In residential lighting, two concerns dominate determination of illumination levels and visual comfort: function and mood of the
environment. Specific tasks, such as sewing, cooking, and reading, require higher levels of lighting than do relaxation activities.
Kitchen lighting should have well overall distribution, free from shadow.
Although illumination specialists discuss lighting levels in terms of foot candles or lumens, these types of measurements are impractical for measuring light in a household. We are more familiar with lighting output denoted in terms of wattage—which is the electrical power of an incandescent or a fluorescent lamp. Generally, a minimum lighting level for a living room lighting measuring sixteen feet by twenty feet, or 320 square feet, would require an overall wattage of 640 watts. This could be delivered by three lamps that provide 150 watts each or 450 together, and two others using 100-watt bulbs yielding together 200 watts. This translates into two watts per square foot or twenty watts per square meter of floor area. Use this as a rule of thumb measure, but it does not take into consideration the decorative lighting that is available. Decorative lighting often provides the added amount of illumination necessary to create a mood with lighting and achieve visual comfort.
In a room where there are very specific activities, lighting should be designed to accommodate them and provide a visual comfort. For example, in a dining room there should be direct light over the table; in a bathroom light is necessary at the mirrors; kitchen lighting should be shadow-less and evenly distributed, and there should also be extra lighting at the food preparation center. Lighting fixtures should also be focused toward the point of need, such as over the pillows of beds via wall sconces or night table lamps