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Third Year > Heat Loss Heat Gain > Flashcards

Heat Loss Heat Gain Flashcards

1
Q

Why do we do heat gain and heat loss calculations ?

A

Ensure size of equitment and comfort

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2
Q

Heat travels in what direction

A

Hot to cold

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3
Q

What are the greatest heat losses on a house ?

A

Windows and doors

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4
Q

What are 3 ways to do heat loss calculations ?

A

Whole house loads
Floor by floor loads
Room by room loads

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5
Q

Below grade walls are walls that are more then _______ feet below grade ?

A

2 feet

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6
Q

Below grade walls are walls that are more than ________ feet below grade

A

2 feet

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7
Q

What is the purpose of ac systems

A

To provide high level of comfort to the home owner

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8
Q

What are six principles that must be addressed when selecting ac system for residential ?

A

Comfort
Tempature
Humidity
Ventilation
Filtration
Circulation and noise

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9
Q

Why is it important to complete a heat loss calculation on a residence ?

A

Determine equitment size requirements so the design tempature can be maintained

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10
Q

What is the result in installing an undersized furnace ?

A

It will not keep up with ing the heating load

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11
Q

What is the result life installing an oversized heating appliance?

A

Poor tempature control and high operating costs

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12
Q

What are some examples of appliances or fixtures that add loads to a building ?

A

Space heaters
Water heaters
Stoves
Fire places
Dryers
Lights

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13
Q

What is heat ?

A

Form of energy

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14
Q

Which way does heat travel ?

A

Hot to cold

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15
Q

Tempature will always travel from hot till cold until ?

A

Both temps are the same

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16
Q

In winter which direction is heat travelling in regards to a house ?

A

The house will be hotter than outside so the heat will flow from the house to the outside

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17
Q

In the summer which direction is heat travelling in regards to a house

A

The higher temp is outside so heat will flow into the house

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18
Q

What four factors affect a building environment?

A

Building envelopes
Mechanical systems
Occupants
Appliances

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19
Q

List some things that separate the indoor environment from the outdoor environment ?

A

Extieror walls
Foundations
Roofs
Ceilings
Floors
Windows
Doors

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20
Q

How do we maintain the in balance of Tempature from inside the house to outside the house ?

A

Heating systems must replace heat that is transfered out side

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21
Q

What is a mechanical systems?

A

A force used to maintain the balance between indoor and outdoor conditions

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22
Q

Occupants generate heat. How much ?

________btuh. __________watts

A

250 btuh
73 watts

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23
Q

What do occupants do to cause discomfort in a house ?

A

Opening and closing windows and doors Useing appliances
Increase moisture levels ,co2, etc.

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24
Q

The building envelope reduced three losses from the outdoor environment what are they

A

Radiative
Convective
Conductive

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25
Q

Why is it important to have air changes in a house ?

A

A need for fresh air and to exhaust contaminated air

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26
Q

Which way does air pressure travel ?

A

High to low

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27
Q

Where would high pressure from outside enter the building envelope ?

A

Cracks and openings

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28
Q

What’s the results of high wind entering the building through leaks in the envelope ?

A

Undesiarable drafts and added loads to the system

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29
Q

Who ensures that construction practices are performed to acceptable and safe standards ?

A

Alberta building code

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30
Q

Which part of Alberta building code refers to heating ventilating and air conditiong ?

A

Part 6

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31
Q

What other parts of Alberta building code play large parts for an hvac designer ?

A

Part 3
Part 9

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32
Q

What are three ways that heat is transferred?

A

Conduction
Convection
Radiation

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33
Q

How is heat transferred through way of conduction accomplished?

A

Through direct contact , it is dependant on thermal conductivity

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34
Q

What materials have high thermal conductivity?

A

Metals

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35
Q

Examples of materials with low thermal conductivity

A

Styrofoam glass fiber air

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36
Q

Describe convection when referring to heat transfer ?

A

A current in either liquid or gas that transfers heat by moving molecules from a warmer area to a cooler one

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37
Q

Example of heat transferred through way of convection

A

Hot air rises
Water on stove rising as being boiled

38
Q

How is radiation heat transferred ?

A

Through electromagnetic waves which transfer heat from a hotter object to a cooler one . The air between is not heated

39
Q

Examples of radiant heat transfer

A

Infrared heaters
The sun

40
Q

Can heat transfer be completely stopped through materials ?

A

No materials cant stop heat transferred through way completely

41
Q

Can heat transfer be completely stopped through materials ?

A

No materials can stop heat transferred through way completely

42
Q

What are two examples of system loses

A

Duct passing through an unconditioned space

Ventilation air

43
Q

What are two types of heat

A

Sensible
Latent

44
Q

What is the definition of effective Tempature

A

How a person feels at a set temp

45
Q

What is the definition of effective Tempature

A

How a person feels at a set temp

46
Q

What are 3 things that can affect comfort in a residential heating / cooling system ?

A

Air movement
Air temp
Relative humidity

47
Q

How is air Tempature controlled in a house ?

A

Thermostat

48
Q

Why does a higher relative humidity in a home make us feel warmer ?

A

Our bodies rely on evaporation per cooling

a higher rlt slows down this action

49
Q

Who determines indoor and outdoor design air tenpatures in Alberta ?

A

Alberta building code

50
Q

What is indoor designed temp for living spaces

A

72 degrees Fahrenheit in all living spaces

65 degrees Fahrenheit for unfinished basements

59 degrees Fahrenheit for heated crawl spaces

51
Q

In which month are the winter outdoor design temp readings taken ?

A

January

52
Q

How many years do we average out the outdoor design temps

A

10 years

53
Q

What is delta t

A

The diffrence between indoor and outdoor design temps

54
Q

Heating systems must be designed constructed and installed to conform to which regulations ?

A

Relevant provincal territorial or municipal regulations

55
Q

If no municipal regulations or territorial regulations which rules should u follow ?

A

Ashare
Hrai
Smacna

56
Q

Are walls adjacent to or part of an attached grage considered exposed walls ?

A

Yes

57
Q

What is the advantaged of doing room by room heat loss calculations ?

A

Most accurate
Allows u to design a reliable air distribution system

58
Q

What is the definition of thermal resistance (r value)

A

The heat flow through an object in a specific amount of time

59
Q

What is heating transfer multiplier (htm)

A

A factor used to calculate the amount of heat energy transferred per square foot per hour through objects

60
Q

How do we use htm ?

A

Multiply the exposed area of an object by the htm to get btuh of heat loss

61
Q

What is the definition of a gross exposed wall ?

A

Full length x full height , including all penetrations

62
Q

Where are the headers located on building envelopes ?

A

Above the top wall plate of the wall where the floor joist butt against the rim joist of the outside wall

63
Q

Should the header area match the wall r value ?

A

Yes

64
Q

Should above grade walls and below grade walls be calculated separately when doing heat loss calculations ?

A

Yes.

65
Q

Why should diffrent heat loss calculations be done for above and below grade walls ?

A

Because the rate of heat loss is diffrent for above and below grade walls

66
Q

How do we calculate a net exposed wall ?

A

Gross wall area minus windows and doors

67
Q

What is the formula for finding the gross ceiling area?

A

Room width x room length

68
Q

What is the formula for calculating net ceiling area ?

A

Gross ceiling minus skylights or any other extrusion

69
Q

What is infiltration

A

Unconditioned air entering a conditioned space

70
Q

What’s the difference between infiltration and ex filtration

A

Infiktraion is outside air leaking into building

Ex filtration conditioned air leaving the building

71
Q

How is infiltration calculated

A

Infiltration factors x volume of room

72
Q

What three things must be taken into consideration when calculating losses due to infiltration

A

Exposure of the site
Number of penetration
Age of building

73
Q

How is site exposure determined ?

A

By its exposure to the wind

74
Q

What are three categories when determining site exposure ?

A

Unexposed - sheltered by buildings trees or wind shelters on all sides

Partially exposed - sheltered on two or more sides

Fully exposed - theee or more sides fully exposed

75
Q

Why is it important to know the number of exposed walls that have windows or doors in them ?

A

The more windows and doors in a room the higher the chance there willl be for leakage

76
Q

What is the name for the loss on a duct passing through an unconditioned space

A

System loss

77
Q

How can we reduce the losses of duct passing through an unconditioned space ?

A

Insulation

78
Q

How do we calculate heat loss summary ?

A

You must summarize the total amount of heat energy required to heat the building . These totals are minimum values

79
Q

How much do we allow for a pick up / set back factor ?

A

10% increase

80
Q

Why do we need to add percentage for pick up / set back factor ?

A

The appliance must have the ability to increase temp of the building beyond design Tempature by code

81
Q

What are ventilation air losses ?

A

The amount of cfm required for heating season ventilation air leaving

82
Q

What four things affect the loads on a building in the summer when calculating heat gain ?

A

Solar radiation
Mass effect
Internal gains
Latent heat factors

83
Q

In Canada what would be the greatest load in which the air conditioning system would be designed to handle ?

A

The greater load would be heating

84
Q

What is the summer indoor Tempature for Alberta?

A

75 degrees Fahrenheit

85
Q

Are we required to do a heat gain calculation for below grade walls or crawl spaces ?

A

No

86
Q

What is mass effect ?

A

As building materials are heated by the sun they absorb this heat energy causing Thier temp to rise dramatically

87
Q

Do shaded and unshaded areas have the same outdoor design temperatures?

A

No

88
Q

From where are Alberta outdoor design Tempature taken ?

A

The Alberta building code January 2.5% column

89
Q

When calculating heat gain where do we addd the solar adjustment

A

Summer delta t

90
Q

When calculating heat gain where do we addd the solar adjustment

A

Summer delta t

Third Year (10 decks)

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