awareness of the need and desire for indoor air quality

By: Joe Zazzera, LEED AP, GRP |  February 1, 2010 | topics: LEED, Indoor Plant Benefits, Environmental Awareness

With the advent of the LEED rating system and with LEED for homes coming on in a strong way, the awareness of the need and desire for indoor air quality improvement and control is greater than ever. Due to our increased environmental awareness, we no longer trust the health and quality of our food, clothing, hair-care products, cleaning products, carpeting and paint.  Plenty of data exists proving the toxicity of these items.  We can no longer ignorantly keep these chemicals near us in any form without risking becoming irritated and sick behind their use. When it comes to our living and working environments, we want the best and healthiest options we can afford.

According to the ASID Study “The impact of interior design and the bottom line”, and The American Journal of Medicine, businesses pay $15 Billion a year in direct medical costs due to problems related to poor indoor air quality.

Over 900 VOC’S (volatile organic compounds) can be present in indoor environmental air.  Not all VOC’S are harmful but the harsh ones like formaldehyde, xylene, benzene, chloroform, ammonia, acetone are commonly used in items like paint, carpeting, construction supplies, glues, ceiling tiles, furniture and finishes.

This poor indoor air quality has negative effects on our health.  Out-gassing, or emissions of these VOC’S, cause problems such as nausea, headache, coughs, fatigue, dry skin and sore throats. These are just some of the results of poor indoor air quality.

How Living Indoor Plants Help

Live Indoor Plants convert harmful VOC’S into carbon-based materials that they then use in the photosynthesis process to make their own food. The resulting byproduct is oxygen.

This is actually a bimimicry action; there is no other known way to convert these compounds into something harmless. It is as nature designed and intended.   Air filter devices and HVAC systems can capture some of these VOC’s but they are still there, they haven’t changed.  Plants do what our most complicated HVAC systems can’t, and plants offer a host of other physical, emotional, and mental benefits.

Scientists have found that there is a microcosm, an ecosystem of sorts that exists in a regular soil mix consisting of plant roots and ordinary harmless bacteria.  The bacteria breaks down the VOC’s and the plant roots nourish and keep the bacteria alive.  Plants absorb the newly converted compounds and use them in the photosynthesis process for food and energy and growth.

In a two-year study by Norwegian Professor Tove Fjeld, in 51 offices with living indoor plants, fatigue was reduced by 20%, headaches and sore throats by 30%, coughs by a whopping 40% and dry skin irritations by 25%.

In yet another study by Texas A&M Professor Dr. Roger Ulrich, it was proven that when plants are present in hospitals, patients are ready to go home after surgery in less time; they require less pain medication; and nurses report that they are less likely to become upset or despondent from their illness or surgery. Ulrich’s study also showed that plants improved problem solving skills, ideation and creative performance. So research definitely shows that plants improve health!

How Many Plants

Research by NASA as well as Australian Scientist Margaret Burchett have shown that 1 plant per 100-160 square feet of indoor space is sufficient to have an effect and improve indoor air quality. They found that the plant size did not matter as long as they were of the 8” nursery pot size or larger.  The studies have shown that upon initial installation, VOC’S were removed within 4-5 days; any added VOC’s (by addition of furniture etc.) are removed within 24 hours. This shows that plants get better at processing VOC’S.

What are the Costs

There have been many return on investment studies that show anywhere from 30% to 300% ROI. The typical return in the office environment shows 12% improvement in productivity along with 60% reduction in absenteeism rates. This translates to a $24 ROI per day per employee commercially for a cost of about $200 per year per employee for plants including maintenance.

The residential environment is difficult to chart due to the fact that there is very little data and not much consistency with which to make accurate measurements. Designs simply vary too much to give accurate ROI numbers.  Experience has shown that most residential clients are not as concerned about specific dollar ROI as they are their interior environmental quality and aesthetics. It is discernible however, that the benefits outweigh the costs.

The Biophilic Connection

When most of us want to relax and unwind, we go for a walk in nature, take our dogs to the park or go camping or fishing. This Biophilic need for plants, life and nature is an archetypical one that is innate in all of us.

In her work Building Biophilia: Connecting People to Nature in Building Design, Environmental Psychologist, Judith Heerwagen, PhD states,  “Studies show that incorporating the natural environment into buildings can have a positive influence on psychological, physical and social well being”.  She goes on to state; “Appreciating natural beauty isn’t something that some people have and others don’t. It doesn’t need advanced education and training. It happens without effort or even conscience awareness. The more our buildings can tap into our ancient sense of beauty, the more likely they will support us psychologically and emotionally, as well as functionally”.

Our job as designers, contractors and builders is to educate and reconnect our clients to this need by providing them with the highest quality of design, décor and environmental quality as we can. Now more than ever the health benefit, productivity improvements and the return on investment for the biophilic connection to nature should be part of that design.


Joe Zazzera, is President and CEO of Scottsdale based Plant Solutions Incorporated and is a Governing Council Board member of the USGBC Central Arizona Chapter. He is a national board member of Green Plants for Green Buildings and Chair of their LEED Advocacy Committee. His goal is to see indoor plants adopted into the Indoor Environmental Quality, IEQ,  section of the LEED rating system. Joe is a LEED AP as well as an Accredited Green Roof Professional, GRP through Green Roofs For Health Cities.