J-2 Heat and Sound

Question 1

Conduction

Answer 1

• heat moves through solid materials by conduction

- cast iron example, burner heats molecules in pan pan heats food

Question 2

Heat capacity

Answer 2

the ability to store heat in a material.

* a piece of steel feels cold because it is more dense and can hold more heat. wood is not as dense

Question 3

Convection

Answer 3

moves in fluids by convection. can be both liquids or gasses.

• holding your hand 10” beside a candle you will feel warm but not hot. 10’ above candle it will get hot fast.
• heat causes molecules to move rapidly then they bump not each other and spread further apart
• as hot air rises cool air flows towards the candle to replace the moving air. this is called the convection current.

Question 4

Radiation

Answer 4

Sun heats the earth using infrared radiation

• when these waves strike na object it causes these molecules to vibrate and heat up.
• if you stand by a fire only your face gets warm not the air in between.
• radiant heat an be deflected. Low E windows reflect hat back out during winter and reflect heat back in the house from heaters.

Question 5

Combination of convection, conduction and radiation

Answer 5

electric baseboard heaters. elements are covered with aluminum fins. heats fins with conduction, fins heat air around them through conduction, heated air rises and cooler air fills the space creating convection current.

Question 6

Sound conductors

Answer 6

Materials that transfer sounds efficiently

Question 7

Sound insulators

Answer 7

materials that no not transmit sounds efficiently

Question 8

Absorption and reflection

Answer 8

sound waves reflect from solid surfaces and are absorbed into soft surfaces.

Question 9

Auditorium seats

Answer 9

bodies or people in an audience are good sound absorbers. auditorium seats should be apolstered with materials that have close to the same absorption rating as a human body. hall will sound same full or empty

Question 10

Vibration

Answer 10

energy in sound cam moves objects, sound waves move our ear drums.

• Sound can be transmitted from one room to another through a stud wall.
• sound vibrates drywall, drywall vibrates studs, studs vibrate drywall on other side of wall.

Question 11

Reverberation

Answer 11

if a hammer strikes a solid surface in a room. the sound will bounce around a room.
- depending on shape and type of wall the sound wil l either die out or linger ( time to die out is reverberation time)
- rooms with short reverberation time are lecture halls, rooms with larger reverberation time is concert hall.
-

Question 12

Acoustics

Answer 12

is the study of sound quality in rooms and buildings. have a big concern in lecture theters and concert halls.

Question 13

Sound transmission class

Answer 13

Building materials are rated for their resistance to transferring airborne sound. (STC)
- walls at doctors office have STC of 45 + two walls in a movie theater have a 50+
most materials that are used for insulating heat are also good for noise.

Question 14

decibles (dB)

Answer 14

used to measure the relative loudness of a sound. increase of 3 dB’s doubles sound. meaning 23 dB’s is twice as loud as 20 dB’s.

Question 15

Sound Transmission

Answer 15

materials chosen to reduce sound transmission have high absorption qualities. these materials absorbe sound . (plexiglass insulation)

Question 16

Acoustical sealants

Answer 16

sound waves travel through air. any components of a sound barrier will leak sound. examples

• gaps around ductwork
• electrical conduit wires.
• plumbing pipes
• joints between walls and floors, intersecting walls,ceiling
• gaps around light fixtures.

Question 17

Double wall construction

Answer 17

a wall system that incorporates two separate plates. the studs are staggered in each wall to allow insulation to be woven throughout.

Question 18

Staggered stud wall

Answer 18

incorporates two sets of studs on one plate. the stud layout is staggered to separate the wall surfaces and to allow insulation to be woven between the studs.

Question 19

Resilient channels

Answer 19

used to dampen sound waves. the channel (often called sound bar or Zbar) had double or single bend that absorbs the vibration of the sound.

• attach to framing using screws and spaces 8” oc on ceilings and 16-24” on walls
• causes 1/2” space between drywall and framing.

Question 20

fiberglass batts

Answer 20

placed in the double wall system significantly increase the sound absorption of wall.

Question 21

Woven fibreglass

Answer 21

fibreglass batts can be woven between the studs in a double wall if it is not used as a fire separation.

Question 22

R / RSI values

Answer 22

all building materials are rated based on their ability to resist heat. this is in RSI (metric) this can be converted to imperial ( r value) by multiplying by 5.7

ex RSI1= R5.7

RSI3.5 = R20

Question 23

Air film

Answer 23

the thin film of air that surrounds objects insulates them from heat loss. the insulating value attributed to air films is small but should be concretes
- air films in dry still conditions (inside) are 4x better then outside.

Question 24

thermal bridging

Answer 24

is heat loss by conduction through materials that are poor insulators

Question 25

true R- value

Answer 25

less then what it says of package. every stud is a thermal bridge so this must be taken into account when finding r value

Question 26

whole wall R value calculation

Answer 26

8’ high

• building perimeter 168’ (rectangle)
• 2x6 wall studs (r7.5)
• fibreglass batt insulation between studs single bottom double top plate and wood siding (r19)
• 10 windows each 5’x5’ (r4)
• 2 doors, each 3’x68” r6

totall wall square feet is 1344 8’ 168’

framing: studs cripples corners 11 x 168 = 168 square feet
plates 1.5 /12 x 168= 63 square feet

Window ares 10 x 5’x5’ = 250 square feet (19 of total wall area) 250/1344

door area : 2 x 3’ x 6.667’ = 40 ft square 3% total wall area 40 / 1344

subtracting area of framing, windows, and doors results in 823 square feet. which is 61% of total 823/ 1344

multiply the percentage of the total wall area by each r -value then summing total will give you whole wall R value

(.61 x R19) + (.17 x R7.5) + (.19 x R4) + (.03 + R6) = R13.8

Question 27

wind washing

Answer 27

wind washing is air moment through insulation it decreases the insulation value.

Question 28

Air barriers.

Answer 28

very important in maintaining the thermal efficiency of a building. air barriers prevent movement of air due to differences in air pressure. one of the biggest heat loss in building is occupants moving and cooking etc creating positive pressure. this pressure along with leaks causes heat to leave building more quickly

Question 29

Heating Degree-days

Answer 29

is a measure of how warm or cold a location is. the higher the number of degree days, the colder the location. this is based on the number of days of the year that the mean outdoor temperature is less then 18°C. for each day under 18°C the days mean temp is subtracted from 18°C. all of these means are then added to arrive at the number of celsius degree days per year.

Question 30

Batts

Answer 30

most common form of insulation used in residential buildings. made from inorganic glass and mineral fibre. prone to wind washing because of air pockets.

Question 31

Loose fill insulation

Answer 31

made of fibreglass, mineral wool, or cellulose insulation chopped into small pieces and blown onto place. this is most effective ay to insulate attic space. prove to wind washing and convection problems.

Question 32

rigid panels

Answer 32

comes in several forms

• rigid minereal wool
• rigid fibreglass
• rigid foam

Question 33

Rigid mineral wool

Answer 33

panels that are slightly denser then mineral wool batts. they are designed to be applied on the outside of the sheathing.the panels are fireproof and vapour permeable.

Question 34

Rigid Fibreglass

Answer 34

a dense sheet of fibreglass insulation. the 4x8 panels come in various thicknesses and finishes. vapour permeable and prone to wind washing. faced with sheathing paper on one side.

Question 35

Rigid foam

Answer 35

three types
- expanded polystyrene
-extruded polystyrene
- polyisocanurate 
are not prone to wind washing is seams are taped. 
they are highly combustable.

Question 36

Expanded polystyrene

Answer 36

lightweight foam board that is not resistant to moisture and must be protected is used below grade.

Question 37

Extruded polystyrene

Answer 37

medium density foam board that is excellent use for damp locations. used to insulate under concrete slabs.

Question 38

Polyisocyanurate

Answer 38

has highest insulation value per inch of thickness out of any foam boards. often used as roof insulation. exterior doors are often filled it this.

Question 39

Sprayed-in-place foam

Answer 39

open cell polyurethane is vapour permeable and can be used as air barrier.

closed cell is vapour impermeable and can qualify as a vapour barrier.

Question 40

Radiant barriers

Answer 40

a sheet of reflective materials. some types of insulating panels will have a foil cover on one face this should be placed in wall with foil against heated side. in hot climates foil is placed toward outside. needs air between foil and material can reflect 90%of radiant energy.

Question 41

foil faced rigid insulation

Answer 41

some rigid insulations come with thin film of polished aluminum on one or both surfaces. very expensive. using this on inside of building with foil against drywall will stop thermal bridging of studs and provide effective vapour barrier.

Question 42

Foild-surfaced bubble sheets

Answer 42

flexible sheets of this are used in attics and crawl spaces. similar to bubble wrap. air bubbles insulate against heat loss by reducing conduction while foil reflects radiant heat energy