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Objectives

Objectives. Review and Groups for Project 1 Start ELECTRICAL SYSTEMS - Review/Learn Fundamentals. Project Assignment 1. Cover the previous course material Homework assignments Reading assignments Similar to a real-world project You will have similar one in ARE 465

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Objectives

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  1. Objectives • Review and Groups for Project 1 • Start ELECTRICAL SYSTEMS - Review/Learn Fundamentals

  2. Project Assignment 1 • Cover the previous course material • Homework assignments • Reading assignments • Similar to a real-world project • You will have similar one in ARE 465 (Integrated design course)

  3. Project Assignment 1 • Design the environmental system for large building • Project that you will have next year • Simplification (one zone for calculation) • Show the logic for zoning • Select the heating and cooling fuel • Select the heating and cooling source • Select and size the HVAC system • Size the Cooling Coil and analyze the process in AHU

  4. Project Assignment 1 5 Groups (teams) – 5 Different assignments Group 3:- Chris Krenek - Amanda Hawkins- Benjamin Ash- Robert Chamra- Jocelyn Citty Group 4:- Brian Burcham- Justin Barrett - Patrick Gorman - Kenneth Greaves - Margaret Lawson Group 1:- Sadie Wilson - Cullen Vance- Ariel Creagh- Stephen Mathai - Brian HertzGroup 2:- Troy Thompson- Christopher Lawrence- Kevin Carbonnier- Alan Del Olmo Group 5:- Elson Wang- Matt McCarthy - Parker Thompson- Jill Monholland - Hannah Romanie

  5. Where are we going? • HVAC • Electrical systems • Lighting technology and design • Acoustics (at the very end)

  6. Specific Objectives • List and define terms associated with electrical design in buildings • Calculate electric quantities with Ohm’s Law and Kirchov’s Law (review) • Calculate electricity costs for residential and commercial buildings • Major emphasis – how do you begin designing an electrical system?

  7. Applied Electrical Concepts • Use terms to describe building electrical system • AC vs DC ch. 10 • Ohm’s and Kirchov’s Laws ch. 10 • Power vs. Energy ch. 10 • Resistors, Inductors and Capacitors ch. 10 • Power Factor ch. 10 • Single-phase vs. Three-phase ch. 10 • Grounding ch. 11

  8. What is the NEC? • National Electrical Code • National Electrical Corporation • A kind of cookie • National Energy Code • A manufacturer of plasma televisions

  9. Electrical Codes • National Electrical Code (NEC) Prepared by National Fire Protection Association Part of the national and state building codes • Library website • Tao and Janis - Section 13.7 • Focus on safety

  10. AC DC • Direct Current (DC) • Sign matters • Alternating Current (AC) • Switching polarity • Which are the following? • Photovoltaic solar cell • Automobile alternator • Household outlet • Outlet in ECJ • Battery • High voltage lines

  11. AC terms • Frequency, f [Hz] • Wall outlet? • Fluorescent light? • Clock? • Electric resistance heater? • Resistor [Ω –ohm] • Capacitor (plates separated by dielectric) • Inductor (coil of wire) • Transformers

  12. Why use AC? • Easier to generate • Able to use inductors and capacitors in meaningful way • Voltage changes much easier • Lower distribution losses

  13. Voltage and Current I [A] E or V [V] R [Ω] Voltage (potential difference) • Units? • Symbols: V, E or U • Current (electron flow) • Units? • Symbol I

  14. Transformers Change - Voltage [E] and - Current [I] Across a transformer I1E1 = I2E2 Es/Ep = Ns/Np

  15. Ref: Tao and Janis (2001)

  16. Ohm’s and Kirchov’s Laws • V = IR or E = IR (E = energy potential [V]) • P = EI = I2R • ∑I = 0 for a node • ∑E = 0 for a closed loop 4) Are these for : A) AC or B) DC or C) both? I [A] E [V] R [Ω]

  17. Single-Phase vs. Three-Phase For three phase: P=√3 E I Ref: Tao and Janis (2001)

  18. Why do commercial buildings use 3 power? • Requires fewer wires • Higher motor efficiency • Requires bigger wires • Smaller space requirements

  19. Why Three-Phase? • Larger loads • Smaller wire sizes (because higher voltages) • P = EI = I2R= E2/R (E = IR) • More efficient use of neutral wire • 3 needed for efficient operation of equipment

  20. Power Factor • Difference between power supplied and power that does useful work “working power” • P=E I cos θ • θ is the phase difference between current and voltage • For circuits that contain reactance (Inductor and Capacitors) • For three phase • P=√3 E I cos θ • Commercial buildings pay for power factor.

  21. Electricity Billing • Electrical Use (energy) • Peak Demand (power) • Power factor • Which is largest portion of residential bill? • What about for commercial buildings? • http://www.austinenergy.com/About%20Us/Rates/Commercial/index.htm

  22. Example: September cost of Electricity for ECJ • Assume ECJ is 120,000 ft2 and that it needs, on average, 8 W/ft2 for 8 hours a day, 6 W/ W/ft2 for 4 hours a day, and 4 W/ft2 for 12 hours a day • Use Austin Energy Large Primary summer service rate • 1.5¢/kWh, 12.60 $/peak kW/month • Assume no power factor charges

  23. Solution

  24. Other Pricing Strategies • Time of use pricing • Becoming more common for residential and commercial • Electricity cost related to actual cost • Requires meter • Interruptible pricing • Utility can shut off electricity for periods of time

  25. Summary • Know about NEC • Compare DC and AC • Calculate current/voltage across a transformer • Describe 3-phase power and compare to 1-phase • List reasons for using 3-phase • List and explain components of electrical billing • Calculate commercial electricity bill

  26. Reading Assignment Tao and Janis: Chapter 10 Chapter 11 Sections: 11.1- 11.3 (including 11.3)

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