Chapter 16 Mechanical and Electrical Systems Coordination Flashcards
Coordination
Although interior designers/architects are not responsible for designing building systems, coordination with consulting engineers concerning locations of plumbing fixtures, air diffusers, sprinklers, and other mechanical/electrical elements
HVAC
- heating, ventilating, and air conditioning
- Includes all equipment for these purposes
Type of HVAC Systems
All-air systems
All-water systems
All air systems
- Cools/heats spaces by conditioned air alone. Air transported with supply/return ducts. Can also supply humidified/dehumidified air as needed
- Each type requires supply air ductwork registers, and return air grilles in all spaces
- Duct penetrations through fire rated partitions must have fire dampers that close automatically in case of fire
All Water Systems
Use a convector in each space through which hot water (sometimes cold, too) is circulated; water heats/cools fins in convector unit, causing change in air temperature
- Air may be circulated by convection, or forced circulation by fan
Combo systems
Combination systems use ductwork to supply fresh air, but use water to heat/cool air before introducing it into space – called terminal reheat systems equipment is located in plenum
- Other installations use all-water system for heating, separate duct system for ventilation & cooling
chases
fully enclosed shafts dedicated to ducts/piping
Mixing Boxes
adjust quantity/temperature of air going into space from main air supply; ensuring adequate clearances for units important coordination issue; terminal reheat systems have boxes with water coils inside, identified by air ducts & copper pipes leading into boxes
Plenum Requirements
Commercial bldg. codes prohibit using wood, exposed wire in plenums used as return air space; some telephone/telecom wiring using teflon-coated wiring allowed, in place of running wire in steel conduit
Access to HVAC
Building codes require access to mechanical/electrical system components, including valves, fire dampers, heating coils mechanical equipment, electrical junction boxes, communication junction boxes, etc.
If suspended acoustical ceiling, access by removing tile; gypsum board ceilings, etc. require access doors-can be rated if required
Thermostats
Normally 48” A.F.F., but may need lowering for accessibility, coordination with light switching, etc.
Registers and grilles
Air supply registers should be placed near windows & other sources of heat loss/gain; return air grilles should be placed away from supply points to provide good heat/air circulation throughout space
HVAC and Window Coverings
Window coverings
Can affect heat/cooling loads, interfere with supply air diffusers/heating units near windows
Coordinate with mechanical engineer
2” between glass & window to avoid excessive heat buildup
Acoustics and HVAC
HVAC & electrical systems often pose acoustic separation problems, especially where ducts, etc. run continuously at exterior, while partitions intersect exterior wall at regular intervals – special detailing may be required to seal floor, ceiling, above ceiling, perimeter walls
Diffusers
several types are available
common ones are slot air and square
Square Difussers
1-2ft square diffusers commonly used in suspended ceilings; also available for wallboard & plaster with trim flange to cover rough opening
Slot Diffusers
Slot air diffusers used where minimal appearance/space require them; typically 2-8 slots, 3-8” overall width – box above slot fed by flexible duct attached to box side
Power System Requirements
Electrical systems include power for lighting, convenience outlets, and fixed equipment
- Designers responsible for schematic layout of outlets/switches, where power required for built-in equipment, appearance of visible electrical devices
Conductors
Extend from service entry to circuit breaker boxes to individual switches, outlets, lights
Nonmetallic sheathed cable (‘Romex)
has two or more plastic insulated conductors & ground wire surrounded by moisture-resistant plastic jacket; can be used with wood studs & grommeted steel studs – protected by wallboard & ceiling materials
Flexible metal-clad cable (armored cable or ‘BX’ cable)
– sim. to sheathed cable, except encased in spiral-wound steel tape; used in remodels because of ease of pulling through existing spaces, also used to connect commercial light fixtures to junction boxes, allowing easy relocation in suspended ceilings when needed
Under-carpet wiring:
thin, flat, protected wire laid under carpet; usually connects pedestals in middle of room with outlets/telephone connections to junction boxes in nearby walls
Junction Boxes
Outlets, switches, & other connections to power supply must be made in junction boxes
Single switches, duplex outlets use 2x4” boxes; larger boxes available for multiple outlets/switches. Most boxes 1-1/2” or 2-1/8” deep
Who specifies minimum outlet spacing ?
National Electrical Code (NEC), International Residential Code (IRC) and ICC Electrical Code
Residential Code requires outlets where?
convenience outlets in every kitchen, family room, dining, living, library, den, sunroom, bedroom, rec. room, etc.
No point along floor line in any wall space can be more than 6’-0” from an outlet
Walls how long unbroken require outlet?
Walls 2’-0” to 6’-0” long, unbroken by doorways, fireplaces, etc. must have an outlet
Telephone&Communication System Requirements
Interior drawings usually show telephone & communication systems on same plan as power outlets
Designer responsible for indicating telephone, intercom, PA speakers, buzzers, computer terminals;
Actual circuits, locations appear on electrical engineer’s drawings
Telephone/comm. systems low-voltage; less stringent conduit & protection requirements
Usually run from junction boxes without conduit, with some exceptions
Plenum-rated cable available – more expensive than standard cable
Light sources
Affect construction detailing due to weight, location, size, mounting method, heat output
incadscent
Consists of tungsten filament placed within sealed bulb containing inert gas
Several types, shapes used in surface-mounted, recessed downlights, etc.
Housings can be large, requiring significant above-ceiling space for recessed downlights
- Incandescent lamps used for low cost, easy dimmability, repeat starting without decrease in life, warm color rendition, ease of output control with lenses & reflectors
Reflector lamps (R, ER, PAR type)
require large clearances, combustible material separation due to heat output unless specially constructed, rated units used
Tungsten halogen lamps
have halogen gas in addition to inert gas; when tungsten burns, halogen causes particles to redeposit on filament, greatly extending lamp life, uniform light color; bulb made from quartz, smaller than standard incandescent lamps, give hotter, whiter light. Due to high pressure/heat, can shatter explosively – always encased in glass/screens
disadvantages of incandscents
Disadvantages: low efficacy (light output relative to energy used), short lamp life, high heat output
Flourescent
Used where more efficient source than incandescent required, linear source needed
Larger than incandescents, so controlling output precisely more difficult
Usually used for general illumination
Compact fluorescents available to fit in reflector housings sim. to incandescents
Ideal for continuous lighting, downlighting used to uniformly wash partitions with light
T8 & T5 (1” & 5/8” diameter) most common due to higher efficacy, better color rendition than older, larger lights; smaller luminaires, higher-efficiency control available
All fluorescents have ballasts – device that supplies proper starting, operating voltage to lamp; can be mounted as part of luminaire, or remotely located
High-Intensity Discharge (HID)
HID lamps produce light by passing electric current through gas or vapor under high pressure; include mercury vapor, metal halide, and high-pressure sodium (HPS) lamps
Mercury vapor lamps: electric arc passes through high-pressure mercury vapor, producing ultraviolet & blue-green light. Phosphors applied to inside of lamp to produce more yellow/red light. Long life, poor color rendition
- HID’s usually limited to gymnasiums, parking garages, industrial settings
Metal halide lamps
: sim. to mercury vapor, except metal halides added, increasing efficacy, improves color rendition, shortens lamp life. Combine best features of HID lamps; good color rendering, high efficacy, relatively long life. Main disadvantage is large shift in apparent color temperature over life
High-pressure sodium (HPS):
pass electric arc through hot sodium vapor. Tube must be ceramic material to resist hot sodium; very high efficacy, long life 10,000-24,000 hours. Standard types have very yellow light; some color correction versions can be used indoors
Neon and Cold-Cathode
- Neon lamps can be formed into unlimited shapes, used for signs, accent lighting; by varying gases within glass tube, variety of colors produced
- Cold-cathode lamps similar, but have higher efficacy, slightly larger (1” dia.), can produce several shades of white as well as colors
- Both types require brackets to hold glass tubes, transformers
LED
these very low energy light sources highly resistant to vibration, can be mixed to provide acceptable color rendition; mostly used for accent lighting, some desk lamps at this time. One manufacturer offers a neon replacement, called ‘plexineon,’ which is field-bendable, outdoor compatible, and has very long life
Lighting Systems
- Recessed lighting
- Recessed fluorescent troffers
- recessed incandescent downlights
- Cove lighting
Recessed lighting
requires sufficient clear space above ceiling to install fixtures
Recessed fluorescent troffers
mounted in acoustical ceilings usually have no clearance issues
Large, recessed incandescent downlights
may require HVAC ductwork, conduit, plumbing pipes to accommodate fixtures
Cove lighting design
requires knowledge of luminaire dimensions, sightlines to conceal fixture, lamp photometrics, desired cove strip design
Control Devices
Designer should decide how lights should be switched, based on lighting function, amount of individual control needed, best switch locations, energy conservation needs, and maximum electrical load requirements on any one circuit
Switches should be located at primary door entering space to enable easy control as people enter/leave; larger spaces often have 3- or 4-way switches, which allow control from 3 or 4 locations
Dimmers can be used on both incandescent and fluorescent lights, but fluorescent dimmers expensive, special fixtures required; fluorescents & incandescents should be on separate circuits
Custom Detailing for Lighting
While most projects do not require custom fixtures, some projects require custom fixtures
Use UL-approved components to ensure approval by code officials, consultation with lighting designer recommended in many cases
Plumbing
Two major components: water supply (hot & cold), drainage
Water is supplied under pressure to individual plumbing fixtures
Due to small size & pressurized lines, relatively easy to locate pipes in wall cavities, ceilings, etc.; closer to source = cheaper
Drainage Systems
Drainage Systems
Systems more difficult; work by gravity, so must be sloped to drain. Require vent pipes; ref. fig. 16.7 for basic components
First drain component is the trap, which is located at every fixture except those with internal traps (like toilets); designed to hold small quantity of water to provide seal against sewage system gases entering building. Multiple sinks sometimes connected to single trap
Traps connect to vent pipes connected to system at multiple locations, open to outside air
Vents
Vents allow sewage gases to escape, allow pressure in system to equalize so discharging waste does not siphon draining water out of traps
Sewage travels…
waste does not siphon draining water out of traps
From traps, sewage travels to a vertical stack via fixture branch lines; stacks carrying toilet waste called soil stacks, other stacks called waste stacks
Vents for fixtures connect two ways:
Vents from individual fixtures connect above fixtures in two ways; if vent connects to waste stack above highest fixture in system, portion above this point called a stack vent, which extends through roof. Multistory buildings use separate pipe for venting, called a vent stack, which either extends through the roof or connects with stack vent above highest fixture, per fig. 16.7
Drain Slope
slope min. ¼”/ft. (1/8”/ft. in pipes larger than 3”)
Plumbing Walls
Many buildings require thicker partitions or plumbing chases to accommodate pipes, such as between back-to-back toilet rooms. Ref. Fig. 16.3 for typical pipe sizes, Fig. 1.13 for chase wall construction
Fire protection
Fire protection systems include detection devices (smoke & heat detectors), alarm, communication, annunciation equipment, and fire suppression systems
Sprinkler Location
Light hazard occupancies require (1) sprinkler head per 200s.f. if system is not hydraulically designed, or 225s.f. if hydraulically designed
- Open wood joist ceilings require (1) sprinkler per 130s.f.
-Min. distance from partitions to sprinklers 4”
- Sprinklers near vertical obstructions (such as columns) 4”-24” wide must be located at a distance at least 3x max distance of obstruction; see fig. 16.9
- When beams, dropped ceilings, other obstructions project below main ceiling, sprinklers must be located certain distance away so water stream is not deflected
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