Modular Building Institute


The Emerging Role
of Portable Classrooms in Sustainable Design

By: Tom Hardiman, Executive Director


Modular Building Institute (MBI)


Preparing for the future:
The modular building industry works to meet demand for sustainable design


This past April, I had the honor of providing an address at the High Performance School Symposium in Washington, DC.  This ground-breaking event gathered leaders committed to environmental efficacy and energy efficiency in our schools into one room.  Architects were present, along with representatives of energy resource teams from Montgomery County (MD) schools, students, government leaders, and—yes—even the manufacturers and dealers of portable classrooms. It occurred to me that this was a watershed event, not only for the modular building industry, but for the worlds of architecture and education as well.

As the executive director of the Modular Building Institute (MBI) in Charlottesville, Virginia, I have worked with all of the leading dealers and manufacturers of portable classrooms. A decade ago, our industry’s attendance at a green building forum would have been revolutionary. These days, it is just necessary.  In the past few years, the commercial modular construction industry has started crossing paths with architects in greater frequency. MBI even offers AIA continuing education programs.  MBI has also reached out on behalf of the industry to join forces with the likes of the Collaborative for High Performance Schools (CHPS) and the U.S. Green Building Council (USGBC) to provide our manufacturer and dealer members with the latest information on green and energy efficient practices.  These affiliations are starting to yield tangible results as companies adopt cost effective ways to implement energy-saving designs. 

For the first time ever, several MBI members submitted entries to a Portable Classroom Design Challenge for high performance and sustainable classroom designs.  The fact that four MBI members received awards and honorable mentions at this contest—sponsored by Montgomery County MD schools, the Council for Educational Facility Planners, and the Emerging Green Builders of the US Green Building Council—underscores a recognizable trend in the modular construction industry. The worlds of green design and modular construction are merging at an accelerated pace. Over-population in our school districts, along with growing architectural recognition of modular’s merits for sustainable learning environments, has prompted portable classroom manufacturers to invest in energy-efficient designs. And, in fact, one sustainable design is slated to be to market this year!

But what does this say about the sustainability of the 300,000 portable classrooms that are already in use in school districts across the United States?  As a quick build-to-site deliverable, portables make a great deal of sense as an immediate space solution.  In the face of population spikes, overcrowding, or funding drives (toward permanent construction), portables become a short-term, but quick space fix. 

And the popularity of portable classrooms is not just about the speed. Other cited benefits include:

Most importantly, portables are built to local codes, just like their stick-built counterparts. It is no wonder, then, that school boards across the nation have made a substantial investment in temporary space solutions. And, they will continue to do so at an accelerated pace as school populations continue to spike.

There is a great deal to be excited about when it comes to portable classrooms, and their fit into a sustainable future. Did you know that portable classrooms built today are much more energy efficient than ones built just a generation ago? The Northwest Portable Classroom Project conducted by Washington State University in 2003 found that portables built to the 1993 code were 44% more energy efficient than models built 25 years prior.  Further, portables built to 2000 codes are 20% more energy efficient than the 1993 models.

And more and more school districts that are committed to temporary spaces are requesting portable classrooms designed to higher energy efficient standards.  As a result, manufacturers and dealers of portable classrooms are taking notice and designing additional energy efficient features into the buildings.  More energy efficient HVAC systems, windows, and doors are becoming standard for many districts across the country.  Our industry’s winning performance in the portables classroom challenge is just one indicator of the in-roads we are making to meet the demand.

Sustaining the present:
Making the most of your temporary space investment with proper operation and maintenance



Despite the recent advances in portable designs to accommodate energy-efficiency, concerns focus on the environmental atmosphere and energy efficiency of the portables that are already in use. It is important to realize that both conditions are dramatically affected at the local level.  Portables, like any other facility, require the proper operation and maintenance to sustain a healthy learning environment, and improve energy efficiency.


A 2004 study of environmental conditions in public classrooms by the California Air Resource Board and the California Department of Health Services found that both portable and traditional classrooms were found to have some environmental conditions that need improvement.  However, the most serious problems occurred only in a small percentage of classrooms. The study concluded that “Design capacity did not appear to be a common problem in this study.  Improved operation and maintenance would go a long way to address many of the problems identified.” 


Below are several actionable items that will improve the performance of today’s portables. Although these measures add to the up-front cost of the portable, those extra dollars will quickly provide results in the form of energy savings, increased student and teacher morale, and improved student performance. 

Protect Indoor Air Quality

First, specify no- and low-emitting building materials and furnishings to reduce airborne contaminants.  CHPS has developed a list of low emitting materials for schools which can be found at  Second, install proper drainage systems and control measures to prevent mold. Some areas to consider are landscaping systems that prohibit water from hitting the actual structure and draining off. Also important is providing the proper grading and drainage systems along with mitigation procedures for water leaks.  The US Environmental Protection Agency provides an Indoor Air Quality Tools for Schools Action Kit that details more indoor air quality maintenance and control procedures. You can order the kit from the Agency at

Support Gains in Energy Efficiency

First, install programmable thermostats in all existing portables and require programmable thermostats for any new portables. Second, choose site placement of portables to maximize the benefits of day lighting.  This measure will not only improve the energy efficiency of the portable, but could lead to improved student performance.  Finally, for any portables that utilize a “wall-mount” HVAC system, specify a Seasonal Energy Efficiency Ratio (SEER) of 12 vs. 10.  The higher the ratio, the more efficient your unit is and the lower your energy bills.

Improve Room Acoustics

It is important to note that acoustics are problematic in traditional classrooms as well as portables. MBI has several suggestions on how to provide the best acoustics (measures equally positive for traditional classrooms):

  • assure seating away from highways and busy roads where possible

  • reduce outside noise levels during instruction periods when possible

  • use wireless microphone systems for cost-effective resonance

Although some teachers turn off the HVAC unit in an attempt to reduce noise, we advise against this practice.  Studies have shown that student comfort and indoor air quality contribute more to a positive learning environment than acoustics.  When you turn off the HVAC system, you are actually diminishing the learning environment.

Activate Proper Maintenance and Timely Replacement

There are two points that go father than any of those already mentioned to ensure a positive learning environment in portable classrooms. Retire older portables when they become unserviceable or do not provide an adequate learning environment and properly maintain the portables currently in use.  Today’s portable classrooms are designed to last up to 30 years.  But the length of this timeline is completely dependent on the proper maintenance of the portable in every year of its life.  It goes without saying that portables should never be used beyond the recommended life of the unit.

The future for sustainable, modular space design is bright

The popularity of portable classrooms is undeniable. The fact that 300,000 are in use today attest to the fact that as a temporary space solution, they are here to stay.  With our industry’s proven, temporary space solutions solidly rooted throughout our nation’s schools, our convergence with the sustainable design movement is not at all surprising. The modular building industry is poised to work together to continue meeting the challenges of overpopulation in our schools, through creating high performance learning environments supported by more sustainable classroom designs.


Tom Hardiman is the Executive Director of the Modular Building Institute based in Charlottesville, VA.  The Modular Building Institute (MBI) is an international non-profit trade association representing nearly 850 companies in 14 countries engaged in the manufacturing and distribution of commercial modular buildings.  For more information, visit  MBI manages the industry’s only labeling program dedicated to increasing public awareness of factory-built buildings. To learn how to find a provider that participates in MBI’s seals program, contact Tom Hardiman at


Environmental Health Conditions if California’s Portable Classrooms – A joint report submitted by California Air Resource Board and the California Department of Health Services - Nov 2004.  Full report can be viewed at

(Northwest Portable Classroom Project, Executive Summary – Washington State University Extension Energy Program – March 2003.)

Modular Building Institute, 2005 State of the Industry Report.  You can obtain a copy of the report at

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