Breathing Wall Modeling to Absorb Indoor Pollutants In a Living Room of a House Inspired by the Buffer Zones of Traditional Architecture in Hot and Arid Climate of Iran Country
Since man has lived in roofed shelter and selected fire for heating and cooking at his shelter, the indoor air quality has become an important issue and also unwanted problem for him because most of indoor pollutants source from cooking and heating. Indoor air quality (IAQ) is a major determinant of personal exposure to pollutants in today's world. People spend much of their time in numerous different indoor environments. Perhaps the predominant environment in this regard is the residence. From time diary research it can be shown that the typical person in the U.S. spends 58 to 78 % of his time in the home. Furthermore , some individuals –the old , the very young , the infirm – who are most susceptible to the effects of pollutants may spend all their time indoors .pollutant concentration levels indoors are sometime higher than in heavily polluted outdoor urban air . Sources of indoor pollution include influx of polluted outdoor air. IAQ became a timely issue when energy conservation efforts focused attention on the influx of unconditioned air into interior spaces. Since the Arab oil embargo of 1973, building owners have been under tremendous economics pressure to reduce the cost of heating and cooling their buildings. Many of actions taken to reduce such costs affect the air quality inside those buildings in ways which range from subtle to dramatic. Various energy conservation measures such as added insulation, caulking, and weather stripping tighten the building's thermal envelope and influence the rate at which air moves into and out of the structure. This rate in turn affects levels of indoor pollutants. Some energy conservation measures involve installation materials which may be strong sources of indoor pollutants. While these energy conservation measures have created some possible indoor air quality problems, more importantly they have increased awareness of overall exposure to indoor air pollutants. Outdoor or ambient air quality has been regulated via the clean air act of 1970 to protect human health by limiting concentrations of such pollutants as sulfur oxides, nitrogen oxides and particles. In contrast, indoor air quality and its contribution to human health have been unregulated with exception of the workplace. In large part this is because individual occupants of buildings can and do affect indoor air quality by buying and using pollutant sources and by regulating the incoming outside air through ventilation. IAQ is a term which refers to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. IAQ can be affected by gases (including carbon monoxide, radon, and volatile organic compounds), particulates, microbial contaminants, or any mass or energy stressor that can induce adverse health conditions. Source control, filtration and the use of ventilation to dilute contaminants are the primary methods for improving indoor air quality in most buildings. Residential units can further improve indoor air quality by routine cleaning of carpets and area rugs. Determination of IAQ involves the collection of air samples, monitoring human exposure to pollutants, collection of samples on building surfaces, and computer modeling of air flow inside buildings. IAQ is part of indoor environmental quality (IEQ), which includes IAQ as well as other physical and psychological aspects of life indoors. We tend to think of air pollution as something outside -- smog, ozone, or haze hanging in the air, especially in summer. But the truth is, the air inside homes, offices, and other buildings can be more polluted than the air outside. The air inside your home may be polluted by lead (in house dust), formaldehyde, fire-retardants, radon, even volatile chemicals from fragrances used in conventional cleaners. Some pollutants are tracked into the home. Some arrive via a new mattress or furniture, carpet cleaners, or a coat of paint on the walls. Children, people with asthma, and the elderly may be especially sensitive to indoor pollutants, but other effects on health may appear years later, after repeated exposure. Most common indoor pollutants are Radon, Molds and other allergens, Carbon Monoxides, Volatile Organic Compounds (VOCs), Legionella and other bacteria, Carbon Dioxide and Ozone. Indoor air quality is one of the most important factors that can influence efficiency and maintenance of the building. Poor indoor air quality and inadequate ventilation causes people not to have their best potential at work, inverse increasing indoor air quality encourage them to activity. Fortunately architectures almost can control indoor air quality in first steps of designs. One of the solutions for absorbing pollutants and reducing them is the use of plants that have the ability to absorb pollutants and can be used as bio absorbent. Houseplants and the medium in which they are grown together can reduce components of indoor air pollution, particularly volatile organic compounds (VOC) such as benzene, toluene, and xylene. Plants remove CO2 and release oxygen and water, although the quantitative impact for house plants is small. Most of the effect is attributed to the growing medium alone, but even this effect has finite limits associated with the type and quantity of medium and the flow of air through the medium. The effect of house plants on VOC concentrations was investigated in one study, done in a static chamber, by NASA for possible use in space colonies. The results showed that the removal of the challenging chemicals was roughly equivalent to the provided ventilation that occurred in a very energy efficient dwelling with a very low ventilation rate, an air exchange rate of about 1/10 hour. Therefore, air leakage in most homes, and in non-residential buildings, will generally remove the chemicals faster than what the researchers reported for the plants tested by NASA. The most effective household plants reported included Aloe Vera, English ivy, and Boston fern for removing chemicals and biological compounds. Plants also appear to reduce airborne microbes, molds, and increase humidity. However, the increased humidity can itself lead to increased levels of mold and even VOCs. When CO2 concentrations are elevated indoors relative to outdoor concentrations, it is only an indicator that ventilation is inadequate to remove metabolic products associated with human occupancy. Plants require CO2 to grow and release oxygen. Since high humidity is associated with increased mold growth, allergic responses, and respiratory responses, the presence of additional moisture from houseplants may not be desirable in all indoor settings In this essay with integrating plants and architectural space, we have investigated the behavior of polluting fluid including its release, publishing and concentration in the room with Ansys –Fluent software. First we had made grids for analysis. for boundary conditions, we have considered ,air input at fixed rate of 0.5 m/s and air output in constant partial pressure at zero atmosphere . Also fixed walls with non-slip condition are considered. In addition, because of complicated flow pattern inside the room, SST K-W RANS models is used to simulate the turbulent flow .on the results of this paper , plants can reduce 10-20% of indoor pollutants concentration by producing oxygen during photosynthesis, depending on the volume of the plant used.
Article Type:
Research/Original Article
Naqshejahan- Basic studies and New Technologies of Architecture and Planning, Volume:8 Issue:1, 2018
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