Live from the Cooling Porch, it’s the Thermal Mass & Buoyancy Ventilation Research Project team! Recently, the students focused on the demonstration space beneath the Test Buildings known as the Cooling Porch. Specifically, they began constructing the retaining walls, made out of old concrete highway barriers, which allow the space to be sunken and trap all the cool air rushing out of the Test Buildings. Let’s get into it!
Mock it up!
To test the structural rigidity, building method, and pattern of the varied in size concrete blocks, the students landed on tying the blocks into the packed earth behind the wall by placing pieces of expanded metal mesh between the block courses. The blocks are dry-stacked, using only their weight and the mesh to stay in place.
The expanded metal mesh makes the wall sturdier, but also allows the students to slip the straps theyre using to move the blocks out after placement without untying the straps from the Bobcat forks.
The students originally planned on using concrete blocks as the benches, but they could not find enough reclaimed materials. The solution? Insert flat steel between the concrete block courses which can hold a lightweight material for sitting. The final material is still up for grabs, but for the mock-up, the team used leftover oak from the woodshop. After nailing down the building process of the retaining wall and bench, the students made sure they had each block and its future location documented. Unfortunately, to complete the design the students needed five more 4′ 3″ X 10″ x 10″ concrete blocks. Good thing they’re pros at a concrete pour!
Prep it up!
To prepare for building the retaining wall, the students dug trenches for small footings. These concrete footings will prevent the wall from settling and becoming unstable.
After pouring the footings, it was time to create formworks for the needed concrete blocks. These were constructed from extra lumber, ZIP sheathing, and rebar. The rebar, leftover from the Test Building foundations, was crafted into cages and hung from the formworks.
With all this prep going on, the research team was also fine tuning their strategy for evaluating airflow in the Test Box small-scale experiments. They are currently working on revising an article for publication which details the results of these experiments and the potential for internal thermal mass design. In particular, Cory, along with Jeff and collaborator Remy Fortin, have spent months nailing down the proper equations for the airflow taking into consideration friction. Thanks to Russian physicist, Idelchik, he finally found an equation which matches the parameters of the TMBV experiments.
Meanwhile, Rowe and Livia revisited metal working, welding angles for the steel bench supports, and cutting metal mesh.
Put it up!
At long last, the retaining commenced! Something different about the actual wall and the mock-up wall is the addition of gravel backfill and landscape fabric. The landscape fabric and gravel cover the column bracings and drain, which runs behind the wall, to prevent corrosion and blockage from the hardy Hale County clay. However, the metal mesh than has to pierce through the landscape fabric so it can be buried in the earth behind. Hot take: expanded metal mesh and landscape fabric is the worse material combination ever.
To let out some steam on a very steamy day, they brought out the concrete saw and sledge hammers. The team needed to shorten just one 8′ x 8″ x 8″ by about 2′. Cory and Jeff showed the mailability of reclaimed cementitious materials.
Three courses up and the TMBV team could not be happier with the result! The pattern and the finger joinery at the shifting walls is just what they wanted. Best of all, she’s quite sturdy. The team will keep you updated on the progress of the wall so, as always, stay tuned!