Dampness and Mould - WHO guidelines for indoor air quality - PRWeb

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58 WHO GUIDELINES FOR INDOOR AIR QUALITY: DAMPNESS AND MOULD Nevertheless, consulting companies have had to use hygrothermal simulation programs in complicated renovation cases that require sophisticated analyses. In the design of new houses, the solutions already developed, tested and standardized are easier to use, accounting for the limited use of simulation tools. In research, simulation tools are used to solve hygrothermal problems of building assemblies. There are good examples for crawl spaces (Kurnitski, 2000a; Airaksinen, 2003), attics and roofs (Salonvaara, Nieminen, 2002; Kalagasidis, Mattsson, 2005) and churches (Häupl, Fechnerm, 2003; Schellen et al., 2004). Such research leads to solutions for typical building envelopes in certain climatic areas (Burch, Saunders, 1995; Karagiozis, 2002; Mukhopadhyaya et al., 2003) and the hygrothermal performance of renovated building envelopes, such as internal thermal insulation (Cerny, Madera, Grunewald, 2001; Häupl, Jurk, Petzold, 2003). It is important that such results be taken into account in revision of building codes and guidelines. 3.9 Measures to protect against damage due to moisture Moisture control is the main method for controlling mould and mites. The reasons for mould and mites are the same all over Europe, but the methods of control may differ. The effectiveness of a measure to control health determinants indoors can vary by climate, existing building construction, and heating, ventilation and air-conditioning systems. Wet surfaces in air-conditioning and ventilation systems are always at risk of microbial contamination and pollution. Air-conditioning systems should be designed and operated so that microbial growth is avoided. Guidelines are available for hygienic design and operation of air-conditioning and ventilation systems (REHVA, 2007a,b), but the maintenance of air-handling systems is often neglected. It is important to keep all surfaces of an air-handling system clean. The effectiveness of actions to control moisture also depends on whether they are for new or existing buildings. A wider variety of control methods can be applied in new constructions (Table 3) than in existing buildings (Table 4). Measures to control moisture may increase or decrease the construction or operation costs of a building, as indicated in the tables. In new constructions, most of the proposed measures reduce the operating costs by lowering energy consumption but slightly increase construction costs. It is particularly important to have an adequate ventilation rate in buildings when the thermal performance and airtightness are improved to meet energy performance criteria. The measures against moisture damage described in Table 3 are grouped into three categories. The first group covers building construction. Structures should be designed, constructed and maintained so as to withstand the indoor humidity without harmful condensation of water vapour that migrates to the structure. The second group covers ventilation. Its effect is twofold: it can remove indoor generated moisture directly and reduce the level of moisture. In some climatic
MOISTURE CONTROL AND VENTILATION 59 Table 3. Methods for controlling moisture in new buildings with better building codes Method Building construction Improve thermal properties of windows. Design structures to resist the moisture loads of local climate and typical use of buildings (e.g. use vapour barriers). Ventilate walls and other building components to prevent condensation. Improve thermal insulation of building envelope to increase indoor surface temperatures to prevent condensation in cold and moderate climates. Prevent moisture migration from ground by draining surface waters. Improve protection by roofing, walls and windows against rain. Design and install material for minimum leakage of plumbing. Ventilation Provide openable windows in all living rooms and kitchen. Provide adequate, controllable average ventilation. Ventilate all rooms where needed. Provide effective kitchen range hood. Provide possibility for controlling ventilation on demand. Use mechanical exhaust ventilation in warm and moderate climates; tighten building envelope to prevent excess ventilation. Use mechanical supply and exhaust ventilation with heat recovery to reduce relative humidity indoors. Heating Use central heating in cold and moderate climates. Do not use unvented open-flame heaters. Control indoor temperature with thermostats. Encourage use of district heating. Require chimneys for all heating boilers and furnaces. Improve control of fireplaces with e.g. dampers or shutters; to improve the thermal efficiency of fireplaces. Source: Seppänen (2004) Effect on construction cost Increase Negligible Negligible Increase Negligible Negligible Negligible Slight increase Slight increase Slight increase Slight increase Slight increase Slight increase Slight increase Slight increase None Slight increase Negligible Slight increase Slight increase Effect on energy consumption and cost Decrease None or small decrease None or small decrease Decrease None or small decrease None or small decrease None May increase or decrease May increase or decrease May increase or decrease May increase or decrease Decrease Decrease due to reduced air leakage Decrease Slight increase None Decrease Decreases use of primary energy Better efficiency; decrease in primary energy Decrease
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WHO GUIDELINES FOR INDOOR AIR QUALI
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Keywords AIR POLLUTION, INDOOR - ad
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Abstract Microbial pollution is a k
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4. Health effects associated with d
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VIII WHO GUIDELINES FOR INDOOR AIR
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X Acknowledgements Preparation of t
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XII Executive summary This document
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2 WHO GUIDELINES FOR INDOOR AIR QUA
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130 HEALTH RISKS OF OZONE FROM LONG
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ANNEX 1. SUMMARY OF EPIDEMIOLOGICAL
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When sufficient moisture is availab
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