A private residence in Fort Washington, Maryland with 2500 square feet and a net-zero energy footprint. The building was designed to maximize the passive solar heat gain in the winter months and shade it in the summer. The walls are built out of structurally insulated panels(SIPs) with an aerated autoclave concrete (AAC) block foundation to create a highly efficient thermal envelope. The active heating and cooling of the house is done through a radiant concrete slab with is a geothermal heat pump system. The residence is also equipped with a 5kw photovoltaic array and enough battery back up to survive for a week if the grid goes down.