High Performance Curtain Wall Using Vacuum Insulated Panel (VIP) Spandrels

Commercial buildings with curtain wall facades have large expanses of vision glass and desirable aesthetics. A curtain wall system can be designed for energy efficiency and does not need to have an overall poor thermal performance. This paper studies the thermal performance of a commercial building that utilizes areas of 40% glass, and 60% spandrel with 4 different glass types, 2 insulating glass units (IGU) and 2 vacuum insulated glass units (VIG & HVIG). The glass types are paired with 2 different spandrel insulation types, mineral wool and vacuum insulated panel (VIP). Thermal modeling of the types is performed using THERM 5.2 and WINDOW 5.2 from Lawrence Berkeley National Laboratory (LBNL). Structural silicone attachment was used for the glazing and spandrel types since it is a continuous - structural attachment, thermal break, and air and water seal. The commercial building model has mullion and framing dimensions and materials that are identical for each type so that accurate comparisons can be made.

The eight combined types are evaluated and ranked based on thermal performance. The best performers, using a model building, are simulated for energy consumption and compared to the poorest performers. The selected combined types are modeled in different locations to obtain comparisons of building energy use for various climates. Basic energy modeling is performed with EFEN 1.3.10, an interface to Energy Plus 5.

The paper concludes that high performance glass, IGU's or VIG's, must be used with VIP insulation in the spandrel area to maximize the energy efficiency and thermal performance of a building.