2. PROBLEMWith a full wall of glazing open to solar gain and regardless of the
extended roof line, there is significant overheating issues in the
summer. Complicating the matter, because glass has a low R-value,
there is significant heat loss in the cold winter climate.
GOALS
Roles
The primary goal is coupled. First is to convert and store solar en-
ergy as heat to replace the heat that is lost through the skin during
the winter. Second is to do so in a way that challenges the aesthet-
ics (or lack thereof) of pure engineering technology. Because of heat
gain in the summer, the secondary goal is to capture solar energy
before it enters through the skin and converts to heat.
Tony Kim (Coordinator/Scientific Researcher)
Blaine Neu (Project Lead/Publisher)
Caleb Summerfelt (Coordinator/Modeler)
Esther Yuen (Researcher/Modeler)
EXPLORATIONParaffin Wax
Evacuated Tubes
3. PARAFFIN WAX
Natures Art: Recording Nature
Paraffin wax, performs in different stages (solid-> liquid) when heat-
ed.
HYPOTHESIS
To observe its transforming forms and to ultimately test the insula-
tion value of Paraffin.
GOAL
Household paraffin wax ( in one inch cube), thermometer, 2 ceramic
container, aluminum container, water, cast iron
TOOLS
Paraffin Wax, usually found as a white, odorless, tasteless waxy solid, has many uses. In culinary
circles, it is known as Bakers Wax. It is often times applied to fruits and vegetables to give it a shiny
appearance and moisture barrier so that the edibles retain their moisture and preserve longer. It
can be used for protecting other foods such as jellies and cheeses. It is a stabilizing agent in many
chocolate deserts and raises its melting temperature so that the chocolate doesn’t melt at room
temperature. It’s also a common component in candelmaking. The materials uses extend to architec-
ture as well. Considered a phase-change material (PCM), Paraffin wax is a substance with a high heat
of fusion which, melting and solidifying at a certain temperature, is capable of storing and releasing
large amounts of energy. Heat is absorbed or released when the material changes from solid to liquid
and vice versa; thus, PCMs are classified as latent heat storage (LHS) units. This suggested that it
would be perfect for use as a screen in our project. We obtained paraffin wax to test the properties
of the substance. We wanted to observe it’s transforming forms and to ultimately test its insulation
value of the wax.
4. AESTHETIC CONSIDERATION
Cell LogicTime Lapse
9:00 AM 11:00 AM 1:00 PM 3:00 pM 5:00 pM
USER INTERFACE
Stages
Stage 1 stage 2 stage 3 stage 4
Our aesthetic consideration was driven by the fact that solar energy
would be captured by the paraffin wax and change according to the
climate and weather. In order to effectually visually “record” solar
energy, a grid was necessary. If there were no grid to break up the
wax, it would melt, sink, and be a blobby mess. But what kind of
grid should we use? As wax has a cellular structure, we ran with the
concept and instead of a rectilinear grid, we well with a cellular grid.
As the solar energy changed throughout the day, each cell would
respond independently, creating differing patterns throughout the
day, throughout the year.
In addition to the cellular structure, one of the general requests was
for some sort of user interaction, or the ability for the user to over-
ride whatever system was created for them. Using a honeycomb
pattern, we were able to allow the user to stack or remove units
from the screen for visibility and aesthetic control.
5. SCIENTIFIC EVALUATION
Note: Room
Temp. At 68o
F
Controlled
Environment in Cast
Iron
Controlled
Environment in
Aluminum Container
Location Time
(minutes)
Temp (o
F) Form Temp (o
F) Form
In oven
(LO boil)
2 105 Partially Melted
(cube + liquid)
95 Partially Melted
(cube + liquid)
In oven 5 115 Clay like (translu-
cent)
95 Partially melted
(cube + liquid)
In oven 15 145 Completely melted
(Transparent)
100 Clay like (translu-
cent)
Placed Outside Oven…
Outside
oven
5 85 Clay like 75 Semi solid
Outside
oven
10 77 Semi solid 70 Solid
6. Cast iron: (145-85 / 145) x 100 = 41.4%
Aluminum: (100-75/100) x 100 = 25 %
*Therefore, aluminum (a less conductive material) has better insula-
tion value.
RESULTS
Pick a less conductive material for framing or/and mullion.
Paraffin wax may perform in different stages when heated.
Paraffin wax may not have a uniform form when melted especially
at the beginning stage.
CONCLUSION
7. aqueousASPEN
DESIGN RESEARCH
EVACUATED TUBES
Evacuated tubes are most commonly “twin glass tubes” that convert solar energy into heat, either
to store and use for hot water or radiant heating. Each evacuated tube consists of two glass tubes
made from borosilicate glass; the outer tube is transparent to allow solar energy to pass through,
angled perpendicular to the sun to minimize reflection. The inner tube is coated with an aluminum
nitride coating which absorbs solar radiation while also minimizing reflection. The void between the
two layers of glass contains a vacuum, the air having been pumped out and then sealed from the top
and bottom by fuzing the layers of glass together.
A vacuum is an excellent insulator. Solar energy transfers through space with minimal heat conver-
sion because space is essentially a vacuum. Once the solar energy enters earth’s atmosphere, it is
absorbed by the particles and released as heat. The vacuum within the tubes achieves this same
principle. It allows the solar energy to enter the inner tube, which absorbs it and converts it into heat,
where it is then trapped by the same vacuum. In fact, the insulation properties of the evacuated tube
are so effective that the inside temperature can be 304o
F while the outer tube remains within a few
degrees of the ambient air temperature. Because the heat is converted from solar energy and not
collected from the ambient air temperature, evacuated tubes can perform exceptionally well even in
the coldest of weather.
Man-made vacuums tend to leak over time due to the container’s seams. To aid the evacuated tube’s
vacuum, a barium getter is used. A barium getter, also found in older television tubes, are a layer of
pure barium that is coated on the bottom of the evacuated tube (inside the vacuum layer where the
two layers of glass meet). This layer has two purposes. The first purpose is to absorb out-gassed
particles such as CO2
and H2
O to increase the longevity of the vacuum, while its second purpose
is a visual indicator of the vacuum’s status. Barium is silver within a vacuum and turns white if the
vacuum is lost.
Our second exploration was driven by the aesthetics of the location
of the project. In what way could we use the aspen? This drove our
research into systems that we could incorporate.
Apricus: Solar Hot Water. Apricus North America, “What is an Evacuated Tube?” http://www.apricus.com/html/evacuated_tubes.htm (accessed Dec 11 2011).
8. DESIGN RESEARCH
CURRENT CONDITION
CURRENT CONDITION APPLIED
This window system contains 3,000 lbs. of water, with the optical
clarity of any modern window. The thermal mass effect allows this
window to capture and store 100,000 BTU’s of thermal energy. The
highest temperature reached in this window system was 115o
F with
an outside temperature of 34o
F. That’s a difference of +81o
F.
DESIGN RESEARCH
thermal mass
Evacuated tubes are purely
engineered systems. Aesthet-
ics are not taken into account.
As seen in the images, they
are visual afterthoughts, re-
gardless if they were a part of
the Architects original intent
for the design. They are usual-
ly attached (very specifically)
to the roof, though they may
be attached and project from
walls like gaudy (and useless)
shelves or in the yard. Some
installations locate the units
in what is called a solar farm,
which removes the visual im-
pact altogether and hides the
system from view off site, usu-
ally shared by multiple struc-
tures (i.e. a housing cluster/
neighborhood). If our group
was to consider using evacu-
ated tubes, we would need to
challenge the aesthetics of
the system. We are architects,
always concerned with the
visual impact of our designs
where engineers may not be.
Evacuated tubes, regardless
if acknowledged, have visual
impact.
9. Aspens add to the composition of the Passive House. Without them,
the aesthetics are diminished. By acknowledging the importance of
them, we pulled from the visual impact of the aspens and incorpo-
rate them as the aesthetic concept of “screen” design.
+
CONCEPT
COMPOSITION VISUALIZED
=
10. Controlled heat transfer
Transparency, Proof of concept
Aesthetic importance
EVACUATED TUBES
THERMAL MASS
CONCEPT
+
+
COMPOSITION ENHANCED
By modifying the general physical nature of evacuated tubes with
the engineered intent and method of a thermal mass wall, we were
able to create a new system by which our aesthetic concept could
be applied. In the image above, the aspen trees from the site be-
come an integral part of the aesthetics of the modified evacuated
tubes, visually extending to the facade of the structure. In this de-
sign, each tube is stationary. At this point, our group did not know
how the system would be integrated into the conditioned space.
11. Exploration
user interface
Expanded
in transition
docked
sliding mechanism connection detail
Water In
Track Wheel
Evacuated Tube
Over complicates the functionality of the
screen system
Raises the question: “Why not keep it
docked?”
RESULTS
trunks would remain out of view. When expanded, they would ex-
press the full extent of our visual concept. The transitional phase
would be up to the users intent. If siting in a chair, does the user
want a filtered view, framed view, or uninterrupted view? As seen on
the right, we developed a sliding mechanism for a unit of evacuated
tubes. Each unit could be different or the same.
Instead of each “trunk” (evacuated tube) remaining stationary, we
explored ways we could incorporate user interaction. The first ex-
ploration was quickly overturned: being able to remove individual
“trunks” so that the whole facade could be adjusted visually and
practically. This method would be far too complicated and unnec-
essary. Instead of individual “trunks” being removed, if there were
units that could be removed? And if not removed, at least moved.
The process of removing a unit was found to be unnecessary as
they could just move out of view. There was a perfect spot that they
could be removed from the view allowed by the glazing in front of
the kitchen where there was an opaque wall. When “docked”, the
12. Exploration
Application
to ground
to deck
application Charette
Screen to deck is more elegant and visually respectable to current design formality
More practical for and honest with our concept
RESULTS
RESULTS
Exploration
window integration
Stopper
Integrated into
window system
Inner pipe con-
nected to floor for
heating purposes
Impractical
No longer fit with concept development
A tangent exploration of the “trunks” was to integrate them directly into the glazing, replacing the
mullions in the process. We pondered whether the heat transfer could happen directly and indirectly.
By removing the vacuum where the “trunk” would be on the interior of the structure, but retaining
the vacuum on the exterior, there would be a direct heat transfer. While this would work in the winter
to heat the house, it would also work in the summer to heat the house. This encouraged the problem
of overheating in the summer instead of achieving our secondary goal to combat this. Incorporating
the trunks into the glazing would also be much too expensive if it could be done at all while retaining
the vacuum on the exterior. The added complication, therefore, was deemed unnecessary when the
same could be achieved otherwise.
Once we eliminated the necessity for the “trunks” to move, we
needed to consider how the trunks would attach. Are the trunks in-
side the conditioned space or outside? This question was easily an-
swered by our secondary goal: to capture solar energy before it en-
ters through the skin and converts to heat. If we placed the “trunks”
inside the conditioned space, the solar energy would have already
entered through the glazing and much of it converted to heat, not
aiding the problem of overheating in the summer. if we placed the
“trunks” outside, wherever they blocked the solar energy from en-
tering the structure, that heat would be collected and used inde-
pendently of the ambient temperature within the conditioned space.
The heat collected, would therefore, be heat that would have other-
wise added to the problem of overheating. But placed outside, there
were several options. The extended roof provided the first practical
connection, assuming there needed to be at least one connection
for each “trunk”. So were they hung? Glass, especially filled with
water is heavy and vulnerable which eliminated this option rather
quickly. Keeping the connection with the roof, we still had two op-
tions: attach the bottom to the ground or the floor plate. The results
to this exploration was subjective. It was opined that to the deck
was more elegant and simple, aesthetically matching the elegance
and simplicity of the design of the Passive Haus. Using the floor
plate for heat transfer also seemed more practical.
13. MODEL A:
Exploration
utility
MODEL C:
MODEL B:
Evacuated chamber
Heat collection only
heat collection
Argon filled chamber
Delayed heat release
delayed heat release (water from
evacuated tubes)
Conductive membrane attached to the inner tube
Hot water use
hot water use in hot water corridor
RESULTS
Overcomplicated
Unnecessary
Once we had the general aesthetic considered, we began to incorporate the systems utility. How
would or should this system work? We began with three types of models, each with a designated
purpose. Model A evacuated tubes are located outside the structure. The inner chamber would be
filled with water while the space between the two layers of glass would be vacuum sealed. This would
be that standard model for heat collection. The solar energy would pass through the vacuum, and
instead of the interior layer being coated with aluminum nitride, it would remain transparent and
instead be filled with water. The water, therefore, is the conductor. The solar energy would excite the
water molecules upon contact, effectively raising the temperature of the water. Model B evacuated
tubes are similar to Model A, but instead of containing a vacuum between the glass layers, the cham-
ber would be filled with argon, which is a relatively effective insulator. They would be placed inside
the structure and act as a heater during the winter. Model A and Model B would work together. Each
Model A tube is paired with and connected to a Model B tube in a closed circuit. Water would be con-
tained in only one of the two tubes at a time, depending on the intended use. When the water needs
to be heated, it would be pumped into the Model A tube. When the structure needs additional heating
(ie. during the winter), the heated water would be pumped into its corresponding Model B tube. Since
the Model B tubes are argon filled chambers, this heat would release gradually from the water. Each
Model A/B pair would work independently from each other and sensors (or by user override) would
detect which part of the structure needs heating and release only those units. Model C tubes are
standard evacuated tubes, to be used for hot water heating. Placed in front of the opaque wall of the
facade, the inner glass layer is opaque, transparency being unnecessary.
14. concluding process
angle at section
5o
Evacuated Tubes
Sun Altitude Angle
Angle of Incidence
24o
0o
15o
worst
best
70o
70O
= 50%
5O
0O
= 4%
In finding what angle the tubes should be placed, we first needed
to know the sun altitude angle on December 21st, when the sun
is lowest (and available solar energy is at it minimum). At the lo-
cation of the house, we calculated that the altitude angle at this
date to be 15 degrees. To minimize reflectivity, having the tubes
angled directly perpendicular to this angle would be ideal. Visu-
ally, though, this angle (bottom) is too extreme. We also explored
the inverse angle (top), regardless of its reflective efficiency.
Regardless, we subjectively agreed against both this angle and
completely vertical (middle) regarding their visual impact.
We settled on an angle 5 degrees from perpendicular to the sun. This angle visually re-
sponds well with the section of the Passive Haus, as it is perpendicular to the roof angle
and parallel with the wall angle in the back of the structure.
The diagram above shows the visual
impact of the extremities for the angle
of tubes in section. The lowest diagram
represents the best angle for minimal
reflectivity at 0 degrees perpendicular
to the winter sun angle at the site. The
top diagram represents the inverse of
this angle. Also represented is no angle
(middle).
15. standing
walking
sitting
kitchen
entry
living room
laying
bedroom
concluding process
1
SITTING
SITTING
SITTING
SITTING
SITTING
SITTING
SITTING
SITTING
WALKING
WALKING
LAYING
LAYING
LAYING
STANDING
STANDING
angle at elevation
To retain the visual concept of aspens, which provide variance re-
garding their growing patterns, we wanted to vary the angle of the
tubes in elevation. But how do we do it? We looked at the program.
From it we designated what kind of activity the user would most
likely be doing in each section of the program. For instance, in the
living room, users would most likely be sitting. Upon entering the
structure, they would be walking forward. Each of these ribbons
would correspond to a unit (2) of evacuated tubes designated for
that action.
The program called for four
designated actions: standing,
walking, sitting, and laying.
In the kitchen, for example,
the user would most likely be
standing while cooking, etc.
At the entry, the user would
be walking. In the living room,
the user would most likely be
sitting, enjoying the view or
each others company. In the
bedroom, the user would most
likely be laying in bed, taking
in the view. The angles of the
tubes respond to the general
head height of the user. While
standing, the tubes expand
near the top and compress at
the bottom, framing a view
corresponding to the action of
standing. Walking is the only
action where movement is a
given. Therefore, the tubes are
parallel to each other framing
the view as if it were a hall-
way. The tubes corresponding
to sitting is the inverse angle
of the tubes corresponding to
standing. The compress at the
top and expand at the bottom,
encouraging the user to sit in
order to take in the view. There
are no tubes corresponding to
the action for sitting,. This
choice was made to respond
to the desire for an expansive
view upon waking up or going
to sleep.
16. concluding process
Envelope Heat Loss
144 BTU/HR
103,680BTU/24HR
-54 BTU/hr
-90 BTU/hr
building mass
glazing
+
=
The following pages explain our process for how many tubes, how
big, and volume of water that was necessary to achieve our goal to
replace the heat lost through the skin of the structure during the
winter. We calculated that through the glazing alone, there is a loss
of 90 BTU’s (British Thermal Units) per hour. Through the building
mass, there was a loss of 54 BTU’s per hour. The sum of these is a
loss of 144 BTU’s per hour or 103,680 BTU in a 24 hour time span.
This means that we would need to collect 103,680 BTU’s every day
to replace the heat lost during that 24 hour time span.
or
meeting the requirement
available solar energy
650 sq ft
614,340 BTUs
assuming 6 hours of sunlight per day.
area of south facing glazing
available solar energy per day
=
We now knew how many BTU’s were lost in a given day, but we didn’t
know if there was even that much solar energy (sunlight) to replen-
ish the heat lost. With an area 650 square feet of south facing glaz-
ing, and assuming that there is six hours of sunlight per day, we
calculated that there were 614,340 BTU’s available per day for us
to capture. But given that we only needed to replace 103,680 BTU’s
per day, we would only need to capture that amount from the avail-
able solar energy. We had plenty and were able to move forward
towards answering the questions of how many and how much?
Total available solar energy
17. meeting the requirement
Total available solar energy
heat replacementrepresented in units of energy represented in percentage of
south facade coverage required
6 units of available so-
lar energy
1 unit of energy lost from envelope
1 unit of solar energy needed to replace en-
ergy lost
Of the 614,340 BTU’s of energy, we only need 103,680 BTU’s of en-
ergy to replace the energy lost from the envelope of the structure.
To help better understand this, we broke up the potential solar en-
ergy that may be collected into units, with the base unit being more
or less the energy lost from the envelope. One unit of energy, then
is equal to about 103,680 BTU’s of energy. Of the incoming solar
energy, there are about six units of energy. To replace the one unit
of energy lost, we need one unit of the six units of available solar
energy (shown in red).
meeting the requirement
heat replacement
16.87%
110
south facing facade
or
square feet of facade area
103,680 BTUs heat lost over 24HR
=
HEAT LOST FROM ENVELOPE
AVAILABLE SOLAR ENERGY
÷
If we were to assume that the available solar en-
ergy was homogenous across the south facing
facade, we were interested to see how much area
we would need to cover with the tubes to capture
the required energy. In order to do that, we did a
simple calculation: Heat lost from the envelope di-
vided by the available solar energy. This equated
to 16.87 percent of the facade would need to be
covered by evacuated tubes in order to collect the
required solar energy to replace the energy lost
through the envelope.
Total available solar energy
=
18. meeting the requirement
thermal inertia of water
heat replacementrepresented in units of energy
Since we are dealing with water as the substance to capture the
solar energy and convert it into heat, it is rather appropriate that
we have used BTU’s as our unit. A British Thermal Unit is a basic
measure of thermal (heat) energy. One BTU is the amount of energy
needed to heat (raise the temperature of) one pound of water one
degree Fahrenheit. In order to replace, 103,680 BTU’s of energy lost
through the skin of the structure, we would need to heat 103,680
pounds of water one degree Fahrenheit. Since evacuated tubes
work more efficiently than this, we needed to know how much water
we would need if we were to heat the water more than one degree.
represented in volume of water
meeting the requirement
heat replacement
Thermal inertia of water
357 gallons + 36o
F = 103,680 BTUs = 1
If we were to calculate a more appropriate number in gallons, we
first needed to convert pounds into gallons. One gallon of water
weights approximately 8.3454 pounds. If we were only able to heat
the water one degree, we would need about 12,424 gallons of water.
This is an impractical volume of water. Fortunately, it is common
that evacuated tubes can easily raise the temperature of water by
36o
F. Therefore, only 357 gallons of water is necessary to achieve
the 103,680 BTU’s required.
19. meeting both requirements
thermal inertia of water
total available solar energy
heat replacementrepresented in volume of water
diameter
(inches)
volume per tube
(gallons)
# of tubes to meet
volume requirement
area of tubes
(sq ft)
# of tubes to meet
area requirement
1.00 0.61 583 729 110
2.00 2.44 146 365 55
3.00 5.50 65 243 37
4.00 9.78 36 182 27
6.00 22.00 16 122 18
8.00 39.11 9 91 14
10.00 61.10 6 73 11
12.00 87.99 4 61 9
mostefficient
REQUIREMENT 1 REQUIREMENT 2
Now that we have the required gallons (volume) and the required
area of solar energy, we could find the most efficient diameter for
the evacuated tubes. Where the least number of tubes to meet both
requirements has minimal difference is the most efficient diameter
but it would also have to meet the third (design) requirement found
earlier of the “angle at section” (shown again at right).
As the table above shows, the diameter of tubes we concluded with
was 6 inches
REQUIREMENT 3
26 TUBES
1
SITTING
SITTING
SITTING
SITTING
SITTING
SITTING
SITTING
SITTING
WALKING
WALKING
LAYING
LAYING
LAYING
STANDING
STANDING
20. 1
SITTING
SITTING
SITTING
SITTING
SITTING
SITTING
SITTING
SITTING
WALKING
WALKING
LAYING
LAYING
LAYING
STANDING
STANDING
design
floor plan
design
elevation
1/8” = 1’0”
temp sensor
two way sensor valve
temp sensor
new unions
steel rod
welded concentric reducer
water filled
L-plate
sealant
1/2” dia. bolt
rubber stopper
vacuum space
sealant
design
connection detail
The section connection detail above shows how the water moves
from the evacuated tube into the floor for radiant heating purposes.
When the water reaches the correct temperature, a temperature
sensor releases a two way valve and the water empties into a radi-
ant heating pipe that is stored within the floor system. The temp
sensor then monitors the water temperate from the other side of
the valve. When the temperature drops enough due to heat release
into the unit, the valve opens again and the water is pumped back
into the evacuated tube to continue the closed loop cycle. Since
each tube is a closed system, water is heated and released indepen-
dent from other tubes and as such creates a more dynamic facade,
some tubes with water and some empty of water.
21. Perspective renders
*photo rendered from physical model
testing
april 9th, 2011
time
temp F
(inside tube)
temp F
(outside)
9:00 65 39
10:00 75 43
11:00 80 45
12:00 83 48
13:00 85 48.9
14:00 85 48.9
15:00 87 50.0
16:00 88 51.1
17:00 89 50.0
18:00 89 48.9
19:00 85 46.0
20:00 80 45.0
21:00 74 44.1
22:00 62 44.1
AVG. 74 AVG. 44.8
+29.4o
F
Instead of buying an evacuated tube, we researched ways we could make our own. We settled on buy-
ing two different vases that would fit inside each other, the central vase extending above the exterior
vase. We then used a veneer to create a seal between the two vases and pumped the air from the cav-
ity. In the central vase we filled it with distilled water and sealed it shut with a thermometer stopper
and recorded its temperature differential over 14 hours. The results are shown in the table above and
concludes that we achieved an average 29.4o
F differential. These results are weak and inconclusive
but do show the project still has potential. As it was a homemade test unit, it is in no way as efficient
as a manufactured unit. The vacuum seal could have been weak, the water could have had additives
and sealed greater than a stopper (weak), and the glass was thicker and of lesser quality than if it
were manufactured. All in all, we were slightly disappointed with the test, though we saw that the
project still had potential to be successful.
