The Living Wall at Drexel University

Drexel University’s Biowall

I find the concept of green roofs and green walls fascinating. Each month, I eagerly await Kevin Songer’s contributionon green roofs. That is why I was happy to learn about a living wall not far from my home in the Philadelphia suburbs and decided to pay it a visit. Drexel University inaugurated its indoor green wall last September. It will serve the purposes of purifying the air and beautifying the location; but, most of all, it will be used to study the functioning and benefits of living walls. This research project is being carried out by a team which includes biologists and an environmental engineer. It also gives students the opportunity of a hands-on learning experience.

Drexel University boasts the largest North American indoor living wall or Biowall, as they prefer to call it. The five-story high living wall stands in the lobby of a new building, the Papadakis Integrated Sciences Building, in the heart of Philadelphia. About 12 species of tropical plants have been selected for this wall. Sorry, no native plants here! Those that grow through the cold winters of southeastern Pennsylvania (hardiness zone 7a) would not survive the constant indoor temperatures. Dr. Shivanthi Anandan explains that plants were bought in local nurseries “chosen for their robust growth, and also to illustrate the fact that these plants can be bought by the general public”.

Close up of some of the tropical plants that make up the Biowall

Still, the ecological value of an indoor living wall makes it worthy of this discussion. Accumulated pollutants are a serious problem of enclosed buildings. This indoors pollution has earned the name of “sick building syndrome” (EPA Fact sheet). It is caused primarily by volatile organic compounds (VOCs for short). There are a few ways to combat the accumulation of such undesirable aerial compounds. Increased air circulation is helpful but requires a larger consumption of fossil fuels used for cooling and heating the building. Air filters are beneficial but they must be replaced constantly. A properly designed living wall would circulate air through it trapping pollutants; a more effective and elegant solution to the problem of “sick building syndrome”.

An important aspect of Drexel University’s Biowall is its role as a living laboratory to study the function of this air filter. More important than the plants themselves are many microorganisms that live on or around the roots. A rich community of bacteria and fungi works hard to capture and destroy some of the volatile compounds mentioned. It turns them into food for themselves and for the plants they live on in a remarkable feat of biochemistry. For instance there are some bacteria that break down benzene and toluene. The team of Drexel researchers plans to learn about these microorganisms, how they work, how beneficial they are.

They will be studying the chemical composition of air before and after it goes through the biowall. Some previous studies show a significant reduction of some pollutants. There will also be more detailed studies at the microscopic level performed in the lab. It is hoped that the results will serve to create improved and more efficient walls.

Living wall planters

In the meantime, I will settle for a very modest version of a living wall. A local nursery carries “living wall planters” which can be hung indoor or under a roof outdoors. They are large pockets made of a thick felt. I am happy to know that the felt is 100% recycled plastics. The waterproof lining is Army tested. Still, I would think carefully about where to place them. The back porch may be a good place. This will be the perfect Christmas present for a plant lover friend of mine. My unsuspecting “victim” will receive a couple of native ferns along with it. I hope that she gets the message about the value of native plants.

All photos by Beatriz Moisset

Read more:
Drexel University’s Biowall
Press realease on Drexel University’s Biowall, September 2011
Biowall at Queens University, Canada

© 2011 – 2012, Beatriz Moisset. All rights reserved. This article is the property of Native Plants and Wildlife Gardens. We have received many requests to reprint our work. Our policy is that you are free to use a short excerpt which must give proper credit to the author, and must include a link back to the original post on our site. Please use the contact form above if you have any questions.

Related Posts Plugin for WordPress, Blogger...

Don’t Miss the Wren Song Community

Wren Winter Singing crop

Free Exclusive Content and Member's Forum

Sign up for a free membership in the Wren Song Community and you'll have access to a lot more valuable information published exclusively for our members.

Meet other passionate wildlife gardeners from around the country. Share your successes. Learn from your failures. Discover the best resources to help you create welcoming habitat for wildlife in your gardens with native plants so that you will attract more birds, butterflies, native pollinators, and other wildlife to your garden.

Learn more about the Wren Song Community


  1. says

    Beautiful. A fun part of indoor gardening is we don’t need to stick to natives; indoors, we can have domestic cats and tropical plants, guilt-free. In fact, for those of us who live in temperate zones, indoors we’re better off with tropicals as our temperate zones natives (squirrels aside) do better when left outdoors in the winter.

    A few years ago, I did some research on the health aspects of indoor houses. What I found was that their abilities as air scrubbers had been a bit overstated in studies that had been paid for by the florist industry — opening a window worked much better. Good to see that actual science is updating the research.

    What has been proven is that, in winter, the presence of a sufficient number of house plants is very helpful in raising the indoor humidity levels from central-heating induced Saharan levels (10-15%), to something like around 25-35%. The higher humidity does improve our ability to ward off colds and the like.

    I think that the indoor plants, particularly in winter, also benefit health because the presence of natural beauty lowers blood pressure, makes us feel more at home, etc.

    For a quick, easy natural wall, that won’t damage the architecture, stuff a floor-to-ceiling bookcase with pots of golden pathos, philodendron, spider plants, hoyas, and Boston ferns. These plants, particularly the old-fashioned species rather than the modern cultivars, are less fussy about light and humidity, longer-lived and lower-care than the plants in the Drexel wall; after all most tropicals prefer humidity in the 50% range.

    A good on-line source for tropicals, that has been with us since mail-order days, is

  2. says

    Very cool stuff! I’m certainly not inclined to quibble about non-natives indoors–they aren’t likely to escape and I can’t imagine there’s a lot of pollinators indoors going hungry. And the benefits of something like this biowall are very cool—can’t wait to hear the long-term results!
    UrsulaV recently posted..Fuzzy-Wuzzy

  3. says

    Thanks for the encouraging comments. I was a little hesitant about publishing this in “Native Plants and Wildlife Gardens”; but I feel that the subject of indoor pollution and battling it by organic means is relevant here, too.
    I plan to follow the research done by Drexel University and see what develops.
    Sue: Thanks for the added information. It seems that an important point in fighting indoor pollution is to keep a flow of air through the roots. It is the microorganisms in and on them that do most of the air purification.
    Beatriz Moisset recently posted..Black-and-yellow lichen moth, a little known pollinator

  4. says

    Nice…I note in a mildly “patriotic” way that we’ve been putting up indoor living walls in Ontario, Canada for some years now, using research done by the University of Guelph. That may help explain why the company that did Drexel’s wall and the architect that designed it are both from here.

    The program here started more than 10 years ago and has had a fair bit of research by two profs from Guelph, plus commercial startups.
    Maybe it’s because the further north you go, the more time you spend indoors in the winter!

  5. says

    Kelly: yes, they are Woolly Pockets; they come with all needed hardware and they are very attractive.
    Clement: you deserve to be proud. Canada is doing a great job with living walls. Drexel U. contracted NEDLAW Living Walls for good reasons. Good point about indoor nature and long winters. I remember how many house plants I used to have when I lived in Maine.
    Beatriz Moisset recently posted..Black-and-yellow lichen moth, a little known pollinator


Leave a Reply

Your email address will not be published. Required fields are marked *

CommentLuv badge