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Systems Flashcards

1
Q

Skin-load dominant building

A

Buildings that have a lot of surface area compared to interior space-buildings that will be influenced by exterior conditions

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2
Q

Internal load dominated buildings

A

Minimal surface area compared to volume - generate a lot of heat - influenced by people, lighting and equipment -typically sheds heat year round

Factory, hospital, office buildings

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3
Q

Solar heat gain coefficient ( Shgc)

A

The fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed and subsequently released inward

Between 0 and I

O = less solar/radiant heat goes through (higher performance) (low=0.2 →> 0.4)
1 = 1/8” untreated plate glass la lot of heat transfer)

SHG through my window/ SHG through 1/8” glass

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4
Q

Solar insolation

A

Radiant energy per sf

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5
Q

British thermal units (btus)

A

The heat required to move 1 pound of water 1º

212°- steam

How many BTUS to go from 212° boiling to 212° steam? 1061 BTUS (changing state liquid → gas)

How many BTus to go from 72° to 212°? 140 BTUS

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6
Q

Do you sweat more when It’s humid or dry?

A

Dry - because the air evaporates the skin faster so it doesn’t feel sweaty

Humid air can’t hold anymore moisture so it can’t evaporate it (think like the air is a sponge or glass of water)

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7
Q

Air temperature and humidity interaction

A

Psychrometry-

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8
Q

Relative humidity

A

% Of moisture in the air at a particular temperature

What spills over from relative humanity to a lower temperature is dew, condensation, clouds - cooler air can’t hold any more moisture

Absolute humidity =humidity ratio

Warm our can hold more moisture than cool air can

When things evaporate, it makes you feel cold

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9
Q

Enthalpy

A

Total heat in the air

Sensible heat ( air temp) + latent heat ( moisture level)

Wet bulb temp is a good indication of total heat

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10
Q

Low - e (emissivity) glass

A

Helps prevent radiant heat

I is like no glass at all
O is like there is an opaque object

Low-e glass boasts a low SHGC

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11
Q

Balance point temperature

A

65°

. Heating or cooling degree days

If it’ cooler outside, we heat, IF its warmer, we cool

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12
Q

Degree days

A

The number of days per year and the differences in degrees from the baseline (balance point) temperature

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13
Q

Heating degree days (winter calculation)

A

Helps plan if we need high efficiency windows _ creates a relationship between high efficiency and low energy - more effective
Cold winter = higher HDDs
More than 5500 HDDs is long and cold
Less than 2200 HDD s is mild

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14
Q

Cooling degree days (summer calculation)

A

A hot or long summer will have more cooling degree days

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15
Q

Conductivity (k)

A

The rate at which heat passes through a specified material

The measure of efficiency of conduction of a material

If heat moves quickly, conductor
If heat moves slowly, insulator

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16
Q

Resistivity (r)

A

1/k = r

The rate at which a material resists the transfer of heat

High resistivity doesn’t change much when heat is applied

We generally want high resistivity because we don’t want materials exchanging heat - especially in cold or temperate climates

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17
Q

Conductance (c)

A

Homogenous materials of any given thickness or for a heterogeneous materials with known thermal properties (cmu block)

Higher number means heat transfers more quickly

C= 1 / R

Inverse of resistance (R)

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18
Q

Resistance (R)

A

Homogenous materials of any given thickness or for heterogeneous materials with known thermal properties
Higher number means heat moves slower

R =1 / C

Inverse of conductance (C)

heat takes 2x longer to go through thicker material = 1/2 as efficient transfer

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19
Q

U -value

A

The measure of the overall ability of a series of conductive and connective barriers to transfer heat

U = 1 / RI + R2+ R 3…

Thermal transmittance of an assembly

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20
Q

Conduction

A

Heat exchange between two surfaces that are in contact ( your elbow and the desk )

Q (BTU / hr )=u (u-value) x A (area )x delta T (temp change)

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21
Q

I F we double the u-value, what happens to the rate of heat exchange across the assembly?

A

It will double the heat exchange ( Q)

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22
Q

If we double the A (area) what happens to Q?

A

It will double the heat exchange

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23
Q

If we cut delta T by 50% what happens to the rate of heat exchange through the assembly ?

A

It reduces heat exchange by 50%

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24
Q

Air change per hour ( ACH )

A

Intentional ventilation- pull air in through HVAC to keep fresh air (internal load dominated buildings require more)

Unintentional - infiltration- cracks that allow air exchange (typically enough for homes)

0.9 ACH means 90% of air refreshes per hour

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25
Q

Convection: infiltration

A

Q= 1.08 X CFM X delta T

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26
Q

For a temperate climate (warm summers and cold, winters) heat transfer for conduction ( Q) is more of a concern in the -?

A

Winter-temperature change is greater in the winter

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27
Q

Higher conductivity is a - – r-value.

A

Lower r-value

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28
Q

Thermal breaks

A

Radiation faults in construction

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29
Q

What causes a building to get stuffy?

A

Build-up of co 2 - why buildings want to “flush” every

day

Don’t put fresh air intake at ground level or near extra co 2 ( loading dock)

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30
Q

Radiation

A

Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter
- the temperature of objects in view (fire)

Function of 4 things
- delta T cubed - if double T then rate of heat exchange is multiplied by 8
- angle of view-as you step closer to a surface you exchange more heat w/ that surface ( large cold bedroom window makes you cold - cold surface ) (bonfire-face is hot, back is cold - does not “turn the corner”)
- absorptance
- Emittance

The mean radiant temperature (MRT ) at any point is a result of the combined effect of a surface’s temperature and angle of exposure

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31
Q

Absorptance

A

Dark and matte materials and surfaces absorb more heat - light or reflective materials reflect heat

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32
Q

Emittance

A

A materials ability to release heat through radiation (dark and matte) - absorbed then emitted

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33
Q

emittance + absorptance = emissivity

A

Think low emissivity glass

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34
Q

Doubling The thickness of a given homogenous wall material will - —_-‘ the wall’s u-value?

A

Halve

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35
Q

In the US during the summer, — receives the most radiant heat?

A

Flat roof

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36
Q

Two bodies in direct contact with each other will transfer heat primary by the mechanism of -?

A

Conduction

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37
Q

Passive thermal buildings

A

Direct-gain space
Trombe wall (indirect gain)
Son space ( indirect gain- buffer zone )

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38
Q

Altitude

A

Suns position in the sky along the vertical axis

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39
Q

If the set point temperature is 70°F, the buildings balance point is 55°F, and the outdoor temp is 70°F which is the mechanical system most likely dong?

A

Cooling

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40
Q

Compression -refrigeration loop

A

( Air conditioning)
A closed loop tube with coolant and the pipe exchanges the heat - pump and valve → pump increases pressure,There’s more fluid /less gas, forces liquid to compress (condensing side) so it heats the pipe and our that is blown over it warms → after valve, there IS less pressure/heat and the liquid evaporates/ boils from liquid to gas ( At room temp) → low pressure/ less fluid makes the pipe cool like an aerosol can
Coolant boils at room temp

Produce heat changing from gasto liquid

This is how a window a/c runs

Big systems are similar but use chilled water systems instead

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41
Q

Exhaust air fans

A

Pulls air from spaces we don’t want the air to recirculate (restrooms, Kitchens)

Creates negative pressure → so it doesn’t push air into adjacent spaces

Can be loud

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42
Q

Economizer cycle

A

Cooling with “free” cold outdoor air _ free coding

Water side economizer vs air side economizer

Water -
Water in cooling tower gets cold from outside air and cold water cools coolant - > expansion valve is opened and pressure equalizes and temp equalizes → chiller becomes a simple heat exchange system

Airside _
Directly introduces cold exterior air → improves IAQ

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43
Q

Heat pump

A

Flip the flow of coolant and inside becomes condenser and heats → recirculates room air

Air to air heat pump

Sometimes coolant doesn’t want to evaporate in cold, so the system is less efficient before you flip.

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44
Q

Geothermal heat pump

A

Ges-exchange or ground source coupled heat pump

Use the earth instead of air as heat sink.

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45
Q

Thermostats in “zones”

A

Tells the system to heat or cool per zone

You can also zone by air quality, schedule, occupancy

Setting a thermostat higher than you want won’t make it heat or cool faster

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46
Q

Grill

A

Air intake

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47
Q

Register

A

dumps air into room.

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48
Q

Diffuser

A

Directs air throughout

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49
Q

What happens when a building is negatively pressurized?

A

Sucks water in through the skin, so we exhaust less than we bring in (positive pressure)

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50
Q

Energy recovery ventilator (erv)

A

For efficiency when it’s cold, bring intake air by the exhaust air for heat exchange → then exhaust air is cooler and we waste less heat, and intake air requires less heating to get to room temp- can take up a lot of space.

Pre-heat or pre-cool the air

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51
Q

What are the advantages of having one independent air handling unit for each zone?

A

Control - disadvantage IF it’s a large building (too many units)

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52
Q

Variable Air volume Unit

A

(Vav) - single zone systems are ideal but not economic - this arrows some control with a damper per zone in a bigger system - variable air volume box with damper entering the zone, allows variable air flow based on thermostat

Damper cannot shut completely - fresh air required by code.

Disadvantage - cannot heat and cool at same time, can only reduce amount of cold air into one part of zone -try to smartly plan systems to have typical expected temperatures/needs connected

Advantage - good for big buildings that don’t need zones of specialized air

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53
Q

Terminal reheat with VAV

A

Similar to VAV but each zone has a heating element inside the VAV that allows the cool air coming from the main system to be heated
Adv - lots of control, space and equipment efficiencies
Dis- wasted energy

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54
Q

Dual duct system

A

Not used anymore- highly inefficient

I hot and I cool duct both feeding a “mixing” box so temps were highly controlled

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55
Q

“Right size” equipment.

A

Designing for typical use, not the one time a year the system may be overloaded

  • cuts cost of equipment, oversized is less efficient, oversized a/c doesn’t workhard enough to evaporate causing moisture to stay in the air
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56
Q

Why do we need preheat in an HVAC?

A

Cooling coil can’t handle something too cold ( air from outside) or it will freeze and burst leading call removes moisture from the outside air)

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57
Q

HVAC common in multi-unit housing

A

Chiller with AHU

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58
Q

Square box with X

A

Supply air

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59
Q

Square box with \

A

return air

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60
Q

Internally lining ductwork

A

Reduces air noise - but could have fibers (bad iaq) or cause condensation (mold)

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61
Q

Fan coil Unit (fcu)

A

Just a fan in a space or adjacent ( single room)

Often in mid-range hotels - wall based _ high control, minimal ductwork

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62
Q

In the compression-refrigeration loop, which IS likely to be warmer? Conduser coil or evaporator coil

A

(Air conditioning)

Condenser coil

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63
Q

A machine that uses a reversible compressive refrigeration loop, so both coils may take the role of either evaporator or condenser.

A

Heat pump

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64
Q

Air - Air system

A

Both coils are cooled and the coils are in their own room (isolated)

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65
Q

Mini-split system

A

Through wall- units (fan and compressor in the room)

Fan coil unit in each zone - can be condenser OR evaporator when needed - the outdoor unit has condenser and fan.

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66
Q

What makes hydronic heating in the floor a low energy strategy?

A

Often feet are the coldest, so heating this makes US overall more comfortable; heat rises from here; floor is a huge area that all allows us to feel heat from many places, allowing us to put the room set temp (for air) cooter

Why doesn’t this work for cooling?
The warm aer would condense on the cooler surfaces → chilled beams are the equivalent

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67
Q

Swamp cooler

A

Add moisture to hot dry air which cools the air

No compression/ refrigeration loop

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68
Q

What causes HVAC noise?

A

If air moves against damper too fast - it vibrates and makes noise → so we slow the air through the duct = less noise and less friction (turbulence) in the system

Bigger ducts = slower air
Smaller ducts = faster air

We still need the same CFM so when we slow the air it means we need more space (bigger duct)

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69
Q

NC level

A

Background noise level - more background noise from equipment means worse performance in the space (classrooms)

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70
Q

What is the difference between a furnace and a boiler?

A

A furnace heats air and a boiler heats water

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71
Q

Rooftop water to water system

A

Chiller and cooling tower on roof → cooler has evaporator/condenser loop → pump cool water into building, fan or VAV pumps into rooms

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72
Q

Remote water to water system

A

Cooling tower and chiller located up to 1/2 mile away from building → same chilled water supply and return (chiller is condenser / evaporator loop)

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73
Q

Geothermal summer water to water system

A

Works best when heating and cooling needs are about the same

Condenser / evaporator connected to water pipes in the ground to collect or shed heat

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74
Q

Rooftop water to air system

A

Condenser connected to cooling tower → air directly blown across evaporator → air sent through building, additional fresh air intakes to keep positive pressure and direct air exhausts per zone (smaller)

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75
Q

Water to water system: basement chiller and rooftop cooling tower

A

Rooftop cooling tower → water sent back to basement to work in the chiller (condenser/ evaporation loop) → water from chiller circulated back through buildings → var or air fans to distribute into o zones

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76
Q

Basement water to air system

A

Cooling tower on roof → sends water to basement into condenser → connects to air blown over evaporator coils → air transmits through building system

Exhaust per zone → the higher on a building the air intake is, the less polluted the air

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77
Q

Split-system

A

Quiet inside but does not scale to large buildings with large cooling load and many zones

Exterior condenser (max 100’away) compressor sends refrigerant inside to evaporator ( air over coils ) → air sent around building

This is most common for single family residential

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78
Q

Air-to- air system

A

Condenser cooled with air and return air is cooled by running directly over the evaporator. No piping, pumps, or cooling tower needed, but not as efficient as water- to-water systems for large buildings

Air intake and exhaust → condensor/evaporator loop with refrigerant → air throughout, intake from zones back to condensor/ evaporator

Consistent temp to all zones, not efficient for custom temps

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79
Q

Evaporative condenser

A

Air and water spray used to cool the condenser - exterior connector that releases heated air and moisture because coils and fan are sprayed with water to cool → compressor sends refrigerant inside to evaporator to be distributed through air system

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80
Q

Window units (also called direct expansion units, DX systems and unitary system)

A

Thermal control and no ductwork needed, but a lot of equipment to purchase se and maintain, lots of noise, and not easily hidden from exterior and interior view

Compression/evaporation loop in single small unit ( heat pumps /reversible)

Simplest but can be hard to design when there are a lot of zones

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81
Q

Single zone design

A

Thermal control but a lot of equipment/ ducts to purchase, maintain and house

Each zone has its own AHU, thermostat, fan, heat source, etc.

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82
Q

Thermostat

A

Measures room temperature and tells fan/valve when to turn on and open up

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83
Q

Fan coil units (fcu)

A

More thermal control and no ducts needed, but because there are no ducts, these systems are loud and often cannot provide core zones with fresh air _ have to rely on opening windows for fresh air in internal rooms

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84
Q

Chilled beams

A

Radiators for coolth, can be near silent

Can be comfortable as a warmer temperature ( think radiant floors )
Good for lab buildings
Can be valance systems

Con - if room is too humid or beams are too cold, can cause condensation

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85
Q

VAV with terminal reheat

A

Less equipment, more thermal control, but sometimes heats and cools the same air,wasting energy

Many zones share one AHu

Terminal reheat is a heater per zone to heat this zone from the main air supply to meet that zones needs

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86
Q

Radiant cooling

A

Can be silent - like radiant heating, not super common. Similar to chilled beams. Requires fewer BTUS, takes more time to work-better for 24/7 occupancy - can cause condensation

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87
Q

Mini split system

A

(20Th century) each zone has a refrigerant coil that can serve as an evaporator or condenser. No ducts needed.

One single outdoor unit - high pressure outside low pressure inside - can reverse flow (heat pump) IF all zones need heating
Valves and compressor send or pull refrigerant from the occupied zones depending on what the thermostat says is needed

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88
Q

Swamp cooler

A

Low energy (no compressor) but only available in arid climates_ The interior maybe exclusively humid and only modest cooling offered on very hot or rainy days

Air is cooled through a wet pad before it goes into the space

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89
Q

Which of the following types of copper pipe would be the best choice for a line buried as an underground water supply

A

Type K (thickest)

Type L - most common supply line

Type m - thinner (low pressure, condensate )

Pipes are rated by thickness of pipe wall

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90
Q

Which types of copper pipe would be installed as a stack vent?

A

DWV - drain, waste, vent

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91
Q

Type K copper pipe

A

Thickest copper pipe- good underground

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92
Q

Type L copper pipe

A

Medium thickness - most common supply line

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93
Q

Type m copper pipe

A

Thinner - low pressure, condensate

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94
Q

Type DWV copper pipe

A

Drains, waste vents

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95
Q

Bring water to the ground slowly

A

Slowly - allows ground to fitter
Quickly-causes erosion, flooding, lose topsail, change stream ecosystem

Take water Off the road

If materials allow water to mare through them, we have better control of how to manage it

Impervious vs pervious paving

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96
Q

Blue roof

A

Ponds water intentionally on roof-slowly releases

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97
Q

Plastic pipe vs metal pipe

A

Plastic pipe
Less friction, less money, smaller buildings

Metal pipe
More friction, more money, bigger buildings

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98
Q

Supply and waste water NEVER meet

A

Make sure there’s an air gap between max water line and supply or a vacuum break - prevent negative suction (backflow preventor)

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99
Q

Gate valve

A

Mostly used for maintenance

Looks like a dropping gate, screws in - can be used for a building or device

Ball valve - similar to gate, used for maintenance _ handle with on /off valve

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100
Q

Globe valve

A

Mostly used for faucets - repeated use - end of the line at a fixture - comfortable to use

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101
Q

Check valve

A

Used for back-flow prevention

Right as water enters the building

Allows water to move one direction and not the other

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102
Q

Vacuum breaker

A

Backflow prevention

Creates a siphon → adds air instead of dirty water

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103
Q

Pressure formula

A

Pressure (psi) = 0.433 (constant) x H (height)

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104
Q

A water tank is 75 ft above a fixture. What will the pressure at the fixture be?

A

P =0.433 x 75ft
P=32.475 psi

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105
Q

—-… —-… —- water line diagram

A

Hot water return

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106
Q

—-.. —- .. —- water line diagram

A

Hot water supply

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107
Q

Water line accesses building -

A

Below frost line → check valve → water meter → gate valve → then to water treatment, heaters etc.

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108
Q

Point of use water heater

A

Under sink for immediate use

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109
Q

Grey water

A

Waste water that Does not include human or food waste - can reuse (irrigation)

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110
Q

Black water

A

Any thing including human or food waste (toilets, kitchen sink)

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111
Q

How do you size pipes?

A

By pressure and flow

Provide enough flow for all fixtures with the knowledge that all fixtures want be used at the same tine

Fixture units → allows us to calculate the amount of water needed and likelihood of it being used simultaneously

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112
Q

Expansion loop

A

For hot water pipes at long hot water runs- allows pipes to expand or contract on either side w/o bursting pipes

113
Q

P-traps

A

Keep water sitting so the sewer gas doesn’t come up

114
Q

Hot water temps

A

140° - kitchen and laundry (kill bacteria)
110°- shower
105° - hand washing

115
Q

Drains and traps

A

Most fixtures require a drain and most drains require a trap

Including a vent Allows gasses to escape and. Prevents them from entering the building and prevents the trap from siphoning

116
Q

Illegal plumbing traps

A

S-trap
Crown-vented trap
Bell trap
Drum trap

117
Q

Legal plumbing traps

A

Bottle trap
P-trap

118
Q

How does a grease interceptor work?

A

Inflow from restaurant, scum and grease float, solids sink, provide pipe 12” from bottom of 1st tank to take cleanest water to second tank, separates more, water goes to sampling boxthen to server city main. Periodically must be cleaned. Manhole access per tank min.

119
Q

Plumbing vents

A

Most traps require A vent, some fixtures can share, depends on code interpretation can be individual that join at soil or vent stack.

Individual vents - one per fixture; meet at branch vent then into soil stack

Circuit vents - fixtures combine into 1 branch vent

Soil stack and waste stack

120
Q

Soil stack

A

Black water - where black water is draining - stack vent is above soil stack

121
Q

Waste stack

A

Grey water - where just gray water is drawing -stack vent is above soil stack

122
Q

Vent stack vs stack vent

A

Vent stack- parallel to stack -only for venting, meets stack vent above soil line

Stack vent - above stack - main vent of entire section of system

123
Q

Why is there a parallel vent to the soil stack?

A

Because you don’t want soil to get into vent system as you go down levels, so one primarily vents while the other is soil

124
Q

Cleanouts

A

Required any time the pipe turns more than 45° ) then every 50’ of horizontal line

125
Q

Manhole frequency

A

200’

126
Q

Septic system

A

Similar to grease trap - solids sink and scum floats - anaerobic bacteria breaks down solids and liquids go to a leach Field through perf. Pipe (from midtank for cleanest (guid) - has vent pipe to get gas escape - have to do percolation test - IF not good percolation, may be unusable or build mound w/ better soil ($$$$)

127
Q

Pipe angles

A

Vertical or near horizontal (1% to 4%) where solids can float adequately

Between 4% and 45° solids often clog because liquid moves too fast

128
Q

Artesian well

A

Water comes from an aquifer under pressure ( can shoot water up)

129
Q

Shallow well

A

Less than 25’, requires pump

130
Q

Deep well pump

A

Sends some low pressure water down to create positive pressure up (almost a siphon)

131
Q

Swamp and ejector pump

A

When there’s a toilet below the sewer ( basement)

132
Q

1 Pipe
2 pipe
Red pipe
Blue pipe

A

Heating and plumbing

1 pipe system - 1 continuous heating pipe throughout the home- everywhere gets the same temperature output
→ a parallel 1 pipe system can allow units to close the system with a control valve and allow water to pass (think radiator) - (series perimeter loop - everything on or everything Off

2 pipe reverse returns - a hot supply and cold return pipe, so the hot stays hotter throughout because the return is separate - can better control heating and coding per zone, but can’t switch systems easily

4 pipe system - more pipes, most common now _ hot and return, cold and return

133
Q

What is hard water?

A

Water that contains mineral deposits

Hard water can cause clogged pipes - reduces ability to exchange heat, bad for hydronic systems

134
Q

Tankless (inline) water heater

A

Hot water is not kept ready, but system heats quickly - gas heats water pipes quickly _ unlimited supply of not water, more energy efficient not holding not water, no AC fighting against hot water sitting there

135
Q

Plastic pipe types

A

Abs - acrylonitrile-butadiene styrene
PE - polyethylene
PVC - polyvinyl chloride
PVDC - polyvinyl dichloride - safe to use with hot water

136
Q

Why insulate pipes?

A

Keep heat or coolth for long distances and keeps it from depositing heat or coolTh where it shouldn’t be
Cold pipes → keeps from condensation

137
Q

For a residence, a circuit includes (4) 100 - watt lamps, (5) 200 watt receptacles, and (4) 75 watt lamps. How many total watts are used in this circuit when fully loaded?

Given that the circuit is a standard 120V, what should be the current ( amperage ) for the circuit? Assume a power factor of 1.0

A

4 (100) +5 (200) + 4(75) = 1700 watts

1700 W /I2OV=14.2amps

138
Q

Electricity

A

The movement of free electrons

Metals have a lot of free electrons (why wire is metal)

139
Q

Direct current (DC)

A

Electrons move from (positive side) of battery through the conductor (wire), across a resistor (lightbulb), then back to the battery (negative side) - eventually voltage becomes equal on positive and negative ends of battery and the battery is dead → battery can be recharged and mores electrons back to the positive side

140
Q

Alternating current (AC)

A

Electrons come from a power source, through the conductor (wire), across resister (lightbulb), to the ground, then go back again (60 times per second in us → 50 times per second in Europe)

141
Q

Ohm’s law

A

W (power in watts) = I (current in amps) X v (votage in volts )

1700 w= I x 120v
14.2w/v= I ( amps)

Acts like pipe size, lower in number of the conductor gauge, thicker in size of the wire

Higher diameter = more current

Big wires, high amp circuits → get hot over long distances and leak electricity to electromagnetism

High amps / low volts → thicker wire, lower pressure
Low amps/high volts → thinner wire, higher pressure (high energy)

142
Q

Power lines

A

Not insulated- need to be high so they don’t arc to the ground, squirrels ( when they touch the wire and pole ) can fry but birds can’t - high voltage transmission lines

DC current would require power plants and generators every few blocks s too much would be lost over the distance and too many wires

DC works better underwater than on land

Power plant (60000V) to transmission substation → high voltage transmission lines → power substation with transformer (transfers to 12000V ( less dangerous) → smaller normal power lines → transformer power drum (120V) and transfers into building -.- the current is always morning back and forth (alternating)

143
Q

Series circuit

A

Bad - of light bulb burns out, entire circuit stops working (Christmas lights)

144
Q

Parallel circuit

A

This IS how we wire → switch allows wire and current to bypass light bulb and still work

145
Q

Cogeneration

A

Using extra heat from steam plants ( heating units) to also produce electricity

Electricity is not effective for heating/water heaters because its a high energy use fuel
Low grade fuel like natural gas for heating water
High grade fuel for high grade use like electronics ( electricity)

146
Q

For a building with 277 / 480 V; three- phase, four- wire service, typically the electric lighting runs on - ?

A

277V

147
Q

Small building electric loading

A

120 v, single phase, 2 wire

On or off, one ground, 1 hot wire at 120V

1 hot 120V wire, 1 neutral

148
Q

Single family residential electric load

A

120V / 240 v
120V / 240 V, single phase, 3 wire

2 hot 120V wires, 1 neutral → connect (2) 120V hot wires to get 240V

Put some on each wire to split load, combine wires for heavier load (appliances)

2408 is the max pressure is the pressure goes up and ( negative) think sin wave, up 240 above o, down 240 below o

149
Q

What are some higher voltage/wattage appliances that you occasionally see around the house?

A

Air conditioning, electric range, electric dryer
(These want 240V)

150
Q

Power vs electricity

A

Power - electricity over time, batteries, coal etc - can be stored

Electricity-cannot be stored -

Power is measured in electricity over time in kWh

151
Q

School level power

A

120V / 208V, 3-phase, 4-wire

3 120V wires, I neutral
I line, one set of CRs, another line another set, etc. (Not phased)

Then 3 lines combine to get 208V 3-phase motor fan _ this staggers electrons coming from each 120V line to not overwhelm any one line.

Staggering allows the motor to run more smoothly

152
Q

120V / 208 V

A

120V + 120 v+120v = sq. Root 360V = 208V - peak voltage is not all at the same time (alternating 3-phase) so its 208, not 360

Use 208V for bigger items, 120V for normal

153
Q

Power option for massive buildings

A

277 v / 480 v, 3-phase, 4 wire

3 line 277 v and 1 neutral, use a lot of copper in the building to help with pressure (smaller wires) to take higher energy to mini transformers

Connect 3 277V wires for hid / fluorescent lighting ( can run on any of the lines at once )

27 7 + 277 + 277 x sq root 3 = 480V

480 V taken on copper wires to 120V mini transformers throughout building to lose less power as it goes down the line

154
Q

Industrial power requirement

A

2400 / 4160 v, 3 - phase, 4-wire

Super high power,

155
Q

3-way switch

A

2 different switch locations to turn a circuit on or off

156
Q

4 way switch

A

3 way switch on either side and central switch that changes from parallel to cross to complete the circuit

157
Q

3-phase from power company to building

A

3 wires into the transformer (no neutral) ) neutral at transformer tied into the ground (has electrons), 4 wires into building including ground to electric panel, then dispersed. Ground from building has no electrons- circuit shorts IF there are

158
Q

Delta power

A

Only has single voltage available. (phase-to-phase) so only 208 V or 480V IF equipment is designed for wye, using delta can cause problems

Transformer connects hots in delta, no neutral
- power company transformers are often delta (3) -look at power lines

3 hot wires, no neutral

159
Q

Wye power

A

Has two voltages available (phase-to-phase and phase-to-neutral ) 50 120/208 V or 277 / 480 V

Allows for choice of voltages

3 hot wires ( Y shape ) plus a neutral

160
Q

Power factor

A

A result of the current and voltage being out of phase

Between O and 1 (like tax on watt output)

161
Q

Non - metallic sheathed cable “romex” - wiring

A

No conduit, really only used in single family residential , not protected well

162
Q

Electrical steel conduit

A

Protects the wire, supports the wire, required in most buildings, expensive and slow, grounds and protects from heat - run conduit to junction boxes then flexible armored cable runs to fixture

163
Q

Flexible armored cable

A

” A C “

2 types
Bx - metal casing in ground (integrated)
Mc- has separate ground

164
Q

Chargers and batteries

A

Need to be DC
Most chargers have mini transformers gong from AC to DC

165
Q

Rectifier

A

Mini transformer _ an electrical device that converts alternating current (AC) which periodically switches direction to direct current (DC) which flows in one direction

166
Q

Inverter

A

Changes direct current (DC) to alternating current (AC) used in buildings with photovoltaics

Pv produce DC but we need AC for appliances and connecting to the grid

167
Q

Overcurrent protection

A

Keeps from starting a five - used to be a fuse

Mechanical breaker, GFCI it.

168
Q

Fuse

A

Low melting point piece of metal that melt’s and “switches” Off IF there’s a short

169
Q

Mechanical breaker

A

Senses heat in a circuit and switches Off

170
Q

GFCI

A

Anywhere there is water, required - measures both directions and makes sure there is no fault

Has a ground wire - will trip if electrons are sensed

171
Q

Poles vs throws

A

Pole- number of circuits the switch can control for one operation of the switch

Throw- the number of contact points

172
Q

Two throw / double throw switch

A

Either or situation

173
Q

Double throw, double pole (2 outlets)

A

2 systems tied together, either or situation

174
Q

Multi-throw

A

Either or switches

Either on or off

175
Q

Multi-pole

A

Switches ganged together

176
Q

Single-pole / single throw

A

Most common - 1 switch, on or Off

177
Q

Double pole, single throw

A

2 switches, on off only

178
Q

Single pole double throw

A

Single switch, this or that on

179
Q

Single-pole, triple throw

A

1 switch, three options on (3 levels of on )

180
Q

Double pole, double throw

A

2 switches, 2 levels of on or off

181
Q

4 pole single throw

A

4 switches, on/off same circuit

182
Q

Three-pole double throw

A

3 switches, either or

183
Q

Single pole - 4 throw switch

A

One switch, 4 options/levels of on

184
Q

Switch gear

A

First thing when power comes on in building, a switch to switch the rest of the switches, keeps you from touching high volts inside the building (steps down the power)

185
Q

Metrics used to establish maximum noise levels

A

A-weighted decibels ( d BA)
Noise criteria (NC)

186
Q

(Metrics) International building code requires a minimum level of 50 between units in multifamily housing

A

Sound transmission class (stc)
Impact isolation class (iic)

187
Q

(metrics) Space fo runamplified music performance is too dry (sound dies too quickly)

A

Reverberation Time (RT)
Nose reduction coefficient (NRC)

188
Q

(metrics) field test measurements include influence of flanking noise

A

Transmission loss (tl)
Sound transmission class ( STC )
Impact insulation class (iic)

189
Q

(metrics) higher number value associated with quieter rooms

A

Noise reduction coefficient (NRC)
Transmission loss (tl)
Sound transmission class (stc)
Impact insulation class (iic)

190
Q

Acoustics

A

The disturbance of molecules (vibration from objects making noise) in an elastic medium (air)
Molecules bumping into each other

Sound molecules move side to side in a wave, not randomly

191
Q

1 hertz

A

1 beat per second

20 Hz is when we can’t differentiate beats (20 beats per second)

192
Q

Octave bands

A

Sound levels vary across frequency, so we break them into octave bands

Lower are more vowel sounds
Higher are more consonants

Geometric increase, doubles each band
63hz, 125hz,250 hz, 500 hz, 1000 Hz, 2000 Hz, 4000 Hz

193
Q

Speed of sound

A

Mores at 1128 ft/sec

194
Q

If you are standing 20’ away from someone, how long will it take for the sound to reach you?

A

20 milliseconds

195
Q

Absorption coefficient (alpha)

A

Quantify amount of sound reflecting back into a room

Between 0 and I

o = all sound reflected
I = no sound reflected

An effective absorber is greater than 0.75 (25% is reflected)
An effective reflector is less than 0.20 (80%; reflected)

196
Q

Noise reduction coefficient (NRC)

A

Average absorption coefficient in the 4 mid range octave zones
Not always effective for low and high frequency

Additional absorption material becomes exponentially less effective

Massive difference when no absorption is present, minimal when absorption already exists

197
Q

(Ray tracing) specular reflection

A

The angle at which a sound is sent and the angle it returns
(Think billiards)

When surface is smooth, bounces back ,when surface is not smooth, it diffuses

198
Q

(Ray tracing) Progressive enclosure

A

Why is sound different inside vs outside?

Anechoic (non-reflective) environment (free field) meaning without an echo
Absence of reflecting sound

Ground and back wall plane _ direct sound and reflected sound - reflected sound arrives later (echoes) and weaker _ some sound energy has been absorbed by the surfaces (first order reflections / second order reflections _ echoes) the more surfaces the more reflections

199
Q

Average mean free path

A

How we quantity sound decay - sound level gets lower over time because some is absorbed and what remains has traveled farther

200
Q

How do you keep sound out?

A

Airtight, massive, structurally discontinuous _ the cracks or leaks in a wall are where sound gets through (penetrations)

201
Q

STC ratings

A

Sound transmission class

( Low frequencies ) amplified, mechanics, transportation - more massive walls handle this better and keep law frequencies out even it STC is the same

Metal studs perform better than wood

202
Q

A-weighted decibels

A

Single number rating that summarizes a sound level across frequency spectrum
dBA
Exterior or environmental nose typically

203
Q

Noise criteria

A

(NC)

Measures background noise (low frequency) - we are less sensitive to low frequency noise

Higher NC levels = more noise

204
Q

S Tc of open window

A

O

205
Q

Airborne noise V.s structure born noise

A

Airborne - people, tv → massive, airtight, discontinuous help

Structure _ hammers, footsteps → here we need something squishy

Massive → multiple layers of gyp
Air tight → minimize penetrations
Structurally discontinuous → staggered/ double stud, resilient channel, resilient clips ( creates a break, no rigid connection), rubber stops between metal and wood connections

206
Q

Structure born noise

A

On surface impact noise- Footsteps - provide something squishy like carpet → better is a floating floor system

Impact insulation class (iic) measures this better than STC (more adjacent sounds)

207
Q

Reverberation Time (RT)

A

Room acoustics

208
Q

Noise reduction coefficient (NRC)

A

Average absorption at speech decibel

209
Q

A-weighted decibel ( dBA)

A

Level of background noise

210
Q

Sound transmission class (stc)

A

Single rating across all octave bunds

211
Q

Impact insulation class (iic)

A

Footfall rating (high=70,low=30)

212
Q

( Metrics) used to establish maximum noise levels

A

A-weighted decibel D BA
Noise criteria (NC)

213
Q

Sound isolation floors

A

Floating floors, insulation under and adjacent

214
Q

Sound barriers

A

The higher the barrier above line of site the better - better still to bury noise, _ barriers are best close to noise source or receiver, not in the middle

215
Q

Why are rooms perceived to be dark

A

Usually from dark finishes causing excess contrast to the outdoor light (glare)

216
Q

Glare

A

Excessive contrast

217
Q

Lamp

A

Light source

218
Q

Minimum egress light requirement

A

I foot candle

Typical classroom or office- 30 -. 50 fc
Bright room =100fc
Bright day = 10000 fc
Typical application = 10 - 100 fc

219
Q

Footcandle

A

The amount of light energy that strikes one square foot sone foot from the source

220
Q

Best for rendering color (highest cri)

A

Incandescent

221
Q

Best efficacy (highest-lumens-per- watt value)

A

Metal halide

222
Q

Lowest heat output per lumen

A

Fluorescent

223
Q

Widest range of color temperatures available ( °K)

A

Fluorescent

224
Q

Lowest color temperature (°K)

A

Incandescent
High pressure sodium

225
Q

Longest lamp life

A

Metal halide
High pressure sodium

226
Q

Worst for color rendering (lowest cri)

A

High pressure sodium

227
Q

Requires ballast for operation

A

Fluorescent
Metal halide
High pressure sodium

228
Q

Slowest start and restart time

A

Metal halide

229
Q

Dimmable

A

Incandescent
Halogen
Fluorescent

230
Q

High intensity discharge (hid)

A

Metal halide
High pressure sodium

231
Q

Incandescent lamp

A

Oldest - Edison
Sends electrons through filament, filament heats, sends photons ( light)

Advantages - high color rendition (cri) because the source provides all ranges of color
100 CRI

Dis-high heat, high wat low lumen → low efficacy, watts wasted as heat instead of lumens, short life - 2000 hours

232
Q

Efficacy

A

Efficiency

High lumen, low watt = high efficacy

233
Q

Color rendering index (cri)

A

1 → 100

100 is perfect, you can see 100% of colors (sun, candle, incandescent)

234
Q

Fluorescent

A

Different technology
Ponder coated inside tube (phosphors ) → this is what the electrons heat and produce light → phosphors can be different “shades”
Low heat, high efficacy
Lower CRI → 85max → 70 - 60 typ
5000 -10000 hours

235
Q

Correlated color temperature

A

The color a lamp appears - we correlate the color of a lamp to the color metal turns when it is heated
→ degrees kelvin
Higher degree is bluer even though it’s “cool”

236
Q

Metal halide

A

Used in stores, stadiums, larger spaces - very bright _ High intensity discharge (hid) - pretty “cool” light _cri=85 - are light, takes longer to turn on - 15000 hours

237
Q

High pressure sodium

A

Usually outdoors, street lighting - very efficient, long life - cri-25 - 25000 hours - 2000K (warmer) - hid - replaced low pressure sodium

238
Q

Discharge lamps

A

Require ballasts - to regulate the current _ used to hum

Electronic ballast - ballast and lamp have to be made for the same function

239
Q

LED lamps

A

Newer technology - cri-85 - little heat → heat that is released is hard to remove (must be through convection) -light fades as it goes out - have to measure life by when they lose half their output → can go in incandescent sockets, but heats quicker so they go out quicker _ 50000 hours, can be any color

240
Q

When designing an art gallery, which metric would be most rekranet in your lighting strategy?

A

CRI - color rendering index

241
Q

What size is an a-17 incandescent lamp?

A

17/8 = 2 1/8”

Measured like rebar

242
Q

Lamp

A

Light bulb

243
Q

F 30 T 12 ww / Rs

A

F = fluorescent
30 = 30 watt
T 12 = tube diameter 1.5”
WW = warm white ( <3000 K)
Rs = rapid start

244
Q

Color (light)

A

The color visible is reflecting from the lamp and what light colors the lamp produces

245
Q

Grazing light

A

Light perpendicular to a wall - shows all imperfections (be intentional when you use this)

246
Q

Lamp lumen depreciation (lld)

A

0 to 1 - if you lose 10% you have an LLD of 0.9

Measured illuminance
Reduced by:
Lumen depreciation
Dirt on fixture
Wall color
Dirt on walls

247
Q

Footcandles (lux) = lumens / area in ft ^ 2

A

(Lamp lumens) x ( lamps per fixture )x (number of fixtures) x cu X LLF
_______
Area in ft ^ 2

1000 lumen / 100 sf = 10 fc

Lamp lumen = available light per bulb
Lamps per fixture = bulbs per lamp
Number offixtures
Cu =coefficient of utilization = % of light that reaches the work plane ( between o and I)
LLF = light loss factor =% of light that reaches work plane (loss due to lamp lumen depreciation, dirt, ballast factor, etc. ) (between O and I)

248
Q

Coefficient of utilization (cu)

A

% of light that reaches the work plane ( between o and I)

249
Q

Light loss factor (llf)

A

% of light that reaches the work plane ( between o and I) (loss due to lamp lumen depreciation, dirt, ballast factor)

250
Q

Daylight factor

A

Measures how well daylit the room is
A daylight factor of 1% means that inside has 1/100th of the light level of outside

Daylight factor (average) =0.2 X (window area / floor area)

251
Q

For daylighting reasons is it better to have a window high in the wall or low?

A

High because it brings light in deeper

252
Q

Power factor

A

Between 0 and I
Walls = volts X amperes x power factor ( circuit only)

120V assumed in America

253
Q

Apparent power (volt-amps)

A

Apparent power (volt-amps) = volts x amps

This measures the approximate power and IS close in value to the watts but does not include the adjustment for power factor

Used in purely resistive circuits, assumes power factor is I → incandescent lamp, waffle iron etc

254
Q

demand charge

A

Demand charge = maximum power demand x demand tariff

255
Q

Sound = lambda = c/f

A

Lamb = wave length, ft
C= velocity of sound, FPS
F = frequency of sound, Hz

256
Q

Dry-pipe fire sprinkler

A

Good for areas it can freeze - outdoors- Loading dock
First x-amount is gas/ air so water sits inboard of insulation / building so it doesn’t freeze
Same typical bulb melts, cur comes out, then water

257
Q

Pre-action fire sprinkler

A

Used where electronics Or important documents are stared so things don’t get ruined (so a small trash can fire or false warm doesn’t set it off )

Loud speaker/intercom stating the sprinkler will start in 30 seconds - chance to reset. So it doesn’t go Off

258
Q

Deluge Fire system

A

Used in high hazard areas like fertilizer plants or plane hangers -if sensor is tripped, they all go off

259
Q

Fire extinquisher types

A

A - water based - used for paper or wood
B - foam based-used for chemical fires
C- foam based - used for electrical fires
D-foam based-used for combustible metals

Kitchens use an ABC

260
Q

In-ground hydraulic elevator

A

Has machine room (pushes all that moves elevator) - slow-limited travel distance, not efficient, good chance of failure

261
Q

Traction elevator

A

More efficient, lasts longer, less maintenance, faster, smoother ride - weight / cables transfer-counter weight

262
Q

Hydraulic elevators

A

2 - 5 floors, 45ft travel - slow and inefficient

Direct plunger _ environmental concerns - water table issues - pushes oil into ground
Hole less - max lift 15’0. - cylinder and plungers above ground
Roped hydro - expensive / problematic _ increased travel distance - plungers and ropes/ jacks
Telescoping holeless - max lift of 40’ _ tekscoping plungers

263
Q

Traction elevators

A

Geared elevator - used to all be this, bumpy , usually bigger / freight elevators - geared = more torque - max rise of 150’ ,5 -15 stops, 500 F pm

Gearless elevator - much more common now, 2000’ rise, 15-60 + stops, 2400 f pm

264
Q

Gearless elevators

A

Traditional - machine room at top
machine room less - motor inside hostway, controller in wall, smooth., minimal maintenance, not powerful enough for really big buildings

265
Q

Elevators

A

Shafts require vents - 3.5% of hoist way size or 3st, whichever is bigger
More than 4 story buildings - elevator is required as an emergency egress for ADA (runs on emergency power)

266
Q

Escalators

A

Slope 30 -35%
Speed 100 - 125 f,pm
7 ft clearance required
125 people per tread
Max rise 20-40 ft,60 ft IF supported

267
Q

Which produces more power on a flat roof, angled or flat pv?

A

Angled - match latitude +/- 15
Flat gets dirty

268
Q

Tankless toilet

A

Flush valve - commercial toilet

269
Q

Tank toilet

A

Residential

270
Q

Halogen

A

A type of incandescent, but has gas and tungsten so it doesn’t burn out -20 - 30% more efficient

271
Q

Classes of standpipe

A

Class I - 2 1/2 inch pipe no nose attached
Class 2 - 1 1/2 “ pipe with 100’ of hose (cabinet)
Class 3 - 2 1/2 “ and I 1/2”

272
Q

Fire detectors

A

Heat detector - slower, not as effective - fire vs smoke
Ionization smoke detector- smoke interrupts a circuit, quickest to catch Fast fires
Photoelectric smoke detector - best for slow smoldering fires
Combination ionization and photoelectric smoke detectors - detects Fast and slow

273
Q

When are we required to use automatic ventilating hatches?

A

Atriums over 3 stories

274
Q

Maximum spacing for outlets behind a kitchen counter

A

4’
3’ clearance in front of electric equipment
30” wide working space in front of equipment operating at 600 V or less
Min headroom is 6’ or height of equip

275
Q

Where can’t outlets be?

A

Lower than 18” above a garage floor (gasoline fumes)
Can’t be over sink, tub or electric baseboard

276
Q

Which piping material has the highest coefficient of thermal expansion?

A

Plastic-can be bad over long distances when not and cold are used

277
Q

Sabine

A

Unit of sound absorption

278
Q

A four pipe fan coil system functions as what?

A

A heating and coding system

279
Q

What types of equipment must have their waste outlets equipped with air gaps adequate to prevent contamination due to any possible backup of sewage through waste piping?

A

Condensation/water dripping

Refrigerators and sterilizers

ARE STUDY (9 decks)

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