Resonating Reflex A Critical Investigation Of The Physical An... by John Rudd

The combined cost of natural and artificial lighting per hour per minimum foot-candle upon the work-plane attains a minimum at about 38 foot-candles for most types of standard buildings. For a minimum of 13 foot-candles, the average time a lighting-unit operates per year in a six-story building surrounded by buildings of its own height varies from 918 hours for 150-foot light-courts to 1,762 hours for 30-foot light-courts.

Under the same conditions the ratio of the annual cost of natural lighting to the annual cost of electric lighting varies from 1.09 for a single-story, flat roof building to 4.03 for a sawtooth building.įor a minimum intensity of illumination of 13 foot-candles upon the work-plane the average time a lighting-unit operates a year varies from 651 hours for a single-story, flat roof building to 253 hours for a sawtooth building. Under average conditions the ratio of the initial costs of natural to electric lighting equipment varies from 2.25 for a single-story flat roof building to 6.3 for a sawtooth building. of floor area with lighting-units spaced on 10-foot centers, varies from $10.20 for 5.5 foot-candles on the work-plane to $17.50 for 38 foot-candles. The initial total cost of electric lighting equipment per outlet or per 100 sq. The annual cost of maintaining and operating the heating system to supply heat losses incident to windows varies from a minimum of 7 cents per square foot of window surface in Building A to a maximum of 12.3 cents in Building C. of window surface for buildings having side windows only, and from $.41 to $.59 for buildings having windows in the roof also. The investment cost of heating equipment to supply heat losses incident to windows varies from $.32 to $.45 per sq. of floor area under normal conditions vary from a minimum in one type of standard building to a maximum in another type as follows:

The major items entering into the initial cost of natural lighting equipment per 100 sq. Though it may be possible to dispense with natural lighting, it would hardly be possible to dispense with artificial lighting if work is to be pursued for eight hours a day throughout the year for natural light is of no greater constancy than daylight itself.

The determination of the initial cost of natural lighting is made by computing the difference in cost between a building equipped with natural and artifical lighting and a building of similar construction equipped merely with artificial lighting. In our endeavor to use natural and artifical light in a more economical manner, it becomes necessary to know the initial and operating costs of each. With the growth of the science of light and vision, the engineer has been putting forth some effort to use daylight to a greater advantage.

Resonating Reflex A Critical Investigation Of The Physical An... by John Rudd