To design a space, I begin with the idea that as space is empty everything is possible. It is then a question of applying skills to make everything possible.
To create an interior decoration or a fresco, I consider first the need to connect to the human scale. As a reference for the right scale I would take the Modulor (the golden number of Lecorbusier). As humans, our perceptions relate to our own bodies, we need to feel comfortable in space and our surroundings; therefore rather than an ego built scale I incorporate human perceptions of space. Without this approach our ego/imagination could create an atmosphere which is outside the comfort of our perceptual abilities.
Human perception and scale in this context relates to consideration of who is going to work in/visit that space and their motivations. I would consider how I can help them to fulfill their potential.