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 1: - Sadie Wilson - Cullen Vance - Ariel Creagh - Stephen Mathai - Brian Hertz Group 2: - Troy Thompson - Christopher Lawrence - Kevin Carbonnier - Alan Del Olmo
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 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) Focus on safety
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) Alternating Current (AC)
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] Resistor [Ω –ohm]
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
4/15/2019
Why use AC?
Easier to generate
Able to use inductors and capacitors in meaningful way
Voltage changes much easier
Lower distribution losses
ARE 346N

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

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, $/peak kW/month
Assume no power factor charges

23. Solution large primary service $/kW $/kWh Daily $ 12.60 $ 0.015 hours$ $
hours kW
kWh 8
960
7680
demand
$12,096.00 4
720
2880
energy
$ 7,344.00 12
480
5760
TOTAL
16320
Total
$19,440.00

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: (including 11.3)