Mechanical & Electrical Systems Flashcards
What type of cooling is most effective in hot-arid climates?
Evaporative cooling is most effective in this climate.
What is the abbreviation for thousand circular mil, the unit of measure for large electrical cables?
MCM
What is a backflow preventer used for?
This device is used to prevent sewage or water from reversing flow and backing up into fixtures or water lines set at a lower elevation.
What type of electrical service is most common in new US residences?
120/240V single-phase, three-wire service.
What building shapes are the most energy efficient for external load dominated buildings in a cold climate?
Squares and Cubes
Human comfort is affected by the quality of what environmental factors?
1 - Temperature
2 - Humidity
3 - Air Movement
4 - Temperature radiation to and from surrounding surfaces
5 - Air Quality
6 - Sound
7 - Vibration
8 - Light
What is true of a partition with a high STC rating?
It reduces sound waves that pass though it.
What is transparent insulation?
A type of insulation that consists of a thick polycarbonate or fiberglass inter layer placed within two sheets of glazing material.
Name TWO types of building insulation that contain resource-efficient materials.
1 - Mineral fiber (made from steel mill slag or basalt rock)
2 - Glass fiber (containing post-consumer recycled glass)
What kind of equipment can be operated using direct current?
Low voltage such as elevator motors, signal systems and controls.
What are some cost-effective ways to control noise from mechanical systems?
1 - Mounting equipment on isolators
2 - Creating flexible connections at ducts and pipes.
3 - Lining ducts (not recommended)
4 - locating equipment away from occupied spaces
What THREE basic physical qualities of sound must be considered in the control of noise transmission.
1 - Velocity
2 - Power
3 - Frequency
Which kind of light fixture is more energy efficient, fluorescent or high-pressure sodium?
Fluorescent
Name FOUR properties of copper pipe that make it well suited for use in water supply systems.
1 - Corrosion Resistance
2 - Low Friction loss
3 - Strength
4 - Availability in small diameters
What type of coating can be applied to make a wall or other surface fire resistant?
Intumescent Paint
What kind of lamp has a color temperature of 6500K?
Daylight Lamp
What safety hazards are contained by the use of compartmentation in a building?
The design strategy is used to control the spread of fire and smoke.
What are the FOUR main stages in the life cycle of a product used in a building?
1 - Raw Materials Collection
2 - Manufacturing
3 - Actual Use in a Building
4 - Disposal or Recylcing
Name FIVE criteria for evaluating the sustainability of a product or construction process
1 - Amount of embedded energy
2 - Use of renewable materials
3 - Use of recycled content
4 - Energy Efficency
5 - Use of local materials
What percentage of the wood products used in a building must come from certified forests for that building to receive LEED credit?
50%
Why is Linoleum considered a green product?
It is durable, biodegradable, and made from natural renewable, materials.
What are some advantages of using a runaround coil in non air-handling system?
This type of airflow heat exchanger offers several advantages:
1 - Incoming and exhaust air streams need not be adjacent.
2 - High Efficiency and energy savings.
3 - Effectiveness in high-volume applications
What mechanical equipment cycle introduces fresh air into the indoor air in order to reduce energy costs and improve IAQ.
An economizer cycle.
At what phase of the project does building commissioning start?
This review, which ensures that building systems perform as expected, begins in the design phase.
-541
1 - Less voltage drop
2 - Use of smaller lines
What type of trees should be planted on the south side of a house in a cool climate?
Deciduous trees are beneficial in this sort of climate because they shade the building in summer, yet allow solar heat gain in winter.
What is a ground fault interrupter (GFI)?
A device that detects a leak in the current and disconnects the hot wore in hype circuit.
What are the THREE primary characteristics of an effective sound barrier?
This type of barrier has: mass, stiffness, and all penetrations and gaps sealed.
What are the TWO most common sources of large water supplies for a city?
The two most common are surface water and ground water.
Name FIVE benefits of a green roof.
1 - Conserves energy
2 - Reduces storm runoff
3 - Absorbs Carbon Dioxide
4 - Filters Air
5 - Protects the roofing membrane from environmental effects such as ultraviolet radiation.
Name THREE water quality problems that can be corrected with filtration.
1 - Odor
2 - Turbidity
3 - Color
Name THREE design strategies that can be used to control smoke.
1 - Containment
2 - Exhaust
3 - Dilution
What is a passive solar energy system?
This is a system that collects, stores and distributes energy without the use of mechanical equipment.
What percentage of the gross building area should be for a mechanical room that uses all-air or air-water system in a large building?
3% - 9%
Name FOUR common strategies for maintaining good indoor air quality.
1 - Elimination or Reduction of Pollution Sources
2 - Ventilation Control
3 - Proper Maintenance
4 - Controlling the activities of occupants
What amount of water pressure is equivalent to one foot (or one meter) of vertical head?
One foot of this is equivalent to 0.434 psi
(One meter of this is equal to 10 kPa)
What feature must be installed in every electrical outlet in addition to the hot and neutral wires?
A Ground Wire
Name THREE types of security that intrusion detection creates.
1 - Object Protection
2 - Room Protection
3 - Area and Perimeter Protection
What are the FOUR levels of LEED Certification?
1 - Certified
2 - Silver
3 - Gold
4 - Platinum
Which of the following would be appropriately designed as a dead space?
A - An Auditorium
B - A Church
C - An Office
D - A Hospital Patient Room
D - A Hospital Patient Room
A dead space is appropriate for a hospital because it would be quiet. The room would contain a large amount of porous materials to absorb sound waves.
Auditoriums and churches are designed as live spaces. These are spaces in which sound waves reverberate due to reflective surfaces. The greater the ratio of reflected sound to directly received sound, the more a space is considered live. Offices need a mixture of live and dead spaces, allowing for some white noise.
What is a direct expansion, or DX, system?
A self-contained unit that passes air over an evaporator and back into a room.
Sabin
A unit of sound absorption.
Named after the American physicist Wallace C. Sabine.
One unit is equal to one square foot of a totally absorptive surface.
The eye is composed of a focusing device, a brightness control and a color sensing surface. Name these parts of the eye.
LENS: Focuses IRIS: Controls Brightness RETINA: Senses color, black and white.
The objective of a fire protection system is to make a building which of the following?
A - Fireproof
B - Fire Retardant
C - Fire Resistant
D - Non-combustible
C - Fire Resistant
The objective of a fire-protection system is to enable structures to resist fire long enough for the safe evacuation of all occupants.
Characteristics of Smoke Detectors
These fire alarm systems contain a photoelectric detector that responds to smoke before the fire breaks out. They may be activated under false conditions, such as kitchen smoke or dust. They are used in offices and apartment buildings.
Decibel
A measure of sound intensity.
(x) IL = 10log I/Io
Where: IL is equal to the intensity level in decibels. I is equal to the intensity of sound heard (watts/sq. cm) Io is equal to the minimum reference intensity, the lowest sound that can be heard with the human ear. Named after Alexander Graham Bell.
Identify this wall type.
Trombe Wall
An indierect-gain solar system where a 10”-16” thick masonry wall is placed between an internal space to be heated and the south-facing glass (Northern Hemisphere). As the sun passes through the glass, it heats the space between the glass and the wall, and the wall itself.
The wall in turn, heats the room (several hours later) through convection or thermal radiation. When vents are provided, natural convection or therosiphoning of the air-space heats the room. It can be used as a bearing wall and provides good acoustical insulation.
Water walls are another alternative.
What are the characteristics of plastic plumbing pipes?
They are durable and non-corrosive, and they create no mineral deposits. They deteriorate when exposed to UV light. Plastic is the least expensive piping material.
The Process of Heat Transfer
The flow of energy from an area of higher temperature to an area of lower temperature. Thermal equilibrium occurs by the transfer of heat between areas of differing temperatures.
Degree Days
The temperature difference between an average 24 hour exterior temperature and an interior temperature of 65 degrees gives the number of degree days for one day. For example, an average outside temperature of 20 degrees Fahrenheit is recorded over a 24-hour period. The number of degree days, then is 65 - 20 = 45 degrees. All degree-day values are added for an entire year to determine the annual degree day total. Used to determine fuel needs and to size mechanical equipment.
What is the best height for a toilet seat in a handicap accessible stall?
Between 17” and 19” is acceptable.
Glare
Extreme contrast between brightness and darkness that interferes with vision.
1 - DIRECT GLARE: Brightness in the field of vision
2 - REFLECTED GLARE: Brightness reflected from other surfaces.
Luminaire
A complete lighting unit consisting of a light source, reflector, refractor and all the parts necessary for the fixture, housing and power-supply connections.
Flux
The rate of flow of lumens or watts through a theoretical surface.
If a well-insulated wall has a high degree of sound transmission, what would be the most likely cause?
A - Very loud noises
B - Poor construction
C - A window
D - A keyhole
C - A Window
Wall penetrations, like windows, are called sound leaks and can override all efforts to insulate a building from sound transmission.
What is the most important thing to consider when dealing with sanitary systems?
It is most important to keep the waste water from contaminating the water system. Sanitary waste can be categorized as grey water or black water. Black water contains human waste. Grey water can be recycled with very little treatment and is used for irrigation.
Identify these pipe hanger types.
A - Clevis Hanger
B - Strap Hanger
C - Trapeze Hanger
Pipe hangers often incorporate springs or rollers into their design and are used to remedy problems such as vibration, noise, and expansion. Hangers are required at truns and junctions and spacing is determined by pipe size.
What is the purpose of the glass bulb in a fire sprinkler head?
When the temperature in a space reaches a given point, the contained liquid will expand and cause the bulb to break, allowing the water to pass through it. This component is available in a range of activation sensitivities from 155 degrees to 355 degrees F (68 to 180C)
Fire sprinklers and finishes
Escutcheons and cover plates are cosmetic. They are available in many different finishes or may be painted. The head itself however, may not be painted due to the potential loss of fire-detection sensitivity.
Due to the sun’s path across the sky, which facade receives the most sunlight in winter? In summer?
The south facade receives the the most sun in winter (in the Northern Hemisphere) when the angle of the sun is low. The east facade, the roof (including skylights), and the west facade receive the most amount of sun in the summer, when the angle of the sun is high. Overhangs play an important role, allowing winter sun in and keeping out the summer sun.
Which climate has large diurnal temperature swings?
A hot arid climate has large diurnal (day to night) temperature swings. Houses that are open to an inner courtyard with water elements and/or planting stay cooler in such climates, because evaporating moisture cools the air entering the house. Small, high windows on exterior walls allow hot air to escape while keeping in cool air.
Identify the follwing components.
A - Vent Stack
B - Stack Vent
C - Soil STack
D - Cleanout
E - Cleanout
Relative Humidity
The percentage of water vapor in the air relative to the maximum amount of water the air can hold at a given temperature. With regard to human comfort, in a cold environment humidity is of little importance. In cold conditions heat is lost primarily by conduction, convection, and radiation. However, in hot conditions, where heat is lost primarily by evaporation, humidity is critical. Whereas in cold conditions skin temperature is an important factor, in hot conditions the percentage of skin covered by water is more important. Levels of humidity can also be expressed as the dew point, wet-bulb temperature, and vapor pressure.
Name the appropriate term for each of the following definitions:
1 - the transfer of thermal energy through a fluid medium (liquid or gas) where the cool molecules of water or air, for example, absorb heat from a warm surface. The molecule rise, are carried away, then cool and fall.
2 - The transfer of heat by electromagnetic waves from one surface to a cooler detached surface across an open space. The rate of transfer depends upon the temperature differential, the thermal absorptivity of the surfaces, and the distance separating the energy source and the receiving surface.
3 - Heat transfer through a solid material, from hotter molecules to cooler molecules through direct contact.
1 - Convection
2 - Radiation
3 - Conduction
Less important for building materials than for human comfort, evaporation is a means of transferring heat to a cooler environment. If an object is a different temperature than the environment , heat will flow from the hotter to the colder.
Name THREE systems for heating water.
- WATER HEATER: an insulated storage tank that supplies a fixed quantity of heated water with a predictable recovery time. 2. CONTINUOUS LOOP: a two-pipe, closed loop system requiring a circulator pump to maintain temperature at the fixture. 3. INSTANTANEOUS: a tankless hot water system that heats the water directly at the point of use.
Microbial growth is the leading Indoor Air Quality (IAQ) contaminant what is the main cause of this phenomenon and how can the architect minimize this occurrence?
Mold, bacteria, viruses, algae, etc. are often caused by excessive indoor relative humidity.
This is a problem particularly for hot-humid climates where condensation can occur on surfaces within the building envelope. The use of fiberglass or mineral wool for internal-ductwork insulation is to be avoided. If exposed to moisture it can harbor microbial growth, which, along with the fibers themselves,can get loose in the air stream and spread contamination. Carpet, acoustic tiles, textiles, vinyl wall covering and paint are also prone to contamination. To minimize the occur acme, the architect should eliminate the use of in tank duct liners, specify products with anti-microbial additives, or use anti-microbial agents as a treatment. Use correct placement of vapor barriers on the building envelope. On the outside is hot-humid climates; on the inside in cool climates. Provide easy access to all HVAC systems for maintenance.
Which type of mechanical system has a high initial cost but a low life cycle cost?
The Fan Coil System Initially expensive because it requires a significant amount of piping (3 or 4 pipe system), but it is very efficient and can either heat, cool or ventilate.
What is the difference between an electrical emergency system and a standby system?
ELECTRICAL EMERGENCY SYSTEM: required by law to provide emergency power and lighting for human safety and the protection or property. STANDBY SYSTEM: supplies back-up power in case of disrupted service and is solely for the protection of property and equipment.
Effluent
Liquified sewage that flows from a building’s disposal system into the public sewer system or to a private, on-site system (septic tank or leach field)
Wet Standpipe System
An emergency fire-fighting system connected to a constant, pressurized water supply. Used in areas where there is no danger of freezing. Equipped with Siamese fittings for fire department hoses or for immediate use by the occupants. It is fast acting and the most reliable automatic fire-sprinkler system.
Ionization Detector
A device that senses the products of combustion emitted into the air during the incipient stages if a fire. Very sensitive, and may cause false alarms. Good for detecting electrical overloads. Used for spaces with high combustion hazards. An expensive system. The best method of fire prevention is regular inspection do the surroundings as well as the system itself.
What building components are affected, in length, by expansion and contraction but not affected in diameter?
Pipes. They undergo significant changes in length due to thermal expansion. Pipes for long runs must be held in place with flexible supports and hangers.
No. 0000 or 4/0 is what type of electrical wire?
A - Telephone
B - Major Appliance
C - Main Feed
D - None of the Above
C - Main Feed Under the American Wire Gauge (AWG) system, 0000 or 4/0 (pronounced “four ought”) is the largest wire at nearly 1/2” in diameter.
Name TWO methods for controlling HVAC noise in a building.
1 - Create a separate foundation for the equipment
2 - Use vibration isolator a (either springs or neoprene pads) between the equipment and the building foundation.
The use of fleecy internal duct liners for both thermal and sound insulation should be avoided. An inherent problem is the absorption of contaminants by the insulation. This can lead to a reduction in the Indoor Air Quality (IAQ).
Comfort Zone
The area located on the psychrometric chart where combinations of temperatures and humidities are considered comfortable by more than 50% of adults. Subjective tests are used to determine these effective temperature ranges.
Identify this equipment
Centrifugal Fan
A type of fan in an HVAC system that is capable of moving large amounts of air.
Also called a squirrel cage blower.
Inverse Square law
Applies to sound and light intensity, which is inversely proportional to the square of the distance between the source and receiver.
I1/I2 = r22/r12
Where: I1 and I2 are the intensities at distances r1 and r2 from a point source.
In simple terms, doubling the distance cuts the intensity of light and sound to 25%.
Note: Do not confuse the intensity of sound (I) which is measured in watts/cm2, with the more common Intensity Level (IL), which is measured in decibels (dB). The _IL is NOT proportional to the inverse square of the distance. _
Type K, L or M
Designations of pipe wall thicknesses, from the thickest, Type K, to the thinnest, Type M. Type L pipe is the most commonly used.
PSI
Pounds per square inch.
A measure of water and air pressure.
Which of the following lamps is the least energy efficient?
A - Fluorescent
B - Mecury
C - Sodium
D - Incandescent
D - Incandescent
DISADVANTAGES: high life-cycle cost, excessive heat waste, short life and high voltage sensitivity.
ADVANTAGES: low initial cost, good color rendition and ability to focus the light beam.
What is the main reason to use task lighting?
A - to add direct light to task areas
B - To conserve energy
C - To increase flexibility
D - To reduce electrical costs
B - To conserve energy
Task lighting avoids the unnecessary lighting of an entire space and reduces energy demands.
Vent Stack
A vertical vent pipe that provides air circulation to and from all plumbing fixtures and extends above the roof line to the open air.
Specific Heat (Cp)
The ability of a material to store heat in relationship to the material’s weight.
Different materials are capable of storing different amounts of heat, even when they are at the same temperature.
Specific Heat is multiplied by a material’s weight to determine thermal capacity.
What is the minimum required width for an exit passage?
No part of any exit passage can be less than 44” wide.
Leach Field
A waste-water treatment system that uses a grid of perforated pipe, laid in shallow trenches with loose gravel. Waste water seeps from the pipes into the soil, where it is oxidized and decomposed by aerobic bacteria.
Name some architectural concerns that may arise from using a refrigeration system.
Noise, Vibration and Heat
If possible the system should be located outside of the building to prevent the transmission of vibration to the structure. Otherwise, a vibration isolator made with springs or neoprene pads should be placed under the equipment.
Name TWO main functions of an automatic thermal control system.
1 - It automatically adjusts heating or cooling output.
2 - it distributes the air between various zones as required.
Tankless System
A water-heating system that services different demand levels.
Operates with variable-speed pumps that continually turn on and off or operate at different speeds to provide service. This system requires little space and no additional structural support. The main disadvantage is that the pumps have a short life.
Identify what is occuring at the following locations:
A - Absorption
B - Transmission
C - Source
D - Angle of Incidence
E - Angle fo Reflection
F - Reflection
What is the principal purpose of am electrical-service disconnect?
It enables all electrical circuits in an entire building to be disconnected from a single switch.
What system moves air from the Air Handling Unit (AHU) to individually conditioned spaces?
Duct System The duct system moves air from the AHU to conditioned spaces at high, medium or low velocities.
What is the minimum clear space for a handicap accessible toilet stall?
Ideally, a handicap accessible toilet stall should have a 60” diameter clear space up to a height of 10” from the floor.
629
The rate of heat flow through a solid material. Since each material conducts heat differently, it is useful to know the rate of heat flow for the standard thickness of common building materials. It is defined as the number of Btu per hour that glow through one square foot of material of a given thickness when the temperature drop is 1 degree F. The units are Btu/h-ft2-*F. The rate at which heat transfers is directly proportional to the temperature differential. It is the reciprocal of resistance (R) that represents the insulating quality of a material.
A new restaurant requires that a sewer system be installed before construction. What type of sewer connections will be required?
A new restaurant requires a sanitary sewer connection as well as a separate storm sewer.
Doppler Effect
The change in frequency of a sound wave due to a change in distance from the source, the receiver or both.
Central Heating System Classifications
1 - Classified by heat carrying medium: steam air or water.
2 - Classified by energy source: electricity, liquid and/or solid fuels or solar radiation.
Supply System
The pipes, fitting and valves that supply potable water under pressure.
Name a requirement for ductwork in a fire-rated wall.
Fire Dampers
A damper with a fusible link that closes the duct and prevents flames and smoke from moving throughout the building through the ductwork.
Electrical HVAC
The simplest HVAC system to install and operate. No space is needed for pipes or ductwork and temperature can be controlled with a separate thermostat in each room. Unfortunately, electricity is the most expensive heat source.
How do septic tanks convert waste material?
As part of a private waste disposal system, it is used in conjunction with a leaching field. Sewage is collected in the tank where the solid waste is treated primarily through settling and bacteriological activity. The resultant liquid waste, effluent, is then directed to the leaching field where it seeps into the ground via a buried manifold of perforated pipe and is treated by bacteria in the soil. A percolation test determines the soil’s ability to absorb effluent.
Hydronic Systems
A water mechanical system used only for heating. Many of these systems are also radiant systems. Some systems circulate hot water or steam through registers, pipes in the floor, etc. and radiate heat into the space. These systems are sometimes combined with forced air systems.
What determines roof gutter size?
The size of the roof area to be drained and the maximum recorded local rainfall.
What is the difference between sound absorption and sound insulation?
Sound absorption is the absorption of sound energy and is dependent upon the physical properties of material, object or space and the sound source. Sound energy is absorbed, dissipated and the transmitted. Sound insulation is the reduction of sound energy levels within a space and is dependent upon the sound-insulating qualities of the construction materials. Sound insulation can reduce sound transmission, but not prevent it.
Color Rendition Index (CRI)
A measure of how closely a light source approximates daylight of the same color temperature and displays the true color of an object.
Effluent flows best in a drainage pipe pitched at what angle?
A - 45 degrees
B - 1/8” per foot
C - 1/2” per foot
D - 1/4” per foot
D - 1/4” per foot
This slope is best for the flow of effluent in a drainage pipe.
1/8” per foot would not provide enough water velocity and 1/2” per foot causes liquids to flow too quickly. A 45 degree slope is required for sewage that flows entirely by gravity. For supply water under pressure, 90 degrees is allowable.
Identify this HVAC system.
Multi-Zone Air Handling System
A simultaneous heating and cooling system that mixes hot and cold air produced in seperate coils. The air is mixed together in the air-handling unit (AHU) to the desired temperatuie for a particular zone.
Good tmperature control.
Keeps constant air volume.
High energy consumption
Critical Distance
The maximum length of drain pipe between a trap and an air vent. Can be no more than 48 times the pipe diameter.
Which valve causes water turbulence in pipes when not completely turned on or off?
A gate valve.
Used when water flow must be either turned completely on or off.
Solar heat gain through fenestration, outside air heat gain, internal heat gain from people and equipment, and transmission heat gain through the building envelope are all factors in the calculation of what?
Cooling load.
These factors are the sources used to estimate, through calculations, the rate at which heat needs to be removed from a space in order to maintain human comfort.
Design Day
The temperature of a day hotter or colder than 98% of the days experienced in a given location.
This allows for the proper sizing of equipment to handle 98% of the temperature conditions.
Soil Stack
A large pipe that connects all the soil and waste lines throughout a building to a vent at the roof.
Electrical Current
The flow of electrons through a conductor. Measured in amperes, which is the quantity of electricity in an electric current.
Identify the following symbols:
A - Exhaust Fan
B - Thermostat
C - Pump
D - Fan
E - Return Air Duct
F - Supply Air Duct
G - Valve
Name the THREE major components of a building’s electrical power system.
1 - SERVICE-ENTRANCE EQUIPMENT: Transformers, service disconnect, fuses, meters and circuit breakers.
2 - INTERIOR-DISTRIBUTION EQUIPMENT: Conductors, raceways, sub-panels and sub-meters.
3 - LOADS: Power demand created by appliances and lights.
Sling Psychrometer
An instrument that measures relative humidity or wet-bulb temperature and is composed of two thermometers, one with a wet sock on the bulb and one without. The instrument is swung in the air to cause evaporation. The temperature differential between two thermometers is then compared to determine the relative humidity.
Interceptor
Also known as a separator, this device prevents the passage of oil and debris into the sewer drainage system. They require periodic servicing and must be readily accessible. It differs from a trap which keeps sewer gas from entering a building.
What is the most desirable surface type for reflecting sound over long distances?
A - Curved
B - Recessed
C - Flat
D - Perforated
C - Flat
Curved surfaces allow sound to concentrate in some areas and leave gaps in others. Circular and barrel-vaulted spaces tend to contain and focus sound. Perforated surfaces absorb sound, rather than reflect it.
Grey water is NOT derived from which of the following?
A - Lavatories
B - Roof Drains
C - Effluent
D - Swales
C - Effluent
Grey water is recycled water from systems and site drainage that does not contain human waste. It is used as water conservation measure for watering plants and flushing toilets. Grey water is non-potable.
Valves
Used to control the flow of water.
They enable parts of a water system to be shut down for repairs without affecting the building’s entire system.
Electricity is analogous to water flow. Voltage (volts), current (amperes), and resistance (ohms) are equivalent to which of the following respectively?
A - Flow Rate (gal/min), pressure (psi) and friction
B - Pressure, Flow Rate and Friction
C - Friction, Flow Rate and Pressure
D - Flow Rate, Friction and Pressure
B - Pressure (psi), Flow Rate (gal/min.) and Friction.
What considerations determine the size of a water heater?
Daily peak hot-water demands and recharge time.
Identify this HVAC system
Constant volume with re-heat
A modification of a single-zone, single-duct system. Return air and fresh air are dehumidified and ducted to all spaces at the samew temperature and humidity with constant volume. Each zone has a terminal box that reheats the air as necessary.
Fire Hazard Triangle
Smoke and heat arew the main causes of fatalities and property loss from a fire. Time is critical to evacuation and fire-suppression
Fire Classifications
Type A: Fires involving ordinary materials such as wood, cloth, rubber and paper.
Type B: Flammable liquids and gasses.
Type C: Electrical fires that must be extinguished by non-conductive means.
Type D: Combustible metals requiring special extinguishers.
Generally, what is considered an acceptable decibel level for a typical office environment?
A - 110-120
B - 80-90
C - 50-60
D - 20-30
C - 50-60
A decibel level of 50-60 is generally acceptable.
130 dB is the human threshold of pain where
20 dB is the level of a whisper.
Zero dB is the threshold of human hearing.
Unitary System
An HVAC system that pulls outside air into the serviced room through the mechanical unit. Used with large buildings that would otherwise require extensive ducting. Used when separate utility bills are required. Can be single zone, multi-zone or heat pumps with heating and cooling functions.
What are some of the criteria for selecting an HVAC system?
1 - Capital and life-cycle costs.
2 - Floor space required by the equipment
3 - Suitability for a building’s occupancy and function
4 - Maintenance requirements and product reliability
5 - Ease of system control.
What is the main reason for placing acoustical tile on the ceiling rather than on the walls?
To protect the material: Acoustical tiles are made with soft porous fiber that can easily be damaged with repeated contact.
Air Conditioning
Refers to the cooling of air, the treatment of air for temperature and humidity control, air quality and circulation.
Heat Detector
A fire-alarm system that senses heat. Reliable and inexpensive, but required some time for heat levels to cause a response. Does not respond to smoke.
When selecting a lighting system for a public parking lot, why might a low pressure sodium lamp be selected over a high pressure sodium lamp?
Low pressure sodium lamps have a higher efficacy making them one of the most efficient lamps available. Although this lighting system produces a monochromatic yellow light, it is appropriate for applications that do not require good color rendition, such as a parking lot.
What is the minimum diameter allowable for a plumbing vent?
1.25”, or twice the diameter of the vented drain, whichever is larger.
Identify the following:
The Refrigeration Cycle
The refrigeration cycle contains four processes: Evaporation, Compression, Condensation and Expansion.
The evaporator (a heat exchanger) transfers heat to liquid freon (the refrigerant) causing it to evaporate into gas. The compressor causes the gas to increase in temperature and to exit as a hot gas. The condenser (another heat exchanger) sheds heat to the outside and causes freon to return into a liquid state. The expansion valve then relives the pressure produced by the compressor and lowers the temperature of the liquid, so that the freon can absorb heat again when it returns to the evaporator.
Lux
A unit of illumination based on the metric system.
It is equal to 1 meter-candle or 1 lumen/sq. m.
In the U.S. Where the foot is the unit of length, 1 footcandle equals 1 lumen/sq. ft.
What is the minimum gauge wire allowed in construction?
14 gauge copper wire Gauge is a measure of the diameter of the wore. A smaller number indicates a larger diameter (or gauge).
Efficacy
The ratio of the total lumen output of a lamp to the total power per watt input. A measure of the energy efficiency of a light source.
Drainage Lines
Vertical and horizontal branches of pipe that carry waste water from the fixtures to a point of disposal. Drain pipes for water closets and urinals are called soil pipes. Other drain pipes are called waste lines.
Hertz (Hz)
A unit of frequency (sound or AC electricity), or one cycle per second. The number of cycles per second is called frequency.
For example, AC electricity systems in the U.S. operate at 60 cycles per second, 60 Hz.
Name FOUR types of dampers.
1 - BALANCING: Regulates the flow of conditioned air.
2 - MOTORIZED CONTROL: Remote systems that vary airflow within an automated control system.
3 - SPLITTER DAMPERS and TURNING VANES: Prevent airflow resistance due to corners in the duct work.
4 - FIRE DAMPERS: Stop airflow automatically in case of fire.
Identify the following:
Cleanout
A “Y” shaped segment of pipe used to provide access to the drainage system. Always required where the building drain meets the sewer system.
Why should a sink have an overflow opening located 2” lower than the faucet?
It prevents waste water from suddenly being siphoned back through the faucet and contaminating the supply water.
Conductors
Wire, cable or busbars that carry electrical current. They range in size from 16 gauge (.0508” in dia.) to 4/0000 (.460” dia.). One insulated 6 gauge or larger, or several smaller ones bound together in a single unit, is referred to as cable. 8 gauge or smaller is called wire.
Describe the characteristics of a raised-floor air distribution system.
The primary supply of conditioned air through a plenum beneath the floor.
It offers improved occupant comfort and the flexibility of individual occupant control at any point. Highly effective compared to traditional overhead systems where supply and return registers can cancel each other’s efficiency. Possible initial-cost benefit due to wire management capabilities and integration into HVAC and furnishing systems. Reduced life-cycle cost due to flexibility of occupant control.
Stack Vent
The length of pipe that rises above the highest fixture in a building. Used to vent the soil stack.
An owner expects to occupy a new building for a period of 25 years. In addition to aesthetics, the choice of material to be used for the exterior cladding might be based on what?
The choice could be based on the life-cycle cost of the material.
For example, painted wood panels may last for the duration of occupancy, 25 years. Including maintenance costs, it may be substantially cheaper than masonry cladding which may have a high initial cost, and last for 50 years with little or no maintenance.
Which of the following is the least desirable source for potable water?
A - Deep Wells
B - Recycled Water
C - Rivers or Streams
D - Runoff
B - Recycled Water
This is not a good choice for POTABLE water. It would require a great deal of expensive treatment to make it potable.
Static Head
The pressure generated at the bottom of a column of water that forces the water up vertically.
Water is lifted 2.3 feet by 1 pound of pressure per square inch (psi) (or .434 psi/ft.).
If the use of incandescent lighting in a space proves to be inefficient, what is the next likely lighting choice?
Fluorescent Lamps
They are much more energy efficient than incandescent lights and have up to 20 times the operating life. They are low in cost and come in a variety of color temperatures. In an effort to limit the amount of hazardous lighting waste, some manufacturers offer low-mercury fluorescents they also offer products in which the lamp base connection is welded or uses a lead-free solder.
(LED is newly available energy efficient technology that is long lasting and has a dropping initial cost).
Why do flues extend beyond the top of a building?
They extend beyond the top of a building to provide a natural draft and to vent the products of combustion above the level of occupancy. They must project a minimum of 2’ above any point on the roof within 10’ (measured horizontally).
Name and define the FIVE generic types of lighting systems.
1 - INDIRECT: 90-100% of light output is directed upward toward the ceiling and upper walls. Fixture at 18” min. below ceiling. Minimum ceiling height 9’-6”. Shadowless, even illumination with no reflectivity or glare. Inherently inefficient.
2 - SEMI-INDIRECT: 60-90% of light output is directed upward. Low reflectivity and glare. Somewhat more efficient than indirect.
3 - DIRECT-INDIRECT and GENERAL DIFFUSE: Approximately equal distribution of light upward and downward. Good diffuse ness. Direct-Indirect fixtures have little horizontal output. Diffuse fixtures give light in all directions. Good efficiency and overall uniformity.
4 - SEMI-DIRECT: 60-90% of light output is directed downward. Diffuseness depends on reflectances of the furniture and floor. Minimal shadowing when the fixture has an upward component of at least 25%.
5 - DIRECT: 90-100% of light output is directed downward.
Light-effect depends on luminaire type. Spread luminaires result in considerable diffusion and good general lighting. Concentrating luminaires produce sharp shadows appropriate for highlighting.
Characteristics of standard escalators.
Commonly referred to as moving stairways.
In the U.S. they are installed at an incline angle of 30 degrees from horizontal.
Minimum vertical clearance of 7’
Available in speeds from 90-125 feet per minute although industry standard is 100 fpm.
Available in three widths, 24, 32 and 40” Treads are 16” deep.
Risers are 8”
Infiltration
Sensible heat loss or gain (qv)
due to unintentional ventilation.
qv = V x 1.08 x _/_T
Where:
V is ventilation
_/_T is the change in temperature.
Panelboards
A set of fuses or circuit breakers that is the central distribution point for electrical loading in a building.
Describe the color characteristics of common light sources.
The color of an object being illuminated is largely dependent upon the type of light source.
FLUORESCENT: Warm white: produces yellowish color and simulates incandescent light. Cool white: Produces white color light.
INCANDESCENT: Produces yellowish/red light and is very flattering to the skin.
CLEAR MERCURY: Produces blue/green light with poor overall color rendition.
HIGH-PRESSURE SODIUM: Produces light with a distinct yellow tint. Low pressure sodium also produces a deep yellow color but has a higher efficacy.
Why is a vapor barrier placed on the warm side of insulation?
This location inhibits condensation from reaching the dew point by restricting the transmission of water vapor through a wall or roof cavity. It is placed on the outside of a construction assembly in a hot-humid climate and on the inside in a cold climate as in the drawing below.
What effect does sound have when it strikes a wall or barrier?
VIBRATION
Wall vibration initiates a sound wave on the opposite side of the wall. Heavier walls have greater inertia and transmit less sound. The thicker the material or wall, the more the sound is absorbed.
Identify the following:
A - P-trap
B - S-trap
C - S-trap
D - U-trap
Thee plumbing traps are typically located beneath lavatories. After the fixture is used, the water remaining in the pipes acts as a plug that inhibits noxious sewer gases from entering a building. Fixtures such as urinals and water closets have self-contained, integrated traps.
Emissivity
The ability to, and rate at which a material absorbs and then emits radiant energy.
It is measured from 0 to 1.0
What is the most critical period of time in the incidence of a fire?
A - The first hour.
B - The first minute.
C - The first 5 minutes.
D - The first 30 minutes.
C - The first 5 minutes
A critical period because smoke and fire spread quickly and can overcome occupants in moments. Fire can spread at a rate of 15 feet per second. However, smoke rather than fire itself presents the greatest danger to building occupants.
What is the major advantage of direct current low voltage lamps?
They have smaller filaments which allow more precise control over light placement.
Identify the following:
A siamese Fitting
A device to which fire-fighting hoses are atatched to provide water to a standpipe. It is made up of two or more inlet fittings.
Light Shelf
A constructed shelf below a window, designed to reflect light up towards the cueing and distribute it back into a space.
How can the sound transmission loss of a wall be improved?
By increasing the mass of the wall. Stud walls should have staggered studs and the drywall should be mounted with a flexible channel. Because of the mass of a concrete wall there is very little sound transmission.
Zonal Cavity Method
A calculation of the lumen output of lamps, the number of lamps in each luminaire, and the efficiency of the luminaire based on a Coefficient of Utilization (CU). This method is most commonly used to determine the lighting requirements for offices, factories and commercial spaces.
In a computer room what is the preferred method of extinguishing a fire?
HALON
A method of extinguishing fire by interfering I. The chemistry of combustion and not by excluding oxygen. No clean-up is required, only airing out is needed. Does not harm computer equipment. Contains CFCs, which are harmful to the environment. Note: Halon is restricted in its use and was to be phased out by the year 2000. Newer Halon-based products are being developed that do not release the amount of CFCs that older Halon products did.
Pre-Action Sprinkler System
A type of dry pipe sprinkler system intended to compensate for the operational delay of a standard dry pipe system
The fire sprinklers work in conjunction with a more sensitive fire-detection system. When activated, the detection system allows water to fill the pipes, but it is not released until the sprinklers themselves are activated. This system is soused in areas where there is danger of serious water damage. The disadvantage of this system is the reliance on additional electrical and mechanical devices that allow water to fill the pipes.
Greenhouse Effect
Radiant heat gain through glass. Also called insolation.
Latent Heat
Heat energy that causes a change of state, such as ice to water. Condensation in the air causes a heat-energy reduction. Transfer of heat energy is not to be confused with temperature, which is a measure of heat.
What is the water pressure of a typical water-shower head?
A - 10 psi
B - 6 psi
C - 12 psi
D - 30 psi
C - 12 psi
Mean Radiant Temperature (MRT)
The average temperature of all radiating surfaces within the line of sight of a body. Used to determine the comfort zone. If the MRT is high, then the comfort zone moves to a lower ambient temperature and vice-versa. MRT is measured using a globe thermometer and is independent of air temperature.
Ground Fault Circuit Interrupter (GFCI)
An outlet receptacle used in wet areas to provide additional protection against electrical shocks.
Vent Lines
Pipes extending up from a fixture and through the roof to allow airflow Within a plumbing system. Keeps water pressure in the drainage system equalized.
Which type of electric current is used by a universal motor?
AC or DC This type of motor is usually used in hand-held appliances, such as construction tools.
Coefficient of Heat Expansion (U)
This is the rate at which heat flows through an assembly of building materials that make up a wall, floor, roof, etc.
U = 1/ΣR
Where:
U = heat transmission
R = resistance to transmission
The reciprocal of the U-value is the R-value
How is the required size of a heating system for a building determined?
The total heat loss must be calculated. Teh coefficient of heat transmission (U) is calculated using the formula:
U = 1/ΣR
This must be done for each of the different assemblies in a building, such as the roof, walls and windows. The total heat loss is the sum of these U-values
Makeup Air Handling Unit (AHU)
An air handling unit specifically designed to supply 100% outside air to a space. This outside air replaces air lost through exhaust fans or the building envelope.
What type of motor is best used for operating an elevator?
DC motor. Good for continuous and smooth acceleration. Can run at high speeds.
Reverberation
The persistence of sound in an enclosed area after the sound source has stopped. Reverberant spaces are considered live spaces. This is a function of the absorptivity of surfaces and the volume of the space.
ASHRAE
American Society of Heating, Refrigeration and Air-Conditioning Engineer, inc.
Publishers of a handbook of fundamentals, giving minimum requirements for energy conservation in buildings. First written in 1975 as a guideline, the manual has been adopted in building codes and made mandatory in most states.
Enthalpy
The sum of sensible heat and latent heat in a material.
Elevators may be the most strictly regulated component of construction. What governing bodies affect the design and installation of elevators?
The essential code is the American National Standards Institute/American Society of Mechanical Engineers (ANSI/ASME) code A17.1, Safety Code for Elevators, Dumbwaiters, Escalators, and Moving Walks.
Other codes influence design as well. The National Fire Protection Agency (NFPA) provides some fire safety and electrical standards regarding life safety issues. The Americans with Disabilities Act (ADA) provides guidelines for accessibility. in addition to ANSI, NFPA, and the ADA, the National Elevator Industry Inc. (NEII) provides standard layouts and suggested minimums for accessibility.
What material expands as temperature decreases?
Water is the only known material to expand as it gets colder. This expansion occurs just prior to freezing.
Name TWO types of active solar hot water systems. What are their particular characteristics?
1 - FLAT PLATE COLLECTORS: The most common and least costly solar hot water panel used for domestic hot-water systems. They are typically a 4’ x 8’, insulated glazed box with a piping manifold connected to the black metal flat plate.
2 - CONCENTRATING COLLECTORS: Use metal reflectors to concentrate the sun’s rays on a tube or point. These panels generate much higher temperatures than flat plate collectors and are a far more efficient use of surface area, but are more complex and expensive.
Identify the following HVAC System
Variable Air Volume, Air Handling System (VAV)
A centralized air-distribution system that provides constant air temperature with varied volume. Can be either a single or multiple duct system. It is not possible for a VAV system to control humidity or provide stringent ventilation. At low-load conditions the air distribution is not effectoive. Simultaneous heating and cooling for different zones is not possible.
After heating capacity, what is the most significant factor in choosing a central heating system?
The selection of a central-heating system is largely dependent upon economic factors.
Which is a better carrier of heat, water or air?
WATER
Water is a good heat-carrying medium for both heating and cooling.
Fire Compartmentation
A means of confining fire, smoke and toxic gasses. Also serves to provide a place of refuge for occupants and fire-fighters by dividing a building into two or more spaces totally enclosed within the fire barrier. Comprised of special floor, ceiling and wall assemblies.
Which type of voltage is most often used in a small office building?
A - 277/480 v three-phase
B - 2400/4160 v three-phase
C - 120/240 v single phase
D - 120/208 v three phase
C - 120/240 v single phase
This three-wire system is most commonly used in residences and small office buildings. It is used where the actual load is not more than 80 amps even though minimum service is considered 100 amps.
A - 277/480 v three-phase, four wire system is used for large commercial buildings.
B - 2400/4160 v three-phase, four wire system is used for very large commercial and industrial buildings with a lot of machinery.
D - 120/208 v three phase, four-wire system is used for small and medium sized commercial buildings. It differs from 120/240 v single-phase in that it allows for various electrics loads.
Which component is NOT a part of an electric elevator?
A - Guiderails
B - Pit
C - Plunger
D - Hoistway Shaft
C - Plunger
An electric elevator is also known as a cable or traction elevator. A plunger, however, is the lift mechanism of a hydraulic elevator.
Sensible Heat
Transferred heat energy that causes a change in the dry bulb temperature of a material but not a change of state.
Name THREE types of private, on-site waste disposal systems.
1 - LEACHING CESSPOOLS: The effluent flows from a septic tank through porous conduits and is absorbed by pervious soil. Least expensive.
2 - SUBSOIL DISPOSAL BEDS: Drainage of effluent two feet or more below the water table.
3 - SAND FILTERS: Used in areas with impervious soil. Collection drains carry effluent to a non-potable watercourse. Most expensive.
What factors contribute to duct-work efficiency?
Having the least possible perimeter distance allowing for less resistance and friction to air movement.
A circular cross-section is the best shape for ducts, especially for high-velocity systems. Increased air friction often causes noise problems in higher-velocity ducts.
Rectangular ducts are used in low-velocity systems.
High-Velocity: above 2,500 fpm
Medium-Velocity: 2,200-2,500 fpm
Low-Velocity: 1,000-2,200 fpm
Name the FOUR regional climatic zones of the North American continent, and the climatic factors that effect human comfort.
Regional Zones:
1 - Cool
2 - Temperate
3 - Hot-Arid
4 - Hot-Humid
Comfort Factors:
1 - Temperature
2 - Humidity
3 - Precipitation
4 - Radiation
5 - Air Movement
What term describes optimum lighting?
Equivalent Spherical Illumination (ESI).
The even, spherical illumination of an area with all shadows and bright reflections eliminated.
Anode
A piece of metal inserted into a water tank or collect hard-water deposits in order to keep them from forming on the heat exchanger.
Dew Point
The temperature at which water vapor in the air becomes saturated and condenses into water droplets. Dependent upon the dry bulb temperature. As the temperature drops, the air can no longer hold as much water vapor and the vapor condenses.
(k)
The symbol for thermal conductivity. It is the ability of a material to transmit or conduct heat or electricity. This is based on the physical properties of the particular material, and is the amount of heat transmitted in one-hour through one square foot of a 1” thick material for each degree Fahrenheit of temperature difference between the two surfaces of the material. Expressed in British Thermal Units (Btu).
Psychrometric Chart
A graphic representation of the thermodynamics and thermal properties of moist air. It is also an indicator of the energy content of the air and water vapor mixture. It is used to find dew points, relative humidity, to calculate enthalpy and to determine humidity ratios. All are values necessary to compute the relationship of heat to air flow in air conditioning design.
What is the predominant use of electrical power in a building?
LIGHTING
It is usually in use for the majority of the day throughout a building. Motors are the next biggest consumer of electrical power in non-residential buildings.
Direct Current (DC)
vs.
Alternating Current (AC)
DIRECT CURRENT (DC)
The flow of electricitiy takes place at a constant time rate, voltage and in the same direction around the circuit. Often found in elevator work.
ALTERNATING CURRENT (AC)
The flow of electricity reverses direction and changes voltage. This is the type of power generally available from utility companies and it operates at 60 hertz.
Busbars
Rectangular copper bars used to conduct high currents of electricity. Power is transmitted through multiple bars, insulated from one another, and arranged in a metal housing called a busway.
Dry Bulb Temperature
Air temperature as measured with a common thermometer.
Light Intensity
The quantity of light generated by a source. Measured in terms of the amount of light coming from a single candle. One candlepower (cp)
An elevator shall be located on an accessible route and comply with ASMR A17.1 (the life safety code). What are the other ADA requirements for elevators?
A freight elevator need not comply unless it is the only elevator and it is also used for passengers. With some exceptions for malls, offices, passenger terminals, etc., an owner is required to install an elevator in an altered facility if it is less than three stories, or less than 3,000 sq. ft. per story.
Car must be self-leveling to within 1/2” of the floor landing.
Lobby call buttons shall be centered at 42” AFF, include visual indication signals and be 3/4” minimum in the smallest dimension.
Hall lantern fixtures with visible and audible signals shall be mounted 72” min. AFF, and be 2.5” min. In the smallest dimension.
Raised Braille character floor designation, 2” high on both jambs mounted at 60” AFF.
Automatic protective door re-opening device activated when obstructed.
5 second min. notification between the time when the lantern is visible and when the directional sound is heard (once for up, twice for down).
3-seconds min. For doors to remain fully open.
Car control buttons are to be between 35” and 54”
Clear door width of 36” min.
Crack Method
Measures Infiltration Based on the total number of linear feet of cracks or joints around building elements such as doors and windows. The amount of infiltration, or leakage, per linear foot is determined by a table that accounts for wind speed and the type of opening.
Fixture Unit (FU)
Used to define the portable demands on plumbing fixtures. One fixture unit is approximately equal to a unit flow rate of one cubic foot per minute.
Foot Lambert
A quantitative unit for measuring brightness as reflected from a surface. Measured in lumens per square foot.
Candle Power
A measure of the luminous intensity of a light source. It is the amount of light emanating from one candle or one candela.
Photovoltaic Power System:
Uses electricity generated directly from sunlight.
This process can only convert part of the sunlight into electricity (appx. 14%). The rest is dissipated as heat and reflected light. PV’s are most efficient at lower operating temperatures.
Coefficient of Utilization (CU)
A ratio of the lumens received on a work surface to the lumens emitted by the light source. Factors taken into account are the direction of the light and the reflectivity of ceiling, walls and other objects between the light source and the receiving surfaces. Common CU values are between .5 and .8. CU is used in the zonal cavity method.
Upfeed System
A water-supply system that uses existing pressure in the water main to supply fixtures. Building height limit for this system is 40-60 feet.
Identify this valve type.
A globe Valve
Used to turn water on and off and to regulate the flow at intermediate rates. Even when wide open, flow is somewhat restricted.
Mame FOUR ways in which heat can enter a space.
1 - Solar Radiation through windows.
2 - Heat Conduction through the building envelope.
3 - Heat generated by people and equipment.
4 - Warm outdoor air entering through vents or by infiltration.
What is the function of a motor?
It is a machine that converts electrical energy into mechanical energy and heat.
Dry Pipe Sprinkler Systems
Used when there is a danger of pipes freezing.
A fire-fighting system with delivery pipes that are filled with pressurized air. Not as immediate and is more expensive it install and maintain than a wet-pipe system.
In the beginning of the design development phase, the architect may need to contact the local water company to determine:
A - the future water costs of the building.
B - the location, size, and pressure of the water main.
C - the pH of the water at the site.
D - the location of the fire hydrant.
B - the location, size, and pressure of the water main
Location is important because, if the water main is not adjacent to the site, the owner will have to pay to extend the line. Pressure and size are important, because they help to determine the type of supply system required.
Automatic Fire Recall (capture) System
Required by elevator codes in case of fire, this system immediately returns all elevators to a predetermined floor (usually the ground floor) where they remain parked with the doors open. This system allows fire fighters to determine that no one is trapped in an elevator in addition, a vented elevator shaft can facilitate the removal of smoke from the floor of the fire.
Identify this HVAC System
High Velocity Dual Duct Air Handling System
This type of HVAC system has two parallel ducts, one hot and one cool. Air is mixed in a mixing box to meet the required temperature. It can respond to different zones simultaneously. RTequires a lot of duct work and is inefficent, because it heats cool air and cools warm air. Not in common use.
When there is no heat loss from the human body due to conduction, convection or radiation, what is the outside air temperature?
98.6 degrees F.
Or when air temperature is equal to body temperature. When the air temperature rises above body temperture, the heat flow reverses evaporation takes place.
STC
Sound Transmission Class
A numerical rating of wall and floor systems for their efficiency in isolating sound transmission. The greater the rating, the more efficient the construction.
Identify this valve type
A Check Valve
A type of valve that prevents back flow. Allows water to flow only in one direction. A flap is pressed shut if the water tries to flow backward. It works automatically to keep contaminated water from entering th water supply
In most high-rise buildings, a fire communications system is required. Where is this system located?
By stair tower doors and at every elevator lobby often accessed with a phone jack.
Downfeed System
A rooftop water-supply system used in tall buildings, where the water flows by gravity. Water pressure is determined by the height difference between the tank and the floor being served. This system can serve the upper floors, while the up feed system serves the lower floors. Adds weight to the roof and may require extensive structural engineering.
Pneumatic Tank System
A water-supply system that uses a pressurized tank, located in the basement to supply water to the upper floors. Used as an alternative to a downfeed system
In an open space, when the distance is doubled between a receiver and a sound source, how much does the intensity level decrease?
6 decibels
The intensity (I) of sound, measured in power (watts) per square centimeter, decreases to 1/4 (the inverse square law) while the intensity level (IL), measured in decibels (dB) only decreases by 6 dB.
What THREE components equal the total incident sound energy?
1 - REFLECTION: a return of sound not absorbed upon contact with a surface.
2 - ABSORPTION SOUND WAVES: sound energy which strikes a material and is absorbed and converted into heat energy.
3 - TRANSMISSION: sound vibration that moves through various materials.
AHU
Air Handling Unit
The heart of the HVAC system. Comprised of blowers, fans, filters, heating and cooling coils, and a drain pan within a single enclosure. It heats, cools, humidifies, dehumidifies, filters and supplies and returns air. It exhausts air to the outside and brings in fresh air. They come in a variety of sizes and forms, such as central, unitary and furnace types.
Flame Detector
A fire-alarm system that is sensitive to infrared and ultraviolet radiation. It is the most rapid type of fire protection. However, such a system does have a tendency to cause false alarms and cannot detect smoke.
Ampere (A)
The practical unit for measuring the amount of electricL current flowing in a circuit. 1 volt applied across a resistance of 1 ohm will cause 1 amp (A) to flow A = W / V
What is a heating or cooling load?
The rate at which heating or cooling needs to be removed or added into a space to maintain a comfortable room temperature.
Resistance (R)
R = 1 / C Resistance (R) is the reciprocal of Conductance (C) and is a measure of the insulating quality of a material. Conductivity measures a material’s ability to conduct heat. Resistance increases as the thickness of a material increases.
Air movement affects body heat by what processes?
Convection and Evaporation The faster the air movement, the greater the rate of heat flow from convection and evaporation.
Luminance
A measured quantity of light at a given point on a surface coming from a given direction. This measure accounts for the reflectance and transmittance of materials.
Foot Candle (fc)
A measure of illumination equal to one lumen. The amount of luminance from one lumen on a one square foot surface.
Btu
British Thermal Unit The amount of heat energy required to raise the temperature of one pound of water by one degree Fahrenheit.
What is wet bulb temperature and how is it measured?
A measure of relative humidity. It is determined by using a sling psychrometer which is made up of two thermometers, side by side, one covered with a wet sock. This instrument is swung in the air so that the moisture from the wet sock will evaporate. The drier the air, the more evaporation takes place and the lower the relative humidity.
Lumen (l)
A unit of luminous flux that is a measurement of the total output of a light source. It is equivalent to the amount of light that flows through one square foot of a surface area located one foot from a one candlepower source.
Given the following R values, find the U vlaue for a wall assembly.
Inside Air Layer = 0.68
½” GWB = 0.45
5½” Batt insulation = 19.00
½” Plywood Sheathing = 0.62
Vapor Seal = 0.00
16” wood shingle @ 7½” exposure = 0.87
Outside Air Layer = 0.17
Using the formula for the coefficent of heat transmission:
U = 1/ΣR
Add all R values in the assembly.
ΣR = 21.79
1/21.79 = 0.045 Btu/h - ft2 - °F
The standard electrical circuit arrangement in nearly all buildings’ wiring is called what?
Parallel Circuits
This is a circuit that has two or more loads or branches connected between the sake two points. That is they are connected in parallel or multiple. In this example the lights are one parallel grouping and the wall outlets are a second. Loads on the current are additive and the same coltqage is imposed on each load.
Note: If there is any connection between a and b, the circuit will be “shortened”. The result is a very high current and a short circuit. In aproper;ly protected circuit, the breaker or fuse will open and the power to the circuit is cut.
What type of conduit can be used anywhere, except underground?
Flexible Metal Conduit It consists of a spirally wound interlocking sleeve and is known to the trade as ‘flex’ or ‘Greenfield’. It is excellent for use on transformers, motors, ballasts, etc. where acoustic and vibration isolation is important. When covered by a plastic jacket it is suitable for use in wet locations. PVC plastic conduit, however, is ideal for underground use.
Define and describe the characteristics of a Transformer.
A device that changes the voltage, not the power, in alternating current (AC). Cannot be used on direct current (DC).
Typically, it is mounted on a concrete pad outside a building and, it is used to step down incoming voltage to 480V for building use. An additional transformer inside the building is used to step the voltage down to 120V for use at receptacles.
There are several advantages to locating a transformer outdoors:
1 - No interior building space is required.
2 - No interior noise problem
3 - Ease of installation lowers initial cost.
4 - Use of oil-cooled units lowers life-cycle cost.
5 - Ease of accessibility for maintenance.
6 - Safety
7 - No interior heat gain
If an exterior location is unavailable or disruptive, a basement installation is preferable. Ideally, excessive heat is handled by natural convection through louvers or if the load is relatively constant the resulting heat can be put to use in the HVAC system.
Specular
A surface that maintains a reflected image, such as a mirror.
Ohm’s Law
The relationship between voltage, current and resistance in direct circuits. It states that the current in a circuit is directly proportional to the resistance. One Ohm is the unit of measure of electrical resistance to the flow of current I = V / R Where: I = Current (amps) R = Resistance (ohms) V = Voltage
Ballast
A component of fluorescent and high intensity discharge lamps that controls voltage and current in order to provide circuit conditions that are needed to start and operate a lamp. Produces noise and heat.
Name the appropriate term for each of the following definitions:
1 - The property of a material that permits the passage of diffused light so an image on the opposite side is not clearly visible.
2 - A material that is impenetrable to the light.
3 - The property of a material that permits the passage of light so that an image on the opposite side can be seen directly.
1 - Translucent: frosted, etched or sans-blasted glass
2 - Opaque
3 - Transparent: clear window glass.
Identify these electrical symbols:
A - Duplex Recptacle - 120v grounding type
B - Duplex Receptacle - 120v ground fault type
C - Double Duplex Receptacle - 120v grounding type
D - Special Receptacle
E - Panel Board
F - Transformer
G - Concealed Circuit
H - Exposed Circuit
I - Switch
Incipient Stage
The first stage of a fire when invisible products of combustion are given off. There is no visible smoke, flame, or appreciable heat. An ionization fire detector reacts at this stage.
What machine converts mechanical energy into electrical energy?
A Generator Other methods of generating electricity of site, other than using a utility company include: Photovoltaic cells Wind turbine Hydropower Thermal-sources
_/_T
The temperature differential between inside and outside, usually during winter. Determined by subtracting the outdoor temp. from the desired indoor temp.
Name some of the advantages of insulated ductwork.
1 - Reduces heat loss from ducted warm air.
2 - Reduces heat gain into ducted cold air.
3 - Isolates air noises in the duct from the serviced spaces.
4 - Prevents condensation on the outside of cold-air ducts when the surrounding air is warm and humid.
Avoid fleecy interior-duct insulation. It can become a sink for moisture, mold and contaminants. Insulation fibers as well as the contaminants can be easily spread through a building and can comprise the overall Indoor Air Quality (IAQ)
Heat Pump System
Based on the principles of refrigeration. A reversible system that can change the direction of refrigerant flow by using the evaporator as a condenser, and vice-versa. It can absorb heat from the outside or can remove heat to the outside. Heat pumps are most efficient in a moderate climate.
Identify this HVAC system.
Water to Air Heat Pump System
An HVAC system that uses water or steam as a source for heating and cooling. These systems have zoning flexibility, low initial cost and ease of placement within existing structures. The main disadvantage with water HVACs is that fresh air cannot be distributed. A fan coil unit must be installed in each space, requireing connection to one or two water circuits.
There are 1, 2, 3 and 4-pipe systems.
Which of the following depends on gravity the most?
A - Water
B - Sewer Systems
C - Storm Drains
D - Irrigation
B - Sewer Systems
Effective Temperature
A measure of a combination of several comfort indexes; dry-bulb temperature, relative humidity, radiant energy and convection. An index of thermal sensation, not a measure of actual thermometer temperature.
Thermal Lag Factor
A numerical representation of the time that it takes radiant heat gain entering a space to be absorbed into the room air and become part of the load on a cooling system. This lag time is determined by the thermal capacity of the materials within and surrounding the space.
Name FIVE techniques used in passive solar cooling.
1 - Ground Coupling
2 - Evaporative Cooling
3 - Shading
4 - Natural Ventilation
5 - Radiative Cooling
Name THREE types of mounting for light fixtures
1 - Surface
2 - Recessed
3 - Suspended
