This article by Amaris Beza was originally published in the March/April 2022 issue of Building Operating Management.
Key Takeaways
- Building enclosure systems play a variety of roles in building performance
- Insulation at enclosure intersections are critical to achieving thermal performance
- Quality and long-term durability in product selection is vital
Overview
Amaris Beza, an associate in Walter P Moore’s Diagnostics Group, examines why it is important to pay close attention to how building enclosure systems intersect. Mistakes at transitions can result in energy inefficiency and premature failure of individual elements.
A properly designed and maintained exterior building enclosure system plays a vital role in protecting building occupants from the elements, but also in lowering the energy demands for the overall building. Air, water, vapor, and thermal control layers all work together to keep interior spaces dry and conditioned.
While each of these individual layers contribute in their own way to the overall performance and energy efficiency of a building, how these layers intersect and interact are just as important. Frequently, the source of air or water leakage into a building occurs at one of the transitions between these varying enclosure control layers. Air leakage can cause a heavier load on the heating, ventilation, and air conditioning systems, increasing the energy demand of the building, and potentially causing condensation on interior surfaces. Water leakage can cause damage to interior finishes, accelerate deterioration of structural components, and introduce the potential for occupant health effects caused by microbial growth. Repairing damage caused by water leakage has financial, time, and energy impacts.
It is critical to examine how the design and construction of the building enclosure control layers contribute to the overall energy efficiency of the building.
Product selection
When it comes to product selection for building enclosure-related systems, there is no shortage of options. Starting from the top of a structure, most commercial buildings have low-slope roof systems, which typically consist of either single-ply membranes, modified bitumen, built-up roofs, metal roof panels, or fluid-applied roofing membranes.
Roofing systems then tie into vertical wall components that may consist of exterior opaque wall assemblies and/or fenestration. Opaque wall systems mainly consist of masonry brick veneer, architectural precast concrete, metal wall panels, stone cladding, stucco, exterior insulation finish systems, and/or other claddings. Fenestration systems are typically comprised of storefronts, curtainwalls, window walls, skylights, louvers, and/or other window types. Below-grade walls are typically comprised of solid concrete or concrete-masonry units with either self-adhered sheet waterproofing membranes, bentonite sheet panels, crystalline admixtures, or fluid-applied waterproofing membranes. Finally, floor slabs typically consist of a concrete slab over a vapor barrier at the foundation.
Insulation at these areas is also important for achieving required thermal performance, and may include batt insulation, rigid board insulation, spray-applied insulation, and/or other types of insulation.
With so many options, it can be a daunting task to make any selection. Apart from aesthetics, it is recommended that facility managers also consider and communicate what level of performance they are hoping to achieve when it comes to thermal and energy efficiency. This gives building designers the ability to present viable options that can meet the owner’s expectations.
Each type of material has its own set of advantages and disadvantages and is suitable for different applications. It is important to understand the benefits and risks of any material before making a selection. For example, materials with a higher solar reflectance index, such as cool roofs or solar reflective glass, are a wise choice for energy savings as they reflect more sunlight and absorb less solar energy. Increasing insulation thickness or selecting insulation materials with higher R-values helps to reduce the thermal load on a building. Product selection and the specified performance requirements should always reflect the owner’s goals and, at a minimum, meet building code requirements.
The selection of quality roofing, fenestration, insulation, and air barrier materials in particular can greatly affect the performance of the building.
Whichever material type suits each building’s needs, it is recommended to choose trusted manufacturers and products with a long history of successful applications. The quality and long-term durability of a product is vital. Often, the higher initial costs of high-end products end up saving building owners money and headaches in the long run due to better performance. Just as important as a quality product is having access to knowledgeable and helpful manufacturer representatives that are available to the designer, contractor, and owner for any concerns along the way.
Single-source manufacturing—selecting the same manufacturer for multiple products on a project—also goes a long way in helping construction, detailing, and warranty requirements run smoothly, which all work to create a more durable, weathertight building and benefit energy efficiency in the long run.
