Good lighting requires good quality of illumination (Art. 15.11), proper color rendering (Art. 15.12), and an adequate quantity of light (Art. 15.13). This result, however, cannot be achieved economically solely by selection and arrangement of suitable light sources. Lighting effects are also dependent on other systems and factors such as the characteristics of surrounding walls, floor, and ceiling; nature of tasks to be illuminated; properties of the backgrounds of the tasks; age and visual acuity of occupants; and characteristics of the electrical system. Design of a lighting system, therefore, must take into account its interfacing with other systems. Also, lighting design must take into account the influence of lighting requirements on other systems, including architectural systems; heating and cooling effects of windows provided for daylighting; energy supply required from the electrical system; and loads imposed by electric lighting on the HVAC system. Sources of light within a building may be daylight or artificial illumination. The latter can be produced in many ways, but only the most commonly used types of electric lighting are discussed in this section. Like other building systems, lighting design is significantly affected by building codes. These generally contain minimum requirements for illumination levels, for the safety and health of building occupants. In addition, electric lighting equipment and electrical distribution must conform to safety requirements in building codes and the National Electrical Code, which is promulgated by the National Fire Protection Association, and to standards of the Underwriters Laboratories, Inc. Also, the Illuminating Engineering Society has developed standards and recommended practices to promote good lighting design. In the interests of energy conservation, federal and state government agencies have set limits on the amount of energy that may be expended (energy budget) for operation of buildings. These limits may establish maximum levels of illumination for specific purposes in buildings. Because of the importance of good lighting, the need to control lighting costs and to conserve energy, and the multiplicity of legal requirements affecting lighting design, engagement of a specialist in lighting design is advisable for many types

6.5.6 Settlement of Cohesive and Organic Soils Cohesive and organic soil can be susceptible to a large amount of settlement from structural loads. It is usually the direct weight of the structure that causes settlement of the cohesive or organic soil. The settlement of saturated clay or organic soil can have three different components: immediate (also known as initial settlement), primary consolidation, and secondary compression. Immediate Settlement. In most situations, surface loading causes both vertical and horizontal strains. This is referred to as two- or three-dimensional loading. Immediate settlement is due to undrained shear deformations, or in some cases contained plastic flow, caused by the two- or three-dimensional loading. Common examples of three-dimensional loading are from square footings and round storage tanks. Many different methods are available to determine the amount of immediate settlement for two- or three-dimensional loadings. Examples include field plate load tests, equations based on the theory of elasticity, and the stress path method (see R. W. Day, Geotechnical and Foundation Engineering: Design and Construction, Mc- Graw-Hill Publishing Co., New York). Primary Consolidation. The increase in vertical pressure due to the weight of the structure constructed on top of saturated soft clays and organic soil will initially be carried by the pore water in the soil. This increase in pore water pressure is known as an excess pore water pressure (ue). The excess pore water pressure will decrease with time as water slowly flows out of the cohesive soil. This flow of water from cohesive soil (which has a low permeability) as the excess pore water pressures slowly dissipate is known as primary consolidation, or simply consolidation. As the water slowly flows from the cohesive soil, the structure settles as the load is transferred to the soil particle skeleton, thereby increasing the effective stress of the soil. Consolidation is a time-dependent process that may take many years to

There are three main types of wastewater: domestic, storm, and industrial. Separate plumbing systems are generally required for each type. Domestic wastewater is primarily spent water from the building water supply, to which is added wastes from bathrooms, kitchens, and laundries. It generally can be disposed of by discharge into a municipal sanitary sewer, if one is available. TABLE 14.6 Hot-Water Demand per Fixture for Various Building Types* [Based on average conditions for the building type, gal /h of water per fixture at 140
F (60
C)] Apartment buildings Gymnasiums Hospitals Hotels Industrial plants Office buildings Dwellings Schools Lavatory, private 2 2 2 2 2 2 2 2 Lavatory, public 4 8 6 8 12 6 15 Bathtubs 20 30 20 20 20 Dishwashers 15 50 50 20 15 20 Foot basins 3 12 3 3 12 3 3 Kitchen sink 10 20 30 20 20 10 20 Laundry, stationary tubs 20 28 28 20 Pantry sink 5 10 10 10 5 10 Showers 30 225 75 75 225 30 30 225 Service sink 20 20 30 20 20 15 20 Hydrotherapeutic showers 400