Zero-Energy Schools: How Innovative Concrete Systems are Making It Possible
Low-Impact Development Strategies
Conserving water is another way to reduce environmental impact and construction cost. The following low-impact development strategies help meet zero-energy goals:
- Utilizing native plantings and rain gardens helps reduce irrigation demands.
- Using permeable pavements reduces stormwater runoff, filters stormwater, and reduces the need for expensive stormwater infrastructure.
- Permeable pavements and rain gardens can eliminate the need for detention basins, leaving more space for athletic fields and outdoor education opportunities for students.
Energize the Curriculum
Finally, make sure you engage the students and teachers by providing learning opportunities about energy efficiency and how the zero-energy building is helping reduce environmental impacts. Richardsville Elementary School used the following displays and interactive stations to help students visualize their contributions to reducing environmental impacts:
- Geothermal energy: Provide detail on how geothermal energy works, and expose piping with a temperature gauge so that students can monitor the system’s performance.
- Solar energy: Provide detail on how solar energy is captured and converted to electricity for use in the building. Provide a gauge to show how much energy is being produced. Provide a laptop computer battery-charging station where students can see the energy being received from the solar panels.
- Water conservation: Provide a station on water conservation that enables students to monitor the amount of rainwater collected and used in the rain garden.
Insulated Concrete Forms
Insulated concrete forms (ICFs) combine two well-established building products: reinforced concrete for strength and durability, and expanded polystyrene (EPS) insulation for energy efficiency. ICF walls are made up of two layers of rigid insulation held together with plastic ties to form ICF units with a cavity in the center. The ICF units are stacked in the shape of the wall, reinforcing steel is added into the cavity, and then concrete is placed into the form. The result is a reinforced concrete wall with a layer of insulation on each side. What makes ICFs different than traditional concrete construction is that the forms remain in place after the concrete is cured to provide thermal insulation. The combination of reinforced concrete and insulation provides an ideal load-bearing wall, thermal envelope, air barrier, fire barrier, and sound barrier.
Photo courtesy of Sheman Carter Barnhart Architects
Richardsville Elementary School used an ICF system.
Ease of Construction
The efficient construction process is what sets ICF building systems apart from other building systems, such as wood-frame, steel-frame, and masonry construction. ICF construction can help contain construction costs and reduce construction time because of the inherent efficiencies of the installed assembly that serves nine functions:
- Concrete form (that stays in place)
- Thermal barrier
- Air barrier
- Moisture barrier
- Fire barrier
- Sound barrier
- Substrate for running utilities
- Substrate for attaching finish materials
- Reinforced-concrete structure
Image courtesy of BuildBlock
Shown are ICF wall and floor components.
In other forms of construction, these functions are installed by several different trades, usually at significantly added cost. General contractors can realize a number of on-site efficiencies, including fewer trades, reduced crew size, and accelerated construction schedules. Because construction schedules are usually much shorter with ICF construction, the general contractor is able to finish on time and within budget. The building owner can then put the building into service sooner, cutting short financing costs.
There are many different ICF manufacturers with similar ICF systems. The blocks range in size from 48 to 96 inches long and 12 to 24 inches high depending on the manufacturer. The most common configuration of an ICF unit is made up of two layers of 23⁄8-inch to 23⁄4-inch-thick EPS insulation spaced 4, 6, 8, 10, or 12 inches apart depending on design requirements. The most common spacing is 6 inches or 8 inches for most low- to mid-rise buildings. But for taller buildings, taller walls, or exceptionally large loadings, thicker walls are necessary. For simplicity, ICFs are generally called out by the width of their cavity. Hence, an ICF with a 6-inch cavity is called a 6-inch ICF and so forth.
ICF manufacturers have a variety of ICF blocks to accommodate any design condition and offer outstanding technical support, including design manuals, design details, engineering support, and all of the test reports needed for school construction, including fire, energy, and noise. They also have special components, including straight blocks, corner blocks, brick ledges, angled blocks, curved blocks, and half-height units, minimizing the need for field modifications, which further reduces construction time.
Another benefit of ICFs is that construction projects can continue through the coldest and hottest weather because of the insulating quality of the ICF forms. This means that concrete will continue to gain strength within the protective formwork despite freezing conditions and not overheat during extreme summer conditions. In addition, all ICF systems have furring strips integrated into the plastic ties that permit easy attachment of any interior or exterior finish.
There are also ICF concrete floor and roof systems. The concept is similar in that the ICF floor or roof is made with rigid insulation to function as a one-sided form at the bottom surface. The forms are installed to span between concrete walls, reinforcing steel is installed, and then concrete is placed onto the forms. The result is a reinforced-concrete floor or roof with rigid insulation on the bottom. Other types of floor systems often used in combination with ICF walls include precast hollow-core plank and composite concrete floors over steel joists.
Beyond Zero-Energy Schools
Schools are not the only building type going zero energy, nor are they the only building type using ICF construction. There are examples of high-performance ICF buildings all over the United States and Canada, including single-family residential, multifamily residential, hotels, dormitories, assisted living facilities, offices, health-care facilities, and manufacturing and warehouse buildings. Theaters are also trending toward ICF construction for superior sound attenuation.
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