Aqueous Aspen

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1. AqueousASPEN 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.…1
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  • 1. AqueousASPEN
  • 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
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