# Formulas.

## Presentation on theme: "Formulas."— Presentation transcript:

Formulas

Heat Loss due to Infiltration & Ventilation
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 Infiltration
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.

Sensible per occupant X number of occupants = Btu h Latent

Sensible Btu 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 Days Temperatures 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 = 6655 CDD = 1154 Degree Day = 65°F - ((high temp. – low temp])/2)

Formula Operating Hours = [Degree Days x 24] /
[ Temperature Difference] Heating Degree Days for Pullman = HDD = 6655 (look up) Temperature Difference =ΔT (for project)

Formula Heating Degree Days Example: The Kirk Building
Operating Hours = [Degree Days x 24] / [ Temperature Difference] Heating Degree Days Example: The Kirk Building Operating Hours = (6655 x 24)/87 Operating Hours = 1,836

Formula Operating Hours = [Degree Days x 24] /
[ Temperature Difference] Cooling Degree Days for Pullman = CDD = 1154 Temperature Difference =ΔT (for project)

Formula Cooling Degree Days Example: The Kirk Building
Operating Hours = [Degree Days x 24] / [ Temperature Difference] Cooling Degree Days Example: 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/Kilowatt Efficiency = 1.0 Note: 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/Therm Efficiency = 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 Ratio The 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 Building Heating \$/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