thermal image

New Cat, New Data, New Designs

July 27, 2020

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.

Thermal camera image of the top of concrete chimney before radiant barrier installed. Temperature registering at 41.7 °C. — Top of Wood Chimney

Thermal camera image of the side of concrete chimney after radiant barrier installed. Temperature registering at 33.0 °C. — Top of Wood Chimney

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!

Thermal camera image of carport ceiling registering at 43.2 °C. — HomeLab ceiling

Thermal camera image of radiant barrier on carport ceiling registering at 32.5 °C. — 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.

Thermal camera image of the top of concrete chimney after radiant barrier installed. Temperature registering at 33.7 °C. — top of chimney before radiant barrier

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.

sizing pod spread sheet — TMBVRP team starts designing once more, not without an analog spreadsheet though

design charrette of pods — TMBVRP team starts designing once more, not without an analog spreadsheet though

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.

Tags: airflow, buoyancy ventilation, HomeLab, Inhabitable Structure, natural ventilation, thermal image, thermal mass, Thermal Mass and Buoyancy Ventilation

Thermal Imagination

July 10, 2020

Live from HomeLab, it’s time to evaluate our experimental environment! While the Wood Chimney Experiment racks up data, the team is trying to better understand the thermodynamics of their Lab. Of course by “Lab” the Thermal Mass and Bouyancy Ventilation Research Project Team means their carport. Let’s get into it!

Students build frame for shade screen with dimensional lumber

Blue tarp shade screen blocking sun from test chimneys

Quickly after building the Wood Chimney the team noticed sunlight hitting it’s lower half in the early morning. Although a small amount of morning sunlight will not stop the Optimal Tuning Strategy from cooling and ventilating the Wood Chimney chamber, it creates unequal conditions between experiments. One of the objectives of this research project is to understand if southern yellow pine is comparable to concrete as an internal thermal mass material. Due to concrete’s thermal properties, it is consistently used as a thermal mass material. If the team can prove that wood can also be a consistent thermal mass material when sized correctly the rural south can utilize their natural resources to provide not only structure in builds, but temperature and ventilation control. Therefore, these experiments need to have equal conditions.

The first step in creating a more equal environment was building a shade structure for the low, eastern light. Made of dimensional lumber and an extra blue tarp, the shade screen blocks any direct sunlight from hitting the chimney while allowing air to enter the bottom of the chimney. This will equalize the amount of heat from direct sunlight, also known as radiant heat, the Concrete and Wood Chimney’s experience. However, the radiant heat on the eastern side of the Lab, shown on the left above, experiences may lead to higher ambient air temperature around the Wood Chimney.

Thermal image of concrete chimney — Concrete Chimney

Thermal image wood chimney — Concrete Chimney

To understand if this is having a significant effect on the Wood Chimney in comparison to the Concrete Chimney the team got out the FLIR thermal imaging camera. Thermal imaging is simply the process of converting infrared radiation into visible images that depict the spatial distribution of temperature differences in a scene viewed by a thermal camera. This will help us understand the distribution of heat in the lab. From the thermal imaging photos, we can see the difference in temperature in the Lab. The eastern side, on the upper left, because of the radiant heat from the sunlight stays consistently warmer. The western side, on the lower right, is cooler than the rest of the space because it is mostly shaded from any sunlight. Also, due to the size of the Lab, there is clear heat stratification. As heat rises, it gets stuck under the ceiling. While this environment is not detrimental to the experiments, the team is hoping to be able to move the experiments to the Fabrication Pavilion on Morrisette Campus. There, the experiments will have more consistent shade in a much larger space. The larger space will make a more consistent environment as heat will stratify farther away from the top of the Chimneys.

Students outline space for mock-up design — Student’s mock up spatial conditions and sketch construction details

students sketch structure for human scale experiment — Student’s mock up spatial conditions and sketch construction details

The team has also begun thinking about their next scale of experiment. They want to test the Optimal Tuning Strategy at human scale. This means the space needs to be large enough for someone to experience the cooling effects as well as see what an internal thermal mass looks like in a space. Scaling up, besides being experiential, will also seek to prove that the Optimal Tuning Strategy is truly proportional and applicable for public buildings. The team has to consider what proportions of space will make the Human Scale Experiment data comparable to the Test Chimney data. This is not so straight forward as they need to make sure the experiments do not become too tall or tight as to impede quick, safe construction as the Human Scale Experiment will be a temporary structure for testing. The Thermal Mass and Buoyancy Ventilation Team is using the Optimal Tuning Application to design the Human Scale Experiment at this schematic phase. The application was recently published by Wolfram Demonstrations Project! The team will soon do a post on understanding and using the app.

Last, but not least, here is a thermal image of HomeLab mascot Dijon. No conclusions were made about Dijon based on his environment. Keep Tuning in as the TMVRP team works from HomeLab!

Tags: concrete chimney experiment, natural ventilation, research project, Test Box Experiment, thermal image, Thermal Mass and Buoyancy Ventilation, wood chimney experiment