climate, noise levels, ventilation and air pollutants. The requirements for the best indoor air quality class (S1) include, for example, the limits of 200 µg/m 3 for total volatile organic compounds (TVOC) and 20 µg/m 3 for airborne particulate matter (PM 10 ). The classification provides guidance how to achieve these goals. This is divided into guidance for design and construction (P categories) and requirements for building products (M categories). The last part consists of emission classification of building materials and cleanliness classification of air-handling components. Thus, in order to achieve the air quality class S1, one should use M1 classified components and to follow the P1 category requirements for the design and installation of air-handling systems. The M1 oil residue requirement is less than 50 mg/m 2 for new round spiral seamed duct components and less than 300 mg/m 2 for those new duct components which require oil lubrication during manufacture. The limit of 50 mg/m 2 is based on the correlation observed between odor intensity and the oil residue. It corresponds to the M1 odor emission requirement (dissatisfaction with odor less than 15%). The limit value for surface dust in new ducts and fittings is 0.5 g/m 2 at factory. The P1 dust requirement is less than 1 g/m 2 for new installed dusts. These values are based mainly on practical aspects. First, the simple visual inspection is selected as the primary method for duct cleanliness evaluation. FiSIAQ has prepared a visual cleanliness scale with photos indicating various accumulations of dust. The limits selected are possible to assess visually. Secondly, these requirements have been found to be feasible in practice and accepted both by manufacturers and installation companies. In addition, the limit of 1 g/m 2 was adopted earlier in Sweden (SNBH 1994). The oil residues are sampled by filter contact method and analyzed by infrared spectroscopy (Asikainen et al. 2002; Asikainen et al. 2003). The samples are taken by pressing a moistened glass fiber filter with a constant pressure device on the surface (flat or evenly round) investigated. For uneven surfaces, the immersed filter covered with a clean polytetrafloroethane film can be pressed down with the tweezers. After drying for 15 minutes at 35 o C, oil was extracted with 5 ml of tetrachloroethylene in ultrasonic bath, centrifuged, and analyzed at 3380 and 3420 nm (the average absorbance is used). The quantification is done against a dilution series of the same oil used in the manufacture. The amount of surface dust is sampled by the vacuum test method (Pasanen et al. 1995; Holopainen et al. 2000). An area of 100 cm 2 is vacuumed with a small plastic nozzle onto a polycarbonate filter (pore size 0.8 µm). The dust is determined gravimetrically. This test was selected based on the comparison of various methods for quantifying the amount of dust on the ventilation dusts in 13 new buildings (Holopainen et al. 2002). The vacuum test was the most effective method. The tape method also gave good results. This method is especially suitable when the amount of dust is low. As mentioned earlier, visual inspection is used as the primary method for commissioning, and measurements should be done only if no agreement can be achieved with this simple method during commissioning. Airborne man-made mineral fibers (MMMF) are known to cause irritation symptoms among persons exposed. In addition to manufacture and installation of insulation products made of MMMF, acoustic boards may act as sources of fibers (Schneider et al. 1990; Fischer 1993). Ventilation filters are often made of glass fibers. However, several studies have shown that these do not generally emit fibers. On the other hand, sound insulation of ventilation systems may cause problems if the release of fibers is not prevented e.g., by covering with a glass fiber fabric (Schneider et al. 1990).

3 3 The Finnish classification also includes a criterion for MMMF released into air flow, 0.01 pc/cm 3. However, this is based mainly on practical detection limit of airborne fibers, and is, nevertheless, difficult to test. In addition, the aim was to test new components in the laboratory. A test arrangement for this purpose has been built in the Technical Research Centre (VTT). After completing the classifications systems, there have been several cases where MMMF originating from ventilation system have been suspected to cause the irritation symptoms suffered by the occupants. In this paper, the experiences on the new cleanliness classification of ventilation components are first summarized, and then the MMMF issue is discussed by means of a large case study. 3. EFFICIENCY OF CLEANLINESS CLASSIFICATION The mean amount of dust collected in ventilation ducts was 13 g/m 2 according to studies done before the cleanliness classification. The amount of dust originating from manufacture and installation was estimated to be 5.1 g/m 2 (Pasanen 1995). These values are based on measurements conducted in 22 office buildings selected randomly from the building stock of two regions in Finland. Shortly before the classification was established, the recommended practices were tested in three buildings under construction. In each case, the processing oil residues were minimized during manufacture of the ducts. The average residue was 0.2 g/m 2. In two buildings, the open ends of the ducts were protected against dust during transportation, storage, and installation while traditional practice was followed in the third building. The protection was found to be effective. The cumulative dust accumulations were only 0.6 and 0.7 g/m 2 in the buildings following the protection practices while it was 3.1 g/m 2 in the third building where the highest accumulation of dust (ca. 70%) occurred during storage and installation of trunk ducts (Luoma 2000). The practical applicability of the new classification system was then studied in 18 new buildings, half of which followed the P1 requirements and the other half was classified to category P2. Ducts in category P1 were washed after manufacturing and protected during the transportation, storage, and construction periods. Even though category P2 has no specific instructions on the means to achieve the required limit of 2.5 g/m 2 for dust accumulation, the ducts were protected during construction in three buildings, the ducts were cleaned after construction in four buildings, and only in two buildings no special measures to ensure the duct cleanliness were taken. The investigation showed that the P1 category ducts were significantly cleaner than the P2 ducts. The mean amounts of accumulated dust were 0.9 g/m 2 and 2.3 g/m 2 in P1 and P2 categories, respectively. Among P2 buildings, the lowest mean dust load, 1.7 g/m 2 was observed in those buildings where the ducts were protected. Surprisingly, the P2 ducts which were specified to be cleaned after construction were the dirtier (mean 2.8 g/m 2 ) than those installed without any specific instructions (mean 2.2 g/m 2 ). 4. FIBERS ORIGINATING FROM VENTILATION SYSTEM 4.1 Materials and methods The building studied was a large art school where complaints of irritation symptoms were common. Mineral fibers released from the sound insulation of the ventilation system were one of the possible reasons for these symptoms. The mineral wool layer in the ventilation system was covered with a plastic film and perforated steel sheet; however, the plastic film was broken in many places. The fibers were investigated from surface samples instead of air samples because this was considered to reflect better long-term conditions. Both duct and interior surfaces were sampled. The fibers were counted from samples ( n = 23) taken with transparent adhesive tape (BM dustlifter gel tape) with an optical microscope. Four interior surface samples were collected from upper surfaces, which were rarely cleaned. Two hundred fields were investigated per sample at x magnification; the area counted per sample was 1.14

4 4 cm 2. In addition, four samples were taken with the vacuum test method (Pasanen et al. 1995) for qualitative fiber analysis. The glass- and rockfibers were identified based on their chemical composition analysed with scanning electron microscopy (XL 30 ESEM TMP) equipped with x-ray fluorescence analyser (Röntec EDWIN). The amounts of surface dust were determined with vacuum test method described in the introduction. The number of dust samples was Results The mean amounts of dust found on duct surfaces were 3.0 g/cm 2 for main ducts (range < g/cm 2 ; n = 15), 5.7 g/cm 2 for branches ( ; n = 4), and 42.7 g/cm 2 for sound attenuators ( g/cm 2 ; n = 3). The corresponding amounts of fibers found per cm 2 were 113 (11 256), 55 (19 98; n = 5), and 661 ( ). The chemical analyses revealed both glass and mineral fibers. The amounts of fibers detected in the interior surface samples were low, from less than 0.2 fibers/cm 2 to 1.8 fibers/cm 2 (n = 4). 5. DISCUSSION The mean amounts of dust accumulated on ducts exceeded the Finnish (P1) requirement of 2 g/cm 2 for existing ducts. However, the dust was deposited very unevenly on the duct surfaces. Most of the samples fulfilled the criterion but, on the other hand, some high dust concentrations were detected. The dust was coarse and it probably originated from the construction phase. The high mean value for sound attenuators was due to one very high concentration (122.9 g/cm 2 ). Fibers were commonly detected on duct surfaces. Both glass- and rockfibers were observed. As could be expected, the highest levels were found in the sound attenuators. However, the ventilation system hardly acted as a fiber source for indoor air because the amounts of fibers were clearly lower than the limit of 3 fibers/cm 2 recommended for irregularly cleaned surfaces in Denmark. The irritation symptoms were probably due to printing and painting activities in the school. Similar results were obtained in another building where occupants suffered from similar irritation symptoms, which were also suspected to be caused by airborne fibers. Fibers were detected on the duct surfaces but not on the interior surfaces. In addition, careful duct cleaning did not alleviate the symptoms. 6. CONCLUSIONS The newest version of the Finnish Classification of Indoor Climate, Construction and Finishing Materials released in 2001, which also includes cleanliness requirements for ventilation components, has been well accepted by the construction industry sector in Finland. It has also been found to be effective and realistic to follow. After completing the classification system, MMMF originating from ventilation systems has been suspected to be the reason for irritation symptoms suffered by the occupants. The classification includes a criterion for MMMF released into air flow. However, this limit (0.01 fibers/cm 2 ) has no clear health relevance but is based mainly on the detection limit of the method used. Nevertheless, it is difficult to apply in practice. It is much easier to take surface samples from the ductwork. These also reflect better long-term conditions. In addition, not only airborne cause irritation symptoms but those may be due to skin contact to MMMF. However, the case presented here other similar recent experiences have shown that even though MMMF are common on duct surfaces they do not necessarily enter the supply air because even the irregularly cleaned interior surfaces remained virtually free from MMMF. Thus, if fibers are suspected to cause problems, it would be advisable to sample first rarely cleaned interior surfaces, and only in cases where fibers were detected in large amounts (exceeding the Danish recommendation of 3 fibers/cm 2 ) ducts would be sampled as possible sources. Even then, attention should also be paid to other potential sources, such as acoustic boards.

5 5 7. REFERENCES Asikainen, V., M. Björkroth, R. Holopainen, and P. Pasanen. Oil residues on HVAC components. Proceedings of Indoor Air 2002, Monterey, CA, Vol. 1, pp Asikainen, V., P. Pasanen, and J. Liesivuori Mineral oil residues on HVAC components: measuring methods. Building and Environment, Vol. 38, pp FiSIAQ Classification of Indoor Climate, Construction, and Building Materials Espoo: Finnish Society of Indoor Air Quality and Climate. Fischer, M Benefits and risks from MMMF in indoor air. Proceedings of Indoor Air 93, Helsinki, Vol. 4, pp Holopainen, R., P. Pasanen, and O. Seppänen Duct cleanliness in new HVAC installations. Proceedings of healthy Buildings 2000, Helsinki, Vol. 2, pp Holopainen, R., V. Asikainen, P. Pasanen, and O. Seppänen. The field comparison of three measuring techniques for evaluation of the surface dust level in ventilation ducts. Indoor Air, Vol. 12, pp Luoma, M Protecting ventilation ducts and accessories against dirt during the construction work. Proceedings of Healthy Buildings 2000, Helsinki, Vol. 2, pp Pasanen, P Impurities in ventilation ducts. In: Engineering Indoor Environments, pp Atlanta: American Society of heating, Refrigerating, and Air-Conditioning Engineers, Inc. Pasanen, P., A-L. Pasanen, and P. Kalliokoski Hygienic aspects of processing oil residues in ventilation ducts. Indoor Air, Vol. 5, pp Schneider, T Man-made mineral fibers and other fibers in the air and in settled dust. Environment International, Vol. 12, pp Schneider, T., O. Nielsen, P. Bredsdorff, P. Linde Dust in buildings with man-made mineral fiber ceiling boards. Scandinavian Journal of Work, Environment & Health, Vol. 16, pp SNBH Checking the performance of ventilation systems, General Guidelines 1192:3E. Karlskrona, Sweden: Swedish National Board of Housing, Building and Planning.