Envelope Flashcards

1
Q

Radon action levels

A

200 Bq/m3

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2
Q

How do you calculate total R value when there are some in series and some in parallel?

A

Each section of materials in parallel should be treated as a layer, and its overall R-value calculated. Then all layers can be summed for the total R-value.

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3
Q

Air has a high resistance to this, and a little resistance to this

A

High resistance to heat conduction
Low resistance to heat convection

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4
Q

When conduction, convection and radiation occur at the same time, the overall thermal resistance of air spaces becomes this

A

Virtually independent of gap with when it is greater than 1 inch

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5
Q

It is most effective when adding layers of insulation in

A

Series, not in parallel. Because in parallel the materials used to divide air spaces might cause what are called thermal bridges.

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6
Q

The density of material is, the better it will

A

Conduct heat

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7
Q

Metals and glass have little resistance to

A

Convection

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8
Q

Describe convection

A

Transfer of heat between objects that are not touching each other. Transferred by means of a fluid such as water or air movement is called convective current.

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9
Q

Difference between permeance and permeability

A

Moisture transmission rate of a material is permeability. (Perm inches)

Permeance is dependent on thickness

Divide permeability of material by its thickness gives materials permeance in perms

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10
Q

Metric measurement for insulation

A

RSI

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11
Q

The three effects of air movement in homes

A

Wind affect
Stack affect
Combustion and ventilation

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12
Q

Will hot or cold water, lower viscosity

A

Heating material lowers viscosity. They permeate faster than cool liquids.

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13
Q

Fungal growth range

A

19- growth continues but can’t start
26- saturation point/growth

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14
Q

Describe framing factor

A

The extent to which wall roof or floor framing reduces R-value

Wall R-20
Framing factor 25%
=R-15

More framing= higher framing factor

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15
Q

Two types of building insulation

A

Bulk
Reflective

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16
Q

Permeance

A

The degree to which material transmits another substance

17
Q

Radon

A

Radioactive gas formed by decay of radium

18
Q

First way heat is transferred

A

Radiation. It can occur in a vacuum unlike convection.

19
Q

What kind of heat flow does radiant heat barriers reflect

A

Reduce downward heat flow because upward he flew tends to be dominated by convection. (better used in hot climates for roofs.)

20
Q

Radon can be breathed into the lungs with a break down further and emit

A

Alpha particles

21
Q

How to calculate, parallel R-value

A

U1= 1/R x area fraction = x

U2= 1/R x area fraction = x

U3= 1/R x area fraction = x

U4= 1/R x area fraction = x

Add them together for total U

R= 1/U

22
Q

Describe R-value

A

Ratio of temperature difference across an insulator and the heat flux (heat transfer per unit area per unit time)

23
Q

Low emissivity windows will transmit these waves, and reflect these waves

A

Transmit light and short wave infrared in
Reflect long, wave infrared radiation

24
Q

Four laws of thermodynamics

A
  1. Heat can either be created or destroyed.
  2. Entropy.
  3. 100% efficiency is impossible
  4. No heat flows between objects at the same temperature.
25
What is U factor?
Heat transfer coefficient that describes how well a building conducts heat. Measures rate of heat transfer. The inverse of R
26
An assembly using foil faced isocyanutate a rigid insulation is classed as
Vapour impermeable
27
OSB sheeting and plywood sheathing, covered with building paper or housewrap and vinyl siding are classed as
Vapour semi permeable
28
Is lower or higher permeability better
Lower
29
Vapour permeance, characteristic of sheathing, cladding assembly is defined by the effective
30
4 principle control layers
1. Rain control. 2. Air control. 3. Vapour control. 4. Thermal control.
31
What would a COP3 stand for?
coefficient performance times three 3x heat out : heat in
32
Equation for permeance
Divide perm inches (permeability) By thickness =permeance