. The EcoExcel energy performance package includes all windows that qualify for the federal energy tax credit and an online service to verify compliance with the tax credit and save the manufacturer’s certification statement. Andersen also sponsors “Windows in Sustainable Design: Design Principles and Federal Tax Incentives,” an AIA-approved continuing education course at www.architectces.com. Pictured: 400 Series Woodwright double-hung windows with Low-E4 glass. 800.426.4261. www.andersenwindows.com.