As we heard last week, interior design deals with seven primary elements. When the designer goes forward to implement these seven elements into a design, seven principles must be considered. These seven principles are as follows.

The first principle is unity. This is the unifying factor, the focus. All the pieces of the puzzle must fit together; each pattern, decoration, or item of furniture. There should always be a smooth transition through the patterns, colors, and textures of a space.

The second principle is balance. Proper balance must be achieved between the objects and the color scheme. Extravagant features must fit into the overall theme desired by the client. The two distinct ways to achieve balance are symmetrical balance through straight lines, perpendicular placement of furniture, or asymmetrical balance through complementary elements placed without basic design restrictions. 

The third principle is rhythm. The concepts of progression, alteration, and repetition can provoke rhythm. For example, radial patterns can be incorporated on the walls, then radial accent lighting hanging from the ceiling can repeat the pattern. Repeated colors or shapes can create rhythm while alternating the pace with patterns and decoration.

The fourth principle is emphasis. Oftentimes people want to showcase their prized possessions within the design. The designer needs to emphasize that object in such a manner that attention is drawn to it. The placement of the object must emphasize its beauty and influence as the focal point of the room, while simultaneously being a complementary fit amongst the theme and other elements of the room.

The fifth principle is contrast. In interior design, the primary emphasis is given to creating flow and connectivity. However, if a single color or variations of a single theme are used, then the design seems monotonous. Therefore, the utility of contrasts bears significance. When exercising contrast, colors and patterns must complement one another, while simultaneously providing a contrasting effect. This will allow multiple design ideas to display, without blurring one another. 

The sixth principle is scale and proportion. Measurements are crucial in interior design. If a sofa or a table is too large or too small, then it'll look out of place. Each and every design element must fit properly in it's intended room, regardless of the desire to use overly extravagant items. 

The seventh principle is details. Charles Eames has stated, "The details are not the details. They make the design." Space planning is important, but so too are decorative details which conclude the design. The details are wide-ranging. They include the patterns, textures, materials, bedding, curtains, doorknobs, lights, angles of the lights, placement of the artwork, and really everything under the ceiling.