| NZB: ENVELOPE |
Staying on Top by Focusing Below One of the many roles of the envelope is to manage thermal temperature and direct heat/cold to the proper place. The roof, as an envelope subsystem, is an integral element of this whole, but beyond its weather barrier role, it must include the right kind of insulation to maximize performance.
Alan Weis, a contributing writer for Architectural Products, covers thermal management issues, including building envelope and HVAC systems.
roof does more than keep it from raining within. Among many other things, it is one of the most important areas of the envelope in terms of a building’s thermal management. There are different ways to maximize this role; employing continuous insulation (CI) has become a popular one. The practice of CI—only catching on in the past few years with wall systems—has been common in roof systems for quite a while, and a great deal of knowledge is there for the learning. According to MacGregor Pierce, Xci product and technical manager for Hunter Panels, interest in CI has been driven in part by code requirements, but also a growing understanding of the crucial role insulation plays in creating an energy-efficient and comfortable building. “Arguably, the most important and cost-effective thing you can do on the path to net zero energy is to install sufficient insulation,” he says.
science is quite clear that this placement is best for overall thermal performance and moisture control, although the AEC industry isn’t necessarily on board yet, as it’s a different method,” says Pierce.
On Extruded Polystyrene (EPS) Achieving an overall building goal of zero net energy use requires a comprehensive whole-structure process, agrees Dale Mullikin, regional sales manager with ACH Foam Technologies. “Insulation is a critical subset of an overall building envelope strategy and we welcome the chance to collaborate during pre-construction,” says Mullikin.
Not surprisingly, he is a fan of polyiso insulation “It performs very well in these situations, and complies with NFPA 285 fire requirements in many assemblies, so it does double-duty.” Regardless of the type of insulation used, Pierce notes it’s crucial to consider the performance of the envelope as a complete entity, taking into account thermal control and moisture and air management. Some insulation products can do all three things. “It’s key not to just look at the bulk of the walls or roof themselves, but also the openings,” says Pierce. “You can have the best insulated building in the world, but without energy-efficient windows, you’ll lose much of that benefit.” On the wall front, there’s been a movement toward outboard insulation—i.e., installing it on the outside face of the wall structure, rather than between studs or inside the structure. “Building
28 | 03.18 | NET ZERO BUILDINGS
Collaborating during pre-construction, achieving an overall building goal of zero net energy use requires a comprehensive whole-structure process.