Multi-Leveled

Down one level off the kitchen is a living area — which is fitted with a three-seater sofa. And, as clever use of space, there is a small shelf in front of the lounge that has a compartment that is big enough for a computer screen.
There are two vents for fresh air — one in the kitchen and one in the bathroom — but the front door can also be opened for ventilation. But how could a space so small house a family of three?