HOW TO BUILD A

SOLAR THERMAL ROOF

by

John Canivan

1

How to Build a

Solar Thermal Roof By

John Canivan

July 2004

Sunny Future Press, Wantagh, NY Copyright © John Canivan 2003

$20.00 All rights reserved. No part of this book may be reproduced or transmitted in

any form or by any means electronic or mechanical without the express

permission of the publisher. On line support is available from www.JC-

SolarHomes.com. If you have any questions or comments about this book feel free to post them on the JC Solar Collector Forum or join the Solar

Energy group or send email to canivan@optonline.net. If you find this book

helpful you may also appreciate my other books:

How to Build a Solar Hot Water System Solar Thermal Energy

Energy Independent Housing

Do-it-Yourself-Solar

RECOGNITION: My appreciation extends to many people that made this manuscript possible such as Professor Dathatri, the chairperson of the Solar

Energy Center, at Farmingdale University, Professor Modi, the chairperson of

the Mechanical Engineering department at Columbia University, NY, my hard

working Dad, the general contractor, my understanding mom, my AutoCAD instructor, Mel Riddick, the critic, Loretta, the best cookies baker on the

block and lets not forget about the little woman who had to put up with my

mood swings and grammatical incongruities, my patient loving wife,

Catresea.

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About this book How to Build a Solar Thermal Roof is based on the concepts developed in

the Solar Thermal Energy Workshops at Farmingdale University, NY and my

book, How to Build a Solar Hot Water System. Rooftops are perhaps the

best place to collect the suns energy. All we need to do is find a cost effective method of heat collection. This book is about that cost effective

method. Photovoltaic systems only collect about 10% of the energy available

while solar thermal systems harvest heat energy at the same heat transfer

efficiency as oil burners. Without rebate incentives installed solar thermal roofs systems can pay for themselves in less time than photo voltaic

systems. They can supply a cold climate household with all or most of it’s

hot water and heating needs.

If you build and install your own solar thermal roof you could be saving

thousands of dollars each year with a system that pays for itself in several

years. How to Build a Solar Thermal Roof is a down to earth, easy to

understand, step by step cutting edge book designed to help you become

energy independent. Over 50 color illustrations are used to clarify construction details and facilitate the learning of basic solar thermal energy

concepts. A glossary is included along with a list of suggested materials for

your convenience.

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CONTENTS

I. Basic Concept 5

II. Absorber Plate Jig 8 III. Making an Absorber Plate 11 IV. Installing insulation 14 V. Installing Absorber Plates 15

VI. Installing the Flow Pipes 16 VII. Energy Independence 18 VIII. Radiant Heating 22

IX. Spinning Sunlight Into Gold 26 X. Glossary 41

4

PROLOG

It is now possible to build a practical renewable energy system that

everyone can afford by using the entire surface area of a roof for collecting the sun’s energy. Why mess around with a few pitiful eyesores when the

entire roof can be used to harvest energy. Every dwelling needs a roof. With

a little planning that roof could become an asset rather than a liability. Did

you know that most roofs have a life expectancy of 20 years or less? A solar roof could easily outlast conventional roof and keep your house cool in the

summer and warm in the winter.

Of course not all roofs are suitable for a solar thermal application. The best orientation and pitch of a roof will depend on its global position as well local

climatic conditions. If you live in the Adirondacks and all you have to work

with is a North facing roof you might consider growing mushroom. East and

West facing roofs are capable of harvesting some heat energy during those

short winter days but if you’re serious about heating and cooling your house with the sun your roof should face south if you live in the North. Of course

the reverse will be true if you live on the other side of the equator. If you

live on or close to the equator you’re in the twilight zone of solar thermal

roof application and you’ll probably have more sunlight than you know what to do with so this book was not written for you. How to Build a Solar

Thermal Roof was written for you cold climate people who live between the

latitudes of 30 and 60 degrees. Since I live North of the equator at a latitude

of 41 degrees my references with respect to roof orientation will be made with respect to this latitude.

How expensive is a solar thermal roof?

An installed solar thermal roof system complete with heat storage vault and radiant floor heating could easily pay for itself in less than eight years

without government, state or local incentives. With these incentives a solar

thermal roof might easily pay for itself in less than four years. The initial cost

of a system will depend on the size of the roof, the size of the heat storage

vault and the size of the radiant floor heating system.

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I. Basic Concept

A rooftop is an ideal place for harvesting the suns energy if it’s oriented and pitched properly. For a northern climate the best orientation is

normally south and the best pitch would be about 13 degrees plus latitude

for winter heat gain. If you read How to Build a Solar Hot Water System

and built a few serpentine collectors you’ll have an experience that that should make the solar thermal roof project more comprehensive.

People around the world have built and installed serpentine collectors.

These collectors are the same kind we build at my all day Solar Thermal

Energy Workshops at Farmingdale University in NY. They’re cost effective and at least as good as any expensive commercial units that I’ve seen.

Building and installing a serpentine solar hot water system gives a person

the practical experience needed to understand the value and dynamics of a

heat gain, heat transfer and heat storage, but I believe we can go one better

when it comes to a practical solar thermal energy project. We have become so dependent on energy concentrates that the

transformation to energy independence based on diffuse renewable energy

resources will be difficult. Most homes aren’t oriented with the sun in mind,

and some new housing design embellish poorly insulated cathedral ceilings with gable roofs that waste, materials, space and heat. New, cost effective,

attractive, energy independent houses are possible but the traditions of

wasteful spending and energy inefficient designs make the process of

change difficult. We’re stuck with a lot environmentally unfriendly houses with roofs unsuitable for this kind of application, but if we look hard enough

I’m sure we’ll be able to find a few that could benefit from a solar thermal

roof.

An 800 sq. ft. solar thermal roof with a 3,000 gallon multi tank heat storage vault, radiant floor heating system and total hot water system would

of course be more expensive than two commercial, 20 sq. ft. collectors with

a 60 gallon SHW tank, but the pay back would be less. Instead of saving

$200/yr on a commercially installed system costing $5,000 with a payback

of 25 years you could save $2,000/yr on a do-it-yourself project that costs $6,000 and has a payback of 3 years.

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The main problems with solar thermal roofs have to do with size and

orientation. Not all roofs are suitable. The roof below has a pitch of 45

degrees. 54 degrees would be ideal for winter heat gain in the Long Island area where I live, but a roof with a 45 degree pitch like the one below could

still put a serious dent in the heating and hot water bills. Let’s focus on what

we can do rather than what we can’t.

BEFORE

Here’s a good candidate for a solar thermal roof. Notice the steeply pitched

south facing roof. If the sewer vent could be moved the entire surface area

of the roof could be used for making hot water all year long. Home heating needs could also be supplemented in the winter.

7

AFTER

This 600 square foot solar thermal roof is capable of a 190,000 BTU

harvest per hour in direct sunlight which is the fuel oil equivalent of 1.26

gallons. In a location like Long Island a solar energy harvest equal to the

fuel oil equivalent of 1260 gallons of #2 fuel oil are available to a roof like

this. As long as your neighbors don’t go crazy and run you out of town on a rail you’ll be saving lots of money that would normally go down the fuel oil

drain.

If you’re not turned off by the appearance of a roof like this and you’d

like to have a go at it I’ll do what I can to guide you through the processes, but before we go on this solar thermal roof adventure we’ll have to make

some absorber plates. To do this we’ll need to construct an absorber plate

jig.

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II. ABSORBER PLATE JIG

Absorber plates provide an inexpensive method of transferring the sun’s

heat to the flow tubes of the solar thermal roof. Absorber plates increase the

surface area exposed to sunlight. More than 700 linear feet of copper tubing would be required to cover the same surface area that could be covered with

60 linear feet bonded to a well-constructed absorber plate.

Copper absorber plates facilitate the soldering of copper tubes, but they’re

expensive, heavy, difficult to fabricate and unnecessary. Aluminum absorber plates are less expensive, lighter, easy to fabricate and also the best

conductor of heat per pound known. You should be relieved to know that

we’ll be using aluminum absorber plates. Individual absorber plates can be

as long and as wide as you wish. The ones that I use to make serpentine

collectors are 20 inches wide and 100 inches long. The jig plans of for this size absorber plate are the ones detailed in the book but you may decide to

make absorber plates 24 inches wide since the lower bonding strips on the

roof will be 24 inches on center.

The starting length of the plate should be about a foot longer than the

distance between the peak of your roof and the edge of your roof. After

pounding the aluminum flashing, the length of the aluminum should shrink

to fit on your roof. If it’s a little too long you could always trim it to fit.

These jig plans are for 20” wide absorber plates made from 20” wide sheets

of aluminum flashing with a thickness of about .01”. Be sure to alter the

construction dimensions if you decide to make 24 inch wide absorber plates.

Are we ready? Let’s build the absorber plate jig.

1. Cut four 1X6 boards 4 feet long. 2. Cut seven 1X6 boards to a precise length of 20+1/8 inches. The extra

1/8 inch allows the 20” aluminum to slid through the jig without

binding.

3. Rip one ½” strip of wood 2’ long and rip two 1X3’s 24 inches long. 4. On a flat concrete floor place two 1x6x4 boards parallel to each other

as depicted in illustration below.

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5. Attach the 20+1/8 inch boards to the 48 inch boards. They should be

perpendicular to the 48 inch boards, parallel to each other and separated by a ½ inch gap between. Use the ½ reference spacers to adjust the gap

so that the boards will be centered six inches apart.

After screwing the boards together in this manner with the ½ inch gap between them, a third 1x6x4 board may be joined to the bottom of the jig

for additional support. My original absorber plate jig looked like the one

above, but the aluminum flashing is difficult to align so I added guides.

GUIDES

Guides make all the difference. They’ll save time and labor. They

automatically align the aluminum flashing and also position the steel rods.

10

Temporarily screw the 1x3 guide supports into the sides of the absorber

plate jig. Translate the location of the slots onto the guide boards with a pencil. Remove the guide boards to cut out the ½ inch steel rod guides in

the guide board. Now screw the guide boards back into position.

The finished absorber plate bending jig is a little different than the one above. It has more slots for bending but the design principles are the same.

Without the guides pounding grooves into the aluminum is a bit tedious.

See what I mean?

11

III. Making an Absorber Plate Now we’re ready to make some absorber plates. With the guides it’s a pleasure.

STEP ONE Lay in a 20 inch wide sheet of aluminum. This one is 50 inches

long but you can make yours as long as you like.

STEP TWO: Place the 7/16 inch steel rods in the slots.

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STEP THREE: After the first rod is pounded into position it’s held in place with a piece of plywood that you’ll kneel on so that the next rod may be

pounded without disturbing the first. This process may be repeated until all

the groves are placed in the aluminum, To pound grooves in sheets longer

than a jig simply shift the sheet down and place the last groove in the last slot in the first slot. Hopefully your absorber plate will look better than this

one done without guide supports.

A finished absorber plate section should look like this from the top:

To press the flow tubes into the grooves you’ll need to paste ½ inch

supports onto the backs of each absorber plate.

13

I like to use ½ inch strips of isocynate insulation 5 inches wide on the backs

Of course the flow tubes won’t be in place when the backing supports are installed. They’re only in the illustration to clarify the position of the

insulation on the back of the absorber plate.

It’s a good idea to make all the absorber plates that you’ll need before preparing the roof for their installation. As a mater of fact it’s a good idea to

gather up all the construction materials first.

When you’re done collecting materials you’ll be ready to assemble the solar

roof. Gathering materials is half the work. Mark off the location of the roof raters on the roof’s ridge and edge. You’ll

need this information when it comes time to screw the flow tube supports

into the rafters.

Before attaching the absorber plates and flow tubes you should tack 4x8 sheets of solid insulation onto the roof.

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IV. Installing Insulation

ISOCYNATE INSULATION

STEP 1. Tack down one inch thick 4x8 sheets of isocynate insulation on

your roof like this: You could use other solid foam insulations if you like, but

this commonly available insulation with a foil backing is easy to come by and

preferred by many siding contractors. Place the foil side up to increase the heat transfer efficiency. This soft bed of insulation provides an excellent base

to mount the finished absorber plates. The following page demonstrates how

absorber plates should be tacked down in an overlapping fashion on a 1000

sq ft roof.

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V. Installing Absorber Plates

This is what an array of interlocking absorber plates would look like on a

20x48 sq ft roof. Notice the 28 absorber plate columns. If each absorber

plate section were 10 feet long it would take about 56 absorber plate

sections 20 inches wide to cover a roof this size. The horizontal grooves of the absorber plates should be spaced about 6

inches apart to optomize heat absorption at a reasonable construction and

material cost.

So far, a side view of our roof would look like this.

Don’t lose me now! A side view of the flow tube inserts would look

something like this:

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VI. Installing the Flow Pipes

Notice below how two sections of ½ inch copper tubing are joined in parallel. This is done to eliminate the expense of ¾ inch copper tubing and maximize

flow rate.

Flow tubes are held in the grooves of the absorber plate by 1X2 inch lower

supports screwed into roof rafters at 4 foot intervals. They may need to be notched to accommodate the raised flow tubes. Additional supports between

these main supports should be screwed into the roof sheathing. Since these

additional supports are not needed to hold the Kalwall glazing they don’t

need to be screwed into roof rafters.

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Before securing the 4x8 sheets of Kalwall glazing to the lower supports, the

aluminum absorber plate will need to be coated with a non reflective coating

that can transform sunlight into heat. There are a number of selective coatings on the market such as black chrome that must be mixed with

bonding agents. Some people usearesol barbeque black or flat black latex

but most paints don’t stick to aluminum. You might like to experiment. use

anything you want and spend anything you want but I’ve found that a mixture of mineral spirits and tar work great. I add a little lamp black for the

final coat. Once this mixture cures it stays put and does a great job of

turning light into heat. If you ever walked on a black asphalt roof on a sunny

day you’ll know what I mean.

Let the sun cure the tar onto the absorber plate for you. After the tar is dry

to the touch you can roll out the Kalwall glazing from the top of the roof and

lightly tack it in a few places. After everything’s in place you can screw down the upper supports every four feet where the glazing sections meet. This

upper support could be made from 1x2’s but strips of aluminum would have

a more finished look. What ever you use be sure that the upper supports are

are sealed with something like silicon calking to keep the water out.

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VII. Energy Independence

Many roofs could benefit from a solar thermal roof application, but as I said

before, some roofs are more suitable than others. We have grown

accustomed to living in standard rectangular houses with ridge or truss roofs. Any deviation from traditional house designs seems to upset building

inspectors and make realestate agents cringe. Change is difficult, but growth

can only take place where there is change. For now I’d like you to put down

your hammer, grab a piece of paper and pencil and design a practical energy independent home of your own. Use your personal experience tempered with

the the concepts presented in this book. Consider cost, aesthetics and

efficiency. After reading this chapter repeat this exercise.

*********************

Ranch houses with a low

pitched roof are still

popular. Attic space is

sometimes used for central air conditioning, but hot

attics with temperatures

beyond 1600 F are not the

best place to lose heat. Low pitched roofs maximize

heat gain in summer when

extra heat is more of a

problem than a blessing.

The south facing surface area of a 50 foot long roof like this is 787 sq. ft. If

a solar thermal roof were installed over this roof all the hot water needs of a

family of four could easily be met but winter heat gain would be minimal.

What would happen if we optimized the pitch of the roof for solar

heat gain for that day with the least amount of sunshine,

December 21?

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December 21 may not be the coldest day of the year but it is the day with the least available sunlight. To maximize heat gain our roof must be

perpendicular or almost perpendicular to the rays of the sun for the best part

of the day. A roof designed to maximize heat gain for this day would have a

pitch around 64 degrees and cast a mean shadow.

What would Santa say about

a roof like this?

I bet Rudolf would have a word or two on the subject.

Carpenters would throw down

their hammers in disgust and

say: “2x6’s don’t come 34 feet long.”

And building inspectors would

just say “Forget it fool! The

roof’s too high. Take it

down.”

It’s a difficult roof to build even if it were allowed. How about changing a

light bulb in the second floor ceiling? Is there anything good about a steep

roof like this? Sure there is. Think about the 1700 sq. ft. of solar thermal

roof heat gain on December 21. In just three hours a roof like this could

harvest the fuel oil equivalent of 9.5 gallons of # 2 fuel oil. After December 21, the roof angle would of course no longer be optimized and by the end of

January when wind chill factors plummet below 00 F you might be wondering

if you chose the best pitch for your roof. A few million BTU’s could make all

the difference between energy independence and another year of fossil fuel dependence.

How would it be if we moderated our tilt angle a bit to meet the height

concerns of the building department, let carpenters use the kind of lumber they’re accustomed to using and also favor those winter months when heat

gain is most needed?

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A roof angle of 550 should keep

everybody happy, but I still think

we could make better use of

construction materials as well as double the living space with a little

more effort. What do you think?

TRREE STORY HOUSE WITH SOLAR THERMAL ROOF

This three story building

has over 3,000 sq ft of

living space compared

with 1,200 sq. ft. for the others. If you’re planning

a second floor addition

you might as well go all

the way as long as you keep the inspector happy

by keeping the height

under 30 feet. An extra

floor doesn’t necessarily

mean more money. If you can live without an

antiquated truss or ridge

roof that wastes valuable

construction materials you should be able to

build a three story house

for about the same cost as a three story house and have a south facing roof

ideally suited for winter heat gain.

21

You’re probably wondering what you’re going to do with all that space.

If you have no children to come home and roost you might consider stuffing

plenty of sound insulation between the floors and renting the entire house out to four sets of strangers. Oh I forgot to mention the finished basement.

A properly designed basement with adequate ventilation can provide

additional living space. Your tenants will love the accommodations and you

won’t have to worry about heating bills with a 4,000 gallon heat storage vault under the solar greenhouse. A 10KW array of PV panels on the shed

roof might even eliminate your electric bill. If you need more power there’s

always the possibility of a solar thermal engine that runs on heat from the

heat storage vault, but this is a topic for another book that’s in progress.

Don’t get too attached to this house. I don’t want you to go mad with all

those balconies and open spaces and plants in the greenhouse. I’ve got a

cozy little solar home in mind for you. It’s not spacey. It’s outer spacey and

it’s coming up soon but first let’s talk about radiant heating.

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VIII. Radiant Heating

The diffuse energy from the sun is all the energy we need to live in harmony

with each other and the world around us. When used wisely it can heat our

homes, supply us with hot water for bathing and maybe even give us the power we need to drive electric cars and log onto the internet. Unlike fossil

fuel concentrates, solar energy requires a lot of space for heat collection,

heat storage and also heat distribution.

Radiant floor heating is about heat distribution. The relatively low

temperature of stored solar hot water (1200-1700) F needs to be spread out

over a large surface area to be effective. This is what radiant floor heating

systems do best. Heating of an entire floor is more comfortable than the localized hot spots provided by wood stoves, hot air systems, and radiators.

A warm floor is a warm house. Heat naturally rises so a floor is the best

place to distribute heat. Radiant heated floors eliminate mildew and bacteria

by keeping floor rugs dry. Moisture has a tendency to condense on the

coldest place in the room which is normally the floor. Mildew and bacteria thrive in these cold damp places, but they won’t survive long if the floor is

heated.

Radiant heating systems are fairly easy to install if you have some plumbing and masonry skills. If you don’t have these skills get them or get someone

to help you. If you’re installing a heating system over a cement floor on a

slab house you’ll first have to insulate the floor with solid foam insulation to

prevent heat loss to the ground.

Wood floors are easy. Metal lath on the floor prevents cement from cracking

and crumbling. It also increased the heat transfer from the polyethylene

tubes to the concrete slab.

RADIANT FLOOR ASSEMBLY STEPS

STEP 1. Install solid insulation if necessary and staple wire lath to floor.

STEP 2. Run polyethylene tubing around perimeter of floor area first and than secure it with pipe clamps.

STEP 3. Pour cement over pipe and floor. Rake it out and float cement till it’s

level and smooth.

STEP 4. Connect the tubing to the input and output ends of the heat storage vault and you’re done.

STEP 5. Multiple level houses should have separate heating systems. Zoning

is an excellent way to conserve heat.

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The following radiant floor heating system applies to a three story house

with the solar thermal roof.

There’s more than one way to bend polyethylene tubing, but this should give

you an idea for a possible lay out. I’ve connected two ½ inch tubes in

parallel to increase the flow rate and the heat transfer rate, but you could

use a one inch tube if you like.

The baseboard heating system in the den is the first to receive heat from the

heat storage vault so it should be hot enough to heat this small, isolated

room. The bathroom is next and then the dining room on the north side of the house. The dining room is a central heating area where most of the heat

is transferred. By the time hot water from the heat storage vault reaches the

kitchen/living room area most of the heat has been transferred. After leaving

the living room the cooled water is returned to the heat storage vault to pick up more heat before being circulated back into the den’s baseboard heater.

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THREE DIMENTIONAL VIEW OF HEATING SYSTEM

The dark red lines are connections under the floor from one set of

polyethylene tubes to another. The network of green copper tubes is where

heat is extracted from the heat storage vault.

Notice that one circulator pump and three relays are being used for three

heating zones. Zone one is for the first floor.

The total heating system consists of three zones. Notice that the second and

third floor zones are not using a radiant floor heating system. The have conventional baseboard heating instead.

25

Why is radiant heating unnecessary for the second and third floor?

If you feel that a warm first floor would partially heat the second and third

floor you’re starting to think like me. That could be dangerous. For more

dangerous incites into the wonderful world of energy independence you should read my book: Energy Independent Housing.

As far as this book is concerned our adventure together is approaching an

end. We’ve done everything but spin sunlight into gold. Perhaps we should give that a try.

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IX. Spinning Sunlight Into Gold

From an early age I believed sunlight could be spun into gold. Farmers make

money with sunlight. Why couldn’t I? Photovoltaic panels convert sunlight directly into electricity and some feel this is the best way to plug into the sun

and sell sun energy but the PV industry is regulated by the fossil

fuel/government conglomerate and there is little room for profit even with

the excessive rebate programs. Anyhow the idea of energy independence based on sunlight never occurred

to me until May 7, 1973 while I was working on my first house in Peru, NY.

At the time I was putting some finishing touches on a roof that was more

difficult to build than I had originally anticipated. The sun was bright on the swamp grass all the way down to the Little AuSable River, the smell of pine

was in the air and spring peepers were still chattering away in the wet bog

on the other side of the road.

A dark haired woman who I later came to know as Karen Votraw was strolling down the dusty road that led to the place I was working. I called

the road a path since it was overgrown and had numerous ruts that made

navigation difficult. The worn path was important because of the connection

it had between River Road on the north side of the property and Harkness

Road to the south. Few people ventured down the path and when they did I wondered why. As Karen approached I looked down from the roof and she

looked up. The sun was on my back as she strained to see me with her hand

cupped over her forehead.

“Is this a solar home”, she inquired? This was the first time I heard the term solar home. I though about her

question and soon realized my roof was unsuitable for any kind of solar

application since the small amount of winter sunlight available was blocked

by a forest to the south and east and the roof was a patchwork of triangles.

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Hexagonal House

The market for hexagonal housing is virtually untapped

although the living space is

ample and the possibilities for

creative spatial arrangements

seem boundless.

The roof could be a problem, if

the framing gets too involved. In

1973 I framed the roof with a series of right and equilateral

triangles that were not very well

aligned. Roof windows took

forever to install and the grand third floor turned out to be not

as grand as I had hoped.

Since that time I’ve learned from my mistakes. I thought about what Karen

had asked and wondered how the sun’s energy could be incorporated into

the design. I figured a large south facing roof section would be needed to

place a house like this in the solar housing category. Years passed before I discovered a simple roof design based on a cube octahedron.

CUBE OCTAHEDRON

A cube octahedron can be made from a cube that has its corners

chopped off. Another way to

make a cube octahedron

involves attaching squares to the side of a hexagon and

joining them at the corners.

Notice the large flat, steeply

pitched surface that’s a natural part of the cube octahedron. As

it happens this surface is ideally

suited for mounting a solar

thermal roof.

28

Summary of ingredients

needed for a practical energy independent solar heated dwelling

1. A large steep pitched roof facing south to harvest energy.

2. A large heat storage vault.

3. Insulation on the exterior of the foundation.

4. A minimum R factor of 25 for walls and ceilings

5. Thermal drapes and thermal shades. 6. Thermal mass to moderate temperature fluctuations

7. Hydronic radiant heating in the floor.

8. An automatic heat sensing and heat exchange system

9. Photovoltaic Panels, storage batteries and an inverter. 10. Practical use of standard construction materials.

11. Easy, uncomplicated fabrication (low labor costs).

12. Aesthetic appeal.

A geometric shape that contains all

the right ingredients for energy

independence is the cube

octahedron. It has the aesthetic symmetry of a geodesic dome,

makes cost effective use of

standard construction materials

and contains a steep pitched roof/wall to capture the oblique

rays from a winter’s sun.

29

By installing gables on three sides of the building, windows and doors are

protected from the elements. Notice the large solar thermal roof on the

south side of the house and the concentric steps leading to the entrance on the north side.

The entrance is placed on the north side of the

building to optimize south

roof heat gain and internal

spatcial arrangements. The

advantages of a cube octahedron will become

more apparent as you

examine the construction

details.

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CONSTRUCTION DETAILS

After a site is chosen with a good southern exposure a hole should be

excavated about four feet deep and about 40 feet square. Next at least

thirty yards of #2 crushed stone should be dumped into the excavation and

evenly distributed about a circle 35 feet in diameter. The excavated material would later be used to backfill the foundation and raise the grade near the

building so that it appears to be on a hill.

Crushed stone provides a solid base for the footing as well as

insulation from the ground. Wet soil conducts heat away from the

foundation. It’s important to place some of the crushed stone exterior to the footing in conjunction with a drainage pipe. This precaution will prevent

unnecessary heat loss from the footing and foundation walls adjacent to wet

soil. After the stones are nicely distributed and leveled, a steel rod could be

driven into the center of the circle as a reference point. This reference point is used to sketch a circle with a radius of 16’4”. A steel wire of this same

length could then be used to find the end points of hexagonal footing.

Remember the radius of an inscribed hexagon is the same as any side of

that hexagon. This information should be used to lay out the footing forms in the manner depicted below.

31

The 16 x 6 inch footing should be poured carefully on a leveled bed of

stones. Felt paper should first be placed on top of the stones to prevent

seepage. Horizontal reinforcing rods are then immersed in the wet cement of the forms. Two foot long vertical rebar pieces should then be spaced every

two feet in the form so that when the cement hardens into concrete the

vertical pieces will be rigid enough to attach 8 foot long sections to support

the foundation.

The exterior corners of the hexagonal footing are 16’ 4”

from the center of the hexagon.

The eight foot high foundation walls are 16 feet wide and measure 32 feet

across. Two basement window openings (not shown) are formed toward the

top of the eight foot high foundation.

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After the concrete hardens six 2x6x16

pressure treated

foundation plates are

installed and the main carrier beam is

mounted on the

support posts.

Next the 2x10 floor

joists are secured to the

face plates. Notice the

area framed out for the stairway.

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The first floor may now be sheathed with two layers

of ½ inch overlapping

plywood.

The installed staircase

is protected with a first

floor wall.

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Three 16x16 foot roof/walls are framed on ground level and raised into

position. The top junctions are bonded with steel plates

The 2x10 top roof rafters

are then nailed in place

16 inches on center.

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Gable roof overhangs

are framed.

Vertical walls are then framed.

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Let’s remove the three roof/wall section for now to get a better look at the

vertical walls. Notice that the entry way is skewed to one side to make room

for the staircase wall.

Here is a close up

view of the entrance

from the south east.

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Here is an overall view of the first floor with finished walls.

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View from South East

Notice the small circle above the front door.

This is where a fan would be mounted to exhaust accumulated summer heat.

Before we leave let’s go down into the basement and take a peek at the heat

storage vault.

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Heat Storage Vault

View from North West of heat storage vault inside basement.

Notice the notch cut out in the basement wall. The well insulated 1,000

gallon heat storage vault has four chambers. For more information about how to build this vault read How to Build a Heat Storage Vault.

So what do you think? Is this enough space for you and your friend? The

total basement plus first floor area is about 1200 sq. ft. If you need more space you could always add a few floors or add a few extensions. Cube

octahedron roofs go well with hexagonal designs.

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HEXAGONAL HOUSE WITH A SOLAR THERMAL ROOF

The living space in a house like this would be about 3,600 sq. ft.

One of the nice things about hexagonal housing has to do with the way

extensions fit together, not to mention the cube octahedron roof with an

ideal pitch for harvesting the suns energy. Many house designs are possible with steep pitched roofs, and I’m sure you’ll come up with a unique design of

your own.

All you need now is a place to store all this heat. That part should be easy compared to the harvesting device. Theory and construction details are

available for a unique, easy to build, cost effective heat storage vault. How

to Build a Heat Storage Vault should solve all your storage and heat

transfer problems. I’m working on a method of using storage vault heat to

generate electricity, but it will be awhile before I put one together maybe you’ll beat me to it. Good luck.

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X. X. X. X. GLOSSARYGLOSSARYGLOSSARYGLOSSARY

Absorber Plate: a heat conductive metallic plate capable of converting light energy into heat energy

Active Solar: solar heating systems that use external power

sources to transport heat from collection areas

to storage areas and from storage areas to living space areas

BTU: British Thermal Unit, a measure of heat or

energy.

140,000 BTU’s are contained within one gallon

of fuel oil.

Calorie: amount of energy required to raise one cc of

water one degree C

Chimney Plumbing: a method of bonding copper tubing to a

chimney for the purposes of extracting heat from a chimney. This method is sometimes

called wood stove plumbing.

Carrier Pipes: large pipes used to transport fluid

Carrier Pipe Fluid fluid transported to and from heat transfer tubes

Circulator pump: a pump used to circulate fluids inside a closed

loop circuit. This kind of pump is primarily used

for heat extraction, heat exchange and heat distribution

Collector Fluid: a mix of water and antifreeze circulated

throughout the collector and chimney heat

exchange system

Collector System: a network of carrier pipes, heat exchange tubes, and collectors connected to a circulator

pump and governed by sensors

Cube Octahedron: a geometric figure formed by connecting

squares with triangles

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Diagonal Glazing: glazing placed at an angle commonly used in

the construction of a solar greenhouse.

Flush Mounting: an ideal method of mounting collectors flush

with a roof

Energy Equivalents: one gallon of #2 fuel oil contains 140,000BTU’s

one gallon of #2 fuel oil contains 41KWH

one gallon of #2 fuel oil contains 130,000 Kcal

Glazing: a transparent covering such as glass plastic or

fiberglass reinforced plastic

Ground Water: well water, city water or town water

Heat: product of temperature and mass

Heat Exchange Tubes: a tube through which fluid is passed for the

purpose of exchanging heat. Such a tube could

be used for heat extraction of for heat exchange

Heat Extraction Tubes: small tubes used to extract heat out of a

medium such as water

Heat Gain System: a method by which heat is gathered. Solar

collector systems and wood stove systems are examples.

Heat Transfer Tubes: small tubes used to transfer heat

Heat Transport Method: a method by which heat is transported from a

collection area to a heat storage area or

from a heat storage area to a living area.

Heat Storage Tank: a container used to store hot water

Heat Storage Vault: an insulated area where heat is stored

Hexagonal Solar Housing: a style of housing suited for solar application because of the naturally occurring steep

pitched roof that results when a cube

octahedron roof is added.

Insulation: a substance used to resist the transfer of heat

like fiberglass, polyethylene foam, sand, gravel or firebrick

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Kalwall Glazing: a light, durable, inexpensive, fiberglass

reinforced plastic used in solar heat gain

applications

Knee Wall: a knee high wall joining a diagonal wall

KWH: Kilo Watt Hours, a measure of power or energy

Multi Tank Heat Storage Vault: a network of water filled tanks used for

the efficient transfer and distribution of heat

Passive Solar: a method of utilizing the sun’s energy without

the aid of an external power interface

Relay: a switch activated when sensors detect temperature difference

Retrofit: an add on structure not planned for in the

original design, an after thought

Solar Collector: a device used to harvest heat from the sun

Solar Greenhouse: a special type of greenhouse designed to add

heat to living quarters

Solar Panel: an array of photovoltaic cells used to harvest

solar energy in the form of electricity

Temperature: the average kinetic movement of molecules

Vertical Glazing: the perpendicular angle of thermo pane

vertical glazing is designed to minimize heat

loss

Wood Stove Plumbing: see chimney plumbing

Zoning: an energy conservation method of heating

specified areas of a dwelling rather than an

entire dwelling

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Author’s Note

I was brought up in a construction environment. My father built houses on

speculation during the depression to

keep food on the table. He worked so

hard that I rarely saw him. As much as I loved dear old Dad I vowed I would

never be like him and work that hard at

anything. Banks often foreclosed on his

construction loans before his houses were sold, but somehow dear old Dad

managed to maintain a crew and a

family during those difficult times. As a

child I spent a lot of time digging holes

and playing pirate. In 1952 at age nine I decided to bury my prize collection of Davy Crocket cards inside a

mahogany treasure chest behind the backyard playhouse. My neighbor, Ned

and I spent the better part of a day digging.

“Is it deep enough, Johnny?” Ned would say. “Deeper,” I would say.

When the sun got low in the sky and supper time was near Ned threw down

his shovel and said: "I quit."

As he walked home I wanted to say something like: ‘What kind of pirate are you’, but somehow I managed to remain silent and

just watch Ned disappear behind the spruce tree in his yard.

I was still digging when Dad came home from a long day on the road and a

tedious time at the Canivan Brothers Hardware store office.

“Diggin’ a hole to China, old man?” He said.

“No, Dad,” I explained I just want the Davy Crocket cards to be safe.

”I see”, he said, as he lifted his hat to scratch the top of his shiny head.

“You’ll fill the hole in when you’re finished, right old man?” “Oh yes” I said as I shook some mud from my face.

At the supper table Dad told my mom I was digging to China, but I corrected

him on the spot. “What will we do with that boy,” asked Mom?

“Don’t worry mother we’ll find something to keep him out of mischief.”

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In the following year after a difficult time in school, I was looking forward to

summer vacation and two months of blissful goof off relaxation, but Dad had other plans. After breakfast he led me outside and grabbed a shovel from

the garage.

“I know how you love to dig, old man,” he said. I’ve got a wonderful job for

you. We need to make a space under the backyard sunroom extension for Grandma and Grandpa and I believe you’re the man for the job.”

I was really looking forward to goofing off, but Dad made me feel important.

He gave me a mission. He helped me understand the glory of purposeful digging. I stood there for awhile in awe at my new found purpose in life, and

when Dad’s car disappeared down Pine Street I jumped on the shovel. By

noon the pile of dirt in the driveway sloped directly into the hole, but I

managed to wiggle out for lunch. By the end of the day a nice pile was ready for inspection. Dad was impressed but Mom just shook her head.

The next day was almost as much fun as the first but I missed my friend,

Ned, so I invited him to play in the clay and sand. He liked throwing dirt

bombs but digging was a problem. “I think my mother needs me, Johnny” he said, and when I turned around

Ned was gone.

As summer progressed I lost track of my best friend because I was too busy breaking through hardpan with a pick and chipping out an 8” thick reinforced

concrete wall with Dad. Mixing cement and learning how to make concrete

forms from scrap wood also took up a lot of my time.

After the basement room was excavated and the foundation walls were

secure Dad taught me how to glaze windows and frame walls. Soon I

learned how to use all the tools in Canivan Brother’s and before long I was

working with Tom, Harry, Peat, and other members of Dad’s elite outside

construction crew. I enjoyed learning how things were put together. Sunlight energy fascinated me from an early age. Pens were easy to melt with

grandmother's magnifying glass. The Coindre Hall Boarding School boys

asked me why my pens looked funny, but when I explained they lost

interest. In Junior high school I designed and built a conceptual model of a solar power generator that used grandma’s magnifying glass. The lens

tracked the suns position with a crank shaft made from a curtain rod

attached to a string that attached to both sides of the lens suspended in

space with steel supports made from hacksaw blades. The focal point of the lens was a steel end cap. Water was fed into the end cap with a copper tube

a little at a time from a V8 can. I figured a small amount of water would boil

faster than a large amount of water. This is the principle of modern

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vaporizers used today. My science teacher liked it and couldn’t understand

why I didn’t win an award at the science fair.

“You should have had a poster to go with your exhibit.” he said. I didn’t care so much about winning a prize I just wanted the tools to build a

working model.

Shortly after graduating from high school I was given an option of inheriting

the Canivan Brother Hardware/Construction business, but my ambitions were too lofty to be held down by the responsibility of the family store so I

decided to attend college, master the sciences and become a teacher. This

was a decision I soon learned to regret.

My college experience during the 60’s were beneficial toward gaining a

better understanding of chemistry and physics and biology, but I never did

fully comprehend the social disorder of that time, and when it came to

finding a part time job I soon found that college was useless. Muddling through three schools was a long, tedious process. It was fifteen years

before I finally became a certified high school science teacher, and an

additional five years to realize that teaching unmotivated students was not

my forte. During this 20 year time interval I worked in the Plastic Products

Laboratory of RC Hooker, cut lawns, sold encyclopedias, pruned trees, built and repaired boats, installed driveways, delivered flowers, built welding

transformers, delivered furniture, repaired furniture, made and sold

furniture, installed roofs, drove a dump truck, built a few houses and

generally regretted not taking the offer to own and run an established hardware/construction business.

Since 1980 I became a self employed home improvement contractor and

grabbed what ever work came my way like: Dry walling, extensions, dormers, house jacking, block work, foundations, walls, floors, ceilings,

roofs, doors, windows, kitchens and bathrooms. Fortunately, I had the

opportunity to designed and build a few solar greenhouses, collectors and

solar hot water systems along the way. I also transformed basements, attics

and garages into energy efficient living spaces. Home improvement jobs supply food for the table, but my soul hungered for more fulfilling projects.

Many things can be done to improve the energy efficiency of a drafty,

uninsulated dwellings, but the challenge of building cost effective energy

independent houses was all I could think about. Now it can be done with a solar thermal roof.

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