experiment

Week 77: A General Update

March 1, 2021

Students working outside on Morrisette Campus

Live from Newbern, Alabama, it’s the Thermal Mass and Buoyancy Ventilation Research Project Team! 77 weeks in Hale County and the graduate student team is still firing on all cylinders. This post, they’ve got updates on concrete panels, drainage, and the steel walkway and stair. Plus, the wonders of the Wood-Mizer, a portable sawmill, for those readers who make it to the very end!

Panel Pour Product

*Section Isometric: a peak at the interior concrete panels*

A couple of weeks back the TMBV team poured four, new concrete panels. These panels were designed to test tongue and groove joining system. Also, this round of test concrete panels experimented with vertical formwork.

As predicted during the struggle of formwork construction and concrete pouring, the vertically poured panels did not turn out so well. However, the team made promising headway with the new joining method. Alright, now that the panels have cured, let’s take a look at the material.

Students undoing concrete formwork from concrete panel — Horizontal Pour… Easy Breezy

formwork lifted from half poured panel — Horizontal Pour… Easy Breezy

First, you’ve got to remove the panels from the formwork. You know from the team’s previous post that one of the vertically poured panels did not make it all the way through pouring. Look at that; live edge concrete!

rough edge of horizontally poured concrete — Vertical Pour Surface

However, the smaller vertically poured panel survived! The results were surprising, as seen above this panel had more air gaps than the traditionally poured panel. The students previously thought having formwork on all sides would create more even and consistent panels. But, without an open surface to trowel, the vertically poured panels were subject to more air bubbles.

The typical, horizontally poured panels turned out smooth and even as ever. And just look at that grooved edge!

Diagram showing the corresponding concrete panel surfaces and joints

Next, the concrete panels were attached to the Fabrication Pavilion pin-up wall to test the joints. The results were inconclusive. Some tongue and groove joints turned out well, while others broke at the edges of the panel. Going forward, the team wants to attempt a shiplap joint for the panels. Also, they’d like to make more, smaller test panels to assemble in a miniature wall configuration.

Drainage Days

As you can imagine, in the everchanging weather of late, the Test Building site became the town swimming pool. The 18″ deep hole containing the foundations was nearly filled to the brim during the past weeks’ rain. Luckily, the team, Mason, and a mini excavator got out while the sun was shining to install the drainage. The French drain leads from the Cooling Porch, betwixt the foundations, into the forest line.

Mason uses mini excavator to dig 18" trench for drain

student digging trench for drain between foundations

Rain between two foundations leading to woods

Walk this way

You might have been wondering how one day you might access the 30′ tall, 8′ above ground Test Buildings. Well, you’ll use the steel ships ladder and walkway of course.

As of late, the TMBV team students have been designing the fabrication and installation process of the stair and walkway. To detail the stair fabrication process, they partook in a classic rural studio technique; the cartoon storyboard.

Next, the team planned out the order of installation of the walkway and the SIPs structural floors. First, they plan to place and secure one assembled SIPs Test Building floor. Second, place the other Test Building floor, using the walkway steel angle frame to square the two to one another. When everything is properly adjusted, lag screw the steel angle frame to the SIPs floors. Third, place 1″ metal grate on top. Next, place and bolt the stair to the walkway and ground connection. Lastly, site weld the handrails to the exterior face of the steel angle frame. Voila! It’s that easy if you only have a crane!

axonmetric drawing showing process of install of steel walkway and stair between test buildings

Wood-Mizer Wonder

And the special bonus; a portable sawmill! Adam Maggard, an Auburn University Forestry and Wildlife professor and Extension Specialist in Forest Systems Management, travels the southeast with the Wood Mizer portable sawmill conducting forestry management research and reaching out to family, forest land owners. Adam collaborates with Auburn Architecture Professor and TMBV colleague David Kennedy and Rural Studio Alum Will McGarity. The three gave the students a Wood-Mizer tutorial as well as an introduction to their research.

Rev. Walker’s Home Project team requested the visitors to help mill some gorgeous tree’s from Rev. Walker’s land. Each student took a turn milling down either the cedar or pecan tree. The students were amazed by the machine and even more amazed that freshly cut cedar is bright, pink. It was a remarkable experience, big thanks to Adam, David, and Rev. Walker from the Thermal Mass and Buoyancy Ventilation Research Project Team!

Tags: concrete, concrete panels, drain, experiment, formwork, french drain, Rev.WalkersHome, tongueandgroove, wood research, woodmizer

Preparing a Timber Pun for a Post Title

June 10, 2020

Live from HomeLab, it’s Wood Chimney Experiment preparation. The Thermal Mass and Buoyancy Ventilation Research Project team members are continuing their efforts to refine a passive cooling and ventilation system which can be deployed to public buildings in the rural South. Due to the fantastic results from the Concrete Chimney Experiment, the team is starting the Wood Chimney Experiment. They have developed an experimental method for designing and building chimneys which test the Optimal Tuning Strategy. They also have honed their data collection workflow and analysis. Now they can move on to testing how timber can work as a thermal mass. You can read about why we are using mass timber as a thermal mass here.

Section of the Wood Chimney Experiment design

The first step in Wood Chimney Experiment preparation is gathering materials. The team collected sensors that the Mass Timber Breathing Wall team is no longer using. Rural Studio has been growing its scientific equipment stock which allows for reuse between research projects. The TMBVRP team is inheriting data loggers, heat flux sensors, thermocouples, power supply, and airflow sensors. They will be using different temperature sensors, thermocouples and heat flux sensors, then are used in the Concrete Chimney Experiment. These sensors, like the GreenTeg Go Measurement System, will still deliver the proper temperature readings. This equipment is flexible and adaptable making it easily reusable between projects.

Sensors and power source for wood chimney experiment. — Reduce, Reuse, Re-sense!

Next, you might remember the team’s good friend, GeoFoam. GeoFoam is a type of dense expanded polystyrene foam usually used for earthwork under roadways. Both research teams have been able to use it as insulation for their experiments after the geofoam was donated to the Studio from a construction site. Remember, the team must cut smaller sections of GeoFoam from a huge 8’ x 4’ x 4’ block using a hot wire. The team was able to do so underneath the Morrisette Campus Fabrication Pavilion for a designated time and with faculty approval to ensure safety during the pandemic. They collected the rest of the batt insulation from storage in Brick Barn as well as materials for the structure of the experiment. Everything was hauled back to HomeLab for construction.

Next, the Thermal Mass and Buoyancy Ventilation team continued cutting down and shaping openings in the Geofoam. The top and bottom pieces of the chimney are made of two 6” thick pieces of GeoFoam that are adhered together as 1’ of insulation is needed for the proper U-Value for testing. The top and bottom pieces have cones carved out to ensure proper airflow. Resident King of Precision, Jeff Jeong, double and triple checks each piece of foam. This way the Chimney comes together like an airtight puzzle.

Student measuring foam insulation. — Gotta keep cutting that Geofoam

student cutting cone into foam insulation with hand saw. — Gotta keep cutting that Geofoam

The base for the chimney is constructed out of 2” x 4” lumber and plywood. The legs of this base are taller than the Concrete Chimney Experiment to match its height after being raised. Another difference in the design of the experiments is the walls of the interior chimney which the wood panels will be attached to. The walls for the Concrete Chimney Experiment are, from the chimney chamber outward, concrete panels, insulation, plywood, and then more insulation. The walls of the Wood Chimney Experiment will be pine panels, insulation, ZIP sheathing, and then more insulation. Notice Dijon doing his best to help in the photos below.

Student screwing legs for wood chimney experiment base. — We are all about the base.

Student hand planing wood for experiment chimney base. — We are all about the base.

Last, but not least, is pre-drilling holes for the concrete panels. The concrete panels will be screwed to the insulation, ZIP sheathing wall. There will be four walls to complete the chimney. Notice the grain direction of the panels. This edge grain allows for parallel heat transfer between the air within the chimney chamber and the pine panels. Not only is the Thermal Mass and Buoyancy Ventilation Research Project testing if timber works as a thermal mass but how the grain direction affects its efficiency as a thermal mass.

Student pre-drilling holes in wood panel.

Student using guide to pre-drill hole in wood panel.

The Thermal Mass and Buoyancy Ventilation Team is excited for the Wood Chimney Experiment to come together. So are the kittens! The team would not leave you without a HomeLab mascot update. While Dijon mostly naps, Rosemary is trying to get some construction experience to build her resume. They’ve had to tell her she is not OSHA certified, but she is fine napping a safe distance from construction now. It was not a hard sell. Stay Tuned to see the completed Wood Chimney Experiment!

Cat getting ready to lunge on saw horse.

Tags: buoyancy ventilation, experiment, mass timber, natural ventilation, passive strategies, research, research project, resilience, Thermal Mass and Buoyancy Ventilation, timber research, wood, wood chimney experiment, wood grain

Insulation and Other Sensations

February 13, 2020

Oh hi, didn’t see you there behind my giant block of Geofoam insulation! Let me explain. Recently, Thermal Mass and Buoyancy Ventilation Research Project Team has been designing their first experiment, the desktop scale experiment known as “the chimney,” and building a mock-up of it.

The team used the data obtained from the thermal conductivity testing in Auburn University’s material testing lab along with their test concrete panel making experience to choose which concrete mix to use. They are going with Quikcrete Pro-Finish 5000, a high strength, smooth finish mix. Next, the team poured nine new concrete panels at the adjusted thickness. The thickness of the panels increased slightly due to inputting the exact thermal properties of the concrete mix into the code of the optimal tuning application.

The desktop experiment takes the form of a 3″ x 1″ x 1″ chimney with the thermal mass panels facing the interior. The desktop experiment needs to operate in nearly ideal conditions which means eliminating as many variables as possible. It is important to remember this is a scientific experiment of an unproven theory of how an internal thermal mass can be sized for a space to control temperature and promote proper ventilation. Therefore, to eliminate the variable of heat loss or gain from the exterior to the interior, and to understand how the thermal mass panels themselves are working, the chimney needs to be highly insulated.

When you need R50 insulation, even for such a small structure, it can get expensive and big. Their creative solution to getting the proper insulative value without spending hundreds of dollars per test was combining Geofoam and Rockwool! EPS Geofoam is much like rigid insulation but is typically used for earthwork such as building up underneath highway on-ramps. It is very dense giving it more insulative value per inch. Rockwool is a rock-based mineral fiber insulation. Thankfully, Rural Studio had extra R30 from a previous donation. The Geofoam was also donated, the Breathing Wall Mass Timber team got in touch with a construction operation that had extra and transported it to Newbern. In the drawing above you can see the concrete panels screwed onto a piece of 1/2″ OSB and 2″ Geofoam which is then surrounded by 9″ of Rockwool then encased by another layer of 2″ Geofoam. This combination of materials results in R50 insulative value.

The Geofoam comes in giant 8″ x 4″ x 3″ blocks because they are typically stacked underground. So another creative solution was needed, how to cut it down to the size we need. The TMBV team did not have to think too hard on that one because their big sister research team, the Breathing Wall Mass Timber squad, had already built a hot wire cutting system for their own Geofoam needs. A copper wire was spanned at the desired height above a table and heated using cables and an external power source.

Next, the Geofoam block was slid across the table and cut through by the hot wire. Once the Geofoam is at a more manageable size it can be cut using a hack saw. Shout out to the best big sister research team ever, Fergie, Jake, Preston, and Anna, the TMBV team appreciates you!