Project Goals and Challenges 

Create an evaporative cooling system that requires no additional metal chaissy structure, increase the efficiency of traditional evaporative cooling systems by introducing  texturing to the surface, and use digital fabrication techniques in conjunction with ceramics fabrication to accomplish a repeatable assembly. 

Overview 

The evaporative cooling block system takes advantage a principle that has been employed in architecture and design for thousands of years: evaporative cooling. As hot air passes over the facade, it picks up water molecules in the soaked terracotta. The resulting evaporation cools the air, creating a cool zone on the other side of the wall. A more in-depth analysis of the water requirements, cooling potential, and testing of this system can be found in the accompanying paper. 

Our evaporative cooling block system was designed, first and foremost, to be flexible in application. It's modular design makes it useful for single-family dwellings, as well as large office buildings and multi-family apartments. The cooling blocks are also, by design, accessible. While the initial form was 3D printed and therefore very expensive, the resulting plaster-cast mold could reproduce thousands of cooling-block units without the need for specialized machinery and technology. 

The evaporative cooling blocks are, as you can see from the split section, hollow inside. This double-walled approach allows each module to act as a mini-zeer-pot, an ancient cooling system that employs evaporative cooling using double-walled jars with wet sand in the interstitial space. similarly, we envisioned the interstitial space in our cooling blocks to be filled either with simply water, sand, grout, or a combination of locally sourced materials. The infill holds the water moving through the system, and allows it to move at a slower rate down the cooling facade. The extremely porous terracotta skin soaks up the water, and it evaporates as air moves across the wall, creating a cooling effect. This could be useful in small applications, like cooling a house without air conditioning, or in large ones, by creating a cool envelope around an already air conditioned building. In all of these use cases, the evaporative cooling blocks offer a novel treatment to an age-old technology. 

This project is currently being showcased at the Harvard Ceramic Studio in Alston, Massachusetts. 

Inspiration 

This work was inspired by many other evaporative cooling facades and mechanisms in architecture. One of the most notable influences on our work is Ron Rael's cool bricks from Emerging Objects. 

Concepts and Form Finding 

Final Form

The design of the actual blocks was dependent on several key constraints. First, the wall needed to interact with as much air flowing through it as possible. In order to determine whether or not our proposed 6-inch diameter would be sufficient to allow airflow and still be easy to fabricate, we performed several thermodynamics calculations to assess the rate of evaporation with the average amount of airflow that the system would likely encounter.

Second, the system needed to be modular, so we designed the connecting feet to have interlocking groves, suitable for stacking the blocks to our estimated usage enough, which was about 10ft. 

Third, the system needed to have an enclosed internal space for water to flow through, that was as narrow as possible while still maintaining structural integrity of the piece. This was accomplished with a three-part assembly system that we determined to be the most efficient way to use a slip-casting method. This involved joining the bottom, core, and top of each piece in post-processing. 

Fabrication: Why not 3D print? 

There exist multiple methods of 3D printing ceramic materials, which in some cases would have been ideally suited to creating a facade like this one. However, we chose to employ a plastic 3D printing method only for our prototype models, which we then made plaster casts of. Our reasoning was simple: most places in the world don't yet have access to ceramic printing machines, and even for those that do, it's a slow process compared to slip casting. Although we were extremely interesting in testing the capabilities of 3D ceramic printing, we also wanted to make a product that could be realized in commercial settings, and could quickly be employed in the field, especially for underserved communities that could benefit the most from any feature that offers refugee from increasingly high global temperatures. 

Process

3D PRINT MODEL -->  PLASTER CAST EXTERIOR AND INTERIOR --> SLIP CAST WITH TERRACOTTA --> CONNECT INTERIOR AND EXTERIOR TO FORM ENCLOSED SPACE --> FIRE --> ASSEMBLE interlocking pieces WITH GROUT  

Testing Tiles 

For the second half of our research, we studied ways in which we might further improve the evaporation potential of our system through the application of texture. We hypothesized that higher surface area would result in more effective cooling, but that the directionality of the texture as it pertains to the direction of airflow would also play a role in the evaporative potential of the surface. 

The testing was exploratory, and not statistically rigorous enough for THIS biologist, but it did serve as a useful indicator of whether or not texture is even helpful in the first place. Though I am not confident in announcing which texture, of the ones we tested, was superior, I am confident in asserting that based on our results, texture does increase the evaporative cooling potential of the system, and in general, the tiles with higher surface areas performed better than those with low surface area. 

Final Prototype 

Next Steps 

Further testing is needed to determine with more certainty which textured surfaces work best for increasing the evaporative cooling potential of the system. 

We would also like to see other form iterations that continue off of this theme of simple tubes. 

Finally, it would be wonderful to see this wall system be employed in a field installment, and judge how it ages. During our discussions, the team agreed that it was likely a wall full of water would invite creatures and plants, but we also considered that this might not be a bad thing. After all, plants are some of nature's ultimate evaporative cooling systems, and their presence scrubs the air. Perhaps as moss-covered system like ours would not only act as a cooling screen, but also an air-scrubber! 
 

Collaborators

Ao Li   

Kenner Carmody         

Maggie George       

Mia Guo