thermal mass

A Moment in Time

The Thermal Mass and Buoyancy Ventilation Research Project Team have a new design approach which is moving the design along swiftly and with confidence. The team struggled to create cohesive or decisive designs, each member picking small bits of the project such as the cladding or the siting without looking at the total package. While this felt like progress, it was more of going through the motions than collaborative design. Then Andrew Freear threw them a lifeline; draw the whole building(s) in ‘a moment in time’.

sketches of cooling patio seating arrangements
Cooling Patio seating arrangement sketches are everywhere

The team was to design and choose the best options at that moment for cooling patio arrangement, structural system, site, cladding material, etc. Next, they were to draw and model the whole thing out, details, and all, as a team assuming the chosen parameters. After the team could really evaluate, decide what works and what doesn’t, and design again. Well, Andrew must have had something in his tea that day because the TMBVRP is now on the fast track. In the past two weeks, the developed four design iterations, built two models, and two mock-ups on Morrisette Campus. Let’s take a look at the process and where the design is now!

Iteration 1

iteration 1 model photo showing full length of super shed
iteration 2 1/4"=1' model birds eye view

For the first full design, the team chose the site at the east end of the Supershed. This is a much dryer location than the previous “Two Trees” site. The Test Pods, in this arrangement, act as an extension of the Supershed by mimicking the slope of the roof. By mirroring and offsetting the pods, both rooms have a view from the doorway looking out over Morrisette campus. This offset allows for the access stair to tuck down the side. The walkway between the pods holds them apart and gives a view of the sky from underneath in the Cooling Patio.

Next, the team explored a vertical, ventilated timber siding. This open-joint cladding system shades the SIPs (Structural Insulated Panel) structure from solar heat gain and wraps both chimneys. The structure supporting the Test Pods, while elevating them 10′ off the ground, was a steel frame attached to columns. This steel frame was able to slide underneath both pods between the Downdraft Chimneys. The relatively light steel columns highlight the cantilevered pods. The 1′ thick SIPs’ floors on each pod act as one large beam able to span across the steel structure while distributing the building’s load. All of this allows for an uninterrupted space for the Cooling Patio while making the two pods appear to float.

Reviewing this iteration, the team decided the Cooling Patio head height was entirely too tall for a small gathering space. There is also little interaction with the Downdraft Chimneys in this first scheme. The project collaborators suggested the doors not be above the Downdraft Chimneys to mitigate airflow disturbance. They also pointed out that vertical cladding is less successful for shading than horizontal. With internal and external feedback the team got to work on a new design.

Iteration 2

Iteration 2 plane

Iteration 2 started with moving the doors from in front of the Downdraft Chimney opening in the pods. This drove the rest of the design because the roof angle is always tied to the chimney locations. The Updraft Chimney, the one on attached to the roof, needs to be on the high side of the sloped roof. This way rain and debris cannot pool around the Updraft Chimney. Also, to distrubute airflow as evenly as possible, the chimneys need to be as far apart as possible. Therefore the Downdraft Chimneys must always correspond to the low side of the roof slope. Switching the roof angle to an “anti-Supershed” slope, allowed for the Downdraft Chimneys to move out from underneath the doors, while keeping the same mirrored, offset pod arrangement.

Whew, the team got the pod arrangement and door to chimney relationship fixed, but they created another problem: structure. The structural steel frame would no longer be able to fit in between the Downdraft Chimneys. So, the team thought to take full advantage of the structural possibilities of the very thick SIPs and attach the columns directly to the underside of the floor. While at first, they thought this would be impossible, their contact at a SIPs manufacturer told them it is done quite often on hunting blinds. “The hunting blind” will go on the long list of nicknames referring to the strange yet recognizable form of the Test Pods. The Tree House, The Periscope, The Wind Catcher….

The cladding, stair, and roof material all took a turn. While the stair and cladding changed direction, the roof material changed from membrane to metal. The roof metal also became the underside material and wrapped corresponding sides of the chimneys. The exterior cladding now acted as a fence around the outer edges of the pods while the metal appeared to wrap underneath. The Cooling Patio height dropped to nine feet, which still seemed a bit high. The team had a good feeling about iteration 2. Mostly, it directed them to give more attention to the Cooling Patio. How does it feel to be in that space? It was also time to see how these Test Pods really looked on Morrisette Campus, not just in model.

Iteration 3

Students level with eachother

First, photomontages, collages of model photos and site photos, were created to get an estimate of just how big these pods look on site. The results are in: the pods are pretty dang big. There was also a slight column movement from the last iteration, but that’s a very boring drawing. These images really got the team thinking they needed more visualization. So it was time to build a mock-up.

This one-day mock-up tested the height of the Cooling Patio space, seating arrangements, and pod siting. The columns are accurately placed and support a frame that represents the underside of the pods. This gives the relative ceiling height of the Cooling Patio. The team first built the columns and frames to give a head height of 8′ 6″. They pretty immediately lowered it to 7′ 6″ as it still felt too generous for an intimate space of gathering.

The mock-up helped to establish an undercroft ceiling height but revealed some disfunction between all of the elements in the space. The team needed a more robust mock-up to understand how the retaining walls, seating arrangements, columns, and Downdraft Chimneys interacted. Plus, the team had a really good time building. It was off to Lowe’s for Iteration 4 and Mock-up 2.

Iteration 4

Before getting to Mock-Up 2, let’s address lateral load. While the columns can be specified to support the weight of the buildings, what will keep the Test Pods from tipping over in the next high wind storm? For iteration 4, the idea was to tie all the columns together underground in the foundation. That foundation than extruded upward to become the retaining wall and the support for the seating. Seating as a way to gather around the cool-air chimneys, which act as spacial barriers, drove the placement of the walls and columns. The resulting design was translated to Mock-Up 2.

The biggest worry about iteration 4 was the distance between and size of the chimneys. However, sitting in the complete Mock-Up 2 space, the chimneys did not feel too crowded or large. Instead, they felt like the integral feature they are. They divided the space into three but still allowed for continuity, through access, and visibility. The space between the chimneys is more compact and private while the larger spaces at the Cooling Patio entries allow for gathering.

The ground to sky connections really began to stand out in the photomontages of iteration 4. This brought to mind both material pallet and column placement. While the team originally thought the benches in the Cooling Patio might be light, thin material, it became quite clear it should be something heavier. This way the Cooling Patio is clearly an element of the ground, while the pods are an element of the sky. This idea also brings into question whether the columns always hitting the foundation/retaining wall perfect actually makes them stand out more. A regular, orthogonal placement, while still keeping clear of the gathering space, may make the columns somewhat disappear.

The Thermal Mass and Buoyancy Ventilation Team is moving on to iteration 5, 6, 7, on and on. They are enjoying their new design process as the idea of building these two floating experiments becomes more real every day. Next up, the team is taking a deep dive into the interior of the pods. Thanks for reading and don’t forget to take it one moment at a time and STAY TUNED!

Lab to Barn, Science to Design

Live from Rural Studio Red Barn, it’s the Thermal Mass & Buoyancy Ventilation Research Project Team! The team, though they might come to miss the cat interns and the AC, is so excited to be back on campus. For health safety measures, the team has an entire studio room to themselves which also acts as a convenient hiding place from Andrew Freear. The TMVRP Team is being as safe as possible as they sorely missed Newbern and the Rural Studio staff and faculty. This week the team will cover their pod design process while bombarding you with design iteration images. Enjoy!

As the Wood and Concrete Chimneys chug along, quite literally, the TMBVRP team have been designing their test buildings. Like the Mass Timber Breathing Wall team’s nearly completed test buildings, the TMBV test buildings apply their research at a small building scale. After some initial testing, the TMBV test buildings can be used as 3rd-year accommodations. The Studio calls the funky dorm rooms for 3rd-years on Morrisette campus “pods.” In true Rural Studio fashion, the design of these pods is an iterative process, but must always be grounded in what is necessary for the experiment. Now, science experiments are not only driven by the hard data we might get out of them. Many experiments are experience-based, especially when trying to describe a phenomenon to the public. Think about going to a science museum, touching the electrified ball and your hair shooting up from your head. Static electricity makes a lot more sense to you when you experience it rather than if you had read data and looked over graphs explaining it. The design of the Thermal Mass & Buoyancy Ventilation pods revolves around both data and experience production. A main objective of the Thermal Mass & Buoyancy Ventilation Research Project, while being rigorously tested for data currently, is for inhabitants to experience the comfort of the cooling and ventilation effects. Let’s journey through TMBV Pod design as the team tries to focus on both experiment and experience!

When massing the general size of the pods, the team can use the Optimal Tuning Strategy app. From the app the team knows the amount of surface area needed for the thermal mass, the thermal mass thickness, and the size of the ventilation openings based on the information they input which is how much ventilation, temperature change, and height the pods need. General massing schemes are quickly generated from these design parameters. The team is creating massing schemes for two to three pods, one with concrete thermal mass walls and one or two with wood ones. These massing schemes also explore whether to share walls in a multi-unit pod or separate the pods to highlight the material difference within. As long as these massings can fit the app outputs, a 3rd-year, a bed, and the sensors we need for testing that’s all of the design work to be done, right? Nah. While these are sleeping quarters for students, they are also examples to the public of how spaces that utilize thermal mass and buoyancy ventilation can feel.

To create a peak TMBV experience, the team is elevating the pods! This will allow for a gathering space underneath the pods where anyone can sit and enjoy the cool air being naturally pumped out of the spaces above. The TMBVRP team calls it, the “Cooling Patio.” Here, students, faculty, or clients interested in the system can experience the effects of TMBV without lingering too long in a 3rd-years dwelling. It also highlights one eventual goal of the work; naturally cooled public spaces enjoyed in the Black Belt. The Cooling Patio is located underneath the buildings because the TMBV system operates in downdraft during the day. This means during the day the air is pushed out of the lowest opening as opposed to at night when the air is pushed out of the highest opening. Therefore in a typical building, you would not need to elevate the structure above the ground, you simply need a low and a high ventilation opening. The TMBV Pods’ ventilation “top and bottom” openings are so literal for both the quality of the experiment and the Cooling Patio.

Why the pod is elevated may now be clear, but why do some of these drawings have such tall chimneys? The exaggerated Chimneys are an experiential detail like the elevation of the spaces. They are not necessary for the experiment or the TMBV strategy to work. A typical building would not need tall Chimneys to utilize Thermal Mass and Buoyancy Ventilation, just as they would not need to be elevated. The tall chimneys are specific to the Thermal Mass and Buoyancy Ventilation Research Project Pod as they highlight the ventilation created by the passive strategy. This is another detail, like the cooling patio, that will work as an experiential demonstration of the research. Increasing the overall height of the structure, beyond what surface area is needed, highlights the ventilation aspect of the system. The elongated chimneys do not increase the amount of air ventilated through the spaces, it does increase the speed of the air as it exits the spaces. The faster the air exits the interior space into the cooling patio, the cooler the patio space will feel. Think of it as the difference between being hot with a fan and without. Moving air always increases the cooling effect and therefore the cooling experience. This increased airspeed will help with explaining how Thermal Mass and Buoyancy Ventilation works as visitors and users will be able to clearly feel the cool air rushing out. Now, the design is focused on three main outcomes: replicating the experiment so TMBV works effectively at building scale; providing a comfortable and useful space for sleeping and demonstrating; and creating a space below the buildings in which people can gather and experience the strategy working for long periods of time. What comes next is siting and about 1,000 other details.

Siting began by looking at various locations around the Super Shed and the existing pods. The Team began exploring the pods as stand-alone buildings. Next, the team explored how they could utilize the roof and structure of the Super Shed. While investigating stand-alone sites, the team also did some surveying of the Super Shed. Both options have benefits. A stand-alone structure would allow for greater height, not being capped by an existing roof, so a more generous cooling patio space and higher airspeed into that space. The existing roof of the Super Shed, however, would provide constant shade and rain protection making it a very similar environment to the Chimney Experiments in the carport at HomeLab. Both have experiential and experimental benefits that the team is still exploring.

The Thermal Mass and Buoyancy Ventilation Team has a lot of hard work ahead, but nothing makes it better than being back in the Red Barn. Seeing the old and new faces of Newbern, even from a social distance, is exciting and motivating. Thanks for Tuning in!

New Cat, New Data, New Designs

Live from HomeLab it’s the newest member of the Thermal Mass and Buoyancy Ventilation Research Project team, Sonic! More on our scrappy, little intern later, we’ve got fresh Wood Chimney Experiment results.

Longhaired black kitten shining in the sun

TMBV Research Project’s last post discussed equalizing the environment of HomeLab to improve the accuracy of the Concrete and Wood Chimney Experiments. While the screen on the eastern side is blocking direct solar radiation, the team discovered a new heat source. The roof of the carport is significantly hotter, even on the underside, than the team thought. This was discovered while trying to understand the Chimney’s airflow data. To show how trapped heat can affect the experiments we will take a look at the long-awaited Wood Chimney Experiment Data.

The above airflow data was taken from the first week the Wood Chimney was up and running and shows both updraft and downdraft. Automatically, the Optimal Tuning Strategy is validated for wood, as well as concrete, by the existence of both airflow directions within the experiment. Go, Wood Chimney, Go! However, the updraft is nearly twice as strong as the downdraft which did not quite make sense. The team looked back to their thermal imaging photos for an answer as to why there is such a large difference between the updraft and downdraft.

The thermal imaging photos show that the top of the Wood Chimney Experiment is much, much hotter than the side of the chimney. This can cause a build-up of hot air at the top of the chimney which explains why downdraft is so much lower. While in downdraft, the air is brought in from the top and expelled out of the bottom of the chimney. It works the opposite in updraft, bringing air in from the bottom and expelling out of the top of the chimney. If there is much more hot air at the top of the chimney, that causes turbulence, making it harder to bring in air during downdraft and too easy in updraft. So what is causing this heat at the top? The HomeLab ceiling!

The team learned, from the thermal images above, that the ceiling of the carport was nearly 120 degrees Fahrenheit, which clearly was the reason for the heat build-up at the top of the Wood Chimney Experiment. To combat this the team stapled a radiant barrier to the rafter of the carport to insulate and reflect heat away from the tops of the chimney, trapping it at the ceiling. The radiant barrier is made of Reflectix insulation which looks like shiny bubble wrap. In the thermal images, you can see the radiant barrier lowers the temperature above the chimney by nearly 10 degrees.

The radiant barrier works! Both the thermal images and data show that the excess heat at the top of the chimney was increasing the updraft and making the downdraft more turbulent. The top surface of the chimney also dropped 8 degrees. The amount of air per second is now mirrored in updraft and downdraft at about 0.05 l/s.

in the last post, the team left y’all with thoughts on a “Human Scale” experiment, to test the Optimal Tuning Strategy and App at a larger scale that can be experienced. After a discussion with the entire Thermal Mass and Buoyancy Ventilation Research Project team, including partners at McGill University and Rural Studio faculty, everyone found the Human Scale experiment is not necessary to validate the Optimal Tuning Strategy. The data from the Chimney Experiments is primo and the team can move on to designing a permanent, Inhabitable Structure. The Inhabitable Structure will be a usable example of the effects of coupling thermal and buoyancy ventilation in a building as well as being a mechanism for producing data. Rural Studio will be able to use the spaces on the day-to-day, but it will also show people the system works and can be applied in the community. While the team has thoroughly enjoyed learning about design through crafting an experiment, they are excited to get back to architecture! There is still plenty of science to come, don’t be fooled.

Balancing science and design seemed like too big a job for 4 students, 2 cats, and a Copper so the team hired a new pet intern. Meet Sonic! He was found at just 4-weeks old out on a county road with only his thoughts and half a tail. As you can see, he is getting along great with the other interns and doing some great sketching. Stay Tuned for updates on Inhabitable Structure design and the teams myriad of four-legged friends.

Wood you believe we did it?

Timber pun prepared and deployed? Scientific apparatus built? Yes to both! Live from HomeLab, the Thermal Mass and Buoyancy Ventilation Research Project team is proud to present to you, the Wood Chimney Experiment! No science lessons today folks, just photos.

Students posing with their test chimneys.

SPOILER ALERT! On the left, you see our tried and true, the one who taught us so much, the Concrete Chimney Experiment. On the right, the Thermal Mass and Buoyancy Ventilation family welcomes their newest member, the Wood Chimney Experiment. Now let’s look at the building process.

The top and bottom insulation blocks are created by adhering two 6″ x 3′ 7″ x 3′ 7″ to make them 1″ thick. If you would like a reminder on why this insulation is necessary for the experiment phase and not necessarily for an actualized building you can read this post. The airflow cones are carved out so that they align with the airflow opening of the chimney interior chamber.

Here we’ve got the chimney walls coming together! Four sandwiches of ZIP sheathing, GeoFoam, and Wood Thermal Mass Panels all attached to create an interior chamber.

Three walls up, the fourth needs its sensors! The TMBVRP team thinks it would be absolutely wonderful to be in a space surrounded by edge grain wood that is also naturally ventilated.

The Sensirion airflow sensors will also be in this experiment. Incorporating how sensors can be attached within the chimney and their cords can make it out of the chimney without being squished is a crucial part of the design.

Before the Wood Chimney Experiment interior chamber is sealed, the fourth wall containing the temperature signal sensors must be attached. The temperature signals, read about temperature signals here, will be sensed with thermocouples and heatflux sensors. Next step in the process will be building up the insulation surrounding the interior chamber.

The Thermal Mass and Buoyancy Ventilation team is aware they used to refer to these scientific apparatus as “Desktop Experiment’s”. Technically the inner chamber could stand on a desk, but a more appropriate name might be Carport Experiments or Taller than the Team Experiments. Let’s just call them the Chimney Experiments for clarity. These experiments are still the first and smallest experiments for the scalable Optimal Tuning Strategy. And look, the Wood Chimney Experiment is done! Batt insulation and 2″ GeoFoam walls encase the interior chamber and ZIP tape is used to seal the entire experiment.

Students posing with their test chimneys.

Thank you to all who have encouraged and supported the Thermal Mass and Buoyancy Ventilation team! The team is very excited to have reached this point, but the work is no where near over. It will take time to learn a new data retrieval and analysis workflow for the new sensors. The team is excited to get to it, but first we are going to celebrate our Wood Chimney Experiment! Cheers y’all and STAY TUNED!

Calibrate and Graduate

Team is posing with their new outfit

Exciting things have been happening at HomeLab lately! First, the Thermal Mass and Buoyancy Ventilation Research Project (TMBVRP) Team were able to install airflow sensors into the Concrete Chimney Experiment. Second, the chimney has brought in some impressive data. And third, the TMBVRP team participated in an end of the semester presentation and round table discussion with their big sister team, the Mass Timber Breathing Wall Research Project, and a cast of professionals in the architecture and building science research field.

This week the team received their Sensirion differential pressure air flow sensors. The sensors record a difference in dynamic and static pressure which the team uses to calculate bulk flow. Bulk flow is the total airflow at the sensor location. The team installed two sensors into the Concrete Chimney Experiment, one at the bottom and one at the top, to measure updraft and downdraft ventilation created by the thermal mass.

Just to refresh your memory, updraft occurs during the night when the cool, night air is brought in the bottom ventilation opening, warmed by the thermal mass, and exhausted out the top. Downdraft occurs during the day, the warm, exterior air is drawn into the top ventilation opening, is cooled by offloading heat to the thermal mass,  and vents out the bottom.  Being able to measure the direction and amount of ventilation is critical to understand if the Concrete Chimney Experiment is performing as expected.

And the results are in, our initial measurements from the airflow sensors do show that during the day the chimney is operating in downdraft and during the night it operates in updraft. This gives us proof of concept, that thermal mass is able to alter the atmosphere inside the chimney so that it goes against the exterior environment.

graph showing airflow in the test chimney

The GreenTeg temperature sensors have also brought in proof of concept data, showing that the thermal mass is having a damping effect on the interior air. It is important that the temperatures of the thermal mass and interior air cycle with the daily swing in temperature so that heat is absorbed by the mass during the day and offloaded during the night. This shows that the internal thermal mass is effectively moderating the temperature in the chimney and causing continuous ventilation. We are continuing our testing to further calibrate the amount of ventilation to achieve the most efficient and effective heat transfer between the internal thermal mass and air.

Temperature signal graph comparison

To wrap up our undergraduate work, we had a roundtable presentation via Zoom to give an update on where our work is and share our exciting results with Auburn, our collaborators at McGill, and professionals in the architecture and building science research field.  This panel included Billie Faircloth, a partner and research director at the architecture firm Kieran Timberlake in Philadelphia, PA.  Second, we were joined by Jonathan Grinham, who is a Lecturer in Architecture and Research Associate at the Harvard University Graduate School of Design.  Last but not least, is Z Smith.  Z is a Principal and the Director of Sustainability & Performance at Eskew Dumez Ripple in New Orleans, LA.  

It was a privilege to be able to present and have a productive discussion with such esteemed professionals.  We gained valuable insight on how to best relay the work we are doing do both those in the research field and the common person. In addition, their backgrounds led to an intriguing discussion on how The Optimal Tuning Strategy could be implemented at the building scale. It was especially awesome to discuss the successful data the team recently got form the Concrete Chimney Experiment. Both the data and the discussion gave the Thermal Mass and Buoyancy Ventilation Research Project Team a boost of confidence and pride in their work. It not always easy for these architecture students to wrap their heads around the science, but the hard work paid off. Thank you to Rural Studio, Salmaan Craig, Kiel Moe, David Kennedy, and the reviewers for a positive end of the undergraduate phase of the Thermal Mass and Buoyancy Ventilation Research Project.

Final shout out to the incredible Mass Timber Breathing Wall Research Project Team. As they complete the paper on their research and graduate from the Master’s program they still had time to do something very sweet for their little sister team. They passed along their Rural Studio lab coats, crossing out their names and writing the names of the TMBVRP team members. Their work, dedication, and attitude could not be a better example for the TMBVRP team to emulate. From one research project team to the other, thank you for helping us whenever we needed and being the best big sister team imaginable. We hope to live up the legacy! Well, everyone, stay tuned (optimally tuned) this summer for the start of the graduate program at HomeLab.