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Systems Flashcards

1
Q

skin load dominated building

A

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

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2
Q

internal load dominated building

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

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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

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4
Q

solar insolation

A

radiant energy per sf of the sun

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5
Q

British Thermal Unit (BTU)

A

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

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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

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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

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8
Q

Conductivity (k)

A

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

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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

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10
Q

Conductance (C)

A

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

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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

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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 + …

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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

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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

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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

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16
Q

Radiation

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

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17
Q

Absorptance

A

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

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18
Q

Emittance

A

a material’s ability to release heat through radiation

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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

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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

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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

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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

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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

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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

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25
heat pump
Reverse flow of coolant so cold side is outside and hot side is inside can be geothermal
26
grille
air goes in
27
register
air goes out
28
diffuser
air is spread out
29
heat exchanger
allows heat from the exhaust air to be shared with the intake air, without coming into direct contact
30
single zone HVAC
se one outdoor condenser and one indoor head for a single area of the home ideal for small homes
31
Terminal Reheat (with VAV)
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
Dual Duct system
not really used anymore, have one hot duct and one cold, mix together in a mixing box per room to achieve desired temp
33
split system
compressor and condenser are outside, evaporator is inside, mostly for residential, must keep evaporator within 100’ of eachother
34
fan coil unit
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
Evaporative condenser
water sprayed over top of the condenser, helps cool it quicker aka more efficient
36
Issues with putting equip on the roof
Structural demands, noisier, ugly, inefficient because heat/cool loss as you run things across the roof
37
Minisplit
Fan coil unit in each zone, and each can be either a condenser or evaporator when needed
38
Rooftop Water to Water System
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
Rooftop Water to Air System
Condenser side has water cooled by water tower, evaporator has fan blowing air over coils
40
types of pipes
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
types of valves
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
Pressure equation
Pressure (P, psi) = 0.433 (constant) x Height (h, ft)
43
hot water requirements
140 deg for kitchen and laundry 110 deg for shower 105 for handwashing
44
types of vents
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
septic system
Solids are anaerobic decomposed, liquids to a leach field Different types of soil absorb at different rates. Need percolation (perc) test
46
Artesian well
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
shallow well
single straw down to water (up to 25’) sucks water from underground
48
deep well
deeper than 25’, uses deep well pump, sends some low pressure water down into the well, uses venturi effect to suck water up
49
1, 2, 4 pipe systems
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
Power equation
W (power in watts) = I (current in amps) x V (voltage in volts, stadndard is 120V) x PF (power factor)
51
Non metallic sheathed cable
two or more insulated conductors in a plastic sleeve (residential), easy to work with, not protected well
52
flexible armored cable
two or more insulated conductors in spiral wound steel tape metal clad (MC) - has a separate ground wire
53
Delta vs. Wye connected power
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
rectifier
electrical device that converts alternating current (AC) which periodically reverses direction, to direct current (DC) which flows in only one direction
55
inverter
electrical device that converts direct current (DC) which flows in only one direction to alternating current (AC) which periodically reverses direction
56
disconnects / safety switches / switch gear
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
GFI (ground fault interrupter outlet)
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
electric meter
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
transformer
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
exterior transformer pro & con
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 con: requires land & shade
61
below grade transformer pro & con
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
interior transformer pro & con
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
Ohm's Law
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
elec setup for shed
120V, single phase, 2 wire
65
elec set up for single family residential
120V/240V, single phase, 3-wire The 240V for the high voltage equipment (AC system, electric range, electric dryer)
66
elec set up for a larger bldg
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
elec set up for a really big bldg
277V/480V, 3 phase, 4 wire 480V for motors, pumps, elevators, etc
68
decibels
(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
A weighted decibels
an expression of the relative loudness of sounds as perceived by the human ear
70
octave bands
groupings of decivels (dB) and frequency (HZ)
71
speed of sound
typically moves 1,128 feet per sec, about 1 ft per millisecond
72
(acoustic) transmission
the propagation of a sound wave through an object or medium
73
(acoustic) reflection
the bouncing back of the sound wave on striking a surface such as a wall, metal sheet, plywood, etc.
74
(acoustic) absorption
the process by which a material, structure, or object takes in sound energy when sound waves are encountered
75
absorption coefficient
respresented by alpha symbol 0-1, 0 means all the sound energy is absorbed, 1 means none of the sound energy is absorbed
76
noise reduction coefficient (NRC)
the avg of sound absorption at four frequency bands 0-1 higher means quieter, good is above .75
77
reverberation time
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
transmission loss
the accumulated decrease in intensity of a waveform energy as a wave propagates outwards from a source, higher means quieter
79
flanking paths
“leaks” where sound can get in ex: through ducts through ceiling into plenum leaks between adjacent construction transmission and impact loss thru partition loss thru outlets and other openings leaks at floor / wall intersection impact sounds thru floor
80
strategies for sound reduction
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
Noise Criteria level (NC)
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
STC (Sound Transmission Class)
an integer rating of how well a building partition attenuates airborne sound, higher means quieter 50 STC req between multi fam
83
Impact Isolation Class (IIC)
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
reducing mechanical noise
Overall - the more space you can allow to mech space the better Buy quiet equipment 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
skylight spacing
1.5 x ceiling height = spacing O.C.
86
Color Rendering Index (CRI)
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
Correlated color temperature
color that the lamp appears (warmer - cooler) higher temperature lights are cooler, lower temperature lights are warmer
88
Incandescent lamp
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
Fluorescent lamp
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
Metal Halide
High color temp (cooler looking), CRI of 85 Long lamp life Used in stadiums, warehouses, car washes, etc
91
high pressure Sodium Lamp
CRI of 20 Often in street lighting Long lamp life, very efficient
92
Light Emitting Diode (LED)
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
strategies to use daylight
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
Lamp Lumen Depreciation (LLD)
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
Footcandles
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
wet pipe sprinkler
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
dry pipe sprinkler
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
pre-action sprinkler
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
deluge sprinkler
for high hazard area, when triggered, all the sprinkler heads in a zone will spray
100
fire extinguisher type A
water based, used for paper or wood
101
fire extinguisher type B
foam based, used for chemical fires
102
fire extinguisher type C
foam based, used for electrical
103
fire extinguisher type D
foam based,used for combustible metals
104
hydraulic elevator
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
traction elevator
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
geared elevator
traction, max rise of 150', 5-15 stops, 500 fpm has more torque, so often used in freight elevators
107
gearless elevator
traction, max rise of 2000', 15-60 stops, 2400 fpm
108
machine roomless elevator
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
shaft requirement for hoistway
required to have a vent that is 3.5% of hoistway or 3 sf, whichever is bigger
110
escalator
Slope: 30-35 Speed: 100 to 125 fpm Clearance: 7ft req. Capacity: 1.25 people per tread Max rise: 20-40 ft, 60ft if supported in the middle
111
pipe "schedule" naming
Pipe sizes are named by wall thickness, have same diameter (ex. Schedule 40 pipe has thinner walls than schedule 80)

ARE 5.0 (16 decks)

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