natural ventilation

Graduate Team Completes Construction and Publishes Paper!

February 4, 2022

The Thermal Mass and Buoyancy Ventilation Research Project (TMBV) graduate students have concluded their work and time in Newbern, AL. In their wake, they leave a published, peer-reviewed paper and two research-ready buildings.

In the course of their graduate year, the TMBV project dove deep into the results of their initial small-scale experiments, culminating in a research paper published in the Journal of Physics: Conference Series as a part of the 2021 CISBAT Hybrid Scientific Conference. At the same time, the team designed and constructed two Test Buildings. The cooling and ventilation effects spurred by the optimized thermal mass will be studied throughout the next year, providing ground truth data for the system at a building scale.

The paper: A synopsis

The open-access research paper entitled, “Synchronized coupling of thermal mass and buoyancy ventilation: wood versus concrete” was published in November 2020 in the Journal of Physics Conference: Series. This was an effort involving the entire TMBV research team including Salmaan Craig, Remy Fortin, Sebastien Asselin, Kiel Moe, David Kennedy, and Andrew Freear. The paper describes small-scale experiments that test the accuracy of sizing parameters which suggest how to optimize the coupling of an internal thermal mass—which allows a building to store heat and thereby avoid major temperature fluctuations—with natural ventilation cycles, regardless of the material or the scale of the building. The results suggest the sizing parameters may be valid for early-stage design. They also show that biomaterials, such as wood, can perform as well as conventional thermal mass materials, such as concrete.

Why is this important? Typical, mechanical thermal comfort systems pump greenhouse gases into the atmosphere, raising the temperature even more. They also cannot perform in power outages during weather events caused by the ongoing climate crisis. Therefore, using regenerative materials, such as wood, to mitigate rising temperatures without reliance on the power grid suggests sustainable thermal comfort with less burden on the environment. That is an ongoing aim of the TMBV Research Project, and these initial results are an encouraging step. Before such lofty goals can be reached, the TMBV Test Buildings will provide more insight into the capabilities of the system.

The buildings: A summary

As stated above, the TMBV Test Buildings examine the coupling of thermal mass and buoyancy ventilation as a reliable thermal comfort system at the building scale. Currently, the buildings are set up for these first large-scale experiments and will later be fitted out for housing. The buildings are designed to be flexible spaces for ongoing experiments as well as dwellings for 3rd-year students. Therefore, the buildings balance valid experimental conditions, the realities of construction, and the basic needs of college students. One Test Building is powered by a plywood internal thermal mass and the other by concrete. Both buildings are designed to achieve the same performance parameters for temperature dampening and ventilation rate despite their material differences—i.e., the surface area and thickness of the material.

The buildings are the first Rural Studio buildings constructed primarily out of Structurally Insulated Panels (SIPs). Towering over the Supershed on Morrisette Campus they hover 8′ off the ground. Underneath the buildings is a gathering space nicknamed the “Cooling Porch.” During the day it is meant to collect cool air flowing out of the buildings, providing a place to enjoy the systems en masse. Air travels here through the extended chimneys, which increase ventilation speed and denote the building’s function.

With such tight buildings, dependent on accuracy, the team showed out on all the details. From three-week welding sessions to mapping out patterns of old sidewalk scrap to calculating the discharge coefficient of rooftop vent caps, this team investigated every inch. Feel free to peruse the TMBV blog to see the process, but for now here are the results.

The mirrored buildings are connected to each other and the ground via a steel walkway and ship’s ladder.

The team obsessed over every detail from the spacing of the ventilated open-joint cladding system to the fit of the steel door frame.

The plywood Test Building is fitted from floor to ceiling in Southern Yellow Pine.

The team made more than 70 1-1/8 inch shiplap joined panels to cover the walls of the concrete Test Building.

Interior of test building with concrete panels — The team made more than 70 1-1/8 inch shiplap joined panels to cover the walls of the concrete Test Building.

The Cooling Porch is constructed from reclaimed concrete materials and fitted with integrated steel benches.

The team: An abridgement

What a journey! These kids, ready to learn how to craft a beautiful building, were not expecting a crash course in thermodynamics, experimental design, and scientific discourse. It was an incredible opportunity to do both. Blending design, construction, and scientific rigor was an extremely unique and fulfilling educational experience. And the TMBV team sharing that experience across North America!

Rowe, the TMBV team’s certified best and most patient construction instructor, has moved to Bozeman, Montana, to join Love | Schack Architecture.

Jeff, a master of power tools and 3D modeling, is taking time to further his coding and woodworking skills.

Cory, a most relaxed, renaissance man, is enjoying his stint at the Ghost Residency with MacKay-Lyons Sweetapple Architects Limited, in Lunenburg, Nova Scotia.

Livia, the heart and volume of the operation, has settled in Austin, Texas, working with Rural Studio Alums at Thoughtbarn.

A huge thank you to the faculty and staff of Auburn University Rural Studio, the teams’ student colleagues, the project consultants (including Joe Farruggia!), the donors and teachers of Turnipseed International, and “Crane” Shane of Sweetwater Construction LLC for your time, knowledge, and support. Most obviously and ardently, thank you to the TMBV research conglomerate Salmaan Craig, Andrew Freear, Steve Long, David Kennedy, Kiel Moe, Sebastien Asselin, and Remy Fortin for the stellar work and dedication. It took a village!

This lot loves Rural Studio and all of its people. Hope to see y’all soon.

Tags: buoyancy, concrete, coolingporch, designbuild, graduateproject, natural ventilation, research project, thermal mass, Thermal Mass and Buoyancy Ventilation, ventiliation, wood

Bit by bit, day by day

December 15, 2021

Everything is officially clad! The plywood is cut! The benches are designed! The Cooling Porch is secured! The wiring is installed! The door is installed!

Rowe and Jeff are ticking big items off the Thermal Mass and Buoyancy Ventilation Research Project checklist. Let’s take a look at what the graduate research team has completed in the last month.

Clad

The Cooling Porch ceiling and Bottom Chimneys were clad last as they did not need the articulating man lift to reach. Now that the entire Test Building is clad with bleach-stained cypress, their form reads less like floating boxes and more like floating funnels. While the main function of the chimneys is to increase overall stack height and therefore air velocity within the system, they also signal movement to onlookers. Two wood-clad heat silos at your service!

Cut

Another TMBV jig on the books, this one helps break down large pieces of plywood with precise cuts. Jeff and Rowe designed and built the jig to make all the cuts necessary for creating the plywood thermal mass panels. Like the concrete panels, the plywood conforms to the slanted ceiling of the Test Building. There is also substantially more plywood panels as they cover the walls, floor, and ceiling of the interior.

Secured

Next up, the Cooling Porch finishing touches. Steel plates for future benches were installed in the construction of the Cooling Porch walls. However, the bench material was undecided. The team chose to use the same metal grate used on the stairs and walkway for these breezy benches. Over the next couple of weeks, the benches will be installed and reinforced with a bracket.

Last up for the Cooling Porch, a little tripping hazard prevention. The top course of the Cooling Porch walls were dry-stacked but untethered to the ground. To keep the course in place, the team used Tap Con masonry screws and small metal brackets to link the top course with the rest of the wall.

Powered

As future dwellings and experiments, the Test Buildings need power for people and sensors. The buildings are wired through chases in the SIP, accessible from floor outlets to keep the walls clear.

Last on our list of tasks completed is the installation of the doors! The test fit showed a bit more blocking needed, but the end result looks great!

Tags: buoyancy ventilation, graduateprogram, natural ventilation, Test Buildings, thermal mass, Thermal Mass and Buoyancy Ventilation, Thermal Mass Test Buildings

The Structure at the End of the Rainbow

December 15, 2020

double rainbow over Morrisette campus storehouse

Live from a double-rainbow kissed Morrisette Campus, It’s the Thermal Mass and Buoyancy Ventilation Research Project team! Recently, as the chill rolls into Newbern, the students and faculty witnessed this heart-warming phenomenon. And if you came for the rainbows, you should stay for the structure. Hang tight to learn how the TMBVRP team is supporting the Test Buildings eight feet off the ground.

students examining stud wall attached to brick wall — Tuesday’s at the Horseshoe Courtyard

students holding tree in place in oversized hole — Tuesday’s at the Horseshoe Courtyard

One more thing before we get on to the structure, a quick look at the Horseshoe Courtyard. During this semester the TMBV Research Project team has enjoyed working on the Horseshoe Courtyard site. Every Tuesday, project teammates Caleb and Claudia are wonderful and patient teachers to the TMBV team. The team certainly appreciates the construction experience and the time away from their computers. Go check out all of the beautiful work the Horseshoe Courtyard project team has done on their blog!

Column Conundrums

iteration 4 photo montage of pod model on top of mock-up 2 — Model on Mock-up montage

Students sitting underneath mock-up 2 between the two chimneys — Model on Mock-up montage

First, a quick reminder of how and why the Test Buildings are up on stilts. Because the Optimal Tuning System uses thermal mass to create airflow, the Test Buildings will expel cooled air. In the Summertime, that cooled air could be a benefit to more than just the Test Building dwellers. Therefore the Test Buildings design was lifted in order to create a Cooling Porch underneath. Here, anyone can enjoy an outpouring of chilled air. The team chose steel columns to do the heavy lifting to keep the focus of the space on the solid Downdraft Chimneys. As seen in previous blog posts, the column’s placement is dictated by the relationship to the Downdraft Chimney’s and the seating arrangement. However, the column arrangement can not just look good on paper and feel right in the mock-up, it’s got to actually, safely stand up.

written column sizing calculations for a 3.5" O.D. column — The team’s first attempt at hand calculations for column sizing

written column sizing calculations for a 4" O.D. column — The team’s first attempt at hand calculations for column sizing

interface of Enercalc engineering software displaying column load calculations — Rowe battles with Enercalc, an engineering software

student frustratedly pushes up knit cap while staring at computer interface of engineering software — Rowe battles with Enercalc, an engineering software

Thankfully, structural engineer Joe Farruggia approved the column placement—now it was time to size the columns. Through a series of hand calculations, the team tested the stiffness of 3.5″ – 6.0″ diameter steel columns to see which ones could handle the weight of the pods. Then, Rowe took this work into Intercalc, an engineering software. Intercalce allowed him to test structural loads such as gravity loads, wind loads, live loads, and overturning forces. It turns out a 5″ O.D. steel column will be more than safe. Now, onto bracing!

8 foot tall column detail showing ground and SIPs connection — Plan showing braced columns within the berm wall

column brace ground connection detail showing concrete footing — Plan showing braced columns within the berm wall

Three of the four columns, per test building, are braced to eliminate excessive drift caused by wind loads on the tall faces of the buildings. Similarly, bracing the columns reduces possible deflection and improves stiffness. The column bracings, hidden in the berm walls surrounding the Cooling Porch, are 4″ x 4″ x 3/8″ steel angles. The six braced columns appear 5′ tall as they disappear into the berms while the other two are the full height of the occupiable space at 8′ tall. These taller, unbraced columns act as entrance markers.

Foundation Demystification

structural plan showing ring beam foundation type intersecting with the locations of pod columns

Originally, the team believed a concrete ring beam foundation would be sufficient for fixing the steel columns, and thus the buildings, solidly to the ground. As seen in the drawing above, the ring beams would extend to catch bracing. However, the team needed to consider overturning moments, or overturning forces, due to the height and the aforementioned wind loads of the Test Buildings. Overturning moments are those applied moments, shears, and uplift forces that seek to cause the footing to become unstable and turn over. This means they needed to make sure the foundations were strong enough to keep the columns and bracing in the ground during bad storms.

Before these moments could be properly designed for, the team needed to do some soil testing. The quality, based on its compaction, of the soil is another factor in determining the necessary size, and strength, of the foundation. Jeff and Cory dug some holes and then used a penetrometer to test the soil. And who would have thought—the site has some pretty decent soil! Unfortunately, Jeff has been stuck in that hole for weeks… We miss you Jeff!

hand written calculation of overturning force loads on east/west pod wall — overturning force calculations

hand written calculation of overturning force loads on north pod wall — overturning force calculations

To counteract the overturning forces, the foundation changed from a ring beam to a buried slab foundation which increases its weight. Each Test Building will have its own foundation. The slab foundations secure all columns and bracing to each other as well as the ground. Below are currents drawings of the foundation, column location, and bracing connections.

pod ground plan showing interaction between cooling porch seating and column locations with slab foundation type — Foundation Plan showing concrete curb seating

slab foundation plan labeling column locations — Foundation Plan showing concrete curb seating

The Thermal Mass and Buoyancy Ventilation team will be jumping into drainage and ground material master planning next. Translating research into design into construction has been an arduous journey. However, the pay off will be worth it when designers anywhere can use the Optimal Tuning Strategy to make building materials work as air conditioners. Thanks for reading and stay tuned!

Tags: Cooling Hearth, Cooling Porch, foundation, natural ventilation, passive strategies, soil testing, Structure, thermal mass, Thermal Mass and Buoyancy Ventilation

Getting Down to the Details Episode II: Attack of the Drawings

November 20, 2020

diagram of Test Building showing all details the team must draw

Live from behind multiple stacks of full-scale detail drawings, it’s the Thermal Mass and Buoyancy Ventilation Research Project Team! The team has continued their pursuit to draw every detail of the Test Buildings. These drawings have cemented aspects of the building such as cladding, roofing materials, and entryway design. Certainly, there is still much more to decide and conquer. Let’s check out what the team’s got so far.

Concrete Barrier Bargains

A skid steer loader drops used concrete barriers on Morrissette campus

First up, a much-needed win for the TMBVRP team; they got concrete barriers! The Cooling Porch, a space for literal chilling underneath the Test Buildings, uses recycled concrete barriers as a retaining wall and seating. Road work being done on Highway 61 in Newbern revealed many of these stackable, concrete barriers just asking to be reused. The construction team doing the roadwork donated and delivered all of the extra concrete barriers straight to Morrisette Campus. However, this generous gift was not the only score for the team. Next, the team found more concrete barriers at the Greensboro Highway Department Office just 10 miles down the road. The Greensboro Highway Department has 40 more barriers and the team can have them if they can move them. Time to start the powerlifting team!

Cladding Conclusions

Meanwhile, as the team solidified the material of the Cooling Porch seating, they also came to exterior cladding conclusions. The last post touched on how the team committed to using timber for their open-joint cladding system. Now they have decided on wood species and size. The team chose Cypress in both 6″ and 8″ boards to clad the Test Buildings.Cypress is a locally available and weather-resistant cladding option.

Pod cross section showing cypress cladding system

The variation in board sizes allows for more flexibility around complex details. For example underneath the walkway, attached underneath the door, 6″ inch boards come up too short. On the other hand, 8″ boards overhang too much and interfere with the cladding on the Cooling Porch ceiling and Chimney. The mix of boards also allows for board spacing to differ slightly without drawing attention. Uniform board sizes make it easier to spot mistakes and the team is keen on hiding those from you.

A Smattering of Details

Because it would be entirely boring to describe each of these details; the TMBV team will just hit the highlights for you. First, the roofing material will be 1/4″ corrugated metal. While Rural Studio is no stranger to corrugated metal, this is a less common type. Being just 1/4″ in depth, this material has the advantages of durability and low price of normal corrugated metal, but with a more subtle profile. Below, you can see just how that ventilated roof and corrugated metal interact with the cypress clad chimneys and drip edge flashing. These were definitely some of the most complicated details due to the aerodynamic shapes of the chimneys and roof.

Axonometric section through roof and chimney intersection hand drawn 1:1 — details of the Top Chimney meeting the Roof

Cut section through roof and top chimney, hand drawn 1:1 — details of the Top Chimney meeting the Roof

top roof drip edge detail hand drawn 1:1 — details of the roof’s different drip edges

bottom roof drip edge detail hand drawn 1:1 — details of the roof’s different drip edges

cut section through door showing door frame and walkway connection — full door section showing walkway connection

cooling porch ceiling to outer wall handrawn section detail — cladding wraps from outer wall underneath to Cooling Porch ceiling and around steel columns which connect Test Building to ground

steel column brace to SIPS connection detail — cladding wraps from outer wall underneath to Cooling Porch ceiling and around steel columns which connect Test Building to ground

Next up is the door. Although the Test Buildings will be used as quasi-dorm rooms for 3rd-year students, the team does not want them appearing too residential. Just in case the polygonal shape and hovering nature of the Test Buildings don’t shout, “Experiment!” loud enough the door has got to be different too. The door acts as a punch through the SIPs wall and Internal Thermal Mass to emphasize that one is entering into an active system. This is done by highlighting the depth of the wall with a thin 13″ aluminum frame, slightly thicker than the wall. This detail was unabashedly stolen from the beloved Newbern Library project, the smart detail treasure trove.

And from the Details, a Mock-up is Born

A mini version of Anna's 20K Home that tested all roofing and cladding details at one to one scale sits underneath the fabrication pavilion — 20K Anna’s Home Mock-up

Interior of Anna's home mockup — 20K Anna’s Home Mock-up

After drawing and redrawing all those tricky details, Steve Long and Andrew Freear suggested the team practice building them before attempting them on the real deal. This is a time-old tradition at Rural Studio known as the mock-up. A mock-up is a condescended version of a building, or a small part of it, that allows students to practice and visualize construction. For example and as seen above, 20k Ann’s Home Project team built a wonderful mock-up where they tested all their cladding and roofing details to scale. The Thermal Mass and Buoyancy Ventilation Research Project team used this mock-up as inspiration when designing their own. You can take a look at the TMBVRP Test Building mock-up construction document set (CD set) below!

Axon and Axon section drawings of the pod mock ups

Section drawings of the pod mock-ups — The mock-up CD set overall drawings

Overall plan and chimney plan section drawings of the pod mock ups — The mock-up CD set overall drawings

drip edge details for the slanted roof of the pod mock-up — Mock-up CD set details

Chimney Sections of pod mockup — Mock-up CD set details

Every detail the team solved can be seen in the mock-up. The entire structure will end up being approximately 6′ x 6′ x 10′. The height is a bit substantial for a mock-up but practicing detailing the chimneys at full scale is very important. The team is making framed walls to the same thickness as the SIPs (Structural Insulated Panels) instead of building with SIPs for the mock-up. This will save a lot of time and money. The team finds the mock-up rather cute on paper though it won’t seem so miniature in person. They plan to start building the mock-up soon, but first, need to gather all the real materials they would use on the Test Buildings. It’s important they practice on something as close to the Test Building design as possible.

The Thermal Mass and Buoyancy Ventilation Research team is happy to be down in the weeds of detailing as their research becomes real. Thanks for Tuning in!

Tags: 20kannashome, Cooling Hearth, Cooling Porch, detailing, details, mockups, natural ventilation, newbern, passive, passivehouse, research, research project, thermal mass, Thermal Mass and Buoyancy Ventilation

Getting Down to the Details

November 9, 2020

Live from behind a stack of full-scale detail drawings, it’s the Thermal Mass and Buoyancy Ventilation Research Project Team! Lately, the team has been investigating all details inside and out. Starting out with material pallet and ending up at chimney flashing, the team is kicking it into high gear.

Cladding Material

1/4"=1' model of pods showing scale figure in cooling patio underneath — Iteration 1 Model

iteration 2 1/4"=1' model birds eye view — Iteration 1 Model

Unsurprisingly for a project so focused on the interior systems, it was difficult to make decisions regarding cladding. Initially, as seen in previous models shown above, the team experimented with separate cladding systems for the chimneys, Cooling Porch ceiling, and exterior walls. For iteration 1 of the test building design included a timber open-joint cladding system wrapping every surface. Next, for iteration 2, the cladding system wrapped only on the exterior wall faces of the buildings and the adjoining chimney faces. However, thin sheet metal covered the roof, cooling porch ceiling, and the chimney faces which touch those surfaces.

timber cladding + stacked timber walls and benches

The consistent cladding of iteration 1 appealed better to the monolithic nature of the SIPs structure. It also reinforced the importance of the chimneys to the buildings as a whole from the exterior. From there the team began to test if the timber was the correct mono-material for the test buildings. Seen above are renderings testing different materials for the cladding, columns, retaining walls, and benches. It is important to view these materials as they interact in the Cooling Porch. While sheet metal and polycarbonate cladding options may look more monolithic, timber is a low carbon material that better represents the heart of the project. In some cases, timber as a building material acts as a carbon-sink meaning it stores and processes more carbon than it produces. This of course relates strongly to the passive goals of the Thermal Mass and Buoyancy Ventilation Research.

Recycled Retaining Wall

Now the team is settled on the timber cladding, but they are not convinced of the retaining wall and bench materials. These aspects want to be a more earthen material as they rise from the ground towards the test buildings. After investigating rammed earth and concrete, the team wanted to find something more stackable. Concrete and rammed earth are beautiful, but they require formwork which requires more time. Something stackable will give the team more flexibility as well as members are movable.

Thankfully, down here on Highway 61 road work is being done to remove a load of 8″ x 8″ x 8′ stackable concrete barriers. The TMBVRP team is getting their hands on some of these reusable members and are calling around to local highway departments to find more similar materials. If they find enough, they will have a durable, stackable, and reusable material for their Cooling Porch. They can also use the old sidewalk pieces as a mosaic, ground material for the Cooling Porch. Above are drawings showing the use of these recycled materials.

Structure and Detailing

laptop screen showing Joe Farrugia on video call with students — living lengend Joe Farrugia on Zoom

For the past three weeks, the team has been meeting consistently with Structural engineer Joe Farrugia. He is guiding the team through lots of math to size their columns. While the gravity load on the columns is extremely manageable, the wind load is more difficult. The test buildings height means they will face more wind load than a structure this size typically experiences. However, Joe is confident that the structural system the team has chosen is doable with the correct column sizing.

While the team is attempting to draw every detail of the test buildings, they’ve found the trickiest spots to be around the chimneys. Making sure water moves off the roof consistently and air moves behind the ventilated screen is crucial. The TMBVRP will spare you the pain of walking through each flashing bend and board cut. Struggles emerge when the chimneys converge with the angled roof, but it’s very doable with lots of thinking, drawing, and redrawing. Then Andrew Freear and Steve Long, come in to save the day because how you’ve redrawn it five times is still wrong. Lots of covered wall reviews later and the TMBVRP team is on their way to compiling all the details in a digital model and drawing set.

students and professors gather in front of a wall full of detail drawings

Looking forward to keeping this momentum going, the TMBVRP can be found in Red Barn from dawn to dusk. Feel free to bring by some late-night snacks but for now thanks for TUNING in!