Vapor Permeable and Non Permeable Air Barrier Systems

We are starting to see more building owners interested in air and vapor barrier systems, both fluid applied and sheet applied. These systems are related to the entire building envelope, from foundation to walls to rooftops, and have been proven to increase energy efficiency and improve air quality.

Air barrier materials resist air leakage and are designed to form a continuous plane around a building to protect uncontrolled air movement in and out of the building envelope.  Air leakage loads are significantly greater than most designers and architects realize, and a study on air barriers by the National Institute of Science and Technology revealed that the right air barrier can help improve building performance by reducing heating and cooling costs by as much as 36%.*

Vapor barrier materials limit the amount of water vapor diffusing through the wall as a result of vapor drive. Vapor drive is a phenomenon that occurs when water vapor naturally diffuses into and through wall structures and is controlled by type of structure, porosity, moisture gradients and temperature gradients.

Remember science class and studying about thunderstorms? This is the same thing just on a molecular level. It incorporates the key principles of air movement: from warm to cold. In a cold climate, vapor drive is primarily from interior of a building to exterior. If you have a hot, humid climate, the vapor drive is primarily from exterior to interior.

Source: Buildingwell.org

There are countless scientific studies and published documents about water vapor, vapor drive and air movement. With the advent of modern building science, it has been found that air leakage - and not vapor diffusion - is the real problem. The air barrier systems we incorporate, however, are a combination of both which afford us the ultimate in design flexibility. **

To manage vapor diffusion there are two types of air barrier membranes: Vapor Permeable and Non-Permeable.

Vapor Permeable Air Barriers
High vapor permeance keeps air and water out, while allowing water vapor to escape.  Positioned anywhere within the wall assembly, they are watertight and protect against air leakage. 

Non-Permeable Air Barriers
These membranes act as air barriers, vapor barriers and rain barriers. When positioned on the warm side of the insulating layer, they serve as an efficient vapor barrier, preventing moisture condensation through the wall cavity. Good for hot humid climates or an extreme mixed-humid climate.

Non-Permeable Air Barrier
Source: Henry Products

The choice of product, between a vapor permeable versus a non-permeable air barrier, is dependent on a wide range of factors, like those mentioned above, and advancements in available materials make it important to work with a professional.

*NIST Report 7238

**The Difference Between a Vapor Barrier and an Air Barrier. Written by R.L. Quirouette, Building Practice Note No. 54, July 1985

Other Sources: 
Solving the Air Barrier Riddle: Permeable or Impermeable? Written by Sonya Santos and published in the Journal of Architectural Coatings, Jan-Feb 2007

Water Vapor Migration and Condensation Control in Buildings. Written by William Acker and published in HPAC June 1998

An Energy Conservation Idea for Building Owners

We have always been interested in energy conservation, which is one of the things that got us started with Spray Polyurethane Foam Roofing in the first place over 35 years ago. Though out the years we were naturally led to maximizing an owner's investment through quality products and installation for the entire building "envelope," which then started to include Polyurethane Foam Air Barrier and Fluid Applied Air Barrier services.

For building owners and our clients it all boils down to this: decreasing your energy consumption and increase profits while protecting the health of the occupants.

As there are many ways for to accomplish this, we found an article interesting in the Commercial Construction & Renovation July/August 2012 issue which talked about ways to reduce building HVAC costs with site-recovered energy by using Energy Recovery Wheel Technology, or Enthalpy Wheels.

According to the article, enthalpy wheels "transfer energy by rotating between outdoor air and exhaust air streams to transfer heat and moisture from one airstream to another." It retrieves the wasted energy in building exhaust air and recycles it and allows the building to increase outdoor air levels without making your HVAC unit work harder.

It also helps enable building owners to participate in energy programs. Energy recovery wheels are available from most HVAC OEMs and distributors.

Top 10 States for LEED-Certified Green Buildings

Back in January, The U.S. Green Building Council (USGBC) released its 2011 list of top 10 states for LEED-certified commercial and institutional green buildings per capita, based on the U.S. 2010 Census information.

The District of Columbia leads the nation, with more than 31 square feet of LEED-certified space per person in 2011, with Colorado being the leading state, with 2.74 square feet per person in 2011.

Other top states include Illinois, Virginia and Washington, with 2.69, 2.42 and 2.18 square feet of LEED-certified space per person, respectively.

The top LEED states per capita, including the District of Columbia, are Colorado, Illinois, Virginia, Washington, Maryland, Massachusetts, Texas, California, New York and Minnesota.

LEED is the internationally recognized mark of green building excellence, with more than 44,000 commercial projects participating, comprising over 8 billion square feet of construction space in all 50 states and 120 countries.

Most products used by Washington Roofing and Insulation are ENERGY STAR®, LEED, CRRC, Miami - Dade County approved and/or certified. 

Source: Press Release Jan. 19, 2012 by the U.S. Green Building Council

Energy Wise Giving

It happened. The year 2011 rolled into December. If you braved through the Black Friday weekend and Cyber madness then you may have already finished your Christmas shopping. For those of us who didn't, and who still have items on the "list" for Santa, we may want to take a moment to adjust our thinking which may help save our planet.

According to the Consumer Electronics Association's (CEA) 18th Annual CE Holiday Purchase Patterns Study report, this year's holiday spending will increase with over one-third of purchases spent on electronics. It is good for the economy to see the increase in spending, and electronics have always been high on the list.

The propensity in human nature is to take the easy road, and let's admit it, cell phones, laptops, wireless printers, copiers, GPS units, garage openers and toys which interact with our children seem to make our lives easier. Bottom line, electronics are used to improve your efficiency in everyday living.

However, old and broken electronics end up in landfills and landfill usage is a monumental environmental concern. Perhaps if all of us over the next month would stop a moment before purchasing a new electronic device and ask ourselves a couple of questions, we may help decrease our own carbon footprint:

Can this be recycled and where? If it is a brand new and improved gadget or prototype, can we wait until the bugs have been worked out?  (Do we hear a 'Bah Humbug?)

According to the cleanair.org waste facts website, "304 million electronics were disposed of from US Households in 2005 and two-thirds of them still worked."  The website also mentioned that if we all recycled cell phones for one year, we would save enough energy to power 18,500 homes for a year.

There are many places in Kansas City that assist with recycling and some communities even have "drives" which are set up throughout the year.  On recyclespot.org you can find a list of service providers near you.

Source: Green Building Elements website : Cleanair.org

New LEED Pilot Credits

Yesterday, the U.S. Green Building Council added nine additional Pilot Credits to their LEED Pilot Credit Library. These include:

• Pilot Credit 44: EQ - Ergonomics Strategy
• Pilot Credit 45: SS - Site Assessment
• Pilot Credit 46: EA - HVAC Commissioning
• Pilot Credit 47: EQ - Acoustic Comfort
• Pilot Credit 48: IP - Discovery - Analysis to Support Integrative Process
• Pilot Credit 49 : IP - Implementing Synergies
• Pilot Credit 52: MR - Environmentally Preferable Non-Structural Products and Materials - Prescriptive Attributes
• Pilot Credit 53: MR - Responsible Sourcing of Raw Material and
• Pilot Credit 54: MR - Avoidance of Chemicals of Concern in Building Materials. 

LEED is a rating system developed by the U.S. Green Building Council in March 2000 for buildings that are "designed, constructed and operated for improved environmental and human health performance."

From homes to commercial buildings, LEED credits can be obtained by following specific guidelines for new construction or renovation, schools, retail, core & shell, commercial interiors, operations & maintenance and neighborhood development. 

Complying with LEED standards is completely voluntary, but has been proven to benefit owners with cost-effective solutions that result from green building. To read case studies, profiles, research and resources on green building, visit the U.S. Green Building Council website.