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Heat Loss Heat Gain Flashcards

(90 cards)

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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
Why is it important to have air changes in a house ?
A need for fresh air and to exhaust contaminated air
26
Which way does air pressure travel ?
High to low
27
Where would high pressure from outside enter the building envelope ?
Cracks and openings
28
What’s the results of high wind entering the building through leaks in the envelope ?
Undesiarable drafts and added loads to the system
29
Who ensures that construction practices are performed to acceptable and safe standards ?
Alberta building code
30
Which part of Alberta building code refers to heating ventilating and air conditiong ?
Part 6
31
What other parts of Alberta building code play large parts for an hvac designer ?
Part 3 Part 9
32
What are three ways that heat is transferred?
Conduction Convection Radiation
33
How is heat transferred through way of conduction accomplished?
Through direct contact , it is dependant on thermal conductivity
34
What materials have high thermal conductivity?
Metals
35
Examples of materials with low thermal conductivity
Styrofoam glass fiber air
36
Describe convection when referring to heat transfer ?
A current in either liquid or gas that transfers heat by moving molecules from a warmer area to a cooler one
37
Example of heat transferred through way of convection
Hot air rises Water on stove rising as being boiled
38
How is radiation heat transferred ?
Through electromagnetic waves which transfer heat from a hotter object to a cooler one . The air between is not heated
39
Examples of radiant heat transfer
Infrared heaters The sun
40
Can heat transfer be completely stopped through materials ?
No materials cant stop heat transferred through way completely
41
Can heat transfer be completely stopped through materials ?
No materials can stop heat transferred through way completely
42
What are two examples of system loses
Duct passing through an unconditioned space Ventilation air
43
What are two types of heat
Sensible Latent
44
What is the definition of effective Tempature
How a person feels at a set temp
45
What is the definition of effective Tempature
How a person feels at a set temp
46
What are 3 things that can affect comfort in a residential heating / cooling system ?
Air movement Air temp Relative humidity
47
How is air Tempature controlled in a house ?
Thermostat
48
Why does a higher relative humidity in a home make us feel warmer ?
Our bodies rely on evaporation per cooling a higher rlt slows down this action
49
Who determines indoor and outdoor design air tenpatures in Alberta ?
Alberta building code
50
What is indoor designed temp for living spaces
72 degrees Fahrenheit in all living spaces 65 degrees Fahrenheit for unfinished basements 59 degrees Fahrenheit for heated crawl spaces
51
In which month are the winter outdoor design temp readings taken ?
January
52
How many years do we average out the outdoor design temps
10 years
53
What is delta t
The diffrence between indoor and outdoor design temps
54
Heating systems must be designed constructed and installed to conform to which regulations ?
Relevant provincal territorial or municipal regulations
55
If no municipal regulations or territorial regulations which rules should u follow ?
Ashare Hrai Smacna
56
Are walls adjacent to or part of an attached grage considered exposed walls ?
Yes
57
What is the advantaged of doing room by room heat loss calculations ?
Most accurate Allows u to design a reliable air distribution system
58
What is the definition of thermal resistance (r value)
The heat flow through an object in a specific amount of time
59
What is heating transfer multiplier (htm)
A factor used to calculate the amount of heat energy transferred per square foot per hour through objects
60
How do we use htm ?
Multiply the exposed area of an object by the htm to get btuh of heat loss
61
What is the definition of a gross exposed wall ?
Full length x full height , including all penetrations
62
Where are the headers located on building envelopes ?
Above the top wall plate of the wall where the floor joist butt against the rim joist of the outside wall
63
Should the header area match the wall r value ?
Yes
64
Should above grade walls and below grade walls be calculated separately when doing heat loss calculations ?
Yes.
65
Why should diffrent heat loss calculations be done for above and below grade walls ?
Because the rate of heat loss is diffrent for above and below grade walls
66
How do we calculate a net exposed wall ?
Gross wall area minus windows and doors
67
What is the formula for finding the gross ceiling area?
Room width x room length
68
What is the formula for calculating net ceiling area ?
Gross ceiling minus skylights or any other extrusion
69
What is infiltration
Unconditioned air entering a conditioned space
70
What’s the difference between infiltration and ex filtration
Infiktraion is outside air leaking into building Ex filtration conditioned air leaving the building
71
How is infiltration calculated
Infiltration factors x volume of room
72
What three things must be taken into consideration when calculating losses due to infiltration
Exposure of the site Number of penetration Age of building
73
How is site exposure determined ?
By its exposure to the wind
74
What are three categories when determining site exposure ?
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
Why is it important to know the number of exposed walls that have windows or doors in them ?
The more windows and doors in a room the higher the chance there willl be for leakage
76
What is the name for the loss on a duct passing through an unconditioned space
System loss
77
How can we reduce the losses of duct passing through an unconditioned space ?
Insulation
78
How do we calculate heat loss summary ?
You must summarize the total amount of heat energy required to heat the building . These totals are minimum values
79
How much do we allow for a pick up / set back factor ?
10% increase
80
Why do we need to add percentage for pick up / set back factor ?
The appliance must have the ability to increase temp of the building beyond design Tempature by code
81
What are ventilation air losses ?
The amount of cfm required for heating season ventilation air leaving
82
What four things affect the loads on a building in the summer when calculating heat gain ?
Solar radiation Mass effect Internal gains Latent heat factors
83
In Canada what would be the greatest load in which the air conditioning system would be designed to handle ?
The greater load would be heating
84
What is the summer indoor Tempature for Alberta?
75 degrees Fahrenheit
85
Are we required to do a heat gain calculation for below grade walls or crawl spaces ?
No
86
What is mass effect ?
As building materials are heated by the sun they absorb this heat energy causing Thier temp to rise dramatically
87
Do shaded and unshaded areas have the same outdoor design temperatures?
No
88
From where are Alberta outdoor design Tempature taken ?
The Alberta building code January 2.5% column
89
When calculating heat gain where do we addd the solar adjustment
Summer delta t
90
When calculating heat gain where do we addd the solar adjustment
Summer delta t

Third Year (10 decks)

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