A rural cottage sits on pilings with a breezeway underneath. It has insulated wooden walls (A_walls = 50 m²,R_walls = 3 m² K/W), a plywood floor (A_floor = 35 m²)2.5 cm thick, and a simple peaked slate roof (slope 30^◦) covering the floor area. The slates are roughly 2 cm thick, laid over plywood sheathing 2.5 cm thick. The cottage has four double pane glazed windows (1/4 "air gap), each 1 m². Estimate the effective R value for the dwelling as a whole. Now imagine doubling the thermal resistance of any component, walls, floor, or roof. Recompute the effective R-value and decide which would be most effective for energy conservation.