Systems Flashcards
Skin-load dominant building
Buildings that have a lot of surface area compared to interior space-buildings that will be influenced by exterior conditions
Internal load dominated buildings
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
Solar heat gain coefficient ( Shgc)
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
Solar insolation
Radiant energy per sf
British thermal units (btus)
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
Do you sweat more when It’s humid or dry?
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)
Air temperature and humidity interaction
Psychrometry-
Relative humidity
% 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
Enthalpy
Total heat in the air
Sensible heat ( air temp) + latent heat ( moisture level)
Wet bulb temp is a good indication of total heat
Low - e (emissivity) glass
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
Balance point temperature
65°
. Heating or cooling degree days
If it’ cooler outside, we heat, IF its warmer, we cool
Degree days
The number of days per year and the differences in degrees from the baseline (balance point) temperature
Heating degree days (winter calculation)
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
Cooling degree days (summer calculation)
A hot or long summer will have more cooling degree days
Conductivity (k)
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
Resistivity (r)
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
Conductance (c)
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)
Resistance (R)
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
U -value
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
Conduction
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)
I F we double the u-value, what happens to the rate of heat exchange across the assembly?
It will double the heat exchange ( Q)
If we double the A (area) what happens to Q?
It will double the heat exchange
If we cut delta T by 50% what happens to the rate of heat exchange through the assembly ?
It reduces heat exchange by 50%
Air change per hour ( ACH )
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
Convection: infiltration
Q= 1.08 X CFM X delta T
For a temperate climate (warm summers and cold, winters) heat transfer for conduction ( Q) is more of a concern in the -?
Winter-temperature change is greater in the winter
Higher conductivity is a - – r-value.
Lower r-value
Thermal breaks
Radiation faults in construction
What causes a building to get stuffy?
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)
Radiation
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
Absorptance
Dark and matte materials and surfaces absorb more heat - light or reflective materials reflect heat
Emittance
A materials ability to release heat through radiation (dark and matte) - absorbed then emitted
emittance + absorptance = emissivity
Think low emissivity glass
Doubling The thickness of a given homogenous wall material will - —_-‘ the wall’s u-value?
Halve
In the US during the summer, — receives the most radiant heat?
Flat roof
Two bodies in direct contact with each other will transfer heat primary by the mechanism of -?
Conduction
Passive thermal buildings
Direct-gain space
Trombe wall (indirect gain)
Son space ( indirect gain- buffer zone )
Altitude
Suns position in the sky along the vertical axis
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?
Cooling
Compression -refrigeration loop
( 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
Exhaust air fans
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
Economizer cycle
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
Heat pump
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.
Geothermal heat pump
Ges-exchange or ground source coupled heat pump
Use the earth instead of air as heat sink.
Thermostats in “zones”
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
Grill
Air intake
Register
dumps air into room.
Diffuser
Directs air throughout
What happens when a building is negatively pressurized?
Sucks water in through the skin, so we exhaust less than we bring in (positive pressure)
Energy recovery ventilator (erv)
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
What are the advantages of having one independent air handling unit for each zone?
Control - disadvantage IF it’s a large building (too many units)
Variable Air volume Unit
(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
Terminal reheat with VAV
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
Dual duct system
Not used anymore- highly inefficient
I hot and I cool duct both feeding a “mixing” box so temps were highly controlled
“Right size” equipment.
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
Why do we need preheat in an HVAC?
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)
HVAC common in multi-unit housing
Chiller with AHU
Square box with X
Supply air
Square box with \
return air
Internally lining ductwork
Reduces air noise - but could have fibers (bad iaq) or cause condensation (mold)
Fan coil Unit (fcu)
Just a fan in a space or adjacent ( single room)
Often in mid-range hotels - wall based _ high control, minimal ductwork
In the compression-refrigeration loop, which IS likely to be warmer? Conduser coil or evaporator coil
(Air conditioning)
Condenser coil
A machine that uses a reversible compressive refrigeration loop, so both coils may take the role of either evaporator or condenser.
Heat pump
Air - Air system
Both coils are cooled and the coils are in their own room (isolated)
Mini-split system
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.
What makes hydronic heating in the floor a low energy strategy?
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
Swamp cooler
Add moisture to hot dry air which cools the air
No compression/ refrigeration loop
What causes HVAC noise?
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)
NC level
Background noise level - more background noise from equipment means worse performance in the space (classrooms)
What is the difference between a furnace and a boiler?
A furnace heats air and a boiler heats water
Rooftop water to water system
Chiller and cooling tower on roof → cooler has evaporator/condenser loop → pump cool water into building, fan or VAV pumps into rooms
Remote water to water system
Cooling tower and chiller located up to 1/2 mile away from building → same chilled water supply and return (chiller is condenser / evaporator loop)
Geothermal summer water to water system
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
Rooftop water to air system
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)
Water to water system: basement chiller and rooftop cooling tower
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
Basement water to air system
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
Split-system
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
Air-to- air system
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
Evaporative condenser
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
Window units (also called direct expansion units, DX systems and unitary system)
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
Single zone design
Thermal control but a lot of equipment/ ducts to purchase, maintain and house
Each zone has its own AHU, thermostat, fan, heat source, etc.
Thermostat
Measures room temperature and tells fan/valve when to turn on and open up
Fan coil units (fcu)
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
Chilled beams
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
VAV with terminal reheat
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
Radiant cooling
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
Mini split system
(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
Swamp cooler
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
Which of the following types of copper pipe would be the best choice for a line buried as an underground water supply
Type K (thickest)
Type L - most common supply line
Type m - thinner (low pressure, condensate )
Pipes are rated by thickness of pipe wall
Which types of copper pipe would be installed as a stack vent?
DWV - drain, waste, vent
Type K copper pipe
Thickest copper pipe- good underground
Type L copper pipe
Medium thickness - most common supply line
Type m copper pipe
Thinner - low pressure, condensate
Type DWV copper pipe
Drains, waste vents
Bring water to the ground slowly
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
Blue roof
Ponds water intentionally on roof-slowly releases
Plastic pipe vs metal pipe
Plastic pipe
Less friction, less money, smaller buildings
Metal pipe
More friction, more money, bigger buildings
Supply and waste water NEVER meet
Make sure there’s an air gap between max water line and supply or a vacuum break - prevent negative suction (backflow preventor)
Gate valve
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
Globe valve
Mostly used for faucets - repeated use - end of the line at a fixture - comfortable to use
Check valve
Used for back-flow prevention
Right as water enters the building
Allows water to move one direction and not the other
Vacuum breaker
Backflow prevention
Creates a siphon → adds air instead of dirty water
Pressure formula
Pressure (psi) = 0.433 (constant) x H (height)
A water tank is 75 ft above a fixture. What will the pressure at the fixture be?
P =0.433 x 75ft
P=32.475 psi
—-… —-… —- water line diagram
Hot water return
—-.. —- .. —- water line diagram
Hot water supply
Water line accesses building -
Below frost line → check valve → water meter → gate valve → then to water treatment, heaters etc.
Point of use water heater
Under sink for immediate use
Grey water
Waste water that Does not include human or food waste - can reuse (irrigation)
Black water
Any thing including human or food waste (toilets, kitchen sink)
How do you size pipes?
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
Expansion loop
For hot water pipes at long hot water runs- allows pipes to expand or contract on either side w/o bursting pipes
P-traps
Keep water sitting so the sewer gas doesn’t come up
Hot water temps
140° - kitchen and laundry (kill bacteria)
110°- shower
105° - hand washing
Drains and traps
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
Illegal plumbing traps
S-trap
Crown-vented trap
Bell trap
Drum trap
Legal plumbing traps
Bottle trap
P-trap
How does a grease interceptor work?
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.
Plumbing vents
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
Soil stack
Black water - where black water is draining - stack vent is above soil stack
Waste stack
Grey water - where just gray water is drawing -stack vent is above soil stack
Vent stack vs stack vent
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
Why is there a parallel vent to the soil stack?
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
Cleanouts
Required any time the pipe turns more than 45° ) then every 50’ of horizontal line
Manhole frequency
200’
Septic system
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 ($$$$)
Pipe angles
Vertical or near horizontal (1% to 4%) where solids can float adequately
Between 4% and 45° solids often clog because liquid moves too fast
Artesian well
Water comes from an aquifer under pressure ( can shoot water up)
Shallow well
Less than 25’, requires pump
Deep well pump
Sends some low pressure water down to create positive pressure up (almost a siphon)
Swamp and ejector pump
When there’s a toilet below the sewer ( basement)
1 Pipe
2 pipe
Red pipe
Blue pipe
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
What is hard water?
Water that contains mineral deposits
Hard water can cause clogged pipes - reduces ability to exchange heat, bad for hydronic systems
Tankless (inline) water heater
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
Plastic pipe types
Abs - acrylonitrile-butadiene styrene
PE - polyethylene
PVC - polyvinyl chloride
PVDC - polyvinyl dichloride - safe to use with hot water
Why insulate pipes?
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
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
4 (100) +5 (200) + 4(75) = 1700 watts
1700 W /I2OV=14.2amps
Electricity
The movement of free electrons
Metals have a lot of free electrons (why wire is metal)
Direct current (DC)
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
Alternating current (AC)
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)
Ohm’s law
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)
Power lines
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)
Series circuit
Bad - of light bulb burns out, entire circuit stops working (Christmas lights)
Parallel circuit
This IS how we wire → switch allows wire and current to bypass light bulb and still work
Cogeneration
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)
For a building with 277 / 480 V; three- phase, four- wire service, typically the electric lighting runs on - ?
277V
Small building electric loading
120 v, single phase, 2 wire
On or off, one ground, 1 hot wire at 120V
1 hot 120V wire, 1 neutral
Single family residential electric load
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
What are some higher voltage/wattage appliances that you occasionally see around the house?
Air conditioning, electric range, electric dryer
(These want 240V)
Power vs electricity
Power - electricity over time, batteries, coal etc - can be stored
Electricity-cannot be stored -
Power is measured in electricity over time in kWh
School level power
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
120V / 208 V
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
Power option for massive buildings
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
Industrial power requirement
2400 / 4160 v, 3 - phase, 4-wire
Super high power,
3-way switch
2 different switch locations to turn a circuit on or off
4 way switch
3 way switch on either side and central switch that changes from parallel to cross to complete the circuit
3-phase from power company to building
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
Delta power
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
Wye power
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
Power factor
A result of the current and voltage being out of phase
Between O and 1 (like tax on watt output)
Non - metallic sheathed cable “romex” - wiring
No conduit, really only used in single family residential , not protected well
Electrical steel conduit
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
Flexible armored cable
” A C “
2 types
Bx - metal casing in ground (integrated)
Mc- has separate ground
Chargers and batteries
Need to be DC
Most chargers have mini transformers gong from AC to DC
Rectifier
Mini transformer _ an electrical device that converts alternating current (AC) which periodically switches direction to direct current (DC) which flows in one direction
Inverter
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
Overcurrent protection
Keeps from starting a five - used to be a fuse
Mechanical breaker, GFCI it.
Fuse
Low melting point piece of metal that melt’s and “switches” Off IF there’s a short
Mechanical breaker
Senses heat in a circuit and switches Off
GFCI
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
Poles vs throws
Pole- number of circuits the switch can control for one operation of the switch
Throw- the number of contact points
Two throw / double throw switch
Either or situation
Double throw, double pole (2 outlets)
2 systems tied together, either or situation
Multi-throw
Either or switches
Either on or off
Multi-pole
Switches ganged together
Single-pole / single throw
Most common - 1 switch, on or Off
Double pole, single throw
2 switches, on off only
Single pole double throw
Single switch, this or that on
Single-pole, triple throw
1 switch, three options on (3 levels of on )
Double pole, double throw
2 switches, 2 levels of on or off
4 pole single throw
4 switches, on/off same circuit
Three-pole double throw
3 switches, either or
Single pole - 4 throw switch
One switch, 4 options/levels of on
Switch gear
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)
Metrics used to establish maximum noise levels
A-weighted decibels ( d BA)
Noise criteria (NC)
(Metrics) International building code requires a minimum level of 50 between units in multifamily housing
Sound transmission class (stc)
Impact isolation class (iic)
(metrics) Space fo runamplified music performance is too dry (sound dies too quickly)
Reverberation Time (RT)
Nose reduction coefficient (NRC)
(metrics) field test measurements include influence of flanking noise
Transmission loss (tl)
Sound transmission class ( STC )
Impact insulation class (iic)
(metrics) higher number value associated with quieter rooms
Noise reduction coefficient (NRC)
Transmission loss (tl)
Sound transmission class (stc)
Impact insulation class (iic)
Acoustics
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
1 hertz
1 beat per second
20 Hz is when we can’t differentiate beats (20 beats per second)
Octave bands
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
Speed of sound
Mores at 1128 ft/sec
If you are standing 20’ away from someone, how long will it take for the sound to reach you?
20 milliseconds
Absorption coefficient (alpha)
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)
Noise reduction coefficient (NRC)
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
(Ray tracing) specular reflection
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
(Ray tracing) Progressive enclosure
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
Average mean free path
How we quantity sound decay - sound level gets lower over time because some is absorbed and what remains has traveled farther
How do you keep sound out?
Airtight, massive, structurally discontinuous _ the cracks or leaks in a wall are where sound gets through (penetrations)
STC ratings
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
A-weighted decibels
Single number rating that summarizes a sound level across frequency spectrum
dBA
Exterior or environmental nose typically
Noise criteria
(NC)
Measures background noise (low frequency) - we are less sensitive to low frequency noise
Higher NC levels = more noise
S Tc of open window
O
Airborne noise V.s structure born noise
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
Structure born noise
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)
Reverberation Time (RT)
Room acoustics
Noise reduction coefficient (NRC)
Average absorption at speech decibel
A-weighted decibel ( dBA)
Level of background noise
Sound transmission class (stc)
Single rating across all octave bunds
Impact insulation class (iic)
Footfall rating (high=70,low=30)
( Metrics) used to establish maximum noise levels
A-weighted decibel D BA
Noise criteria (NC)
Sound isolation floors
Floating floors, insulation under and adjacent
Sound barriers
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
Why are rooms perceived to be dark
Usually from dark finishes causing excess contrast to the outdoor light (glare)
Glare
Excessive contrast
Lamp
Light source
Minimum egress light requirement
I foot candle
Typical classroom or office- 30 -. 50 fc
Bright room =100fc
Bright day = 10000 fc
Typical application = 10 - 100 fc
Footcandle
The amount of light energy that strikes one square foot sone foot from the source
Best for rendering color (highest cri)
Incandescent
Best efficacy (highest-lumens-per- watt value)
Metal halide
Lowest heat output per lumen
Fluorescent
Widest range of color temperatures available ( °K)
Fluorescent
Lowest color temperature (°K)
Incandescent
High pressure sodium
Longest lamp life
Metal halide
High pressure sodium
Worst for color rendering (lowest cri)
High pressure sodium
Requires ballast for operation
Fluorescent
Metal halide
High pressure sodium
Slowest start and restart time
Metal halide
Dimmable
Incandescent
Halogen
Fluorescent
High intensity discharge (hid)
Metal halide
High pressure sodium
Incandescent lamp
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
Efficacy
Efficiency
High lumen, low watt = high efficacy
Color rendering index (cri)
1 → 100
100 is perfect, you can see 100% of colors (sun, candle, incandescent)
Fluorescent
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
Correlated color temperature
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”
Metal halide
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
High pressure sodium
Usually outdoors, street lighting - very efficient, long life - cri-25 - 25000 hours - 2000K (warmer) - hid - replaced low pressure sodium
Discharge lamps
Require ballasts - to regulate the current _ used to hum
Electronic ballast - ballast and lamp have to be made for the same function
LED lamps
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
When designing an art gallery, which metric would be most rekranet in your lighting strategy?
CRI - color rendering index
What size is an a-17 incandescent lamp?
17/8 = 2 1/8”
Measured like rebar
Lamp
Light bulb
F 30 T 12 ww / Rs
F = fluorescent
30 = 30 watt
T 12 = tube diameter 1.5”
WW = warm white ( <3000 K)
Rs = rapid start
Color (light)
The color visible is reflecting from the lamp and what light colors the lamp produces
Grazing light
Light perpendicular to a wall - shows all imperfections (be intentional when you use this)
Lamp lumen depreciation (lld)
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
Footcandles (lux) = lumens / area in ft ^ 2
(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)
Coefficient of utilization (cu)
% of light that reaches the work plane ( between o and I)
Light loss factor (llf)
% of light that reaches the work plane ( between o and I) (loss due to lamp lumen depreciation, dirt, ballast factor)
Daylight factor
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)
For daylighting reasons is it better to have a window high in the wall or low?
High because it brings light in deeper
Power factor
Between 0 and I
Walls = volts X amperes x power factor ( circuit only)
120V assumed in America
Apparent power (volt-amps)
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
demand charge
Demand charge = maximum power demand x demand tariff
Sound = lambda = c/f
Lamb = wave length, ft
C= velocity of sound, FPS
F = frequency of sound, Hz
Dry-pipe fire sprinkler
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
Pre-action fire sprinkler
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
Deluge Fire system
Used in high hazard areas like fertilizer plants or plane hangers -if sensor is tripped, they all go off
Fire extinquisher types
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
In-ground hydraulic elevator
Has machine room (pushes all that moves elevator) - slow-limited travel distance, not efficient, good chance of failure
Traction elevator
More efficient, lasts longer, less maintenance, faster, smoother ride - weight / cables transfer-counter weight
Hydraulic elevators
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
Traction elevators
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
Gearless elevators
Traditional - machine room at top
machine room less - motor inside hostway, controller in wall, smooth., minimal maintenance, not powerful enough for really big buildings
Elevators
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)
Escalators
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
Which produces more power on a flat roof, angled or flat pv?
Angled - match latitude +/- 15
Flat gets dirty
Tankless toilet
Flush valve - commercial toilet
Tank toilet
Residential
Halogen
A type of incandescent, but has gas and tungsten so it doesn’t burn out -20 - 30% more efficient
Classes of standpipe
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”
Fire detectors
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
When are we required to use automatic ventilating hatches?
Atriums over 3 stories
Maximum spacing for outlets behind a kitchen counter
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
Where can’t outlets be?
Lower than 18” above a garage floor (gasoline fumes)
Can’t be over sink, tub or electric baseboard
Which piping material has the highest coefficient of thermal expansion?
Plastic-can be bad over long distances when not and cold are used
Sabine
Unit of sound absorption
A four pipe fan coil system functions as what?
A heating and coding system
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?
Condensation/water dripping
Refrigerators and sterilizers
