Exterior Enclosure Commissioning
An upfront investment in EECx commission is likely to return healthy long-term returns.
I realize that Engineered Systems readers are primarily interested in commissioning systems inside buildings; however, the United States Green Building Council (USGBC) has indefinitely tied commissioning of the buildings’ exterior enclosure to commissioning of the inside systems through its Leadership in Energy and Environmental Design (LEED) v4 for Building Design and Construction rating system.
Prior versions of LEED focused on commissioning the dynamic energy-consuming building systems for confirmation of successful implementation of LEED’s sustainability objectives for each project. LEED v4 recognizes that the performance of the building itself, e.g., walls, windows, roof, doors, is also critically important to achieving those objectives. In fact, failure of exterior enclosure systems can be more insidious and costly to correct after the fact than faulty HVAC or lighting control systems.
Without delving into the ambiguities of the LEED v4 exterior envelope commissioning (EECx) prerequisites and credits, I’m dedicating this month’s column to a high level declaration of support for EECx.
Let’s start by looking at the risk of not commissioning the building envelope systems. Similar to HVAC system commissioning, one of the driving factors behind EECx is the fact that, historically, many new buildings have been constructed with defective walls, windows, and/or roof assemblies. These projects have been problematic for building owners, designers, product manufacturers, and installation contractors and have bubbled up as an industry-wide problem that needs to be resolved.
How do defective exterior envelope systems manifest themselves? In a majority of situations the answer is water, which may be leaking through the envelope from rain and/or snow and/or condensing on interior surfaces during cold weather. Water may also be carried into the building as moist air passes through non-airtight assemblies. In the “lucky” cases, these water issues are obvious soon after occupancy, when the original project team can be engaged relatively easily to deal with the situation. In the “unlucky” cases, water remains invisible for years before structural damage, mold, and/or other symptoms of long-term water damage become evident.
Regardless of when water problems rear their ugly heads, the cost to correct them is almost always monstrously significant. There could be a small defect in a window product or installation that might be manageable to correct, but most buildings have many windows, and large buildings have hundreds of windows. The scale of even an easy fix is daunting when multiplied by the number of locations requiring the fix.
That monetary cost becomes untenable when the fix is complicated and requires new products, destructive access to the interior of the envelope, and/or total reconstruction. The cost of remediation is only part of the price associated with poorly performing exteriors. Owners may also need to deal with the following other potential “costs” throughout the life of the building.
- Disruption to business or other activities in the building;
- Facilities operations and maintenance staff time;
- Indoor air quality concerns;
- Cost of expert consultants; and
- Cost of attorneys.
From the vantage point of the MEP commissioning professional, I have peripherally observed that most owners choose to live with their exterior envelope problems — and apply Band-Aids to address symptoms — for as long as possible (indefinitely) instead of proactively attacking the root cause(s).
Building owners would not need to make those hard choices if they’d invested in EECx during the original design and construction project; however, the vast majority of new building and major renovation construction projects do not engage third-party EECx professionals. Why is that?
- Lack of awareness about EECx; and
- Cost of meaningful EECx services.
Once a building owner gets past No. 1 through word-of-mouth or education, he is often stopped in his tracks by No. 2. EECx costs are the same order of magnitude as MEP commissioning costs, and very few have EECx as a project budget line item during the planning process (yet).
MEP commissioning may be an easier sell because building owners have had more problems with new MEP systems than new exterior envelope systems. However, when there are problems, the cost of correcting building envelope systems is typically much higher than correcting MEP system deficiencies. I recommend building owners very carefully weigh the cost of design- and construction-phase EECx commissioning against the potential cost of not commissioning the buildings’ envelope systems.
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