Building Systems

Question 1

What is R-Value?

Answer 1

R-value measures how well building insulation can prevent the flow of heat in and out of the building. Higher R-value means greater insulation performance. R=Difference of outside - inside temp/heat flux through barrier

Question 2

List 15 common building materials and their R-Value

Answer 2

brick-.11, wallboard-1, Wood pine - 1.28, air - 1.44, fiberglass blown/vermiculite-2.2, perlite/rockwood blown - 2.75, fiberflass batt- 3.16, rock wool batt - 3.38, cellulose blown - 3.67

Question 3

What is U-Value?

Answer 3

Inverse sum of R-values. Measures the ability (conductive/convective) to transfer heat.
u=1/(r1+r2+r3)

Question 4

What is Conductivity (K)?

Answer 4

The ability of a material to transfer or conduct heat. Conductors have high k / insulators have low k.

Question 5

What is Solar Heat Gain Coefficient?

Answer 5

The amount of solar radiation (heat) flow through a window (transmitted and absorbed) that is released inside. Greater than 0 less than 1, 1 equal to high amount of solar heat inside.

Question 6

What is a degree day?

Answer 6

+ - Daily temperature mean (high temperature + low temperature divided / 2 ) - 65°F. Cooling degree day is the mean above 65. Heating degree day is when the mean is below 65.

Question 7

What is a Balance Point Temperature?

Answer 7

The temperature of a building interior relative to the outside temperature. Low balance point is when a building produces a lot of heat.

Question 8

What is BTU?

Answer 8

The amount of heat ((si or joule) a form of energy associated with the act of motion of atoms/molecules, capable of being transmitted by convection, conduction, or causing substance to rise in temp/fuse/expand/evaporate) required to raise the temperature of one pound of water 1 degree F

Question 9

The amount of heat a person emits?

Answer 9

500 BTU/hr (250 Latent, 250 Sensible)

Question 10

What is a Therm, triple point and Kelvin?

Answer 10

A unit of heat equal to 100,000 british thermal units.

The particular temperature and pressure at which the liquid, gaseous, and solid phases of a substances can exist in equilibrium.

The base SI unit of temperature equal to 1/273.16 of the triple point of water

Question 11

Explain an internal-load dominant building

Answer 11

They are buildings that have higher mass to surface area ratio. Majority of their cooling it to remove heat from interior lighting, plug loads, other fixtures, etc and people.
ex: hospitals, skyscrapers, factories

Question 12

Explain skin-load dominated building?

Answer 12

A building where its energy consumption design is dictated by climate and the buildings skin.

Question 13

How do you passively heat a building?

Answer 13

-Windows for solar heat gain
-Well insulated and sealed building envelope
-Heat held in thermal mass

Question 14

What is a minsplit?

Answer 14

Ductless heat pump. A type of heating and cooling system that doesn’t require any ductwork. It moves heat energy around, rather than producing it. The system has an outdoor compressor unit that’s connected to one or more indoor units.

Question 15

Dry-bulb temperature and wet-bulb temp?

Answer 15

Dry bulb - the temperature of the air-water mixture as measured with a standard dry-bulb thermometer

Wet bulb - the temp of the air measured with a sling psychrometer. its a more critical measure of heat in high humidity bc it indicates stress on body neat upper limits of temp reg by perspiration

Question 16

Dew point

Answer 16

the temperature at which water vapor in the air becomes saturated and begins to condense to drops of water

Question 17

Explain Latent heat, Sensible heat, and Enthalpy.

Answer 17

Latent heat - heat that causes a change of state of a substance, such as the heat required to change water into steam.

Sensible heat - heat that causes a change in temperature of a substance but not a change of state

Enthalpy - the total heat in a substance, including latent heat and sensible heat

Question 18

Insolation

Answer 18

the total solar radiation on a horizontal surface

Question 19

specific heat

Answer 19

the number of Btus required to raise the temperature of a specific material by 1°F (1K). Specific heat is a measure of a material’s capacity to store heat as compared with the storage capacity of water.

Question 20

In what 3 ways does the body lose heat?

Answer 20

convection - the transfer of heat through the movement of a fluid, either a gas or liquid. ex when air temp is less than the body
evaporation - occurs when moisture changes to a vapor as you sweat and breathe
radiation - transfer of heat energy through electromagnetic waves from one surface to a colder surface
(conduction- transfer of heat through contact between to diff temp objects.)

Question 21

What contributes to human comfort in an environment?

Answer 21

Temp, humidity, air movement, temp radiation to and from near surfaces, air quality, sound, vibration, and light.