what is a heating degree day? - each degree that the average daily temperature is
below the base temperature (65 degrees F) is one heating degree day. HDD
What is a cooling degree day? - air temperature differences btwn the outdoors and 78
degrees F over the hot season
If the high was 60 degrees F and the low was 30 degrees F, how many HDDs occured?
- base temp-delta T so 60+30 divided by 2=45. 45 is the delta T. so 64(which is the
base temp always) minus 45 =20 HDDs
Heat will always move from - hot to cold (more to less) 2nd law of thermodynamics
pressure will always move from - high to low (more to less) 2nd law of thermodynamics
moisture will always move from - wet to dry (more to less) 2nd law of thermodynamics
what 2 things are needed ofr air to move? - path and change in pressure
if condensation occurs on a window, what 2 things must be true? - the window surface
is below dew point and there is moisture in the air
if air is heated, does the relative humidity go up or down? - down
what is the definition of the building envelope? - any part that creates a separation of
indoor and outdoor spaces. this is where the thermal and pressure boundaries will be
located.
what is a vapor diffusion retarder? - vapor barrier
what natural force is a vapor diffustion retarder attempting to stop? - diffusion
define vapro diffusion - flow of water vapor through a solid material
what doea sling psychrometer measure? - relative humidity
how many thermometers does a sling psychrometer have to measure RH? - two
what is the soffit? - under side of the roof overhang or a small lowered ceiling like above
cabinets or a shower
, what does a blower door measure>? - air leaks, measures the square inches of holes in
a building
what is the single most important thing to do if attempting to control moisture in the
home? - control air flow/leaks
if a house has 50 CFM going out through the bath exhaust,how many CFM must be
coming back in? - 50 CFM, for every cfm in, there is 1cfm out
when air sealing a home you should always start where? - the top and bottom (some
answers say the top is the top priority and some say top AND bottom) because of stack
effect
define stack effect - draft established in a building from air infiltrating low and exfiltrating
high
what are four reasons to fix the hole around loose HVAC boots in the floor? - 1. IAQ
(indoor air quality)
2. comfort/cost
3. effective air flow
4. to maintain pressure flows
5. prevent moisture from entering from crawlspace
6. prevent harmful gases/vapors/pollutants from entering home
name 3 forms of heat transfer - conduction, convection, radiation
what has more potential energy, propane or natural gas? - propane
what does MSDS mean and how is it used? - material safety data sheet, and shows mfg
and product infomation health and safety issues
what is the typical human comfort range in RH? - 40-60%
define infiltration - the inflow of outdoor air into the indoors which is accompanied by
equal outflow of air from the indoors to the outdoors
define exfiltration - air flowing out of a residence from the conditioned space through the
shell to the outside
define ventilation - movement of air through an area for the purpose of removing
moisture, air pollution and unwanted heat
what is the neutral pressure plane? - where air coming in and going out are the same,
separates the bldg's negative and positive pressure zones, and is usually somewhere in
the middle of the bldg
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