INDOOR AIR QUALITY AND MATERIAL EMISSIONS IN NEW BUILDINGS

Transcription

1 INDOOR AIR QUALITY AND MATERIAL EMISSIONS IN NEW BUILDINGS H Järnström * and K Saarela VTT Building and Transport, Service Centre, P.O. Box. 141, FIN-244 VTT, Finland ABSTRACT A research project was established to create numeric reference data for material emissions during the time of construction as well as for indoor air quality follow-up in new buildings. 1 measurement sites, representing the present construction practice in Finland, were chosen for investigation. Material emission measurements for surfaces, using the field and laboratory cell (FLEC) technique, were performed during the time of construction. The emission rates for VOCs (Volatile Organic Compounds), formaldehyde and ammonia of the floor structure were measured for the floor structure build-up stages. In addition, decay behaviours for the emissions of underlying floor structures were investigated. The concentration of VOCs, formaldehyde and ammonia in indoor air as well as the air exchange rate were defined for the newly finished building. The results obtained were compared to indoor air concentration and emission rate target values, defined in the Finnish Classification of Indoor Climate 2. INDEX TERMS IAQ, material emissions, new buildings, VOC INTRODUCTION In order to improve the quality of indoor air the Finnish classification of indoor climate was developed (FiSIAQ, 21). The classification gives emission limits for materials as well as target values for indoor air concentrations of TVOC, formaldehyde and ammonia. It is suspected that some of these compounds might be responsible for health effects among inhabitants. This three-year study was established to investigate how the limits for material emissions and indoor air concentrations defined in the classification can be reached in normal buildings. The objective is to create an extensive reference data for material emissions and indoor air quality for newly finished buildings. This data can be used as a part of the quality control in today's building practice and in the identification of material/moisture-based problems in suspected cases. This paper describes a selected part of the results obtained during METHODS The measurement sites were chosen in collaboration with three different construction partners. Indoor air and material emission measurements were performed in six apartment buildings (site built and manufactured) and in one (site built) 2-family house. Five buildings have a mechanical exhaust ventilation and two a mechanical supply and exhaust ventilation. Six of the buildings are located in the Helsinki area and one in the city of Turku. The time of construction for the buildings was months during the years The follow-up measurements were performed every time in the same room (usually the bedroom) and at the same site at all building stages. An opening was made in the floor covering to enable floor * Contact author: helena.jarnstrom@vtt.fi * 21

2 structure follow-up measurements. The opening was tightly sealed between the measurement periods. The measurement schedule is presented in table 1. Table 1. Measurement schedule Measurement point Measurements Floor structure TVOC-, ammonia- and formaldehyde- emission: floor structure Floor structure TVOC-, ammonia- and formaldehyde- emission: floor structure with screed Floor coating TVOC-, ammonia- and formaldehyde- emission: floor structure 4 week old TVOC-, ammonia- and formaldehyde- indoor air concentration Newly finished TVOC-, ammonia- and formaldehyde- emission: all surfaces Building (floor, wall, ceiling) 6 and 12 months inhabited building TVOC-, ammonia- and formaldehyde- indoor air concentration TVOC-, ammonia- and formaldehyde- emission: all surfaces (floor, wall, ceiling) TVOC-, ammonia- and formaldehyde- indoor air concentration MATERIALS At all measurement sites low emitting, M1-classified materials ( were used. That is, the laboratory tests performed for a 4 week old sample gives a TVOC-, ammonia- and formaldehyde emission lower than 2, 3 and 5 µg/m 2 h respectively. At all measurement sites the walls were finished with screed and painted. Wall paper was laid on the screed at one site. Ceiling structures were finished with screed. The floor structure was finished with fine screed (dispersal 2-5 mm) in the site built houses and with gross screed (dispersal 1-3 mm) in the case of manufactured houses. Different types of PVC materials and parquets were used as floor coatings. Table 2 summarises the floor structure and coating materials as well as the air condition type. Table 2. Measurement sites. Site Floor Structure Floor coating material Air condition Type Site 1, 2 nd floor On site concrete Parquet 1 Mechanical exhaust Site 1, 4 th. Floor On site concrete PVC 1 Mechanical exhaust Site 1, 5 th floor On site concrete PVC 2 Mechanical exhaust Site 2, 6 th floor Manufactured PVC 3 Mechanical exhaust Site 3, 2 th floor On site concrete Parquet 1 Mechanical exhaust Site 4, 3 rd floor On site concrete PVC 4 Mechanical exhaust Site 5, 2 th floor Manufactured Parquet 2 Mechanical supply and exhaust Site 6, 1 th floor Manufactured Parquet 2 Mechanical supply and exhaust Site 7, 2 th floor Manufactured PVC 5 Mechanical exhaust Site 7, 3 rd floor Manufactured PVC 6 Mechanical exhaust SAMPLING AND ANALYSIS Indoor air sampling was performed in the closed room at approximately 1,4 m above the floor level. No additional ventilation through doors or windows were done 24 h prior to the measurement. The temperature and relative humidity were registered using a Vaisala 22

3 HMP41 moisture detector during the one- hour measurement period. The air exchange rate for the facility was determined simultaneously with a Alnor AXD-53 pressure difference meter. Field measurements for material emissions of structures were performed using the Field and Laboratory Cell (FLEC)- technique (CEN, 1999). The humidity of the structure was determined with a Vaisala HMP44 moisture detector according to the instructions given by the Finnish Building Foundation (RTS, 1998). The total amount of VOCs was determined by sampling 2-5 l of air on Tenax TA adsorbent and analyses with GC-MSD/FID after thermal desorption. The TVOC was calculated as toluene equivalents from the total integrated FID signal between hexane and hexadecane. The sampling of ammonia and formaldehyde was performed on a,5 M sulphuric acid- solution. The ammonia concentration was determined with a ion-selective electrode and the analysis of formaldehyde was done with the spectrometric acetyl-acetone method RESULTS The material emission results of the floor structure during the time of construction are shown in figures 1 and 2. In figure 1 the TVOC and ammonia emissions of the site built and manufactured structures are combined. It can be observed that the site built houses have higher TVOC and ammonia emissions in comparison to the manufactured structures. The TVOC emission level was 1-26 µg/m 2 h for site built houses and <5 µg/m 2 h for manufactured. The ammonia emission was at the level 3-7 µg/m 2 h for site built houses and for the manufactured <3 µg/m 2 h. Material emission: concrete ammonia SER (ug/m2h) TVOC SER (ug/m2h) construction T (oc) surface T (oc) indoor air surface RH (%) construction RH (%) M1- class: TVOC <2 mg/m 2 h ammonia <3 mg/m 2 h SB 7 weeks SB 11 weeks SB 26 weeks M 1 weeks M 1 weeks M 14 weeks Figure 1. Material emission: concrete (SB= site built, M= manufactured). In the site built houses fine screed (dispersal 2-5 mm) and at the manufactured houses gross screed (dispersal 1-3 mm) was laid on the floor structure. The TVOC- and formaldehyde emissions were relatively high compared to the material classification M1-limit of 2 µg/m 2 h and 5 µg/m 2 h respectively (figure 2). The fine screed (dispersal age 1-3 weeks) had a M1- class emission whereas gross screed did not reach the M1-limit in two weeks. No ammonia emission above the M1-limit 3 µg/m 2 h was measured at any site. 23

4 Material emission: concrete+ screed TVOC SER (ug/m2h) ammonia SER (ug/m2h) formaldehyde SER (ug/m2h) construction T (oc) 3/3 ammonia, formaldehyde/ TVOC 15/ 15 M1- class: TVOC <2 µg/m 2 h ammonia <3 µg/m 2 h formaldehyde <5 µg/m 2 h surface T (oc) 5/5 indoor air surface RH (%) construction RH (%) FS 5 mm 2 days FS 5 mm 1 week FS 5 mm 3 weeks GS 2 mm 4 weeks GS 2 mm 2 weeks GS 2 mm 2 weeks Figure 2. Material emission: concrete + screed (FS= fine screed, GS= gross screed). The emission from the concrete structure under the floor covering was measured as a function of time to investigate how different floor coverings and underlying materials and structures affect the emissions. Figure 3 and 4 describes the TVOC and ammonia emissions for the floor surface and the underlying structure 1 and 3 days after opening at site 1 (site built concrete structure). The relative humidity of the structure decreased from 88% to 78% during the measurement period of 74 weeks. SER µg/m 2 h 5 4 TVOC emission measured from the floor structure before and after removing the floor covering before removal removed, day 1 removed, day 3 M1- class <2 µg/m 2 h parquet 1 4 weeks 23 weeks 49 weeks 74 weeks PVC 1 4 weeks 18weeks 47 weeks 71 weeks PVC 2 4 weeks 1 weeks 48 weeks 72 weeks Figure 3. TVOC emission measured from the floor structure before and after removing the floor covering. The difference between the emissions of the parquet and the two different types of PVC coverings was striking: the surface TVOC emission of the parquet and PVC 2 was <2 µg/m 2 h whereas the emission of PVC 1 was 2 µg/m 2 h. The underlying floor structure gave very different emission results for the three coatings: the TVOC emission measured under PVC 2 remained 2 µg/m 2 h for 72 weeks whereas the emissions for the PVC 1 slowly decreased from the same level to 1/1 in 18 weeks. The emissions measured 24

5 under the parquet decreased from 1 µg/m 2 h to 2 µg/m 2 h in 5 weeks. These results indicate a difference in the permeability for VOC compounds between the different PVC materials. The ammonia emission measured from the structure 3 days after the removal of the parquet was 5 µg/m 2 h and 5-1 µg/m 2 h after the removal of the PVC materials. Ammonia emission measured from the floor structure before and after removing the floor covering SER µg/m 2 h before removal removed, day 1 removed, day 3 M1- class <3 µg/m 2 h parquet 1 4 week 23 weeks 49 weeks 74 weeks PVC 1 4 weeks 18weeks 47 weeks 71 weeks PVC 2 4 weeks 1 weeks 48 weeks 72 weeks Figure 4. Ammonia emission measured from the floor structure before and after removing the floor covering. The indoor air concentration of TVOC, ammonia and formaldehyde in the newly finished buildings are shown in figure 5. Indoor air TVOC, ammonia and formaldehyde concentration in newly finished buildings ammonia concentration formaldehyde concentration TVOC concentration ammonia: µg/m 3 S1&S2 < 3 µg/m 3 S3 < 4 µg/m 3 formaldehyde: S1 < 3 µg/m 3 S2 < 5 µg/m 3 S3 < 1 µg/m Site 1, 2. floor Site 1, 4. floor Site 1, 5. floor Site 2, 6. floor Site 3, 2. floor Site 4, 3. floor Site 5, 2. floor Site 6, 1. floor Site 7, 2. floor Site 7, 3. floor 25 µg/m TVOC: 5 S1 < 2 µg/m 3 S2 < 3 µg/m 3 S3 < 6 µg/m 3 measurement site Figure 5. Indoor air TVOC, ammonia and formaldehyde concentrations in newly finished buildings. The target values for indoor air quality classes S1, S2 and S3 are shown (FiSIAQ, 21). The TVOC concentration in the newly finished buildings varied between µg/m 3. The highest amount of TVOC was measured at site 7 where the air conditioning had been functioning for only 4 days. No relation between the use of parquets or PVC as floor coverings and the TVOC concentration could be concluded from the results. The time of air conditioning operation and the time of final construction work as well as the building type 25

6 were of less importance. The only parameter that seemed to affect the TVOC concentration was the type of air conditioning; at sites 5 and 6, where mechanical supply and exhaust ventilation systems were used, the lowest TVOC concentrations of µg/m 3 were measured. The indoor air ammonia and formaldehyde concentrations varied between 2-6 µg/m 3 and µg/m 3 respectively. DISCUSSION The Finnish Indoor Climate Classification gives target values for indoor air chemical compound concentrations as well as their material emissions. The field measurement results gained in this study revealed to some extent what limits can be reached with today's building practice when using tested, low emitting materials in apartment buildings. The variety of different materials and construction work methods gives variability in the results. However, the results obtained so far give good frames and guide lines to consider for quality control. The classification limits for material emissions of the floor structure may, with a selection of certain material combinations, be reached in a new building. However, from the results in this study it is concluded that when using tested low emitting materials on all surfaces, the indoor air quality did not reach the classification limit in any of the 7 newly finished buildings before occupancy. The average TVOC concentration was approximately 1 µg/m 3 and above the S3 indoor air target value of 6 µg/m 3 representing satisfactory indoor air quality. For comparison, a S1- class indoor air climate was reached in an office building in two months, where low emitting materials were used and the air exchange rate was above 3 h -1 (Saarela, Villberg and Ruotsalainen, 2). The study presented here gave implications on the effectiveness of a controlled supply and exhaust ventilation system in comparison to a mechanical exhaust only system in minimising the indoor air TVOC concentration in new buildings before use. The follow-up measurements in the inhabited buildings will continue until the end of year 22. CONCLUSION AND IMPLICATIONS Building designers and constructors can use the knowledge gained during this project to develop their building practice in the course of producing buildings with high indoor air quality. The applicability for material suppliers is to develop long-term resistant, low emitting surface materials. In addition, the on site reference data can be utilised in the identification of material/moisture-based problems in suspected cases. ACKNOWLEDGEMENTS This project is part of the national Healthy Building-project Verification, Source Apportionment and Remediaton of an Indoor Air Problem and it is partly financed by the Finnish National Technology Agency (TEKES). REFERENCES CEN ENV , Building products. Determination of the emission of volatile organic compounds. Part 2: Emission test cell method, Bruxelles: European Committee for Standardization. FiSIAQ. 21. Classification of Indoor Climate 2, Espoo: Finnish Society of Indoor Air Quality and Climate. RTS RT Building Information File : Determination of the humidity of Structures, Helsinki: The Finnish Building Information Foundation. Saarela, K, Villberg, K, and Ruotsalainen, R. 2. Demonstration of Good IAQ in Finnish Allergy House, Proceedings of Healthy Buildings 2, Vol 4, pp Helsinki: Healthy Building 2. 26