climate control
definitions
Quantity
CFM: flow rate, cubic feet per minute Energy
Watt-hour (Wh): a measure of electrical energy, equivalent to the power consumption of one watt for one hour British Thermal Units (BTU): the amount of energy necessary to raise the temperature of one amount of water from 60F to 61F MBH: thousands BTUs per hour Efficiency:
Coefficient of Performance (COP): ratio of thermal output (heating or cooling) to energy input energy modeling
Building envelope conditions % savings=1-SEERcurrentSEERcurrent*100%
*only applies if rated cooling output and operating schedules remain the same after upgrade, otherwise energy consumption in kWh must be calculated separately for existing and projected running conditions
air conditioning
types
Coolant
R-410a: new standard, more efficient, no ozone damage, higher pressures (requires tougher, more durable parts, increasing life of system) R-22 (freon): old standard, illegal in any system manufactured after 2010, no longer imported or manufactured after 2020. Less energy efficient (heat transfer), contributes to depletion of ozone, rising prices. Metrics
Efficiency: ratio of cooling output (BTU) to heating input (watt-hours) (unit = BTU/Wh)
Energy Efficiency Ratio (EER): fixed set of operating conditions (Tindoor = 80F, Toutdoor = 95F, relative humidity = 50%) Seasonal Energy Efficiency Ratio (SEER): averages performance across a range of outdoor temperatures typical of the cooling season.
Degradation
Estimated Capacity: BTU/Hr
US DOE: 3% degradation for unmaintained, 1% for completely maintained systems Florida Test: median 5.2% degradation=-0.0454+0.00269(Age)+0.030(Tons)-0.00127(SEER) heating
Metrics
Efficiency:
Heating Seasonal Performance Factor (HSPF): analogous to SEER, applies for heat pumps in heating mode only SEER: describes heat pumps during cooling season Annual Fuel Utilization Efficiency (AFUE): used for combustion-based appliances (boilers, furnaces), ratio of effective heating output to total energy contained in the fuel consumed Cannot compare w/ the HSPF. Would have to estimate yearly running costs,
sources
home air conditioning.xlsx
12.3 kB
