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House designed for solar - combination of photovoltaic and active and or passive heating

D

David Dawson

Jan 1, 1970
0
I'm in the dreaming stage and collecting information on house designs/
guidelines with a view to building one with a combination of solar
photovoltaic, perhaps active hot air panels for house heating plus active
hot water panels for the domestic hot water.

I live in Vancouver, British Columbia and plan to put up the house in the
future somewhere on the sunshine coast in the Sechelt region or near.

No definite plans as yet, just want to understand the engineering details.
I can do the heat flow calculations, have university level math ability and
am a computer programmer.

Most important, I have a brother-in-law who worked in house construction.

I have a small collection of the ASHRAE volumes including the Fundamentals.

I am asking to see if anyone has some research guidelines and what really is
practical in this geographical region.

Our power utility is in the process of being broken up and sold, so I can
anticipate prices soaring in the future, as they did in the province of
Ontario when the same thing happened.

but first practicality, then cost calculations.
What is practical?

Thanks
 
David Dawson said:
I'm in the dreaming stage and collecting information on house designs/
guidelines with a view to building one with a combination of solar
photovoltaic, perhaps active hot air panels for house heating plus active
hot water panels for the domestic hot water.

How about a $35 fountain pump (eg Tractor Supply's #3119117) and a $60
1"x300' pressurized plastic pipe coil in a $170 3'x8'x2' tall metal stock
tank (TSC #2177285) inside an 8'x12'x7' tall A-frame structure with a $100
8'x12' Dynaglas polycarbonate south wall at a 30 degree tilt. Where I live
near Philadelphia, it might collect 0.9x12(4x620+8cos(30)1000) = 101.6K Btu
of sun and lose 6h(Tg-34)8x12/R1 = 576Tg-19.6K on an average 34 F January
day, where Tg (F) is the A-frame air temp. If we collect Q Btu/day of useful
heat, Tg = 210.4-Q/576.

If a 4'x12' tank cover collects 90% of the sun that enters the glazing
(91.4K Btu, with the help of 2'x12' of Big Fins on the south tank wall)
in Tw F water and loses 6h(Tw-Tg)1.5x6x12 = 648(Tw-Tg), Q = 305(352-Tw).
Tw = 140 F makes Q = 64.5K Btu (19 kWh) per day, with Tg = 98 F. It might
look like this, viewed in a fixed font:

Y

^
|
7'| . <------------------------- sun
| .
| . ru . south -->
| .
| U. ru down-reflected upper ray
| . .
| . ru
| (x,y) 45 .
| . <---------- sun ru \
| . rl .8'
| L. rl ru \
| . rl down-reflected lower ray (not to scale)
|. 67.5 degrees
2'|----------------------------F .
| i | 300' pipe coil | i B
| n | | n i .
| s | | s g
| u |300 gal stock tank| u F .
| l | | l i
| | | n white 60 .
0' ------------------------------------------------------------------> X
0' 4' 8'

The north wall could be made from 4'x8' 2" double-foil polyiso boards.
.... 500 W of standard PV panels under a water duct on the lid might
produce 1000 W of electrical power...

20 PI=4*ATN(1)
30 F=4'max focal distance (ft)
40 A=PI/8'kerf angle (radians)
50 X=F/(1+1/TAN(A)/TAN(2*A))'x breakpoint (ft)
60 Y=X/TAN(A)+2'y breakpoint (ft)
70 L=SQR(X^2+(Y-2)^2)'lower segment length (ft)
80 H=8*COS(PI/6)'height (ft)
90 U=SQR((F-X)^2+(H-Y)^2)'upper segment length (ft)
100 ALD=180*(PI/2-A)/PI'lower elevation angle (degrees)
110 AUD=180*(PI/2-2*A)/PI'upper elevation angle (degrees)
120 PRINT F;L,ALD,U,AUD,2+L+U

focus -- lower segment -- -- upper segment -- total segment
(ft) length (ft) elev (deg) length (ft) elev (deg) length (ft)

4 3.061468 67.5 3.522649 45 8.584117

With lots of insulation, the 300 gallon tank could provide 300x8.33(140-60)
= 200K Btu of water heating over 5 cloudy days.

For house heating, you could scale it up...

Nick
 
D

David Dawson

Jan 1, 1970
0
How about a $35 fountain pump (eg Tractor Supply's #3119117) and a $60
1"x300' pressurized plastic pipe coil in a $170 3'x8'x2' tall metal stock
tank (TSC #2177285) inside an 8'x12'x7' tall A-frame structure with a $100
8'x12' Dynaglas polycarbonate south wall at a 30 degree tilt. Where I live
near Philadelphia, it might collect 0.9x12(4x620+8cos(30)1000) = 101.6K
Btu of sun and lose 6h(Tg-34)8x12/R1 = 576Tg-19.6K on an average 34 F
January day, where Tg (F) is the A-frame air temp. If we collect Q Btu/day
of useful heat, Tg = 210.4-Q/576.

If a 4'x12' tank cover collects 90% of the sun that enters the glazing
(91.4K Btu, with the help of 2'x12' of Big Fins on the south tank wall)
in Tw F water and loses 6h(Tw-Tg)1.5x6x12 = 648(Tw-Tg), Q = 305(352-Tw).
Tw = 140 F makes Q = 64.5K Btu (19 kWh) per day, with Tg = 98 F. It might
look like this, viewed in a fixed font:

Y

^
|
7'| . <------------------------- sun
| .
| . ru . south -->
| .
| U. ru down-reflected upper ray
| . .
| . ru
| (x,y) 45 .
| . <---------- sun ru \
| . rl .8'
| L. rl ru \
| . rl down-reflected lower ray (not to scale)
|. 67.5 degrees
2'|----------------------------F .
| i | 300' pipe coil | i B
| n | | n i .
| s | | s g
| u |300 gal stock tank| u F .
| l | | l i
| | | n white 60 .
0' ------------------------------------------------------------------> X
0' 4' 8'

The north wall could be made from 4'x8' 2" double-foil polyiso boards.
... 500 W of standard PV panels under a water duct on the lid might
produce 1000 W of electrical power...

20 PI=4*ATN(1)
30 F=4'max focal distance (ft)
40 A=PI/8'kerf angle (radians)
50 X=F/(1+1/TAN(A)/TAN(2*A))'x breakpoint (ft)
60 Y=X/TAN(A)+2'y breakpoint (ft)
70 L=SQR(X^2+(Y-2)^2)'lower segment length (ft)
80 H=8*COS(PI/6)'height (ft)
90 U=SQR((F-X)^2+(H-Y)^2)'upper segment length (ft)
100 ALD=180*(PI/2-A)/PI'lower elevation angle (degrees)
110 AUD=180*(PI/2-2*A)/PI'upper elevation angle (degrees)
120 PRINT F;L,ALD,U,AUD,2+L+U

focus -- lower segment -- -- upper segment -- total segment
(ft) length (ft) elev (deg) length (ft) elev (deg) length (ft)

4 3.061468 67.5 3.522649 45 8.584117

With lots of insulation, the 300 gallon tank could provide
300x8.33(140-60) = 200K Btu of water heating over 5 cloudy days.

For house heating, you could scale it up...

Nick
Thanks

Well I was really thinking of using both photovoltaic panels and a solar hot
air collector system _and_ possibly a solar hot water collector just for
domestic hot water. Vancouver is a bit more northerly than Philly but temp
is probably a bit warmer in the winter on average.

I understand that rock box storage is an easy way to store hot air heat in
the night and I calculated that (neglecting heat loss; I need the values
for insulation, etc) that a 4 foot deep rock box the area of the house
could hold plenty of heat for a while. I calculated that this size box
would hold enough for 14 days; with losses added in, maybe a week?

That's what I need to know -- the heat flow within a normal house and how to
minimize losses through walls.
 
A

Anthony Matonak

Jan 1, 1970
0
David Dawson wrote:
....
I understand that rock box storage is an easy way to store hot air heat in
the night and I calculated that (neglecting heat loss; I need the values
for insulation, etc) that a 4 foot deep rock box the area of the house
could hold plenty of heat for a while. I calculated that this size box
would hold enough for 14 days; with losses added in, maybe a week?

While I'm no expert in these things, you might want to explore using
scrap iron or steel in place of rocks. Assuming you can get the stuff
in appropriate size and shape, of course. As I understand it, steel is
relatively inexpensive and will store more heat than rock.

Also, while you are at it, you may want to explore adding solar cooking
to the design of your home. A modest sized concentrating collector,
less than 100 feet square, should be more than enough to provide all
your cooking needs and some to store for a rainy day. It might even
be used as a backup for heating water and air.

Anthony
 
Anthony Matonak said:
David Dawson wrote:
...

Storing 18 hours of overnight over a 6-hour solar collection day in January
requires a large warm-air-to-store heat transfer rate, which requires lots of
mass surface to keep the air-to-mass temp diff low at the surface. Rocks have
lots of surface, but they also have lots of airflow resistance, which means
rock beds need lots of electrical blower power. CSI's New Hampshire building
is 100%-heated with rock beds with "98% solar power and 2% blower power."

The same volume of water or steel can store 3X more heat. Water is cheaper
and it can be stored in a smaller box with less heat loss. Water can also
be stored in a compact tank with no wasted airspaces required for airflow,
and it can be moved around.

The heat loss from a box that's in or under the house can heat the house.

A store that releases heat over a week or two can have less heat-transfer
surface than an overnight store, with larger containers like plastic 55
gallon water drums. Or a 4'x8'x2' deep plywood tank with a folded EPDM liner
and fin-tube pipe under a ceiling to collect and distributes solar heat.
... you might want to explore using scrap iron or steel in place of rocks.
Assuming you can get the stuff in appropriate size and shape, of course.

Our local recycling center sells crushed tin cans for $2/ton, plus postage.
These might provide fascinating olfactory sensations for a few years.

Nick
 
N

no spam

Jan 1, 1970
0
I'm in the dreaming stage and collecting information on house designs/
guidelines with a view to building one with a combination of solar
photovoltaic, perhaps active hot air panels for house heating plus active
hot water panels for the domestic hot water.

I live in Vancouver, British Columbia and plan to put up the house in the
future somewhere on the sunshine coast in the Sechelt region or near.

No definite plans as yet, just want to understand the engineering details.
I can do the heat flow calculations, have university level math ability
and
am a computer programmer.

Most important, I have a brother-in-law who worked in house construction.

Have you though about concrete domes? There are several types out there,
the one I am looking at comes in a kit which is fairly easily constructed.
They are very air tight and very well insulated as well as structurally
incredibility strong. I have moved into a hurricane area from a tornado
area so strong is important to me.

I also am planning on passive solar heating (home and water) and trying to
find info to build a solar AC unit for my home. I'm just a little (<-that's
a joke) south of you so AC not heating is my major worry.

The company I'm looking at is American Ingenuity Dome's web site
www.aidomes.com. For one thing they are not that far from me so the
shipping cost would be low and another is the fact its a DIY construction.
 
D

David Dawson

Jan 1, 1970
0
no said:
Have you though about concrete domes? There are several types out there,
the one I am looking at comes in a kit which is fairly easily constructed.
They are very air tight and very well insulated as well as structurally
incredibility strong. I have moved into a hurricane area from a tornado
area so strong is important to me.

I also am planning on passive solar heating (home and water) and trying to
find info to build a solar AC unit for my home. I'm just a little
(<-that's a joke) south of you so AC not heating is my major worry.

The company I'm looking at is American Ingenuity Dome's web site
www.aidomes.com. For one thing they are not that far from me so the
shipping cost would be low and another is the fact its a DIY construction.
Thanks, I'll look at this, but being 'part of the neighbourhood' is
important to me and in the region being considered, this might not be in
keeping with the local architecture (or building _design_ rules).
A purpose build wooden solar house might be enough of a struggle to get
approved! And then the probable need for a wind generator...!!
 
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