resilience

Preparing a Timber Pun for a Post Title

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.

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.

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.

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.

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!

Auburn Opelika Habitat Homes

A major goal of the Front Porch Initiative is to expand home ownership in areas outside Rural Studio’s service area of West Alabama. Recently, we collaborated with another studio within Auburn University’s School of Architecture, Planning and Landscape Architecture (APLA) and the McWhorter School of Building Science (BSCI) as well as Auburn Opelika Habitat for Humanity to build two homes in Opelika, Alabama. The design of these two projects is based on 20K Buster’s Home. The homes for this collaboration were optimized for energy efficiency using different efficiency standards, which offers the opportunity to study two models of energy consumption. Additionally, both homes are designed to provide beyond-code resistance to damage from high winds and blowing rains.

View of a 20K/Front Porch home at sunset with the lights on
House 66 Dedication – Image by Matt Hall

The first house, dubbed House 66, is Passive House Institute US (PHIUS) certified, which requires homes to be super-insulated, minimize air leakage through a tight envelope, have high-efficiency windows and doors, active ventilation, and energy efficient equipment. The house was also built to the Insurance Institute for Business and Home Safety’s FORTIFIED Home – High Wind standard, which certifies that a home’s construction strengthens it against severe weather. House 66 is the first home in Alabama to receive PHIUS certification and, as far as we know, the only house in the country ever certified both PHIUS and FORTIFIED Gold. The second house, House 68, is built to Zero Energy Ready Homes (ZERH) and FORTIFIED standards. Though not as stringent as PHIUS, ZERH also focuses on energy efficiency and preparing the home to adapt to renewable energy sources as they become available. Both House 66 and House 68 have a HERS rating of 38 (learn more about the HERS index here), but our energy models predict that it will cost approximately $100 more in energy costs per year to operate House 68. These costs can further offset by the installation of a photovoltaic (PV) panels, also known as solar panels, which generate energy. A PV system has already been installed at House 66, where excess energy produced is fed into the local energy grid.

Each house is also outfitted with monitoring devices to collect data about energy usage at the level of the individual circuit. David Hinson of APLA is co-leading the project and explains the research: “We will monitor the actual operating costs […] and compare the operating savings against the cost of incorporating these special features. Our aim is to find the balance point between the initial cost of constructing the home and lower operating costs that results in the best long-term solution for the families.” Along with Hinson, Mike Hosey of BSCI and Mackenzie Stagg of the Front Porch Initiative have received funding to analyze the data collected at the homes. Analysis of this data will help us better understand which changes to the building design have the largest impacts on energy consumption.

Habitat House 68 exterior
House 68 Dedication

Awards:

At the 2019 PHIUS Passive House Projects Competition, House 66 was awarded Winner of the Affordable Category.

Recent Press:

Auburn University 2019 Press Release: Building Better Architects: Auburn University partnership with Habitat for Humanity gives architecture students experiential learning opportunities

Auburn University 2018 Press Release: Auburn University students design, build energy efficient Habitat for Humanity Home

WLTZ News: Auburn University Students Help Design Energy Efficient Habitat for Humanity Homes

Opelika-Auburn News: Opelika takes step toward renewable energy

Learn more about the Front Porch Initiative here.