A building is described as a multifunctional agent of environmental change that has to achieve adequate and acceptable performance so that a safe and comfortable environment will result for any human activity. The 14 aspects of whole building performance are listed and examples of advantageous and disadvantageous interactions are offered. Fire safety performance interacts with all other aspects and is distinguished by not being part of the day-to-day environment. All fire safety problems cannot be solved by the application of conventional elements of fire safety technology, and, therefore, the performance approach to fire safety is important as more flexibility in the selection of solutions becomes possible. The identification of relative values of the components of fire safety is an important problem, and these values change according to building type. Performance profiles and levels of acceptability are discussed. Difficulties associated with the measurement of fire safety performance are discussed, and the selection of appropriate appraisal techniques is emphasized. The control of fire safety standards by governmental officials and private professionals is examined, and mention is made of the possible introduction of self-regulation for continuing fire safety standards in buildings.
WATTS AND VARSDear Sir-Two contributors to this correspondence support the view of the International Organization for Standardization (I.S.O.) that one var equals one watt, seven reject it. Those who support the I.S.O. reveal a misconception of the meaning of the technical term 'reactive power' and its unit, the var. They seem to believe that reactive power is the product of the voltage in a reactor and the current that flows in the reactor at the same moment of time. It is not. This quantity is not called reactive power and is not measured in vars, even if it occurs in a reactor or a capacitor. It is called power and is measured in watts.Reactive power is obtained by taking the product of two quantities that occur at different instants of time. In a 50c/s system these instants are separated by 1/2OOth of a second. When one multiplies a voltage that occurs at one instant of time by a current that occurs at another instant, the product is not a rate of change of energy, and I doubt whether any of the conflicting theories of dimensions could provide proof that a quantity that is not a rate of change of energy has, nevertheless, the dimensions of power.This argument is implicit in the contributions from many of your correspondents, but Mr. B. B. Jacobsen (October 1961 Journal, p. 604) comes nearest to removing the misconception. Let me repeat a little from his letter.Let the instantaneous value of a sinusoidally varying voltage be v = \/2 V sin cot and the instantaneous value of the current at the same moment of time be i = -\/2I sin (cot +
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