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Sheet Metal 3rd Yr > Heat Loss and Heat Gain > Flashcards

Heat Loss and Heat Gain Flashcards

1
Q

When doing Heat Loss calculation, define : Gross Exposed Walls.

A

Gross Exposed Wall is the full lenght of the wall by the full height, includes all penetrations.

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2
Q

Which way does heat travel?

  1. up
  2. down
  3. cold to hot
  4. hot to cold
A
  1. hot to cold
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3
Q

Appliances add loads to a building.

TRUE or FALSE

A

TRUE

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4
Q

Which direction does Air Flow move?

A

From Higher pressure > Lower pressure

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5
Q

With Heat Loss and Gain define : Mass Effect

A

Mass Effect is the heat energy gained from the building materials heating up by the sunlight.

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6
Q

What are the 3 types of AIr Tightness concerning buildings?

A
  1. Loose (built earlier than 1960’s)
  2. Average (built late 1960’s to lat 1980’s)
  3. Tight (built late 1980’s to present)
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7
Q

In modern times do we used Rules of Thumb when calculating heat loss and gain?

TRUE or FALSE

A

FALSE

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8
Q

With Outside Winter design, heating equipment is required to maintain what temperatures in a residential building?

A

No Less than

  • 72*F (22*C) in all living spaces
  • 65*F (18*) in unfinished basement
  • 59*F (15*C) in heated crawl spaces
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9
Q

Fresh (outdoor) air losses are a direct loss to the individual room calculations.

TRUE or FALSE

A

FALSE

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10
Q

What are 3 items that must be considered to determine the leakage of a room?

A
  1. Exposure of the site
  2. Number of penetrations
  3. Age of the building (how air tight)
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11
Q

When the Total Heat Loss for a building is completed, what is the PIck-up and Set-back factor to be used?

A

10% increase is required.

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12
Q

If the direction of the house is known, the wall with the most windows shall be calculated for heat gain as if that wall were facing ____ or ____.

A

east or west.

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13
Q

From where are Alberta outdoor design temperaturres taken?

A

The Alberta Building Code January 2.5% column

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14
Q

What must the Heating System of a building be able to maintain when dealing with Appliances in the building?

A

Maitain the correct Indoor Design Temperature whether the appliances are USED or NOT.

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15
Q

What is the relationship between RH (relative humidity) and comfort?

A

Higher RH (relative humidity) makes you feel warmer.

Our bodies rely on evaporation to cool down, higher RH slows down this process.

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16
Q

What 4 factors affect building environments?

A
  1. Building Envelope
  2. Mechanical Systems
  3. Occupants
  4. Appliances
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17
Q

Solar adjustment must be made when the Summer Mean Temperature is greater than what?

A

8*C

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18
Q

Define : Total Resistance

A

Is the total conductive resistance of all materials that construct a wall that divides Outdoor enviroment from Indoor conditions.

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19
Q

What affects the speed of heat transfer?

A

The GREATER the temperature difference, the FASTER the transfer will take place.

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20
Q

Heat loss (load) calculations can be done using what 3 different methods?

A
  1. Calculating the load of the whole building
  2. Calculating the loads or 1 level at a time.
  3. Calculating each room on an individual basis.
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21
Q

Define : Conduction

A

When heat transfers through the direct contact with another object.

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22
Q

List some Design Manuals used in HVAC design.

A
  • ASHRAE handbooks and standards
  • HRAI digest
  • Hydronic Institute manuals
  • SMACNA manuals
  • ACCA manual J
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23
Q

Define : Radiation

A

When energy is transmitted though electomagnetic waves, which transfer heat from a hotter object to a colder object.

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24
Q

Net Wall calculations are completed by what?

A

Length X Width of the wall, MINUS all penetrations

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25
What are the disvantages and advantages of calculating Floor by Floor Loads?
Floor to Floor Load calculation IMPROVE on how distribution is between floors. BUT Doesn't tell you Room to Room. Should be used as a estimate ONLY
26
Define : Thermal Resistance (R-Value)
* Is the heat flow through an object in a specific amount of time. * R-valve = ( hours X sq. ft. X \*F) / Btu * Higher resistance materials are called Insulators
27
When doing Heat Loss calculation, define : Below Grade Walls
Below Grade Walls are walls that are more than 2 inches below ground level.
28
When wind speed increases around the outside what happens to the amount of undesirable leakage to the building?
Wind Speed Increase = Undesirable Leakage Increase
29
Above and Below Grade walls have the same R-Vlaves. TRUE or FALSE
FALSE
30
What does performing correct Heat Loss and Gain calculations ensure?
Proper selection of equipment that will provide comfort for the occupant.
31
What is the formula to calculate : Ventilation AIr Heat Loss
Btuh = Ventilation cfm X 1.08 X Design Temperature Difference.
32
Radiant heat adds a load to the load of a building. TRUE or FALSE
TRUE
33
What is the default used when calculating heat gains for glass?
No shade or drapes are used.
34
With heat losses and gain, what is the purpuse of the Mechanical System?
Mechanical System is a force used to maintain the in-balance between indoor and outdoor conditions. The load is changing constantly pending time of day and season to season.
35
What is the most ACCURATE method of calculate heat loss (load) in a building?
Room to Room Load calculations.
36
What is the concern when dealing with the Air Change in a modern building with a tight envelope?
The LESS the leakage rate there is a NEED for fresh air and exhausting of stale contamated air INCREASES.
37
The overall performance of a building and it's systems are affected by what Air-Flow's?
1. Air Change Rates 2. Air-Pressures 3. Ventilation 4. Exhaust Systems 5. Flues 6. Stack Effects 7. The Wind
38
HTM is a factor used to calculate what?
BTUH per square foot
39
How do Occupants change the heat loss and heat gain of a buiding?
1. Controling the Mechanical System 2. Opening and closing windows and doors 3. Occupants generate HEAT (approx 250Btuh, 73W per person).
40
Duct passing through un-conditioned spaces must be what?
Insulated
41
Solar Radiation will change the : 1. heat loss calculation 2. direction of the house 3. indoor design temperature 4. outdoor design temperature
4. outdoor design temperature
42
What are the disvantages and advantages of calculating Whole House Loads?
Advantages are that it can be done quickly. Disadvantages is how these loads distribute throughout the building Whole House Calculations should ONLY be done as an estimate.
43
What are some points about Ventilation Air Losses
* Introduction of ventilation air are System Losses. * DO NOT effect losses to individual rooms * Their are Direct Losses to the HVAC unit, must be added to the Total Conductive Heat Loss. (ensure proper HVAC unit selection)
44
Which material has a greater R-valve? 1. Glass Fibre 2. Double-Glazed Windows 3. Cement 4. Sheet Metal
1. Glass Fibre
45
Define : HTM (Heating Transfer Multiplier)
Is a factor used to calculate the amount of heat energy transferred per square foot per hour through walls, floors, ceilings, windows and doors. HTM = Design Temp. Difference / RT (total resistance)
46
Define : Design Temperature Difference
Is the difference between the Indoor Design temperature and the Outdoor Design temperature
47
Outdoor design temperatures are the same for all locations. TRUE or FALSE
FALSE
48
What codes must a HVAC designers must be familiar with?
* Alberta Buiding Code makes reference to heating , ventilating and AC in Part 6. Also these codes must be concidered * Fire Protection * Occupant Safey * Accessibility * Housing and Small Building : Part 9
49
Latitude will not affect shade factors on a building TRUE or FALSE
FALSE
50
Define : BUILDING ENVELOPE
Is what seperates the interior from the outdoor environments. Building structures that provide the neccessary barriers are : * Exterial Walls * Foundations * Roofs * Ceilings * Floors * Windows * Doors * Vapour Barriers
51
How does the Air Movement affect the temperature you feel?
* Volume of air passing you Increases - Cooler you feel. * Volume of air passing Decreases - Warming you feel
52
What are he 6 principles of comfort?
1. Temperature 2. Humdity 3. Ventilation 4. Filtration 5. Circulation 6. Noise
53
What are 3 factors that effect Effective Temperature?
1. Air Temperature 2. Relative Humidity 3. Air Movement
54
When doing Heat Loss calculation, define : Above Grade Walls
Above Wall Grade is all walls that are above ground level.
55
What 3 factors are used to find the correct infiltration factor.
1. Site Exposure 2. Penetrations 3. Air Tightness
56
What is the HTM (heat transfer multiplier) for a wall having a total resistance of 16.25 and a design temperature difference of 98\*F?
HTM (heat transfer multiplier) = design temperature difference / total resistance (R-valve) HTM = 98\*F / 16.25 HTM = 6.03
57
Effective Temperature could be defined as :
How a person feels at a set temperture.
58
How do we find the valves for winter design in conditons?
From the Alberta Building Code, using the chart for "January @ 2.5% values" The Outdoor Design temperatures for Northern climates will normally be GREATER than those in Southern climates.
59
What is the Solar Adjustment for fully shaded walls and indoors?
-11\*F
60
Design Temperature Difference is the difference from indoor design temperature from outdoor design temperatures ? TRUE or FALSE
TRUE
61
Define : HEAT
HEAT is a form of energy that flows between 2 bodies due to their differences in temperature.
62
What is the indoor temperature for living spaces?
72\*F (22\*C)
63
What Building Envelope is about reducing what types of losses to the outdoor environment?
* Radiative Losses * Conductive Losses * Convective Losses
64
Define : Convection
The current in a liquid or gas that transfers the heat by moving molecules from a warmer area to a cooler area.
65
Gross wall calculations are completed by multiplying what?
Lenght X Width of the wall, including all penetrations.
66
An energy efficient home consists of what type of building materials?
Materials that have : * High R-Valves (high resistances) * Good vapour Barriers That minimize heat loss or gain to the structure.

Sheet Metal 3rd Yr (7 decks)

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