# Systems Flashcards

1
Q

A

have a lot of surface volume relative to their volume, thermal response is heavily influenced by the conditions outsid

2
Q

A

minimal surface area relative to volume (hospitals, skyscrapers, office buildings) or buildings that generate a lot of heat regardless of their volume (theater while in use, factory) aka have a lot of loads. Only need heating on worst winter nights, and around the perimeter. It’s more about shedding heat year round

3
Q

Solar heat gain coefficient

A

the fraction of net solar radiation through a window, both directly transmitted and absorbed and subsequently released inward
ranges from 0 - 1, higher means more of radiant heat goes through
Typ high is 0.7 - 0.9, low is 0.2 - 0.4

4
Q

solar insolation

A

radiant energy per sf of the sun

5
Q

British Thermal Unit (BTU)

A

the heat needed to move 1 lb of water up 1 degree F

6
Q

Psychrometry

A

relation between air temperature and humidity
When things evaporate, they make everything around them colder
Warm air can hold more moisture than cool air

7
Q

degree days

A

a unit used to determine the heating requirements of buildings, representing a fall of one degree below a specified average outdoor temperature (65°F) for one day
The higher the CDD, the longer or hotter the summer
The higher the HDD number the most severe the winter

8
Q

Conductivity (k)

A

the rate at which heat passes through a specified material
- higher conductivity the faster heat moves across

9
Q

Resistivity (r)

A

the rate at which a material resists the transfer of heat
-inverse of conductivity, 1/r
-we generally want materials with high r
-can be higher than 1

10
Q

Conductance (C)

A

homogeneous materials of any given thickness or for heterogeneous materials with known thermal properties

11
Q

Resistance (R)

A

homogeneous materials of any given thickness or for heterogeneous materials with known thermal properties
- Inverse of conductance
- R = r x d

12
Q

U Value

A

measure of the overall ability of a series of conductive and convective barriers to transfer heat
value between 1 & 0
the lower the value, the better the insulator
U = 1 / R1 + R2 + R3 + …

13
Q

Conduction (including equation)

A

heat exchange between two surfaces that are in contact
-heat will move as a function of the temperature difference between the two surfaces (delta T), the area of the surfaces that are touching (A), and the U Value of the materials touching
Q=UxAxdeltaT

14
Q

Outdoor Design Temperature

A

worst case scenarios seasonal low, similar to 100 year flood
Allows to calculate what equipment you need to heat on the coldest day

15
Q

Air change

A

rate per hour at which an entire volume of air leaves and is replaced by outside air
-0.9 air change means 90% in one hour
-Need to convert air change per hour to cubic ft or air per minute
-2 is good amount, anything below 0.3 you have to intentionally bring in outside air

16
Q

A

thermal radiation is electromagnetic radiatoin generated by the thermal motion of charged particles
-Ex. surfaces around you have higher temps than the air - higher radiant heat

17
Q

Absorptance

A

dark and matte surfaces absorb more heat. Light or reflective material reflect heat

18
Q

Emittance

A

a material’s ability to release heat through radiation

19
Q

Low E Glass

A

microscopic layer of reflective coating inside glass
reflects heat back inside during winter, reflects heat out in the summer

20
Q

Thermal Mass

A

the ability of a material to absorb, store and release heat
-Thermal lag - peaks are later and less sharp
-Moderating effect takes severity out of temp swings

21
Q

3 types of passive solar gain

A

Direct gain space - you are occupying the space that’s being heated up
Indirect gain space - solar energy heating up a gap between window and concrete wall (Trombe wall), thermal mass has a good view of the sun
Sun space - also indirect, sun heats up one space, which is not conditioned, conditioned space is inboard of that

22
Q

evaporator loop

A

Coolant that is evaporating or boiling is cold
Low pressure induces boiling
The side that is typ inside the house

23
Q

condenser loop

A

Coolant that is condensing is warm (heat is produced when changing from gas to liquid)
High pressure induces condensation
The side that is typ outside the house

24
Q

economizer cycle / free cooling

A

Cooling large buildings on cold nights with cool air using cold air outside the building (need to cool b/c heat generated inside the building offsets some of the heat losses from the envelope)
Can be air or water

25
Q

heat pump

A

Reverse flow of coolant so cold side is outside and hot side is inside
can be geothermal

26
Q

grille

A

air goes in

27
Q

register

A

air goes out

28
Q

diffuser

A

29
Q

heat exchanger

A

allows heat from the exhaust air to be shared with the intake air, without coming into direct contact

30
Q

single zone HVAC

A

se one outdoor condenser and one indoor head for a single area of the home
ideal for small homes

31
Q

Terminal Reheat (with VAV)

A

If a room needs to be heated, a valve opens to allow heating water to flow through the reheat coil which reheats the air that passes through the coil. The controls that monitor air flow and heating coil are normally linked to the room’s thermostat.
advantages are lots of control & space and equipment efficiencies, disadvantages are wasted energy

32
Q

Dual Duct system

A

not really used anymore, have one hot duct and one cold, mix together in a mixing box per room to achieve desired temp

33
Q

split system

A

compressor and condenser are outside, evaporator is inside, mostly for residential, must keep evaporator within 100’ of eachother

34
Q

fan coil unit

A

Fan in the space rather than remotely, generally minimal ductwork, but noisier, efficiency and maintenance, increase control, need less space (pipes rather than ducts), common for multifam

35
Q

Evaporative condenser

A

water sprayed over top of the condenser, helps cool it quicker aka more efficient

36
Q

Issues with putting equip on the roof

A

Structural demands, noisier, ugly, inefficient because heat/cool loss as you run things across the roof

37
Q

Minisplit

A

Fan coil unit in each zone, and each can be either a condenser or evaporator when needed

38
Q

Rooftop Water to Water System

A

Chiller using water to cool the condenser (cooling tower) bring cool to building through chilled pipes
Can have the chiller be remote (up to ½ mi away) and feed multiple bldgs
Can have chiller in the basement and cooling tower on roof
Could be geothermal water to water - condenser heat goes through pipes in ground to cool/heat depending on season

39
Q

Rooftop Water to Air System

A

Condenser side has water cooled by water tower, evaporator has fan blowing air over coils

40
Q

types of pipes

A

Copper - more expensive, more friction
Plastic - less expensive, less friction (ABS, PE, PVC, PVDC - can be used with hot water)
rated by thickness (k thicker, l medium, m thinner)
DWV - used for drains and vents

41
Q

types of valves

A

Gate - used for maintenance, can open it completely or close it
Globe - used for faucets, repeated use
Check - used for backflow prevention, near where water enters the bldg

42
Q

Pressure equation

A

Pressure (P, psi) = 0.433 (constant) x Height (h, ft)

43
Q

hot water requirements

A

140 deg for kitchen and laundry
110 deg for shower
105 for handwashing

44
Q

types of vents

A

Traps require vents, some can share, some need their own
Soil stack - black water
Stack vent - vent above the soil stack, lavatory, etc
Waste stack - grey water
Vent stack - not directly above stack, off to the side

45
Q

septic system

A

Solids are anaerobic decomposed, liquids to a leach field
Different types of soil absorb at different rates. Need percolation (perc) test

46
Q

Artesian well

A

comes from an aquifer under positive pressure (earth on top of the water is so much that if you stick a pipe down into it, the water will come up)

47
Q

shallow well

A

single straw down to water (up to 25’) sucks water from underground

48
Q

deep well

A

deeper than 25’, uses deep well pump, sends some low pressure water down into the well, uses venturi effect to suck water up

49
Q

1, 2, 4 pipe systems

A

1 pipe system - water is not as hot near end of loop, but has a control valve so you can turn on / off different zones in a basic not that effective way
2 pipe system - for each fan coil unit has a return
4 pipe system - each coil has a hot and cold and a separate supply and return

50
Q

Power equation

A

W (power in watts) = I (current in amps) x V (voltage in volts, stadndard is 120V) x PF (power factor)

51
Q

Non metallic sheathed cable

A

two or more insulated conductors in a plastic sleeve (residential), easy to work with, not protected well

52
Q

flexible armored cable

A

two or more insulated conductors in spiral wound steel tape
metal clad (MC) - has a separate ground wire

53
Q

Delta vs. Wye connected power

A

Delta - has a single voltage available (phase to phase) so only 208V or 480V, 3 hot wires connected in a triangle
Wye - has two voltages available (phase to phase and phase to neutral) so 120/208V or 277/480V, has a neutral wire, connected in a Y shape

54
Q

rectifier

A

electrical device that converts alternating current (AC) which periodically reverses direction, to direct current (DC) which flows in only one direction

55
Q

inverter

A

electrical device that converts direct current (DC) which flows in only one direction to alternating current (AC) which periodically reverses direction

56
Q

disconnects / safety switches / switch gear

A

first thing where power comes in bldg, a switch that can turn off other switches behind it, for emergency situations so you don’t have to touch high voltage high amp
leaves emergency power on

57
Q

GFI (ground fault interrupter outlet)

A

receptacles that will interrupt circuits if they sense a 4 to 6 milliamp difference in current between the hot and neutral wires at the outlet
used wherever there will be water

58
Q

electric meter

A

measure the consumption of electricity for billing purposes
master metering - one meter for the whole biilding
direct metering - a meter for each individual tenant

59
Q

transformer

A

step down public power to a voltage usable by buildings
watts stay constant, but volts and amps change
occasionally can be used to step power up

60
Q

exterior transformer pro & con

A

pro: no bldg space, no noise in bldg, low initial cost, easy maintenance & replacement, no interior heat generated, can use oil without having to fire rate

61
Q

below grade transformer pro & con

A

common in urban settings
pro: useful when little land is available, o bldg space, no noise in bldg, low initial cost, easy maintenance & replacement, no interior heat generated, can use oil without having to fire rate
con: earthwork costs

62
Q

interior transformer pro & con

A

oil filled transformer must be located in a fire rated vault with the switchboard in an adjacent row
dry type transformers may be combined with switchboard in a main elec room or suubstation
con: requires proper ventilation for safety & heat loss, noise, heat generation

63
Q

Ohm’s Law

A

current is directly proportional to voltage & indirectly proportional to resistance. if current increases, voltage increases
V = I x R, I = V / R, R = V / I

64
Q

elec setup for shed

A

120V, single phase, 2 wire

65
Q

elec set up for single family residential

A

120V/240V, single phase, 3-wire
The 240V for the high voltage equipment (AC system, electric range, electric dryer)

66
Q

elec set up for a larger bldg

A

120V/208V, 3 phase, 4 wire
3 phases - because voltage cycles to 0 twice per second (sine wave) and you want to ensure the 0s don’t line up because that wears down your motor, req more maintenance, and more power

67
Q

elec set up for a really big bldg

A

277V/480V, 3 phase, 4 wire
480V for motors, pumps, elevators, etc

68
Q

decibels

A

(dB)
unit of sound pressure / intensity
0 dB = threshold of hearing
130 dB = threshold of pain
every time you double a distance there is a 6db drop

69
Q

A weighted decibels

A

an expression of the relative loudness of sounds as perceived by the human ear

70
Q

octave bands

A

groupings of decivels (dB) and frequency (HZ)

71
Q

speed of sound

A

typically moves 1,128 feet per sec, about 1 ft per millisecond

72
Q

(acoustic) transmission

A

the propagation of a sound wave through an object or medium

73
Q

(acoustic) reflection

A

the bouncing back of the sound wave on striking a surface such as a wall, metal sheet, plywood, etc.

74
Q

(acoustic) absorption

A

the process by which a material, structure, or object takes in sound energy when sound waves are encountered

75
Q

absorption coefficient

A

respresented by alpha symbol
0-1, 0 means all the sound energy is absorbed, 1 means none of the sound energy is absorbed

76
Q

noise reduction coefficient (NRC)

A

the avg of sound absorption at four frequency bands
0-1
higher means quieter, good is above .75

77
Q

reverberation time

A

time it takes for the sound to drop by 60 dB
Decay takes longer in a larger room or less absorptive room
2 sec - concert hall (least amt of speech)
1.5 sec - opera house
1 sec - theater
.75 sec - classroom
.5 sec - small office
.25 sec - living room

78
Q

transmission loss

A

the accumulated decrease in intensity of a waveform energy as a wave propagates outwards from a source, higher means quieter

79
Q

flanking paths

A

“leaks” where sound can get in
ex:
through ducts
through ceiling into plenum
transmission and impact loss thru partition
loss thru outlets and other openings
leaks at floor / wall intersection
impact sounds thru floor

80
Q

strategies for sound reduction

A

massive - single layer gwb < multilayer GWB with staggered panel joints
airtight: ex. standard block wall < grout filled block wall
structurally discontinuous: ex. standard stud wall < staggered stud wall or double stud wall or resilient clip

81
Q

Noise Criteria level (NC)

A

relative loudness of “background” noise in a space, higher means more noise
Lower than NC 30 is quiet, louder than NC 55 is loud

82
Q

STC (Sound Transmission Class)

A

an integer rating of how well a building partition attenuates airborne sound, higher means quieter
50 STC req between multi fam

83
Q

Impact Isolation Class (IIC)

A

measures impact sound transmissions through floor assemblies
higher means quieter
req atleast 50 between multi fam,
fix with resilient mat in the floor detail

84
Q

reducing mechanical noise

A

Overall - the more space you can allow to mech space the better
Have silencer inside duct
Increase duct length
Internally lined duct - but there are air quality concerns with this
Have slower duct velocities
Smooth duct transitions rather than abrupt

85
Q

skylight spacing

A

1.5 x ceiling height = spacing O.C.

86
Q

Color Rendering Index (CRI)

A

a quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with a natural or standard light source, 0 - 100 with 100 being perfect
For us to see a color there has to be that color in the source light

87
Q

Correlated color temperature

A

color that the lamp appears (warmer - cooler)
higher temperature lights are cooler, lower temperature lights are warmer

88
Q

Incandescent lamp

A

tungsten filament placed in a sealed bulb with inert gas
Pro: high color rendition index (CRI=100), inexpensive, compact, dimmable, warm light
Con: low efficiency (lot of watts going in and less lumens going out), short life, high heat

89
Q

Fluorescent lamp

A

a mixture of inert gas and low pressure mercury vapor. Requires a ballast which produces noise. Class A lights are quietest, Class F are loudest
Pro: high efficiency, low cost, long life, variable colors, dimmable
Con: CRI of 65-85

90
Q

Metal Halide

A

High color temp (cooler looking), CRI of 85
Long lamp life
Used in stadiums, warehouses, car washes, etc

91
Q

high pressure Sodium Lamp

A

CRI of 20
Often in street lighting
Long lamp life, very efficient

92
Q

Light Emitting Diode (LED)

A

Pro - high CRI (85), produce minimal heat, low energy cost, long life span, very efficient
Con - have a hard time shedding heat, fade as they die

93
Q

strategies to use daylight

A

Occupancy sensor
Zoning of lights - lights closest to window on one sensor, mostly off, next row in 50% on, etc
Demand response - shed lighting laid during peak energy usage times

94
Q

Lamp Lumen Depreciation (LLD)

A

over time lamps produce less light, so you overlight at beginning, knowing that the lamps will degrade, number from 0-1, if you lose 10% of LLD you have an LLD of .9

95
Q

Footcandles

A

the unit of illlumination, equal to the number of lumens falling on each SF of a surface
= lumens / area in sf
normal interior levels are 10-100

96
Q

wet pipe sprinkler

A

most common, the sprinkler piping is constantly filled with water. When the temperature at the ceiling gets hot enough the glass bulb or fusible link in a sprinkler will break. Since the system is already filled with water, water is free to flow out of that sprinkler head

97
Q

dry pipe sprinkler

A

filled with pressurized air or nitrogen instead of water to prevent frozen and burst sprinkler pipes in areas with colder temperatures, best for unconditioned space in a cold climate

98
Q

pre-action sprinkler

A

a dry sprinkler system, water is not contained in the pipes but is held back by a pre-action valve. A voice command will then say sprinkler are about to go off in 30 second, giving the opportunity to cancel the sprinklers

99
Q

deluge sprinkler

A

for high hazard area, when triggered, all the sprinkler heads in a zone will spray

100
Q

fire extinguisher type A

A

water based, used for paper or wood

101
Q

fire extinguisher type B

A

foam based, used for chemical fires

102
Q

fire extinguisher type C

A

foam based, used for electrical

103
Q

fire extinguisher type D

A

foam based,used for combustible metals

104
Q

hydraulic elevator

A

powered by hydraulic jack, which are fluid-driven pistons that travel inside of a cylinder
pro: low initial cost, low maintenance cost
con: high energy demand, hydraulic fluid is an environmental hazard, slow, limited travel distance

105
Q

traction elevator

A

utilize steel ropes or belts on a pulley system
pro: more efficient, last longer, require less maintenance, faster, smoother ride, longer travel distance
con: high initial cost, medium maintenance cost

106
Q

geared elevator

A

traction, max rise of 150’, 5-15 stops, 500 fpm
has more torque, so often used in freight elevators

107
Q

gearless elevator

A

traction, max rise of 2000’, 15-60 stops, 2400 fpm

108
Q

machine roomless elevator

A

either traction or hydraulic
mac height 250’ max
500 fpm (traction), 150 fpm (hydraulic)
pro: requires less space, energy efficient, similar cost to general traction
con: difficult to implement, restricted by code, no destination dispatch system, not suitable for freight

109
Q

shaft requirement for hoistway

A

required to have a vent that is 3.5% of hoistway or 3 sf, whichever is bigger

110
Q

escalator

A

Slope: 30-35
Speed: 100 to 125 fpm
Clearance: 7ft req.