Energy-Efficient Heating, Ventilating and Air Conditioning

The facility is heated by a mix of 100% efficient make-up air units and 80% efficient indoor air heaters; with an average heating efficiency of 90%. Calculate the annual fuel savings (mmBtu/yr) if the R value of the 250,000 ft2 roof is increased from R = 5 hr-ft2-F/Btu to R = 15 hr-ft2-F/Btu during a required resurfacing of the roof. ................
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