04/03/2006

Insulation: Are All SPFs Created Equal?

There are three types of SPF commonly used within the construction industry

 

Medium-density polyurethane foams are formulated to have a closed-cell content of greater than 90 percent, combined with an effective R-value of over 6.0 per inch and excellent air-leakage rates.

Air Barriers Go Legit
The U.S. Department of Energy (DOE), Washington, D.C., reports that 40 percent of the energy costs of heating and cooling a building are wasted by uncontrolled air leakage, which also contributes to premature building deterioration, condensation, poor indoor air quality, mold growth, etc.

A report from the National Institute of Standards and Technology (NIST), Gaithersburg, MD, confirms that air barrier systems can reduce air leakage by up to 83 percent and energy consumption by up to 40 percent.* Now, for the first time, continuous air barrier systems will be required by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), Atlanta, under Addendum z to Standard 90.1-2004, Energy Standard for Buildings Except Low-Rise Residential Buildings.

Massachusetts, Michigan, and Wisconsin mandate air barrier systems for all new construction as part of their Commercial Energy Codes. Learn more at (www.airbarrier.org).

 

*Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC Use, Emmerich, McDowell, and Anis, 2005, National Institute of Standards and Technology

 

You probably don’t spend a lot of time thinking about chemistry when you consider adding insulation to improve energy efficiency. Yet one popular insulation material - spray-applied polyurethane foam (SPF) - relies entirely on chemical cleverness.

Not all foams are created equal. Spray-applied polyurethane foam is a two-component product that is manufactured on-site but engineered at the molecular level to optimize performance for a specific application. By varying key components, the finished product can be modified to meet specific performance requirements for roofing applications, insulating air barrier systems, adhesive applications, or wall insulation.

Currently, three types of SPF are commonly used within the construction industry:

  • Medium-density (MD) 24 kg/m3 to 48 kg/m3 (1.5 pcf to 3 pcf).
  • Low-density (LD) 8 kg/m3 to 12 kg/m3 (0.5 to 0.7 pcf).
  • Sealant foams.

The most important distinction is whether the formulation produces an open-cell or closed-cell foam. MD foams are formulated to have a closed-cell content of greater than 90 percent combined with an effective R-value of over 6.0 per inch. LD open-cell foams have approximately 60-percent open-cell content and offer an R-value between 3.0 and 3.6 per inch. But, R-values are only the beginning when it comes to energy efficiency. It is the air-permeability capabilities that are the true differentiator.

Yes, you need insulation; but, in order to make a building truly energy efficient, you need an effective, continuous air barrier system. Without it, conditioned air escapes through the building envelope and the HVAC system has to work harder to keep the indoor environment comfortable (see Air Barriers Go Legit, right).

Most open-cell foams have not been tested and, therefore, do not qualify as air barrier systems in “typical thickness” of less than 4 inches. One open-cell foam manufacturer’s product requires an application of 5.5 inches (its maximum allowable thickness) to pass the minimum requirements of ASTM Intl. E 2178, Standard Test Method for Air Permeance of Building Materials (air-leakage rate of 0.005 L/s/m2 at 75 Pa). Compare this with closed-cell foams, some of which provide air-leakage rates of <0.001 L/s/m2 at 75 Pa at 1.5-inch thickness.

Because the systems are spray-applied, fully adhered, and seamless, they also eliminate connective loops behind the insulation and, therefore, eliminate moisture. Since mold requires three things to grow - moisture, warm temperatures, and a food source - and closed-cell foams do not provide any of these things, MD closed-cell SPF can help prevent dangerous mold infestations.

Open-cell foams offer a slight cost advantage when compared on an equal-thickness basis and, in general, provide greater sound control. On the other hand, closed-cell formulations can actually improve building durability and structural strength. Both closed-cell SPF systems and open-cell foams provide environmental responsibility, have no adverse effect on the ozone layer, and do not emit volatile organic compounds.

Tom Harris is the product manager for Minnea­polis-based BASF Polyurethane Foam Enterprises LLC (www.basf.com/urethanechemicals/spray).

 


Visit our website today to learn about the design flexibility of a Morton building and the endless possibilities of partnering with our designBUILD team.


Wood construction is both cost and energy efficient. Check out Morton Buildings and our designBUILD team online today to discover all the benefits of post-frame construction.


When choosing a metal-clad building for your next construction project, consider Morton Buildings, Inc., and their designBUILD team, we’ll make your dream a reality.

We Can Help You Reduce Energy by 30%

Our mission is to help our customers manage their buildings' energy costs, improve reliability, and enhance performance while having a positive impact on the environment.
CLICK HERE to find out how.

Add highly responsive multi-zone comfort to any building project, in any climate. Our CITY MULTI H2i R2- and Y-Series VRF systems give you flexibility to fit the needs of any building. Enjoy 100% heating capacity at 0°F outdoor ambient, and 85% heating capacity at -13°F outdoor ambient.  For more information, log on to www.mitsubishipro.com


Visit our website today to learn about the design flexibility of a Morton building and the endless possibilities of partnering with our designBUILD team.


Wood construction is both cost and energy efficient. Check out Morton Buildings and our designBUILD team online today to discover all the benefits of post-frame construction.


When choosing a metal-clad building for your next construction project, consider Morton Buildings, Inc., and their designBUILD team, we’ll make your dream a reality.

We Can Help You Reduce Energy by 30%

Our mission is to help our customers manage their buildings' energy costs, improve reliability, and enhance performance while having a positive impact on the environment.
CLICK HERE to find out how.

Add highly responsive multi-zone comfort to any building project, in any climate. Our CITY MULTI H2i R2- and Y-Series VRF systems give you flexibility to fit the needs of any building. Enjoy 100% heating capacity at 0°F outdoor ambient, and 85% heating capacity at -13°F outdoor ambient.  For more information, log on to www.mitsubishipro.com

 
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