Evaluating Options for Insulation Retrofitting

March 21, 2017

Proper insulation practices will afford you more control over your facility's thermal performance.

Alphagraphics, a printing company in Nashua, NH, works out of a three-story, 29,000-square-foot building that underwent a thermal upgrade consisting of HVAC upgrades, air sealing and an insulation retrofit through New Hampshire’s Better Buildings Program, funded by the DOE’s Better Buildings Neighborhood Program.

Using spray foam in the building’s attic among these other thermal improvements, the roughly $30,000 retrofit project (pre-rebate) now saves the building 15.6% in annual energy usage and provides an estimated electricity savings of nearly 30,000 kWh each year.

Improving your building’s insulation can help your building cut back on energy costs considerably, as it has at Alphagraphics. What do you need to know when considering an insulation retrofit for your facility?

When to Retrofit Insulation

The obvious benefit to installing new insulation in a building is that it improves thermal performance in a building. Insulation that has a high R-value, allows minimal air filtration, does not settle and is UV stable will typically provide peak performance, according to the North American Insulation Manufacturers Association’s Insulation Institute. Installing insulation in your building with these attributes will cut back energy expenditure and reduce your building’s carbon footprint.

Other added benefits include the potential for better acoustics, occupant comfort and fire protection. The right insulation can reduce noise pollution in buildings and ultimately increase worker productivity. Furthermore, it can prevent moisture from disrupting consistent indoor temperatures and prevent facilities from extensive fire damage.

The main reason you might consider an insulation retrofit is because either you have no existing insulation or what you do have is inadequate. If insulation is old, does not work optimally or poses some kind of health issue, an insulation retrofit makes sense. Moreover, if you have changed your HVAC system in any way, it must be compatible with the insulation. This is why many HVAC upgrades also come with an insulation retrofit to optimize its thermal performance.

However, not every building will need an insulation retrofit to address thermal energy issues. The National Renewable Energy Laboratory explains, “The insulation of the envelope is much more important in heating-dominated climates – it may not be cost-effective to add insulation to cooling-dominated buildings.”

In environments like these where thermal control is the main concern, other strategies like preventing solar heat gain via radiation in windows with films or coatings might be a more effective approach based on your goals.

Exterior Insulation

To insulate your building, you can approach it from the exterior or the interior. One of the main benefits of tackling an insulation retrofit on the exterior of buildings is that it provides continuous insulation around the envelope of the building.

“To create continuous insulation spanning the enclosure, installation on the outside of the wall assembly is the most effective,” explains NREL. “Interior options are viable, although they provide slightly lower energy savings.”


Exterior insulation prevents thermal bridging, which can threaten the efficiency of your insulation. It occurs when conductive components of a building's structure – like wall studs, for example – allow heat to transfer into the building easily. If thermal bridging is untreated, R-value does not as effectively illustrate thermal performance because the heat simply finds its way in through poorly insulating materials.

If you want to perform your retrofit on the exterior, you can also give your building a different look with insulated facade systems or structural insulated panels (SIPs).

“For buildings that need a facelift, consider some of the new high-performance insulated facade systems as an alternative to the overused and occasionally problematic synthetic stucco exterior insulation and finish system (EIFS) products,” says NREL.

Interior Insulation

However, if you prefer to provide interior insulation, preventing thermal bridges is not a lost cause. You simply need to be proactive about it.

“In some buildings, thermal bridging may be more important to address than insulation,” claims Pacific Northwest National Laboratory. “Such bridges can be corrected by adding a thermal break, though this often entails replacing entire door or window assemblies.”

Insulation installed in interior walls, floors or ceilings will provide clearer benefits to acoustics in the building in addition to providing thermal stability. Insulation with a higher Sound Transmission Class (STC) rating will improve sound dampening.

You ultimately have more options when insulating the interior of your building than the outside, so do plenty of research about insulation types and attributes that will work best for your building. Utilize resources like the DOE's Buildings Performance Database (available at www.commercialbuildings.energy.gov) to forecast energy usage based on similar projects.

Finally, and perhaps most importantly, make sure your insulation is properly installed. Retrofitting can be quite the investment, and if the building lacks a proper air barrier or if moisture can enter, it will not work properly or last long.

Justin Feit [email protected] is assistant editor of BUILDINGS.

5 Types of Insulation

Batts, Blankets and Rolls
Batts made from fiberglass, rock and slag wool are easily customizable for a retrofit, providing a variety of R-values, thicknesses and sizes, according to the North American Insulation Manufacturers Association’s Insulation Institute. Blankets can be cut to fit into the wall cavity. They are relatively inexpensive and fire-resistant but can cause gaps in coverage if you are not careful.

Loose Fill
Loose-fill insulation is made up of small particles of fiber, foam or other materials that can conform to spaces without disrupting any structures. The DOE says, “This ability to conform makes loose-fill insulation well suited for retrofits and locations where it would be difficult to install other types of insulation.”

Structural Insulated Panels (SIPs)
SIPs are comprised of an insulating foam core located between two structural facings that are typically oriented strand board (OSB), according to the Structural Insulated Panel Association. Manufacturers usually fabricate them to fit a specific building’s design.

Liquid Foam
Liquid foam insulation expands to fill cavities in the interior of buildings, and the application varies depending on the type. “Some installations can have twice the R-value per inch of traditional batt insulation and can fill even the smallest cavities, creating an effective air barrier,” explains the DOE.

Foam Board or Rigid Foam
Foam boards, which are rigid panels of insulation, provide a versatile solution because they are lightweight and are easy to cut to form. “They provide good thermal resistance and reduce heat conduction through structural elements like wood and steel studs,” notes the DOE.

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