Site specific, energy efficient, cost effective residential construction- This is an 800sf ADU. It's built to PGH standards (Pretty Good House). We used recycled XPS insulation to insulate under the slab, outside the walls, and above the roof. All sheathing was air sealed with Siga tape, and windows are triple pane. HVAC is ductless mini-split and hot water is on-demand gas. It's cozy and comfy all year and didn't break the bank.