You wouldn’t buy a new car unless you knew someone had tested its doors and windows for reliable operation and tight seals. But it’s common for owners to move tenants into a brand new building only to find problems with the walls, windows, and roof (the envelope). At Urban Green’s recent Salon, Designed, Sealed, and Delivered, Matt Copeland (Simpson Gumpertz & Heger) pointed out that envelopes comprise 10-20% of a building’s total cost, but are responsible for 70% of construction-related insurance claims. Water and air leakage are key problems, but so are condensation and sound. Wouldn’t it be better to catch these problems through envelope commissioning before the project is finished?
Envelope commissioning is similar to mechanical systems commissioning in that it ensures that a completed building operates as it was designed. But unlike mechanical equipment which is accessible for maintenance, important bits of the façade get enclosed and hidden during construction. Trying to discover the source of a leak after construction is complete may be costly and disruptive, if not impossible. In addition, fixing a faulty fan or chiller is a single job, but a systemic problem during façade construction may be replicated hundreds or thousands of times throughout the building.
Copeland said that this argues for involving envelope commissioning agents as early as possible in the project, including pre-construction laboratory mockups, field-constructed mockups, and onsite testing at milestone intervals. It’s advice worth considering, although unlike mechanical systems commissioning, which has a solid track record and will soon be required in the NYC building code, envelope commissioning will be new territory for many.
Copeland says that commissioning adds to 2-4% to the cost of the envelope, but project savings are potentially much larger. Risk reduction may provide another driver. Because the field is still young, he says there’s not a lot of data and metrics to clearly prove value to owners. On the other hand, envelope commissioning is included in LEED for the first time in v4, which may help spark the market.
To find leaks, envelope commissioning agents use everything from smoke pencils to theatrical smoke machines. Special rigs spray walls with water to test for seepage, and infrared cameras help find gaps in roofing that may lead to problems later. Even with these cool tools, Copeland said “commissioning breaks down if it’s used as a replacement for good design. Field testing to make sure the finished building meets the design won’t help if the design itself is inadequate.”
Justin Whiteford (Kohn Pederson Fox) is working on Related’s Hudson Yards project.
He says for all-glass buildings, the stakes on material choice are high. “There aren’t a lot of materials that make up 98% of the building façade, so people come out of the woodwork to advocate for their material.” Even small cost differences will be multiplied throughout the entire façade, so price competition is intense. In the end, the façade must perform under harsh conditions and for decades, so materials undergo extensive testing before selection. These are not off-the-shelf products, so commissioning of the façade is essential to make sure the building is designed, sealed, and delivered.