The U.S. Department of Energy (DOE) reports that buildings account for 39 percent of total energy use and 38 percent of total carbon-dioxide emissions in the United States. If the nation takes steps to increase the energy efficiency of buildings, it will reduce consumption of non-renewable fossil fuels, lessen dependence on foreign and non-renewable sources of energy, and lower greenhouse-gas emissions.
The DOE has mandated that by October 18, 2013, all states must adopt a commercial building energy code that meets or exceeds ASHRAE Standard 90.1-2010. One of the requirements in this standard is the expanded use of continuous insulation to eliminate energy loss from thermal bridging. The use of an external air barrier also will be required. Many states will adopt such measures for the first time as they update to the 2012 IECC code.
Meeting the required level of functional performance and maintaining aesthetic excitement can be achieved even though the energy codes are becoming more stringent. Such a balance of form and function is especially important in an educational environment; building designs must meet the day-to-day needs of the occupants and offer the diversity of aesthetics that transforms a campus into a community.
A variety of building materials are available that can be used to create a code-compliant building that meets the needs of architects, contractors and building owners or managers. In order to make an informed decision, education administrators should have a thorough understanding of the new design standards and the building materials available to achieve the standards.
The vertical, opaque surfaces of a building envelope play a significant role in energy efficiency. In most commercial construction in the United States, these exterior walls are constructed using stud framing (metal or wood) with batt-type insulation between the studs. In this configuration, the studs act as conductors of energy between the interior and exterior of the building. This is known as “thermal bridging,” and it substantially reduces the energy efficiency of the wall.
The effective insulation value of such cavity-insulated walls also is reduced by air leakage, which occurs at joints, gaps and penetrations. This undesired airflow into or out of a building affects energy efficiency, indoor air quality and operating costs. To worsen matters, cavity insulation may absorb and retain moisture, which can accelerate the deterioration of the studs, exterior sheathing and drywall. Thicker cavity insulation does little to improve the thermal efficiency of the wall, because it does not mitigate thermal bridging or air leakage.
Changing energy codes
Once stakeholders understand clearly what the code changes mean and how they will boost energy efficiency, the next step is to learn about the building materials that will help fulfill this need.
The most effective way to eliminate thermal bridging and air leakage issues associated with traditional stud framing and cavity insulation is with exterior continuous insulation (CI). CI eliminates thermal bridging as well as unintended air leakage, and by itself can translate into a 20 to 30 percent reduction in annual energy costs.
Exterior insulation and finish systems (EIFS), which incorporate CI and meet all current energy codes and proposed changes, have been available in the United States for decades. An EIFS places insulation outside a building, providing CI and increasing energy efficiency. Many of these systems also incorporate air-barrier and moisture-drainage components that, combined with the insulation, make the CI even more effective. In fact, EIFS may be one of the only claddings that is engineered to combine an air and weather barrier, CI and many aesthetic options into a single system.
An EIFS is installed by a trained contractor and warranted by a single manufacturer. Other claddings, such as brick masonry, are an assembly of many components that are supplied by different manufacturers and installed by numerous subcontractors. A single-source warranty streamlines not only the construction schedule, but also the maintenance process for the lifetime of the building.
Building performance and energy efficiency are important for most education facility owners, managers and leadership, but curb appeal also is a priority. Education facilities compete to attract students, and their employees all desire an attractive and comfortable environment in which to work. An EIFS provides many aesthetic options that can be achieved with new construction or renovation.
EIFS finishes traditionally resemble stucco or concrete textures, but modern technology has produced other finishes that can be customized to resemble brick masonry, granite and metal panels.
Change and opportunity
Just as course material and teaching methods have modernized with time, so, too, will energy code changes improve the way future school buildings are designed, constructed and maintained.
Thorough understanding of the new codes and the critical role of the building envelope, in terms of initial cost and in operating costs for the lifetime of the building, is essential to superior facility management.
Sidebar: Energy savings
Clay brick masonry is the foundation of modern Oklahoma City, and the look of brick and stone masonry continues to be popular. However, the demands of high construction costs, energy efficiency and life-cycle performance often lead education institutions to seek alternative building materials.
One building that exemplifies the benefits possible with exterior insualtion and finish systems (EIFS) is Metro Career Academy (MCA) in Oklahoma City. The original design called for 24,000 square feet of clay brick and 13,000 square feet of cast stone. After quick analysis, the school learned that EIFS would save nearly 50 percent in construction costs (materials and installation) vs. clay brick and stone.
The EIFS assembly enabled the architect to increase the insulation value of the wall, enhance the moisture protection of the building envelope and lower the cost of the exterior cladding, while retaining the desired look of masonry.
Other benefits of the lightweight cladding include less structural support required, a reduced construction schedule, LEED points, projected energy savings and fewer delivery trucks.
Measured against the modeled performance of an identical structure built with traditional cladding, the MCA building was predicted to have an energy savings of 34.8 percent and an energy cost reduction of 42.8 percent annually.
Based on this model, energy cost savings (in 2012 dollars) for the 50-year life cycle of the building are projected to be more than $1.7 million.
Dazel, AIA, LEED GA, is marketing manager, strategic accounts, for Dryvit, West Warwick, R.I., a manufacturer of EIFS.