Energy conservation is a key tenet of sustainability and a major benefit of using precast concrete components. Precast concrete’s inherent capabilities to provide energy efficiency rely on the high thermal mass of the material, which benefits exterior wall applications. Precast concrete’s high thermal mass can delay or reduce peak loads, reduce total loads in many climates and work well regardless of the placement of mass.
Precast’s high thermal mass can help shift the peak hour of electric demand for air conditioning to a later hour and help reduce time-of-use charges. Nighttime ventilation can be used to cool thermal mass that has been warmed during the day. Local outdoor humidity levels influence the effectiveness of nighttime ventilation strategies. These strategies can help to reduce the overall load in many climates.
Its high mass provides benefits to the inside surfaces as well by absorbing heat generated by people and equipment. Interior mass from interior walls, floors and ceilings will help moderate room temperatures and reduce peak energy use.
Light-colored precast concrete will reduce energy costs associated with indoor and outdoor lighting. The more reflective surfaces will reduce the amount of fixtures and lighting required.
Insulated sandwich wall panels, which typically include 2 or more inches of high-performance insulation between two wythes of concrete, provide even more energy efficiency. The walls’ fabrication process ensures the insulation cannot shift during or after construction, which can leave gaps in the protection. Precast’s high thermal mass also minimizes energy consumption naturally, offering a concrete advantage that drops right to the bottom line. This is especially significant for large spaces, such as gyms and pools.
Because precast panels eliminate worries about moisture penetration, office, school, and other building managers can reduce HVAC usage when the building is unoccupied for long periods without risking mold growth or creating bad indoor air quality.
To maximize the effectiveness of the insulation used with precast concrete panels, thermal bridges (disruptions of insulation between two layers of concrete) should be minimized or avoided. Fiberglass composite fasteners or thermal breaks offer the best approach, as they will minimize thermal bridges. Concrete thermal bridges may occur at the bottom and the top of concrete panels. Metal thermal bridges may occur as fasteners that penetrate insulation to connect concrete layers.