Green House...
Solar Chimney Foundation...
Spring 2006
At first glance
this may appear to be one of those gratuitous "Please-the-Wife"
Projects, which it is on one level, but I was able to establish a greater sense
of enthusiasm by incorporating some neat ideas that hopefully will pay off later
this summer and possibly into the winter as well.
The images above
are of a small deck area off of my "New"
Office (half way down the pg of the link). The base is a heavy fiberglass
layer that was originally installed in the 1970's. All things considered it has
held-up remarkably well.
The first step was
to remove the heavy wrought iron railing and patch holes and seams that have
been leaking for years into the garage.
After
considering a number of options we ended up using a specialized paint that is
some sort of advanced polymer called EPM-6.
Elastometric
Protective Membrane (or so the can sez) is formulated to adhere to virtually all
materials, retains it's pliability over a broad spectrum of temperatures and
provides a water tight seal rated for 1 year per mil thickness of application.
I'm not sure how
you would determine how many years coverage you applied, but we did 2 coats at a
cost of almost $100 for two 4L cans.
The area covered
is approx 12ft by 16 ft.
If this project
was to stall and go no further I'd be quite pleased in that we've tried to patch
various parts of the deck numerous times over the years, but now we've finally
stopped all the leaks.
The deck sat like
this for about 2 weeks while the wife & bickered about how large to make the
enclosure and how high to make the ceiling.
In the end, we
arrived at a series of compromises that satisfied both of us. My primary concern
was to avoid tying into the roof above the existing fascia (meaning that we'd be
lifting shingles), and that the slope of the green house roof be able to easily
shed water and snow.
As I'm not much of
a carpenter/builder I spent a few days reading-up on building codes and decided
to draft out a fairly comprehensive set of plans that would allow us to
visualize what this would look like and provide a materials list (to stay on
budget).
The images above
are the 3 (three) main elements of the structure that I drafted in Corel Draw.
After putzing about for a few hours trying to determine an easy way of setting a
scale that would fit a letter size page, I eventually drew the whole thing at
1:1 scale within Corel on a "Custom" page layout that was 13ft by 9ft.
This was fantastic
as I drew the lumber to finished dimensions and was able to literally readout my
cut sizes down to 1/8th". The finished drawings were then scaled to 8
1/2" by 11" and printed for the construction crew.
This is the stack
of 43 "Prime" spruce 2 X 4's and 1 X 6 strapping, as well as a couple
2 X 6's for the header that joins to the existing house.
It should be noted
that else where on this site if I'm building a project for theworkshop.ca, it's
recycled lumber assembled with bent nails and old chewing-gum, but if it's for
my wife, suddenly it's "Prime Spruce" and the base of the walls has to
be Pressure-Treated lumber.
The weather report
has been calling for rain for the entire Easter long-weekend, but we thought
we'd start into this and work as long as we could.
And so it begins.
The walls were
pretty much dead on the money against the diagrams for cut dimensioning.
The tricky part
that the diagrams addressed was a 3" slope over a 12ft run of the floor for
the south facing long wall.
But as you can
imagine I was beside myself and almost had a severe
anxiety attack when Sandy insisted that the opening for the door be moved from
the center of the wall to the east end.
This project is
partially being driven by the dire circumstances facing Ontario Farmers in 2006.
Just a few of the
issues are increased cost of fuel, and the potential issues of fertilizer and
pesticide manufacturing moving off-shore to access cheaper natural gas
feed-stock for production.
And the flooding
of our local markets by cheap food goods that are more highly subsidized than
our local growers.
In other words I
suspect that we can add rising food prices to the list of problems that spins
out of the current shortage of liquid transport fuels and the increase in Natural
gas prices.
It was somewhat
foreboding that the week leading up to construction saw a significant blockade
of a major grocery distribution center by farmers and their tractors impeding
the movement of food to market in protest.
Earlier in the
week & the week prior both the Federal buildings and province of Ontario
legislature were protested by hundreds of farmers and their tractors in the
downtown cores of Ottawa and Toronto.
The roof like the
walls fell into place in record time.
Between my wife,
twin daughters and myself we have less than 12 hrs construction time to this
point (not bad for a 3 women and a guy that can barely see)
It's a nice place
to grab a bite to eat working the "High Steel", except that it's wood
not steel, and the height is only about 16 ft to the ground (actually 6 ft to
the deck and then another 10ft to the concrete of the garage door opening if you
rolled off the deck.)
But it's still a
nice view.
Initially the plan
was to use actual glass for the glazing of the green house.
Our inventory of
glass would have been sufficient to sheet the structure but it would have been a
patchwork quilt of varying tempers, thicknesses and tints.
Instead we opted
to use a less conventional covering, clear vinyl table-cloth.
The vinyl is laid
flat onto the 2X4 frame and stapled into place. The stapled material is further
re-enforced by brad-nailing a 1 1/2" by 1/4" plastic molding over the
2X4, essentially sandwiching the vinyl into place.
The selection of
the clear vinyl wasn't done in haste, as we have a 4 X 8ft sheet that has spent
3 years outside covering numerous items from the elements through all 4 seasons.
What struck me was that it retained it's pliability even in the harshest cold,
has not yellowed or degraded from exposure to the sun and is available in a
fairly heavy/thick grade of sheet.
In total the vinyl
cost just under $75 to cover approx 100 sq ft of wall area.
This image
illustrates one of the compromises that we arrived at.
To gain the approx
sq footage Sandy wanted, while retaining an adequate slope for the roof, the
opening to the deck ended up being 5 ft 6" after the rafters and headers
were accounted for.
In an effort to
keep from walking into the header (as this area is largely just a wash of white
to me) I opted to place a band of conspicuity tape on both sides of the opening.
The roofing was
likely the most expensive (per unit) material. There were only 2 brands to chose
from at our local hardware/lumber supply. One was a waved material that was
slightly thinner and did not explicitly state that it was UV rated, while we
opted for "Sun-Tuff Poly Carb" that has a square wave pattern and was
slightly heavier but most importantly had a UV rating that resisted
discoloration as well as deterioration.
The poly carb had
to be specially ordered as well as the retaining brackets.
The images
pictured above have the roof almost finished, the last section that has been
left open is to accommodate a solar chimney of sorts that will offer ventilation
to the greenhouse, but more importantly will act as a solar siphon to pipe-out
hot air from theworkshop.ca machine-shop located directly below.
The issue of
cooling in the machine-shop came to a head when all production ground to a halt
due to severe heat for about 3 weeks last summer, and substantially reduced
productivity for the balance of the summer.
Given that the
province of Ontario is lifting the hydro cap of 5 cents/KWH that we've enjoyed
for the last 2 or 3 years on May 1st 2006 (likely the first of numerous hikes to
come) I'm hoping that this is a more cost effective way of managing the heat
than adding an air-conditioner and the attendant operation cost beyond the
capital out-lay for the unit itself.
The idea of using
a chimney to engage a passive convection-based air-loop system unfortunately is
not my brain child but rather is based on the design of Schlaich Bergermann and
Partner of Germany.
The image to the
left is of an SB&P prototype Solar chimney built in Spain, that demonstrated
the potential for vertical thermal wind generation to the tune of 50KW given the
specs as listed below.
http://www.sbp.de/en/fla/mittig.html
Click on either the image or the link to read more about SB&P's technology.
Chimney height 200
m
Collector diameter 240 m
Turbine 50 kWel
Chimney diameter 10 m
Collector height 2 m
Collector area 45,000 m²
Chimney weight 125 t
Collector weight 5.5 kg/m² (without glass)
The basic premise
is that the solar collector is a hybrid of functionality, implementing a substantial
food production area that actually acts a a thermal sink to extend the operation
of the generator beyond the immediate influx of solar energy available during
daylight hours.
In our case, the
chimney will not house any form of electrical generation given the reduction of
scale (if we were to try I think it would be in the order of milli-W/h not
Kilo-W/h). But rather a simple hole in the floor and some duct work strategically
placed will be added, as mentioned for air circulation.
The next
installment will feature the actual chimney assembly, the duct work, the
addition of passive solar collectors (identical to the Shop
Doors made earlier in January/06) and possibly some active electronics based
on the DS1615 sensor and active air flow into
the shop during the heating season.