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08/24/2012

Evaluate Your Envelope for Efficiency

Defects, failures, or unsatisfactory appearance may require recladding or renovation

By Christopher Curtland
 

Defects, failures, or unsatisfactory appearance may require recladding or renovation.

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Air and moisture infiltration are major causes of energy loss in commercial buildings. Thermography can detect envelope leakage, which may require recladding or renovation.
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When considering your building’s skin, look for defects. Is there indication of structural failure or evidence of air and moisture infiltration? Is the appearance aging or unsatisfactory, presenting an opportunity to rebrand your facility?

If so, your review may reveal a need for recladding or renovation. These projects are not inexpensive, but an ideal payback will be generated by the opportunities to improve energy performance and attract higher paying tenants to a more modern, sustainable facility. Let these factors guide you to the right solution.

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Where To Begin
The most common problems are outdated systems, material failures, and energy loss through leakage.

“Ultimately, the real low-hanging fruit – the grapefruit lying on the ground – is air infiltration. That’s the easiest issue to deal with,” explains Rob Kistler, principal at the Facade Group. “Nearly 40% of your building’s energy loss is air infiltration. For every cubic foot of air that leaks through, you have to provide almost twice that through your HVAC system, and at a much lower or higher temperature, to temper it.”

Occupant discomfort can be telling, but enlist an energy consultant for air infiltration testing and infrared thermal imaging to accurately detect defects, Kistler recommends.

Insulation problems are best identified when there is a temperature difference of at least 18 degrees F. from inside to outside. Air leakage patterns can be enhanced, directed, and quantified by artificially inducing a pressure difference on the building, which can be done with an HVAC system or blower-door fan.

Moisture is also identified with thermography, but it is recommended to perform supplemental testing with a moisture meter to confirm findings.

Results may indicate the need for recladding or renovation.

Exterior Structural and Material Failure
Sometimes recladding is simply a matter of need.

A 37-story office building in Indianapolis features an exterior of glass, aluminum, and marble. During a wind storm, about 10% of the curtainwall blew off the building.

William Bast, principal at engineering firm Thornton Tomasetti, believed the anchoring system was defective and didn’t have the strength to hold the system.

“We considered only reinforcing or replacing the anchors and repairing the wall where it blew off. However, the owner elected to do an entire recladding project,” Bast says.

Recladding was a favorable option because it prevented disturbance inside the building and addressed the owner’s goal of improving energy efficiency.

“He wanted something more modern too,” Bast explains. “An aesthetic facelift.”

Improved energy efficiency, enhanced appearance, and heightened worker productivity due to comfort and lack of disturbance helped the owner rationalize a lengthy payback period on the nearly $40 million project.

Skin Impact on Other Systems
If the opportunity presents itself for recladding, you have a significant opportunity to vastly improve energy and weather performance.

“It will cost you more to reclad in the future versus right now, which pushes payback out even further,” Kistler explains. “If you do it now, it puts you ahead of the curve. Tenants will choose one building over another due to energy efficiency.”

Even if other building systems are efficient, you have to be mindful of your envelope’s performance, Kistler warns.

“It doesn’t matter how efficient different systems within the building are if you have loss through the skin,” he explains. “An efficient skin maximizes the potential of other systems.”

Payback
If you factor in credits, grants, and financing along with energy performance, paybacks are attractive.

“You can’t do energy analysis of a building piecemeal. You need to look at the whole building,” Kistler says. “If you take a holistic perspective, the skin starts to pay for itself.”

In the end, consider your building as an investment to protect.

“It’s not about money; it’s about leaving a long-lasting, viable building for the users. It’s not about changing the skin; it’s about the entire building,” Kistler explains. “You’ve got to look at the building as an entity – a living, breathing thing. You don’t heal a heart attack by putting a bandage on your finger. The whole body affects the health of the organism, and you need to think of a building the same way.”

 

Chris Curtland (christopher.curtland@buildings.com) is assistant editor of BUILDINGS.