Solar Shades: Cheap Passive Heaters
One can reduce one's heating bills and CO2 sinning by installing inexpensive
solar shades. The porch windows were equipped with five pull-down shades
that generated quite an amount of heat.
Being a nerd, time and temperatures were kept for a period to document benefits.
Not only was the air temperature measured but small thermometers attached
to the back of the shades indicated the temperature that the reached, normally
110 degrees or more. The total surface area of the shades was about 140 square
feet (5x7x4). Needless to say, understanding the thermodynamics of this
temperature and surface, a hot porch should not be surprising.
The following are some roughly listed results. Normally, on a sunny day,
by 10am the porch/house door was opened to share the passively generated
heat with the house. The porch temperature has reached 80 degrees (which
this person finds uncomfortable, especially when wearing de rigor winter
long-johns!)
Normally, most of this sunlight energy goes into breaking down molecules
that make up the colors and furnishing of our rooms. Interestingly, the optimal
heat transformation of radio energy is the bedrock of quantum physics: black
body radiation (e=hf).
 |
-
0712?? Outside 38 degrees, shades at 110, temp at 65 degrees
-
071231 Temp outside 45, porch 70 degrees ... front door of house open with
thermostat set at 49 degrees ... house temp ... Cannot stand next to shade,
feels like lying on a beach on a hot, cloudless day.
-
When the sun shifts past the shades, the temperature drops to the outside
temperature.
-
080101 Propping open the front room door causes the porch temperature to
drop ten degrees from 70 to 60 as inside cooler air (themometer set at 49
degrees) comes out at the bottom with warmer air going in at top.
-
080104@12:00 39 degrees w/65 porch
-
080125@11:00 32 degrees w/70 porch
-
An hourly recording of temperature changes.
| time |
out |
in |
difference |
| 08:30 |
35 |
38 |
3 |
| 09:00 |
38 |
49 |
11 |
| 09:30 |
38 |
54 |
16 |
| 10:00 |
41 |
61 |
20 |
| 10:30 |
42 |
64 |
22 |
| 11:00 |
42 |
67 |
25 |
| 11:30 |
44 |
68 |
24 |
|
 |
Using cheap roll up shades painted flat black (total cost for five shades
and paint was $25 in 2007). Here they are drying in the basement. Took about
two hours to paint using a roller and a quart of paint (in lower right hand
corner of picture). Use spray paint only if you want to spend a lot of time
and money.
|
 |
These are the two shades on the south side of porch. Three face
the east.
Shades are also present on several south- and west-facing windows on both
mainfloor and basement. |