Civil Engineering Reference
In-Depth Information
Table 6.1
Energy consumption inventory
Item
Measurement
Units
Time period
Office TV—CRT
0.12
kWh
1 h
Computer—Notebook
0.04
kWh
90 min
Computer—LED screen
0.01
kWh
1 h
Refrigerator
0.13
kWh
1 h
Office lamp—Halogen
0.26
kWh
1 h
Floor fan
0.04
kWh
1 h
Microwave
0.05
kWh
2 min
Temp. diff.—AC
−11.0
Degrees F
6 pm
Temp. diff.—Skylight vs walls
6.0
Degrees F
Noon
Temp. Diff.—Ceiling vs walls
0.9
Degrees F
Noon
Temp. diff.—Floor vs walls
−1.1
Degrees F
Noon
0.
13 kWh24h 365 days
×× =
1 138 8kWh peryear
,
.
That is about four times what a newer, more energy efficient refrigerator would
consume. Since I know my electric cost is about 10 cents per kWh, it costs me about
$ 113 per year for my refrigerator. This is why keeping that old refrigerator in the
garage is probably not such a good idea.
The
P3 Kill A Watt
monitoring device is a great tool for monitoring the consump-
tion of anything that plugs into a standard 115 V AC power outlet. The device will
start tracking time and kWh consumed as soon you plug it into the power outlet.
It also displays volts, amps, watts, Hz and VA. This device sells for about $ 22
(Fig.
6.1
).
I took the temperature differential measurements in the inventory with a
Black &
Decker Thermal Leak Detector
. This is a great tool for checking the effectiveness
of your heating and air conditioning system, your insulation and your windows.
You can also use it to check around doors, windows, floors and ceilings for air leaks
(Fig.
6.2
).
You can see that the difference in temperature between my air conditioning air
intake and air outlet is fairly good, more than 10 °F. It is best to take these measure-
ments throughout your home and at different times of the day. I must have a fairly
well insulated ceiling since the temperature difference between it and the walls is
very small. And, the temperature difference between the ceiling and my skylight is
quite large. Notice that the floor temperature is lower than the wall temp. That is the
way it should be. Cool air trapped in the crawlspace overnight is pushing up against
the floor. If we could only find a way to harvest that cool air and bring it up into the
living area during the heat of the day.
I think if I disconnected one of my floor vents from the duct that is in the crawl-
space I could open it up at certain times and let the air conditioner return air flow
draw that cool air up from the crawlspace into the living area. This will only work
if the outside humidity is very low. I wouldn't want to pull humid air up into the
