In Feng Shui there is the concept that not only is there yin and yang energy, but also five types of elemental energy: Fire, Earth, Water, Metal & Tree (sometimes refered to as wood).
Each element has a distinct relationship with the other four; they are all inter-related and affect each other by nourishing, draining or destroying others in the cycle. This knowledge can be used to enhance or diminish Chi in particular areas of the home depending upon whether the chi is lacking or too abundant.
The use of familiar imagery makes it easy to see how this works. For example, we can clearly understand that water is needed to feed a tree and also that too much water would put out a fire.
Each area of the Bagua is associated with a particular element. It is this particular energy that is necessary to bring about an enhancement of that part of life. For example; if you are hoping to be offered a promotion at work (which falls into the illumination or fame sector of the life areas) the type of energy required to boost the chances of this happening is fire. There are many ways to increase the fire energy and an experienced Feng Shui Practitioner will be able to advise you on how this could be achieved to suit your circumstances.
Each element can be introduced in the home by the placement of either the pure Yang form such as a candle for fire, crystal for earth or a healthy plant for tree, or by a more Yin form such as pictures of the actual element (perhaps a painting of the sea for water element), or using the colours or shapes of the element, etc. Once the elemental energy is in the right part of the home it can be enhanced by introducing an elemental energy that will nourish it. For example, to go back to the scenario of wanting a promotion at work, which requires fire energy, having the colour of red on a wall will introduce that energy in the first place and then tree energy will feed the fire. Tree energy could then be introduced by placing some green plants or even having some tall upright wooden candlesticks to represent tree energy. If there was too much fire energy and arguments and confrontation were occurring the fire energy could be drained by using its controlling element, which in this case would be water. In this way balance can be regained and the right amount of the helpful energy found.
Each element is associated with a shape and colour. For example water is represented by the colours blue or black, and by wavy, curved shapes. Fire is represented by the colours red & orange, and zigzag, pointed shapes, etc.