REVIEW Green Professional Building Skills Training Electrical Systems.

REVIEW

Green Professional Building Skills Training

ElectricalSystems

What are the benefits of sustainability in green building

design?

• Promotes new and better jobs• Helps fight climate change• Better Indoor Environmental

Quality• Lowers operating costs

1 SUSTAINABILITY IN ELECTRICAL SYSTEMSPage 12

What is peak demand and under what circumstances is it most

likely to occur?

Peak demand (or peak load) is the maximum power drawn at any given time.

Peak load is most likely to occur on the hottest days of the summer when the most

air conditioners are in use.


What is the difference between site energy and source energy

and how are they related to electricity usage?

Site energy is the amount of energy delivered to a building and source energy is the amount of

energy in the fuel used to generate the electricity. The amount of useful electrical energy delivered to a building is typically about one-third of the amount of energy used to generate it. The other two-thirds

are lost in thermodynamic inefficiencies at the generating plant and in transmission.


What are the codes and standards related to green building and what

are their functions?There are two standards or codes that are widely

adopted and aimed at lowering energy consumption. The first is ANSI/ASHRAE/IES Standard 90.1, which has been made significantly more stringent with each

revision, aiming for extremely efficient buildings as standard construction by 2030. A parallel effort is the

International Energy Conservation Code (IECC), which is often adopted as the state or local energy

code in conjunction with ASHRAE 90.1.


What is ENERGY STAR and how does it relate to the LEED rating

system?


The U.S. Green Building Council’s LEED rating system is a design standard, establishing criteria for

the energy and water efficiency and broader sustainability of the design of buildings. ENERGY

STAR is similar to LEED but aimed almost exclusively at energy-related items. A project

pursuing an ENERGY STAR rating will install the high-efficiency systems used in LEED projects.

What is a lumen, what is a foot-candle, and how are they related?

A lumen is the basic unit of visible light emitted from a source, analogous to the power in watts

produced by a generator. A foot-candle is a measure of the illuminance, which is the amount of light falling on a surface. A foot-candle is the

illuminance on a one square foot surface on which 1 lumen is uniformly distributed.

2 LIGHTINGPage 33

What is Lighting Power Density (LPD)?

The lighting power density (LPD) is the maximum electrical power

allowed per square foot for lighting, and is specified by energy codes for

different types of spaces.

2 LIGHTINGPage 33

Lamps with a lower color temperature produce light of what

color?

Lamps with lower color temperatures, 2700K – 3500K,

produce yellower or visually "warmer" light and are typically

used in residential spaces.

2 LIGHTINGPage 33

How are magnetic ballasts different from electronic ballasts?

Magnetic ballasts may contain dangerous PCB's, are less efficient, and their lower

frequency causes them to flicker and hum. Electronic ballasts use transistorized circuitry,

create very high frequency AC which eliminates flicker, are smaller and lighter, and

allow a more precise control of operation cycle.

2 LIGHTINGPage 33

What type of lamps are discharge lamps and how do they work?

Metal halide lamps and sodium vapor lamps are discharge lamps.

High-intensity discharge is an electric charge in gas vapor that

produces light.

2 LIGHTINGPage 33

What are some installation tips for occupancy sensors?

Some installation tips for occupancy sensors are:1.Location is very important.2.Proper sensor placement will diminish chances of nuisance action.3.Locate PIR sensors at least 4 – 6 feet from HVAC diffusers and other heat sources.4.Do not mount sensors in locations blocked by door swings.5.Do not use with metal halide lamps.6.Range of ceiling mounted sensors can be diminished by partitions. 7.Sensor placement should be included in all drawings.8.Beware of in-rush with fluorescent lighting. 9.Be aware of minimum load requirements.

2 LIGHTINGPage 33

What are vacancy sensors and how do they compare to occupancy

sensors?

Vacancy sensors operate very much like occupancy sensors with the distinction that a person must

manually turn the lights on, but sensors will turn them off after a set

period of no detected motion.

2 LIGHTINGPage 33

How is using a VFD on a motor efficient? What is an important issue to keep in mind when wiring a VFD?

With a variable frequency drive (VFD) installed on a motor, the speed of the motor can be adjusted to match the load. This is much

better than throttling the output, which wastes a significant amount of power. There should

be no on/off switch external to a VFD combination because the controller may lose

its program if switched off.

3 HEATING AND COOLINGPage 50

What are the effects of using oversized pumps, motors, or control

valves?

Using oversized pumps, motors, or control valves leads to excessive

energy consumption.


How do heat pumps work?

A heat pump movies heat from one location (the source) at a lower temperature to another location called the heat sink at a higher temperature using mechanical work, generally supplied by an electric motor. The device operates by passing refrigerant through a heat exchanger called the evaporator, where the heat required to boil it into a vapor is taken from the fluid in which the evaporator is

immersed, either air or water. Cooled air or water is the result of this process.


What are some of the capabilities of building management and

information systems?Some capabilities of BMS systems are:

• Scheduling timely operation of equipment• Controlling temperature, pressure, and humidity • Controlling fans and pumps to regulate the flow of

air and water• Responding of equipment to fire alarm system

operations• Alarming and providing building operators with

notifications of predefined conditions


Give examples of central, distributed, renewable energy and nonrenewable energy generation.• Central generation: Large generation stations

powered by coal, natural gas, nuclear power, or hydropower

• Distributed generation: Rooftop photovoltaics, gas-fired cogeneration, and small local wind turbines

• Renewable energy generation: Solar energy, tidal power

• Nonrenewable energy generation: Fossil fuels

4 RENEWABLE AND DISTRIBUTED ENERGYPage 69

Why is a secure disconnect system needed for a distributed generator?

A secure disconnect system is needed for a distributed generator because it can be

dangerous if the grid has gone down and the distributed source continues to generate electricity, as the power could electrocute workers. A secure disconnect ensures that even if the building continues to generate power, none of it should feed back to the

affected grid.


What should you consider when determining the most cost-effective

size of a building's cogeneration system?

You should make sure the cogen system is always running at full capacity by measuring the minimum electric load of

the building. Then determine the building’s thermal load and compare it to the thermal output of the cogenerator, to not

waste thermal energy. The simplest approach is to specify a cogen unit with a thermal output about equal to the building’s thermal base load, but a larger cogen unit can be installed if

storage tanks for hot water are added.


What does a fuel cell produce?

A fuel cell produces electricity, heat, and water by an electrochemical

reaction.


What is the relationship between maximum voltage and maximum power in photovoltaic panels?

In photovoltaic panels, a connection in parallel means that the current will be high but the voltage will be low. Connection in series means that the current will be low

but the voltage will be high. A typical PV panel will generate the highest voltage when no current is being drawn; this is the open circuit voltage. The short circuit current is the largest current, produced when the output terminals are connected to each other through a zero-

resistance ammeter.


What type of power is generated in a PV cell and how is it used in a

building?

The power generated in a PV cell is DC, but the power used in most buildings is AC. This means that

the panels have to be connected to an inverter to convert the DC power

to AC power.


What are some factors to consider when determining the most effective

location of a wind turbine?Some factors to consider when

determining the most effective location of a wind turbine are wind speeds and

stresses on buildings. Turbines are placed where wind velocities are highest in order to maximize generated energy.


What are the responsibilities of the CxA?

The CxA is responsible for the entire commissioning process. The CxA prepares the Cx Plan, forms, tests, and reports, and is

responsible for training and turnover.

5 ASSURING BUILDING PERFORMANCEPage 81

Name 2 steps that should be taken prior to the start of field testing.

1. Providing and maintaining necessary documentation required for testing

2. Meeting with the CxA prior to testing to go over forms and what will happen on test day


Why would a CxA plan for deferred testing?

Deferred testing is used when a building system cannot be tested

until the building is actually occupied and the system is

being utilized under design conditions.


What is a proper comparison to estimate the energy and water consumption savings in a new

building?Designers construct a computer model of the building to determine what the energy

and water consumption would have been if the building had been constructed using standard techniques and compare that to the actual energy and water levels after

construction.


Describe some scenarios where inter-trade coordination is critical for

building performance.

• Floor penetrations• Underfloor distribution of HVAC

and wiring• Building management systems • Low VOC materials

6 JOB MANAGEMENTPage 87

What should every worker on a green building job understand?

• Safety should never be compromised• This is a green and sustainable building project• Rating systems, such as LEED and ENERGY

STAR• Strategies for conserving resources such as

water, energy, and materials• The importance of good indoor air quality• What makes this project green

6 JOB MANAGEMENTPage 87

REVIEW Green Professional Building Skills Training Electrical Systems.

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