PDX_14_Hvac Building Design Flashcards
The amount of heat lost at design outdoor and indoor conditions which must be made up by the HVAC system to maintain occupant comfort
Peak heat loss
The maximum output potential of a heating/cooling system in one hour and is used to size HVAC equipment
Full load hours
Used for calculating heat game through building envelope, and takes into account air temperature differences, effective son, thermal mass storage affect the material, color finishes etc.
Design equivalent temperature difference
DETD
Used for calculating he came through glazing, takes into account glazing type, interior shading, and outdoor temperature
Design cooling load factor
DCLF
And equivalent temperature difference used for calculating the instantaneous external cooling load across a wall or roof
Cooling load temperature difference
CLTD
The speed with which he passes through a material
Conductivity
Equipment that permits the use of outdoor air instead of refrigeration units for building cool link when conditions are right
Economizer
Evaluates both temperature and humidity, mixes appropriate outdoor/indoor air to achieve comfortable conditions without cooling
Enthalpy economizer
Gravity heating systems used by the Romans to keep public baths and private houses
Hypocausts
I’m out of cooling required to convert a time of water to ice in a 24 hour period, equivalent to 12,000 BTUH
Ton
1 Watt = ___ BTU per hour
3.41 BTU per hour
1 kWh = ___ BTU per hour
3,400 BTU per hour
1 ton of AC = ___ BTU per hour
12,000 BTU per hour
Or 3.5 to kilowatt ours
Units for ventilation:
CFM per person
Units for heating:
BTU per hour
Units for cooling:
BTU per hour
And tons
U-value is
The conductance of the assembly
The change in temperature, ΔT =
Difference between outside and inside air temperature
R-value is better the larger or smaller?
Larger
How to find the U-value:
Find the R-value of each component and add them together, then calculating 1 / total R-value
When HVAC systems exhaust more hair than they take in,
It can result in negative pressurization inside the building.
Ideally the air pressure in a building should be:
Equal to or slightly positive to the air pressure outside the building.
Negative pressure can cause cold draft and noxious odors coming in through cracks in openings.
When warm air rises and goes out the top, pulling in cooler air at lower levels through cracks in openings this is an example of:
Stack effect
Building success depends on:
How comfortable people are inside, and how affordable it is for them to be that way.
Tool used to identify drafts and air leaks
Smoke pencil you lie
Pull the trigger and see how smoke moves to show air movement
Electric air cleaner operation:
High-voltage of static charge are applied to dust which is then attracted to oppositely charged plates on the cleaner.
What process has been widely used to identify “at risk areas” for radon?
Geological mapping
Pathogen destruction can be achieved using these lamps
UV lamps
HEPA air filters are frequently found in
Hospitals
Furnished with HVAC equipment and function mainly to protect fans from large particles of lint or dust. The least effective in cleaning the air.
Fibrous panel filters
Hey more fine filter that use paper in place within the frame, working by straining and impaction. 90% efficient
Media filters
This filter is more costly upfront, the produces less air movement as two sets of charged plates attract dust. Or cleaned by washing off.
Electrostatic filter’s
This filter is for gaseous removal and very depending on pollutant.
Absorption filter
This absorption filter is more common and absorbs materials with high molecular weights and allows low weights to pass.
Activated Charcoal filters.
This filters sometimes used to control bacteria growth and control humidity.
Air washers
These air cleaners can pose a threat due to ozone production, but demand less maintenance.
Electronic air cleaners
Exhaust fan capacity should be at least__% of the total HVA system airflow capacity in a residential building
50%
Required air change rates for ventilation is based on
Size and occupancy of space.
The worst local air quality problems tend to be around:
Hospitals, shopping areas, or public transport hubs
Where large numbers of vehicles move slowly or idle
