LIFE-CYCLE COST (LCC) ANALYSIS, A VARIATION OF BENEFIT-COST ANALYSIS, COMPARES ALL PRESENT AND FUTURE EXPECTED BENEFITS WITH ALL PRESENT AND FUTURE COSTS TO EVALUATE PROGRAMS OR INVESTMENTS. LONG-RUN BENEFITS OR COST SAVINGS PRODUCED BY AN INVESTMENT MUST EXCEED THE LONG-RUN COSTS TO BE WORTHWHILE ECONOMICALLY. AS APPLIED TO ENERGY CONSERVATION FEATURES IN BUILDINGS, LCC ANALYSIS IS THE EVALUATION OF THE NET EFFECT OVER TIME OF REDUCING FUEL COSTS BY PURCHASING, INSTALLING, MAINTAINING, OPERATING, REPAIRING, AND REPLACING ENERGY-CONSERVING FEATURES. THE RESULTS OF THE ANALYSIS MAY BE EXPRESSED AS (1) THE TOTAL OF CONSERVATION INVESTMENT AND ENERGY CONSUMPTION COSTS, (2) THE NET SAVINGS FROM THE INVESTMENT IN ENERGY CONSERVATION, OR (3) THE RATIO OF SAVINGS TO COST. DISCOUNTING, TAXES, AND INFLATION ALSO CAN BE APPLIED TO LCC. TWO OTHER EVALUATION METHODS ARE RELATED TO LCC ANALYSIS--THE PAYBACK AND THE INTERNAL RATE-OF-RETURN METHODS. FOUR POSSIBLE APPLICATIONS OF LCC TO ENERGY CONSERVATION INCLUDE INSULATING AN EXISTING BUILDING TO LOWER UNDESIRABLE HEAT LOSS AND GAIN; SELECTING WINDOW SIZE, DESIGN, AND ORIENTATION TO REDUCE ENERGY AND LIFETIME BUILDING COSTS; DETERMINING WHETHER A HEATING SYSTEM WILL BE COST-EFFECTIVE IN REDUCING THE CONSUMPTION OF NONRENEWABLE ENERGY RESOURCES; AND DESCRIBING THE USE OF LCC IN DEVELOPING ENERGY CONSERVATION PERFORMANCE STANDARDS FOR BUILDINGS. SOME DETERRENTS TO AND USES FOR LCC AND POTENTIALS FOR THE RELATED METHODS, ARE DESCRIBED. TABULAR DATA ARE INCLUDED. (AOP)