Environmental Issues Flashcards
radiation
transfer of heat between surfaces that are not in direct contact
conduction
transfer of heat between objects that are in direct contact
convection
transfer of heat that requires requires fluid medium to transfer
latent heat
heat required to change states without change of temperature
sensible heat
amount of energy absorbed or released during a change of temperature
British Thermal Unit
amount of energy needed to raise 1 pound (or 1 pint) of water by 1 degree F
OR to burn 1 match
Clo
normal amt. in winter and summer
amount of insulation which will maintain normal skin temperatre of the human body
winter indoor dress: 0.8
summer: 0.4
relative humidity
approximate ratio of actual density of water vapor in air to maximum density of water vapor that is could contain RELATIVE to the temperature
100% is when dry blub temperature = wet bulb temperature
degree day
amount by which the average outdoor temperature is below the reference temperature for one day
design day
day that is colder than 98% of all days of the year - this is what the system is designed to handle
dry bulb temperatre
aka air temperature; indicator of heat content
wet bulb temperature
lowest temperature that can be reached by evaporation of water only (air temp. remains constant)
dew point
the temperature at which water vapor starts to condense out of the air
comfort zone
range of temperatures and humidities in which most people feel comfortable dressed in typical clothing and engaged in typical indoor activities
enthalpy
sum of internal energy in a system plus the product of the pressure of gas in the system and its volume
air changes/hour (ACH)
rough estimate of how many times the entire volume of indoor air is replaced with outdoor air in one hour
psychometrics
study of physical and thermodynamic properties of gas-vapor mixtures
mean daily range
average temperature swing from night to day
mean radiant temperature (MRT)
average radiant temperature of surroundings independent of air temperature
typical home furnace BTUs/hour
80,000-150,000 BTUs/hour
person at rest BTUs/hour
250-350 BTUs/hour
US home BTUs/year on space heating
50 million BTUs/year
units for energy
BTU or Watt Hours
Watt Hour
amount of energy to run a 3600 watt appliance for 1 second
OR run a 60 watt lightbulb for 1 min
OR run a 1 watt appliance for 1 hour
rate of energy units
BTU/hour or Watts (J/s)
BTU/hour uses
describe heat gain or loss
report input or output of a device
Watt uses
represent a unit of energy over time
imply a rate (per second value)
measure instantaneously
convert 1 Watt to BTU/hour
3.412 BTU/hour
BTUs/lb of ft^3 for:
coal
natural gas
wood
15,000 BTU/lb
1,000 BTU/ft^3
7,000 BTU/lb
design dry bulb (97.5%)
97.5% of the winter (December-February), the temperature will be higher than this listed #
design dry bulb (2.5%)
2.5% of the summer (June-September) the weather is warmer than the listed #
heating degree day (HDD65)
amount by which the avg. outdoor temp. is below 65
HDD65 defined 0-1000 1000-3000 3000-5000 5000-7000 7000+
0-1000 : no need to heat
1000-3000 : good insulation is enough
3000-5000 : moderate, use 2 systems
5000-7000 : need serious heating
7000+ : year-round heating (don’t live here)
air pollution inversion phenomenon
heavier, cooler air is trapped below warm air and releases pollutants
carbon dioxide sources (3)
respiration
combustion
fermentation
carbon monoxide sources (4)
gas-powered motors
gas or oil-powered industrial equipment
building systems
biomass burning
sick building syndrome
10% of occupants are sick
20% complain
bake-out
heat interior air to 100 degrees F; release the heat and heat again. repeat for 2 weeks.
this removes pollutants
ecosphere
area of earth from surface to 5 mi deep
biosphere
area from earth’s surface to 5 mi into troposphere
biophilia
love of living things; humans subconsciously seek connections with the rest of life
organic feedstock
materials that mold can use as an energy source
The Natural Step
1996 credo by scientists, designers, and environmentalists
goal of protecting eco- and bio-sphere:
don’t extract faster than you replenish
don’t manufacture faster than it can be integrated back into nature
protect and preserve living organisms
use resources fairly and efficiently
Awanahee Principles
1991 plan for sustainable development mixed use walkable mixed use 24-hour variety of uses and users conservation of resources SEE NOTES FOR MORE DETAIL
LEED credit categories
sustainable sites water efficiency energy and atmosphere materials and resources indoor environmental quality innovation in design
daylight factor
% of outdoor light that is available indoors (based on overcast conditions)
solar altitude
angle of sun above the horizon (always 90 degrees or less - positive in the am, negative in the pm
solar azimuth
angle of sun from due north, clockwise
albedo
ratio of radiant to incident flux on a surface
equation for light penetration into a room
height from floor to top of window x 2.5 = depth of penetration
building commissioning
ensure that systems are designed, installed, and tested for effective operation and maintenance for owner
retro-commissioning
commissioning of existing buildings; to improve/optimize operating and maintenance
ground aquifer heating and cooling
differential thermal energy is used to heatt adn cool a building
geothermal
collect warmer underground air with heat pump to supplement other heating systems
biogas
made from waste and discarded crops to power turbines. high productivity, reduces landfill waste, no emissions
embodied energy calculation:
concept model
rough - based on building type and square footage
embodied energy calculation:
inventory model
accurate - based on actual amounts of all materials used
embodied energy calculation:
survey model
for existing buildings - assumes the bulk of the embodied energy is in the architectural materials (for older construction, this is generally true)
