Lawrence Berkeley National Laboratory

Improving the performance of building envelope is essential to energy conservation and emission reduction. Adaptive building envelope (ABE) has the potential to effectively reduce building energy consumption at a lower cost. Movable window insulation is an instantiation of the ABE with great application potential in buildings, but it has not been systematically studied. Trying to fill this gap, this paper proposes an automatic control system and a manual control rule for movable window insulation. The energy consumption of double-glazed windows, triple-glazed windows, movable insulation with automatic/manual control, and electrochromic windows is compared in different scenarios using building energy simulation (BES). In some scenarios, the optimal solar heat gain coefficient (SHGC) for windows with movable insulation is higher than that required by the building code. Triple-glazed windows are only effective in reducing the heating energy, while electrochromic windows are only effective in reducing the cooling energy. Infiltration has a great impact on the performance of movable insulation. The net preset value (NPV) analysis shows that movable insulation has a great application potential in Minneapolis, Atlanta, and Phoenix, while triple-glazed windows are only viable in some cases in Minneapolis. Electrochromic windows are not a profitable investment at their current prices.