building systems analysis Flashcards
what is energy
I’m on fire
quantity such as heat
what is power
football player using his power to knock someone on their asses
the rate at which energy is transferred of energy
what is the only unit of measurement in powers with hours at the end of it
Btuh
British thermal unit hours.
Using Q=MCTD calculate
10’ x 10’ x8” thick floor warmed to 80 and cools to 70 over night how much heat is released
floor weighs 144 lb Ft^2
.156 btu lb f
100.66=66’^2
66144=9600
9600 lb ft^2.156 btu lb f 10 f= Q
1500 btu
what does power equal related to energy and time
energy/time
energy is what related to power and time
power* time
energy and power related to watters
energy is watt hours
power is watts
Heat is measured in
and what is it
British thermal units, or Btus.
amount of heat required to raise a temperature of 1lb of water 1 degree
in the equation Q=500GPMTD where does the 500 come from
weight of 1 gallon of water 8.35 *
1 hours or 60 min
what systems are used to convert and move fluids to make buildings habitable and functional
mechanical and electrical
it takes 15,000 btu to lower a concrete slab from 60 to 50 degrees what is the average capacity of slab over this period of time
15000 btu/8 h= 1875btuh
when using fuels to heat a building where is some heat lost to
radiating heat
what is air flow measured in
CFM
Why can’t you use PSI for air pressure and what is used instead
to small number to use would be created
use inches of water column
water flow is measured in
water pressure is measured in
GPM
PSIG and ft of head
(1 PSIG = 2.31 ft of head)
what is steam measured in and flow measured in
lb and lb per hour
sustainable
having an overall beneficial effect on productivity, health, resources, economics, and the environment. Sustainable design acknowledges responsibility for future as well as current outcomes.
LEED
leadership in energy environmental design
buildings acount for ?? of overall energy in US and ?? of electrical usage
30 and 60%
heat transfer of air equations
standard air pressure .076 specific heat .24 so the equation is
1.1 x CF x TD
Conduction
Heat transfer by conduction is proportional to the temperature difference between the warm and cold sides of the building envelope element.
ASHARE
American Society of Heating, refrigerating and air conditioning energineers
equation is used in calculating heating load to estimate conduction heat loss through a wall, roof, or window.
Q= (atd)/r= UA*TD
Q=btuh
a= area of assembly ft^2
r= resistance )hrft^2/btu)
U= u-factor (BTU/hrft^2 F)
what is the U-factor
overall coefficient of thermal transmittance
U is the reciprocal of total resistance R
ie U= 1/ (sum) R
