As building and material technologies advance for greater energy efficiency, residential, office and commercial buildings are designed and built to allow little unwanted ventilation. As a result, indoor air pollutants are unable to escape and are typically 5-10% more concentrated. Moreover, insufficient ventilation can often lead to ‘sick building syndrome’ resulting in discomfort and serious illness for the occupants.
Studies originally conducted by NASA (National Aeronautics and Space Administration) have shown that certain common houseplants such as the Spider Plant, Bamboo, rubber plants and others, provide a natural and refreshingly low-tech, cost effective means to clean and purify indoor air. The studies concentrated on three main airborne pollutants: formaldehyde, benzene, and chloroethylene. Other common indoor pollutants such as asbestos, radon, lead and carbon monoxide that are emitted from furnishings (fabrics, carpet, wall coverings, etc.), office equipment and other building materials were also studied. The findings showed that, the use of houseplants (at a rate of two per 100 sqft. of floor space), could absorb up to 85% of these pollutants contributing to safer and cleaner indoor air.
The studies conducted over the last 20 years verify that the use of certain indoor plants (listed below) clean the indoor air of toxins such as Trichloroethylene, Benzene and Formaldehyde.
- Benzene, a common solvent is used in gasoline, oils, paints, plastics and rubber. Although it is being used less in the industry, Benzene is also used in the manufacture of detergents, pharmaceuticals and dyes. Trichloroethylene (TCE) is used in many industries from dry cleaning to the printing process where certain inks contain TCE. Typical paints, lacquers, varnishes and adhesives also contain TCE.
Formaldehyde is still the most commonly found material of the three (3)chemicals. It is typically present in nearly all indoor environments. Particle board and presses wood products as well as urea-formaldehyde type insulations are the most common sources. But, consumer paper products like grocery bags, waxed paper, facial tissues and paper towels are treated with urea-formaldehyde resins. Many household cleaning agents, wrinkle resisters, water repellents, fire retardants and adhesive binders used in floor covering and carpet backing also contain formaldehyde. It’s even present in our permanent press clothing! Cigarette smoke and heating fuels such as kerosene and natural gas are a few more common sources of formaldehyde.
In their efforts to develop a way to keep the atmosphere in future space stations clean, NASA scientists studied the use of plants as living air filters. The result of the research is very encouraging, especially if you like houseplants. Their findings show that houseplants are very effective at filtering organic compounds from indoor air. In fact, NASA reported on the effectiveness of Spider Plants in removing up to 2.27 µg of formaldehyde and 2.86µg of Carbon Monoxide per square centimeter of leaf area during a 6 hour photo period (Foliage Plants for Removing Air Pollutants from Energy Efficient Buildings, B.C. Wolverton, NASA, April, 1985). For example, the study estimates that approximately 8 to 15 Spider Plants should be “sufficient to meet the formaldehyde and Carbon Monoxide air purification needs of an average home (2)”.
The houseplants tested for their effectiveness at filtering the organic pollutants from indoor air included ivy, pothos, mums, dracaenas, ficus and gerbera daisies. The plants were grown in conditions as close to those in offices and homes. Left in their original pots, they were watered when they were dry and fertilized periodically with “Miracle-Gro”.
Furthermore, data from another two-year study of microbial life interrelated with the plants biodiverse ecosystem indicated that houseplants can contribute to keeping our indoor air safer to breathe by absorbing the pollutant. In fact, when some plants and potting soil were exposed to air containing toxic chemicals such as benzene, they actually become more effective air cleaners as time went on. The microorganisms living with the plant adapt genetically to their surroundings. Consequently, if a plant is exposed to higher levels of the before mentioned organic materials, they will, over time, adapt and become able to use more of these chemicals as the food source.
Interesting enough, in this analyst’s literature search we found that studies intorduced by Oxford Brookes University in Great Britain also illustrates the perceptions that can be created with interior plantings further documenting the presumption that most if not all occupants including employees felt as of their spaces looked more expensive, were more welcoming and provided a more relaxing environment
According to researchers, 15 to 20 specific species of houseplants from the before mentioned classification list will purify the interior of a typical 1,800 square foot house. The plants that are most effective at filtering indoor air are Aglaonema (Chinese Evergreen), Spathiphyllum (Peace-Lilly), Syngonium (Arrowhead vine), Hedera (English ivy), Dracaena (Cornplant), and Scindapsus (Devil’s ivy).
One could argue that the most effective use of indoor plantings is to improve Indoor Environmental Quality in private spaces as well as, the often seen interior lobby plantings so typical in the hotel and corporate buildings. In the single family home for example, certain interior plants could significantly improve the indoor air quality particularly in a home with forced air. Another use for indoor plants is in private and semi-private rooms in hospitals where aesthetic benefits in addition to, the air purification benefits could arguably reduce patient stay. In fact, studies are showing that patients in hospital “experience shorter recovery times when plants are present (Wolverton, 5)”.
Therefore, planning for energy efficiency and Indoor Environmental Quality includes the use of indoor plants that reduce harmful indoor air pollutants. We at A Design Consulting would like to see more studies and monitoring plans that provide for ongoing measuring and documentation which in turn, should be followed by thorough analysis and public dissemination of data.
Kelly Jon Andereck, A Design Consulting, brings over 20 years of experience to the environment, technical architecture and design to any project. A specialist in sustainability, building performance, daylighting, photovoltaics and the environmental marketplace, he has served as Environmental Architect/Coordinator for Skidmore, Owings & Merrill, LLP where he established environmental teams and studios worldwide, conducted LEED Seminars and sought to change partnership goals and business strategies. A Design Consulting, is a full-service energy and environmental design consulting firm committed to providing the development community with sustainably driven design assistance, education, research, and technical analysis and LEED© documentation.
