on yearly energy requirements was determined. Reducing the window to exterior wall ratio (based on floor to ceiling height) from 50% to 10% resulted in a savings of yearly energy demand for all services by over 10%. Perhaps the ratio of 10% is too small; however, the architect should strive for a pleasing design giving proper fenestration due consideration. Consideration should definitely be given to effective amounts of glass in residences. to FHA for inclusion into their Minimum Property Standards, NBS in 1972 devised figure 18 for determining allowable percentages of glass for any individual room. Under winter design conditions with the indoor air temperature at 75°F, the glass area of a living room/unit expressed as a percentage of its total exterior wall area should not exceed the value along the ordinate of the figure. The abscissca is the ratio of the floor area of the room/unit to the total exterior wall area including glass areas and doors and the third parameter "X" is as shown, the U value of the glass times the temperature difference at winter design conditions. This rationally derived chart thus accounts for the geographic location as well as the kind of glass used i.e., larger amounts of glass could be used for a given location provided one went from single pane to storm windows or insulating glass. ENERGY CONSERVATION FEATURES LIGHTING In office buildings, lighting consists of from 25 to 60 percent of the cooling load of air conditioning equipment and contributes from 20 to 30 percent of the total annual demand for electrical energy. Clearly, the reduction in lighting or the better utilization of energy expended for lighting will have a pronounced effect on not only the power demands for lighting, but also the power demands for operating air conditioning equipment. Without altering life styles or increasing total costs, energy required to light new buildings could be reasonably reduced by 25 percent. Demand for lighting could be cut by at least 15 percent in most existing buildings. Suggestions for the reduction in or better utilization of 7/ energy expended for lighting is summarized as follows: 1. Turn off lights when not needed. When the working or living space is empty, secure and not used for display or observation there is no need for lighting. The power energy savings realized are direct in winter and could be one and one half times the energy output of the lighting fixtures that have been turned off in summer due to the additional savings in cooling. 2. Control window brightness and utilize daylighting as practicable. The levels of illumination required for working and living spaces can be made adequate by the control of window brightness and proper utilization of daylighting. Control systems could be utilized to turn off or reduce the amount of electric lighting when daylighting provides adequate illumination. 3. Provide planned operation and maintenance procedures. Operation and maintenance of lighting (electric and daylight) should be considered for both the utilization of power and economic considerations. Maintenance involves keeping lighting equipment clean and in good working condition so that illumination levels remain adequate for prolonged periods of time. 4. Use lighter colors on surface finishes of ceilings, walls, floor and furnishings. Light finishes increase the utilization of available light. By repainting ceilings, walls and floors and using lighter colors of furniture, the average illumination level of the room using the same light sources could be increased by as much as 30 footcandles (amount of light received by a Reflectances of the surfaces should be in the following surface). American Standard Practice for Office Lighting, ANSI |