How much air should be supplied in residential buildings

How much air should be supplied in residential buildings? KIRIL NAYDENOV 1 , STEFANO SCHIAVON 2,3 , ROBERTO ZECCHIN 2,4 ALECTIA A/S, Teknikerbyen 34, 2830 Virum, Denmark, www.alectia. com Universita degli Studi di Padova, Dipartimento di Fisica Tecnica, V. Venezia,1 IT-35131, Padova, Italia www.dft. unipd.it Technical University of Denmark, International Centre for Indoor Environment and Energy, Department of Civil Engi- neering, Building 402, DK-2800 Lyngby, Denmark, www.ie. dtu.dk TiFS Ingegneria S.r. l. , Corso Stati Uniti 56, IT-35127 Padova, Italia, www.tifs. it HOME INDOOR ENVIRONMENT Houses are spaces for human habitation, created as a viable alternative to living outdoor. The created indoor environment is meant to ensure health and safety of the occupants, and to keep them comfortable. The home indoor environment intensively interacts with humans (e.g. lighting, acoustics, thermal comfort, indoor air quality, spread of diseases, sleeping quality, safety, etc.). An important factor is the effect of the home indoor environment to the air to which the inhabitants are exposed. It is a complex system that is a result of the interaction between the building, the construction techniques used, contaminant sources, the building occupants and the outdoor sources. It is affected by the original design and subsequent modifications in the structure and systems, building materials and furnishings, processes and activities. Poor indoor air quality, noise, excess humidity and mould growth, thermal discomfort, substances such as formaldehyde, asbestos, lead and radon, lack of hygiene and sanitation equipment and crowding are some of the possible health threats to be found in dwellings. In the last decade several interdisciplinary reviews of the scientific literature conducted in Sweden (Ahlbom et al., 1998; Sundell, 1999), in the Nordic countries (Andersson et al., 1997; Bornehag et al., 2001) and more generally in Europe (Wargocki et al., 2002; Schneider et al., 2003; Bornehag et al., 2004) have shown a strong evidence of an association between indoor environmental exposures and human health (e.g. risk factors such as dampness, ventilation, pets, and house-dust mites, and health effects such as allergy and asthma, airway infections and Sick Building Syndrome). BUILD TIGHT, VENTILATE RIGHT Since the energy crisis in the mid 1970s, energy saving has become a priority in most industrialized countries for economic and ecological reasons. More recently, environmental concerns of a global climate change have reinforced the urgency of rational energy use. The drive for energy saving may appear to conflict with good indoor air quality. In fact, reducing ventilation to reduce energy con- sumption leads to higher levels of indoor pollutants and humidity, thus increasing the exposure of the occupants. Excess air moisture may result in dampness problems. Dampness indoors can result in chemical and microbial processes that can release toxic substances as well as induce the prolife- ration of house-dust mites. In combination with the implementation of new synthetic materials for fittings and furnishings as well as the use of new consumer products, human indoor exposure has been changed substantially. Negative health consequences of energy saving measures (e.g. insuffi- cient ventilation) are often indicated. A classical example showing the indirect connection between the changes in people’s health status and energy saving measures, is a study from Germany (von Mutius et al., 1998a) where in 1998 the prevalence of atopic sensitization (1990:19.3% vs. 1998: 26.7%) and Allergic rhinitis, also named hay fever, (2.3% vs. 5.1%) among children in former East Germany increased significantly and more rapidly than in West Germany (von Mutius et al., 1994) after the German reunification (1990). The children had spent their first three years of life under socialist living conditions and were later exposed to a western style of life. Von Mutius (1998b)