HVAC – Air Handling Unit Heating Ventilating AC =Cooling HVAC – Basic Terms hQ = 200,000 Btu/h CO2 20 cfm/ pers 50 people 1000 cfm cQ assume to = 20 tr = 70 ti = 62 tsi = % coil Q= V*rho*cp*TD 5000 cfm hQ vent = V*rho*cp*TD

HVAC – Basic Terms By Conduction Convection Radiation (Heating Load) Heat Out =Heat In (Cooling Load including “Latent Load”) Heat and Humidity in = Heat and Humidity out

HVAC – Basic Terms Conduction Area Temperature Resistance

HVAC – Basic Terms Conduction

Convection Radiation HVAC – Basic Terms

HVAC – Basic Systems Heating hQ sen + hQ vent = coilQ sen hQ sen = 200,000 Btu/h

HVAC – Basic Systems Heating

w w HVAC – Basic Systems - AC AC Water to Water

w A HVAC – Basic Systems - AC

A A

w A

Constant Volume Double Duct Terminal Box Damper blades change air flow as the pressure at the inlet to the box increases or decreases and in response to room temperature

Variable Volume Single Duct Terminal Box Pressure Independent (between Max and Min), based on room thermostat. If temperature rises, damper opens for more cooling. Air Flow is unaffected by other boxes in the system. 55 – 60 o P Sensor Thermostat = Master Velocity = Sub Master cfm

Inlet Guide Vanes

Variable Speed Drives

COP – dimensionless! – EER – dimensions of Btu/h/W! HVAC - Cooling ideal evQ kpH’

The energy efficiency rating (EER) of an air conditioner is its BTU/h rating over its Wattage. Example: window air conditioner Rating: 10,000-BTU/h Power Consumption: 1,200 watts EER = 10,000 BTU/h/1,200 watts = 8.3 Btu/Wh Normally a higher EER is accompanied by a higher price. HVAC - Cooling

Choice between two 10,000-BTU/h units 1. EER of 8.3, consumes 1,200 watts 2. EER of 10, consumes 1000 watts. Price difference is $100. Usage: 4 months a year, 6 hours a day. Electricity Cost: $0.10/kWh. =========================================== 4 mo. x 30 days/mo. x 6 hr/day = 720 hours (720 h x.2 kW) x $0.10/kWh = $14.40 Savings Since the EER 10 unit costs $100 more, it will take about seven years for this more expensive unit to break even HVAC - Cooling

Energy Analysis Example

ECM: Heat Recovery