Mar 28, 2015
Heat Loss due to Infiltration & VentilationInfiltration
1.1 x [(ACH x vol.) /60] x (Ti -To)-or-
.018 x ACH x Vol. x (Ti- To)Note: CFM = (ACH x volume) / 60 min per hour
Ventilation 1.1 x [( Ra x SF) + (No. of people x Rp)]
x (Ti –To) Area out Outdoor Rate (based on SF)
People Outdoor Air Rate (based number of people )
Heat Loss Due to InfiltrationInfiltration
Please Note: For tight construction use 0.5 for ACH.For medium construction use .85 for ACH.For loose construction use 1.3 for ACH.For really bad construction use 2.0 for ACH
For the summer months (cooling) use 70% of the winter values.
Heat Gains from Occupant Loads
Sensible per occupant X number of occupants = Btu h
Latent per occupant X number of occupants = Btu h
Heat Gains from Infiltration Loads
SensibleBtu h = 1.1 x CFM x TD
Latent Btu h = 4,500 x CFM x (Wroom – Woa)
Heat Gains from Outside Air for Ventilation Loads Sensible
Btu h = 1.1 x CFM x TD
Latent Btu h = 4,500 x CFM x (Wroom – Woa)
-or-Btu h = .68 x CFM x (W2 – W1)
Degree DaysTemperatures between 600 and 800
Fahrenheit are comfortable. Temperatures between 600 and 800 are
nicknamed the Goldilocks Zone. Degree days HDD heating is based on each
degree below the base of 650 U.S. 60o in Great Britain
Degree days CDD cooling is based on each degree above the base of 800 U.S. 60o in Great Britain
Degree Days for Pullman
HDD = 6655CDD = 1154
Degree Day = 65°F - ((high temp. – low temp])/2)
FormulaOperating Hours = [Degree Days x 24] /
[ Temperature Difference]
Heating Degree Days for Pullman = HDD = 6655 (look up)
Temperature Difference =ΔT (for project)
FormulaOperating Hours = [Degree Days x 24] /
[ Temperature Difference]
Heating Degree DaysExample: The Kirk Building
Operating Hours = (6655 x 24)/87 Operating Hours = 1,836
FormulaOperating Hours = [Degree Days x 24] /
[ Temperature Difference]
Cooling Degree Days for Pullman = CDD = 1154
Temperature Difference =ΔT (for project)
FormulaOperating Hours = [Degree Days x 24] / [ Temperature Difference]
Cooling Degree DaysExample: The Kirk Building
Operating Hours = (1154 x 24)/25 Operating Hours = 1,108
Estimating Annual Energy
Heating $/Yr
Electric (BTU/Hr) * (hours of operation) * $/energy
unit BTU/energy Unit * Efficiency
Electric conversion = 3,400 BTU h/KilowattEfficiency = 1.0Note: Does not include fan energy. Add 10% for
residential and 20% for commercial fan energy
Estimating Annual Energy
Heating $/Yr
Gas (BTU/Hr) * (hours of operation) * $/energy
unit BTU/energy Unit * Efficiency
Electric conversion = 100,000 BTU h/ThermEfficiency = 80% - 96% Note: Does not include fan energy. Add 10% for
residential and 20% for commercial fan energy
Estimating Annual Energy
Cooling $/Yr
(Btu/Hr) * (hours of operation) * $/energy unit
SEER * 1000
Note: Does not include fan energy. Add 10% for residential and 20% for commercial fan energy
Estimating Annual Energy
SEER Seasonal Energy Efficiency Ratio
The U.S. Department of Energy claims energy we use in an average house is responsible for twice as many greenhouse gas emissions as an average car.
Estimating Annual Energy
Estimating Annual Energy
SEER Seasonal Energy Efficiency RatioThe efficiency of central air conditioning regulated
by the U.S. Department of Energy (DOE). The SEER is defined as the total cooling output (in
British thermal units or Btu) provided by the The change from SEER 10 to SEER 13 represented
a 30 percent improvement in energy efficiency.
SEER = (seasonal Btu of cooling) / (seasonal watt-hours of electricity used)
Estimating Annual Energy
SEER Seasonal Energy Efficiency Ratio
Great strides have been made in the last 10 years in efficiency of air conditioners and heat pumps.
SEER ratings for air conditioning and air-source heat pump systems manufactured today range from 13 SEER to 24.
Central air conditioners that are in the top 25 percent of efficient may carry the ENERGY STAR® label. To qualify, they must have a minimum SEER efficiency level of 14
Estimating Annual Energy
Example: The Kirk BuildingHeating $/Yr
(2,324,056) * (hours of operation) * $/energy unit
BTU/energy Unit * Efficiency
Note: Does not include fan energy. Add 10% for residential and 20% for commercial fan energy
Electrical Cost to Heat[(BTU/Hr) * (hours of operation) * $/energy unit]/
BTU/energy Unit * Efficiency
.08 electrical cost per kilowatt hours
[(2,310,240) * (1,836) * .08]/ (3,400 * 1 .00) = $99,802.37