unit for measuring the amount of electricity current flowing in a conductor.
1 Volt applied across a resistance of 1 Ohm results in the flow of 1 Amp
I - Current
W = Power (watts)
V = volts
sum of sensible heat and latent heat
measure of sound intensity
20 db is a whisper
130 db is threshold of human pain
rate of flow of lumens or watts through a theoretical surface
Measure of the energy efficiency of a light source.
ratio of the total lumen output of a lamp to the total power per watt input.
measurement of the total output of a light source.
Makeup Air Handing Unit
AHU specifically designed to supply 100% outside air to a space replacing air lost through exhaust fans or building envelope.
Mean Radiant temperature (MRT)
average temp of all radiating surfaces within the line of sight of a body.
used to determine comfort zone.
measured using globe thermometer.
Heat energy that causes a change in state.
such as ice to water.
A unit of sound absorption.
one unit is equal to one s.f. of totally absorptive surface.
0 = all sound is reflected
1.0 = all sound is absorbed
R = 1/C
Resistance is the reciprocal of conductance.
Is a measure of the insulating qualities of a material.
R = x/k
x = thickness
k = conductivity
A measure quantity of light at a given point on a surface coming from a given direction accounting for the reflectance and transmittance of materials.
Liquified sewage that flows from a buildings disposal system.
Flows into a public sewer, septic tank, or leach field.
Foot Candle (fc)
measure of illumination equal to one lumen.
the amount of luminance from one lumen on a one s.f. surface.
Metric equivalent to the foot-candle.
Equal to 1 meter-candle or 1 lumen/m2 (squared)
unit of frequency
number of cycles per second is called the frequency.
60 cycles per second = 60 Hz
Electricity is analogous to water flow
Voltage (volts) - Pressure (psi)
Current (amps) - Flow Rate (gpm)
Resistance (ohms) - Friction
Preaction Sprinkler System
used in dry pipe sprinkler systems where the danger of serious water damage is present.
used ion conjunction with more sensitive fire detection systems that when triggered initially empty the pipes of the compressed air and fill with water. the water is not released until the sprinklers are triggered.
Objectives of Fire Safety
1. Protection of life.
2. Protection of property
3. Maintaining Building Operation
British Thermal Unit (BTU)
the amount of heat energy required to raise the temperature of one pound of water by one degree F.
Parts of the Eye
Iris: Controls brightness
Retina: Senses color, and black and white
1. ASHREA - American Society of Heating, Refrigeration, and Air-Conditioning Engineers, Inc.
2. ANSI - American National Standards Institute - minimum requirements for energy conservation in buildings
3. ASME - American Society of Mechanical Engineers
Flat Plate Collectors
Active Solar Water Heating System
-most common / least costly
-4'x8' insulated glazed box with piping manifold connected to the black metal flat plate.
Active Solar Water Heating System
uses metal reflectors to concentrate suns rays on a tube or point.
generate higher temps and more efficient use of surface area
more complex and expensive
Type of voltage systems and their uses
120/240 v single phase - 3 wire system used for residence and small office.
277/480 v 3 phase - 4 wire system used for large commercial
2400/4160 v 3 phase - 4 wire system used for very large commercial and industrial
120/208 v 3 phase - four wire system used for small and medium commercial. allows various electrical loads.
transferred heat energy that causes a change in the dry bulb temperature of a material nut not a change of state.
1. Drainage Field
2. Seepage Pit or Dry Well
4. Sand Filter
5. Percolation test
1. Drainage Field - onsite sewer treatment system - Effluent form septic tank drains to perforated pipes surrounded by gravel in trenches - seeps into soil.
2. Seepage Pit or Dry Well - onsite sewer treatment system. below grade perforated concrete cylinder.increase risk of waste water flowing into water table. - concentrated point of distributing
3. Mound - onsite sewer treatment system. drainage field above existing grade. may require pump to move effluent from septic tank.used when water table is high
4. Sand Filter - onsite sewer treatment system. effluent from septic to open air filter treatment pit at or above grade.- flows through sand to soil.used when water table is high
5. Percolation test - determine rate at which soil can absorb effluent
Regional Climate Zones
Factors that affect climate comfort
Equivalent Spherical Illumination (ESI)
Optimum lighting -the even spherical illumination of an area with all shadows and bright reflections eliminated.
a piece of metal inserted into a water tank to collect hard-water deposits in order to keep them from forming on the heat exchanger
the temp at which water vapor in the air becomes saturated and condenses into water droplets.
as the temp cools, the air can no longer hold as much water vapor and the vapor condenses
ability of a material to transmit or conduct heat or electricity.
determine the size of a heating system for a building
calculate total heat loss
the coefficient of heat transmission (U valve) for each assembly (walls, windows, roof) and add all the U values.
changes voltage, not power, in an AC.
used to step down voltage from line to building.
surface that maintains a reflected image - mirror
states that the current (I) that will flow in a DC circuit is directly proportional to the voltage (V) and inversely proportional to the resistance (R) of the circuit.
Four Stages of Fires
1. Incipient Stage - no visible flame or significant smoke or heat. invisible products of combustion are given off - ionization or gas detectors
1. Connected load - total load on a system if everything is on simultaneously
2. Maximum demand - greatest load delivered over a specified amount of time
3. Demand factor - ratio between max demand and connected load. used to estimate the capacity of a system accounting for the probability that only a portion of the connected load will be applied at a time.
5. First Elec Code
1. first battery 1800
2. first motor 1821
3. light bulb 1879
4. AC vs DC 1880
5. 1881 N.E.C.
1. Reciprocating - cylinder and piston with valves - similar ot car engine
2. Rotary - spiral rotor
3. Ejector - uses venturi effect and a water jet sent from surface to impel water to rise
4. centrifugal - a wheel like impeller rotates - spiral paddle system
1 PSI lifts a column of water 2.3 feet.
Expansion Bend / Loop
extra set of curves in a pipe run that can contract and expand to accommodate thermal movement
helps to absorb water hammer
Maximum height of water fixture?
take pressure at water main, subtract known pressure losses and pressure required at fixture, then multiply by 2.3 to get max height.
Pipe Thermal Expansion
∆L = L K (T2-T)
∆L = change in length
L = Length
k = coefficient of expansion
T = original temp
T2 = final temp
Water pipes unsupported lengths.
4, 6, 12
pvc = 4'
copper = 6'
steel = 12'
used mostly for plumbing, has metering or flow restriction capabilities
entirely on or off
restricted flow even when open
Fire Alarm Systems;
conventional - alarm signal only
addressable - identical to conventional but each detector is a separate zone
addressable analog - smart detectors, computer analyzes alarm to cut down on false alarms
60db + 65db ≠ 125db
for the difference between db's, add to the higher
0 to 1 = 3
2 to 3 = 2
4 to 9 = 1
< 10 = 0
60 + 65 = 66db
Properties of sound;
4. Reverberation Time (RT)
1. Reflection - sound bounces after hitting a hard surface at the same angle of incidence
2. refraction - some sounds are bounced back
2. Diffraction - Sound Bends
4. Reverberation - sounds persist because of multiple reflections
5. reverberation time - time it takes for the sound to decay 60 db
6. resonance - vibrating at increasing amplitude at certain frequencies.