Posted by Thomas on September 16, 2003, 4:49 pm
Long time lurker, first time poster so bear with my ignorance on the topic.
I'm nearly retired looking for way's to minimize winter heating expenses in
south east New York. Having read the posts detailing solar closets and
spaces I decided to see if the following was viable.
I have a good, not great, southern exposure on the end of a split level
rancher. The interior space on the south side of the house is the kitchen
and the living room. There are 440 sq ft. floor and 3520 cubic ft of space.
The building is slab on grade with the kitchen and living room on the upper
floor.
My thought is to make a sunspace on the south side on the ground
approximately 15 feet wide by eight feet high x eight feet high. I have yet
to calculate the number of bottles and water volume. I thought it best to
get obtain opinions prior to taking this further. The cold air in side would
be drawn from the lower level family room, kept at about 60F in the winter,
and have the high end return side ported into the kitchen and or living
room. I would use clear two liter soda bottles as the storage (high surface
area, clear, cheap) stacked up like firewood inside the sunspace, perhaps
two deep. Added to each two liter of water would be a teaspoon to two of
bleach to minimize organic growth.
I am not looking for this to heat the room, merely to serve as a booster of
sorts.
Does this have merit? Thank you in advance
Thomas Riley
side view
< south
-------------------
| |
| |--> warm out
| |___________kitchen level _________
| b |
| o |
| t |
| t |
| l |
| e |
| s |
| | <-- cold in
|___|_____________Slab on grade________
Posted by Joe Fischer on September 17, 2003, 1:02 am
: I have a good, not great, southern exposure on the end of a split level
: rancher. The interior space on the south side of the house is the kitchen
: and the living room. There are 440 sq ft. floor and 3520 cubic ft of space.
: The building is slab on grade with the kitchen and living room on the upper
: floor.
:
: My thought is to make a sunspace on the south side on the ground
: approximately 15 feet wide by eight feet high x eight feet high.
: I have yet to calculate the number of bottles and water volume.
Chances are that amount of water will not help much,
and it takes a long time to drink that much soda.
Figuring 4 pounds in each bottle, a pound of
water will hold 1 BTU for each degree of temperature rise,
and even 30 degrees rise during the day would only amount
to 120 BTU per bottle maximum.
That is about 40 watt hours, so over the long
winter nights, it would be like a 3 watt light bulb
for each bottle at best.
Eutectic salts can be mixed to melt at 75 degrees,
which would store about considerably more heat in the
phase change, but I don't know if they are safe to put
in plastic bottles.
:
: < south
: -------------------
: | |
: | |--> warm out
: | |___________kitchen level _________
: | b |
: | o |
: | t |
: | t |
: | l |
: | e |
: | s |
: | | <-- cold in
: |___|_____________Slab on grade________
Storing energy is the tough part, there is lots
of energy available from the sun.
And passive solar energy needs a way to avoid
it on warm fall and spring days, so a lot of thought
is needed about living in the space that would be
heated during the day.
A few years ago I started saving bottles,
and stored them with the caps on tight in an unheated
shed all winter, and the air inside got cold and the
volume got smaller and all the bottles were deformed,
so I didn't get to try them.
A window can let in as much as 1500 BTU per hour
per square meter (yard), and solar black chrome on copper
foil will help heat the air quickly, providing a lot of
heat during the day.
Insulation is the most cost effective way to
reduce heating costs, and rooms that are used during
sun hours can be warmed by just windows, but it isn't
good for furniture and drapes or wood.
Depending on the material that the south facing
wall is made of, some consideration of having a glass
wall outside the existing wall, to create a Trombe
wall, and any amount of mass that could safely be
added would help.
It might help to make small models and use
thermometers to measure the effects.
My car sets facing southwest in winter,
and when the sun shines, by noon it is 70 degrees in it,
while the house furnace is running half the time.
Joe Fischer
--
3
Posted by Nick Pine on September 17, 2003, 8:29 am
>: I have a good, not great, southern exposure on the end of a split level
>: rancher. The interior space on the south side of the house is the kitchen
>: and the living room. There are 440 sq ft. floor and 3520 cubic ft of space.
The volume isn't very important here...
>: The building is slab on grade with the kitchen and living room on the upper
>: floor.
How big is the building? How much insulation?
>: My thought is to make a sunspace on the south side on the ground
>: approximately 15 feet wide by eight feet high x eight feet high.
Sounds good. You might make it bigger. You might collect 0.9x980x8x15
= 106K Btu of sun from the south and 0.9x610x8x15 = 66K of overhead sun
and lose about 6h(100-30)200ft^2/R1 = 84K Btu on an average December day,
for a net gain of 88K Btu/day, a bit less than a gallon of oil. How does
that compare with your fuel bill?
>: I have yet to calculate the number of bottles and water volume.
A 2 liter bottle is about 4" D x 12" high. Hexagonal vs square stacking
adds about 10% to the number of bottles...
> Figuring 4 pounds in each bottle, a pound of
>water will hold 1 BTU for each degree of temperature rise,
>and even 30 degrees rise during the day would only amount
>to 120 BTU per bottle maximum.
You might store overnight heat in 120K/120 = 1000 bottles...
A few years ago, the local 7-Up bottling plant gave me about 1200
2-liter bottles on a 4'x4'x8' tall shrink-wrapped pallet, way more
than a pickup truckful, loose. But water vapor permeates through
PET bottle walls over time, esp when warm, so the bottles
might need topping up every year...
> Eutectic salts can be mixed to melt at 75 degrees, which would
>store about considerably more heat in the phase change...
But they get tired of changing phase.
>: < south
>: -------------------
>: | --> warm out
>: | |
>: | |___________kitchen level _________
>: | b |
>: | o |
>: | t |
>: | t |
>: | l |
>: | e |
>: | s |
>: | <-- cold in
>: |____________________Slab on grade________
The cold and/or warm vents need one-way plastic film dampers to prevent
warm house air from flowing into the sunspace through the top vent and
cooling and returning to the house via the bottom vent at night.
And this is just a crippled sunspace, not a solar closet. In this picture,
the bottles store heat during the day, but a lot of that heat goes back out
through the glazing at night.
You might sprinkle some sand above the kitchen ceiling, under the attic
insulation. Or stack the bottles inside the kitchen, on a wall, as in
a large wine rack. Or put bottle gabion columns around the house: place
one bottle vertically on the floor, surround it by 8 radial bottles, necks
inward, wired in a ring, put another radial layer on top, and so on. Build
one around a pole lamp for more interior drama. This water could come in
handy if well pump power fails during a hurricane.
>A window can let in as much as 1500 BTU per hour per square meter (yard)
A single layer of polycarbonate with 90% transmission might pass 0.9x800
= 720 W/m^2 of AM2 sun, ie 2456 Btu/m^2 or 2055 Btu/yd^2.
>and solar black chrome on copper foil will help heat the air quickly,
>providing a lot of heat during the day.
Black paint or black window screen is cheaper, but that foil (where can
we buy it?) can help a Trombe wall, another form of crippled sunspace...
>Depending on the material that the south facing wall is made of, some
>consideration of having a glass wall outside the existing wall, to create
>a Trombe wall, and any amount of mass that could safely be added would help.
Maybe, with that unobtainium foil.
>It might help to make small models and use thermometers to measure
>the effects.
PE Norman Saunders says you can learn with a cardboard box and saran wrap.
Nick
In our home solar heating system we used water as the thermal storage
medium for an air-transfer unit, the water being contained in 1000
one-gallon polyethylene bottles stacked so that air could flow between
them. They worked satisfactorily until some desert pack rats invaded
the storage bin, making nests of the insulation and chewing holes
in the water bottles.
p 468, _Applied Solar Energy_, by
Aden B. Meinel and Marjorie P. Meinel
Addison-Wesley, 1976
Posted by Thomas on September 17, 2003, 11:32 am
>: The building is slab on grade with the kitchen and living room on the
upper
>: floor.
>How big is the building? How much insulation?
Each level is 1100 sq ft. Lower wall is standard cinder block and R11 poly
board on the inside, upper level walls are Walls are R19 Attic R30
My thought is to make a sunspace on the south side on the ground
approximately 15 feet wide by eight feet high x eight feet high.
TYPO this should 15W x 8H x 1 or 2ft deep
>Sounds good. You might make it bigger. You might collect 0.9x980x8x15
>= 106K Btu of sun from the south and 0.9x610x8x15 = 66K of overhead sun
>and lose about 6h(100-30)200ft^2/R1 = 84K Btu on an average December day,
>for a net gain of 88K Btu/day, a bit less than a gallon of oil. How does
>that compare with your fuel bill?
i do not know how to compare fuel bills to 88K btu's.
I have propane and NG is not an option. Average bill winter dec02 jan and
feb 03 was 350.00
>A window can let in as much as 1500 BTU per hour per square meter (yard)
I should have noted that the southern exposure has no windows at all. That
is whay I am trying to find a way to obtain the heat and disperse it into
the two upper rooms.
>A single layer of polycarbonate with 90% transmission might pass 0.9x800
>= 720 W/m^2 of AM2 sun, ie 2456 Btu/m^2 or 2055 Btu/yd^2.
>Black paint or black window screen is cheaper, but that foil (where can
>we buy it?) can help a Trombe wall, another form of crippled sunspace...
This suggest to me an exterior trombe wall with metal backer or other
material to heat the air faster. Perhaps is is more prudent to heat the air
rather than attempt to store the heat (thus making it over complicated).
That is more in line with the goals of heating during the day and closing
venting during the evenings.
Is the air flow in my previous post reasonable (pull from lower level, dump
in upper level)??
Thank you folks for your remarks
Thomas
Posted by Nick Pine on September 17, 2003, 12:59 pm
>>How big is the building? How much insulation?
>Each level is 1100 sq ft. Lower wall is standard cinder block and R11 poly
>board on the inside, upper level walls are Walls are R19 Attic R30
That's about 1100ft^2/R30 = 37 Btu/h-F for the attic plus 176ft^2/R2 = 88 for
windows(?) plus 1947/19 = 102 for walls(?) plus, say 1achx17600ft^3/60 = 293
for about 293 cfm of air leakage (which might be reduced a lot, with caulking),
so the total thermal conductance might be about 432 Btu/h-F.
> My thought is to make a sunspace on the south side on the ground
>approximately 15 feet wide by eight feet high x eight feet high.
>TYPO this should 15W x 8H x 1 or 2ft deep
Seems easy to make it bigger, with more solar gain and useful floorspace.
>>Sounds good. You might make it bigger. You might collect 0.9x980x8x15
>>= 106K Btu of sun from the south and 0.9x610x8x15 = 66K of overhead sun
>>and lose about 6h(100-30)200ft^2/R1 = 84K Btu on an average December day,
>>for a net gain of 88K Btu/day, a bit less than a gallon of oil. How does
>>that compare with your fuel bill?
>i do not know how to compare fuel bills to 88K btu's.
>I have propane and NG is not an option.
As I recall, a gallon of propane contains about 92K Btu.
>Average bill winter dec02 jan and feb 03 was 350.00
...$350/mo is about $6/day, equivalent to about 6 gallons of oil per day.
You might double the sunspace size with no thermal storage without wasting
much solar heat in December. At 432 Btu/h-F, your house would need about
24h(65-32)432 = 342K Btu/day to stay 65 F on an average December day in NYC.
>This suggest to me an exterior trombe wall with metal backer or other
>material to heat the air faster.
Trombe walls are badbadbad in SE NY. Thermal mass cripples solar performance.
>Perhaps is is more prudent to heat the air rather than attempt to store
>the heat (thus making it over complicated).
Good idea, unless you are shooting for 100% solar house heating.
>Is the air flow in my previous post reasonable (pull from lower level, dump
>in upper level)??
Sure.
Nick
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>: rancher. The interior space on the south side of the house is the kitchen
>: and the living room. There are 440 sq ft. floor and 3520 cubic ft of space.