Author: RS Thermal Mass Team

When it rains, it pours!

After a very rainy neckdown week, the Thermal Mass and Buoyancy Ventilation Research Project team is back and pouring concrete panels.

First, the team had to make molds for 18″ x 18″ panels to test for the Habitable Structure, 12″ x 12″ panels for the Desktop Experiment, and concrete samples for material thermal conductivity testing. They used melamine covered OSB, which is reusable, for the panel formwork and PVC pipe siliconed onto rigid insulation for the sample molds. The samples or “biscuits” are small cylinders of the three different concrete types they are considering; fiber-reinforced, high finish, and pure cement. These samples will be taken to Auburn University’s engineering lab to test their thermal properties. This information will help sharpen scientific experiments!

When the formwork was done, the team was ready to pour their panels and samples. However, due to the extremely low temperatures this week the team got to work in the Plug-in House! Don’t worry though, they taped down tarps and the Plug-in is staying clean. You can read all about the Plug-in House and what it’s doing underneath the Rural Studio Fabrication Pavillion here: http://ruralstudioblogs.org/2019/09/18/the-plugin-house/

The TMBVRP team prepped the panels by taping and oiling them. Vegetable oil helps prevents the concrete from sticking in the mold. Next, the team mixed the concrete with shovels in a wheelbarrow adding small amounts of water at a time. They think, for next pour, they will use a hand mixer attachment for a drill and a bucket to mix the concrete. Part of this process was figuring out a better way to complete this process.

Finally, the pour! The team used trowels and a bladeless reciprocating saw to smooth and vibrate the panels. It is important that concrete is vibrated to remove air trapped within. The panels and samples will stay in their forms for three days until they are cured. Next, the team will test its panel attachment system and work on their Desktop Experiment mock-up.

You will have to check in next week to see how our concrete turned out and maybe you’ll get a sneak peek into the testing at Auburn University’s engineering lab!

Panel Making

This week the Thermal Mass and Buoyancy Ventilation Research Team got to use the largest skill saw they’ve ever seen and we’ll tell you why!

In the technical workshop Sal last week, the team decided to narrow the number of materials they will test throughout the experimental cycle from four to two. The lucky two will be concrete and softwood! Concrete is often used as a thermal mass material while softwood is not which will make comparing the data collected from the separate experiments all the more interesting. The Optimal Tuning Theory calls for the thermal mass to be externally insulated which allows the thermal mass material to be much thinner than a typical thermal mass. Therefore, the concrete and wood need to be panelized.

The thermal properties of wood act most efficiently as a thermal mass when the cross grain is exposed to the air. This means that panelizing the softwood is more like creating giant cutting boards. To practice this process the team used 8″ x 8″ Cypress timbers and their matching 16″ diameter skill saw leftover from the Newbern Town Hall project. The team learned that 6″ x 6″ timbers would be ideal for their project, that way they can cut the cross-grain pieces in one cut with their 16″ skill saw without having to rip down the timber.

The concrete panels are far more straightforward, build a mold, pour the concrete, let it cure. However, the team has to think about how the panels would be attached to a larger structure. To solve this they cast PVC into the panel which will allow it to be screwed into a structure.

Voila! We have much refining to do of the panel making process, but the first two turned out well. We also have here a rendering of the habitable structural with the separate concrete and wood panel rooms. Our next step is to apply what we learned working with these materials to designing and building our first experiment. Thermal Mass and Buoyancy Ventilation Research Team out.

The Experimental Cycle

The team with the longest name possible is back this week diving deep into the science behind the Optimal Tuning Theory with its author, engineer, Sal Craig. Sal, along with his colleague, architect Kiel Moe at Mcgill University in Montreal, Canada, are our partners in the Thermal Mass and Buoyancy Ventilation Research Project. The team has weekly meetings via Skype with Sal and Kiel to discuss the project, but this week they had an in-depth technical workshop.

Behind our simple understanding of the Optimal Tuning Theory, there are very intricate scientific equations that Sal has written, solved, and published in his peer-reviewed paper, The optimal tuning, within carbon limits, of thermal mass in naturally ventilated buildings. Although the student team does not need to obtain an engineering degree to work on the project, it is important they grasp the basics so the project is truly a collaboration. They need to be able to have a conversation with Sal about the possibilities of the project instead of asking his permission. 

The team studied up for their technical session with Sal


Thankfully, Sal is a wonderful teacher and the students were able to reach a deeper understanding of the theory with him during their day-long technical workshop. Afterward, they were able to make a couple of important decisions about the project together one of which was defining the undergraduate phase of the project as an experimental cycle.

The experimental cycle will be comprised of testing the Optimal Tuning Theory at three different scales they are calling Desktop, Human, and Habitable. These scales are important because the theory is meant to be proportional. The Desktop experiment will resemble a small chimney made of thermal mass material, the Human scale experiment a full-sized thermal mass wall, and the Habitable experiment will be a full structure i.e. the pod where the interior walls will be entirely thermal mass. 

Livia with her beloved schedule

Defining the experimental cycle has allowed the team to start scheduling and setting deadlines, something Livia has been dying to do. Completing this cycle in the undergraduate phase of the project will allow freedom for the graduate phase. Thanks for tuning in!

Ready to Transform

From costume contests to coding classes, the Thermal Mass and Buoyancy Ventilation Research Project takes on a new form everyday.

In the past weeks, the team has been designing a Pod which is a small dwelling or dorm that 3rd-years use for sleep and storage. The Pod will be used to test the Optimal Tuning Theory. The team presented the Optimal Tuning Theory and their current pod design at the annual Rural Studio Halloween Review. Unfortunately, all of you lovely readers were not able to make the review, so this post will be dedicated to explaining the Optimal Tuning Theory and showing off the teams Halloween Review Costumes.

What is the Optimal Tuning Theory?

First, let’s get a couple of definitions out of the way, what are Thermal Mass and Buoyancy Ventilation? Thermal Mass is a property of the mass of a building which enables it to store and release heat. A typical example would be an adobe home or pueblo where the thick, earthen walls absorb the hot, desert sun during the day keeping the interior space cool. Later during the cold, desert night the thick, earthen walls release that heat into the interior thus warming the space. Buoyancy Ventilation, often refereed to as the “stack” or “chimney” effect, utilizes the natural ventilation cycle of hot air rising and cool air falling to supply air to a space without mechanical systems.

The Optimal Tuning Theory theorizes that a space can be comfortably and passively ventilated, heated, and cooled by coupling an internal Thermal Mass with Buoyancy Ventilation. If these systems are synchronized or “optimally tuned” it would allow architects and builders to use the ancient practice of Thermal Mass building in a more predictive manner. The typical issue with Thermal Mass buildings is that the Thermal Mass is never able to release all the heat it absorbed in the day, therefore the cycle does not start over the next day and the passive system does not work efficiently. By keeping the Thermal Mass on the interior, shaded from the sun and insulated, and using Buoyancy Ventilation to draw out access heat or supply heat from the air, the system is able to reset for the next day. The Optimal Tuning Theory is the crux of the Thermal Mass and Buoyancy Ventilation Research Project.

The Thermal Mass and Buoyancy Ventilation Research Project Team will build a Pod as a scientific instrument to test the Optimal Tuning Theory. A Pod is an appropriate, human scale that they can test the temperature and air flows of easily and can be inhabited by 3rd-years later on.

Now for the real magic, Rural Studio’s own Transformers! Each TMBVRP team member transformed into a classic Rural Studio vehicle. From left to right starred: Livia Barrett as Andrew Freear’s Honda Fit including his front license plate that reads “British Nut;” Rowe Price as the crisp, new Student Truck; Cory Subasic as Hale County Classic Tractor fit with hand wheels; and Jeff Jeong as our beloved Johnny Parker’s beloved BobCat. The team came second in the local costume contest, but Jeff won Best Pumpkin! Thanks for TUNING in, we hope to see you at Soup Roast!

Of Local Interest

Howdy from the new center for Thermal Mass and Buoyancy Ventilation Research in Newbern, Alabama!

The team is fresh off their first presentation with reviewers Kim Clements and Joe Schneider. Kim and Joe are the founders of J.A.S. Design Build in Seattle, Washington. They helped the team develop a clearer way to explain the thermal mass and buoyancy ventilation theory.

The team reviewing the review on Monday morning.

Eventually, the team will be publishing a paper, with their partners at McGill University. The paper will aim to speak to architects and builders who could implement the thermal mass and buoyancy ventilation system in their buildings. Reviews with folks like Kim and Joe will help the team learn how to communicate best with the design and construction world.

The chosen materials, their components, and their processing

Besides preparing for their first presentation, the team has been working on material research. A crucial part of the Thermal Mass and Buoyancy Ventilation Research Project is understanding the embodied energy of their construction materials. The team will study exactly what goes into the making of the materials from harvesting natural resources to transporting the finish material to the construction site. Timber, brick, rammed earth, and concrete are the materials the team are considering for the thermal masses. To limit energy lost to transportation and as an investment in Alabama, the team is investigating local material manufacturers within the state.

Speaking of local, here in Newbern, the Hurricane Lilies are still in bloom, Rural Studio students are stealing all the sunshine, and a shark must have been spotted downtown. From the T.M.B.V. Research Project Team to you, keep it real and real local!