Hey, that’s me!
I have been interning in the office at Maine Passive House for about three months. My time at Maine Passive House has mostly been spent creating BEAM models for MPH projects. With almost three months of work put into the program, I feel proficient and would like to share my findings.
For those who do not know what the BEAM Estimator is:
It is a program used on google sheets that provides an estimate for the amount of carbon dioxide equivalent emitted by the materials used to construct a house. The estimations done by BEAM only show the embodied carbon of the building’s materials; they do not provide estimates for operational carbon, nor do they include appliances, electric, plumbing, etc. The tool can be used at any stage of developing or building a house, so it can be used to show how much embodied carbon there was after the fact and to help designers and builders make eco-conscious decisions while in the building process.
Builders for Climate Action saw a gap in the industry knowledge of building materials’ embodied carbon and made BEAM.
““The majority of a building’s emissions between now and 2050, when the industry is targeting a zero emissions goal, comes from the building materials. As buildings become more efficient and increasingly powered by renewable energy, more of the emission burden is on the materials. It is critical to be able to not just evaluate the emissions of building materials, but come up with actionable strategies to reduce these emissions within project budgets and workflows. This is why we created the BEAM tool - to empower designers and builders to make actionable data-driven decisions quickly and easily to draw down these upfront material carbon emissions.””
Picture taken by Chris Bennett Photography
To start, I will share my difficulties and challenges I have had with the program. A lot of struggles I have had with BEAM have been user error or my lack of general knowledge. BEAM was designed for people with experience. I am a high school student and my previous experience in the construction field was limited to one week of job shadowing a year and a half ago. This lack of general knowledge has resulted in numerous Google searches and trips to BEAM’s glossary asking what purpose a product serves, finding what an abbreviation stands for, etc. I struggled with unfamiliar terms and definitions but once I was able to get a better hold of what something meant in greater context, I found more success.
After learning how to understand and navigate the spreadsheet, my biggest problem became figuring out what materials were used. BEAM includes some very specific materials so one needs to have a thorough understanding of what is being used on a project. When blueprints do not explicitly list materials, BEAM can become a guessing game. Despite the long list of materials BEAM includes, there are still gaps people need to manually fill in themselves.
Picture taken by Chris Bennett Photography
On the project I am currently working on, Glavel was used- a material that is not on BEAM. So, I have been working on figuring out how to manually enter values into BEAM’s additional materials section. This has not been an easy task. Despite the list of instructions provided on BEAM’s user guide outlining steps to find the net emissions of a material, I do not trust the answers I have gotten. To fact check my answer for the net emissions of Glavel, I used the same process to solve for products in BEAM, and I have not consistently gotten the same answer as BEAM. This has been a frustrating process because BEAM does not show the calculations used to get its values, so I am not able to see where I have gone wrong in my own calculations.
An explanation of how Beam’s “Net Emissions” are calculated could enable more people to manually calculate different materials that aren’t already listed in BEAM.
Additional Materials Section
Beyond the challenges I have faced with BEAM, I have also noticed many interesting things about the program. One thing I find fascinating is how much carbon one product can emit or store.
For example, concrete emits a lot of carbon. Some projects I have recorded in BEAM have had as much as 16,000 kg CO₂e emissions from concrete alone, which accounts for over 70% of the project’s total emissions. 16,000 kg CO₂e means there will be 16,000 kg of carbon dioxide equivalent (greenhouse gases) released over a certain period of time, typically 100 years. That being said, concrete has lots of different mixes resulting in higher or lower levels of emissions.
Range of Concrete Values
Cellulose insulation is another material that has been used on all the projects I have modeled for MPH. Cellulose insulation, on the other hand, stores a lot of carbon. On all the models I have made, cellulose insulation has stored at least 2,000 kg CO₂e. So, the value given to cellulose insulation in BEAM is always negative. Cellulose insulation’s storing abilities are a result of its natural elements. When products are deeply processed and refined, they have high carbon emissions but since cellulose insulation is made from mostly natural and recycled materials, it has carbon storing abilities.
Example of Cellulose Insulation’s Carbon Storing Values
A Triple-Pane Window, Picture taken by Chris Bennett Photography
Another value I did not expect is from windows. A house with 480 ft² of triple-pane windows emits at least 3,700 kg CO₂e from just the windows, for reference this house has 2011 ft² of floor space. On this project, the windows accounted for 16% of the total carbon emissions. These are just the values from materials that have been used on houses MPH has built. While searching through options of materials I have seen some things, such as different types of insulation, that range between -20,000 to 75,000 kg CO₂e.
This range in values reinforces the importance of material selection. Going into working on my first model, I am not sure what I expected, but the wide range of values present is definitely larger than I thought it would be.
Triple-Pane Window Options
Wide Range of Insulation Embodied Carbon Values
Storytime:
Despite there being a wide range of possible values across the BEAM materials, I have familiarized myself with a considerable amount of them. A strange, yet interesting side effect from spending lots of time making BEAM models, is being able to accurately estimate the levels of embodied carbon in certain materials. The first time I visited an active jobsite was about a month into my internship with MPH, so I already had a fair amount of experience with BEAM modeling. As I was walking around the site learning about the different materials that I had previously only heard about on BEAM, numbers kept popping into my head. These numbers were estimates of the materials’ carbon emissions and when compared to an actual BEAM sheet were not that far off.
As I have finished more BEAM models I have seen a variety of results. BEAM breaks down houses into sections and gives embodied carbon values to each section as well as the house as a whole. Once the project is done, one can see the material carbon emissions by section, the project emissions, and the project emissions intensity. BEAM measures material carbon emissions by section by material carbon emissions (MCE), the project emissions by MCE, and the project emissions intensity by material carbon intensity (MCI). The MCE numbers are a total measurement, whereas the MCI is a ratio. The MCI number is then put on an existing chart in BEAM to show the builders where their project stands from storing, low, average, or high carbon emissions.
MCE Example
MCE, MCI Example
While modeling MPH houses, I have seen a range of MCI totals. The highest I have modeled was 237, which falls on the cusp between average and high, and the lowest I have modeled was 84, which is low, based on the chart given by BEAM. The house with a 237 MCI was the Beaver Pond Retreat and the house with an 84 MCI was the A-frame cottage. There are many factors that affect the MCI, in this case the biggest differences between houses are the garage/carport setup and the concrete usage. The A-frame cottage had a garage incorporated into the basement whereas Beaver Pond Retreat had a carport attached to the side of the house. Having a basement garage allowed for less concrete to be used making foundational elements for the house and garage.
A-Frame Cottage MCI Chart
Beaver Pond Retreat MCI Chart
Beaver Pond Retreat was partially built into a hill, the ground floor and carport are level with the top of the hill, and the walkout basement is at the bottom of the hill. This design led to the usage of a lot of concrete to build big and strong foundation walls and discontinuous foundation elements in order to support the carport. Beaver Pond Retreat also has concrete foundation walls and a slab, whereas the A-frame cottage has concrete foundation walls and a partial slab. The differences in concrete usage amounted to about 4,000 kg CO₂e more concrete getting used at Beaver Pond Retreat even though the A-frame cottage is a bigger house.
The A-Frame Cottage’s Partial Slab and Basement Garage
On top of the mass concrete usage for Beaver Pond Retreat, the carport is not insulated. I have begun to look to the storing qualities of cellulose insulation to bring down the total carbon emissions while modeling. But since the carport is not a conditioned area there is no cellulose insulation to help bring down the carport’s net emissions. Having a space like a carport that is not conditioned, leads to more embodied carbon per ft² because there is less conditioned floor area per ft² of foundation. All that being said, it is important to remember BEAM only estimates building materials. So having a conditioned garage space adds to total operational carbon energy that is not shown in a BEAM model.
Steel Helical Pier, Picture taken by Chris Bennett Photography
Along with the strategies to change the formation of the garage in order to lower the carbon footprint of a house, MPH has also used some other interesting approaches. In the Gorham Passive House, no concrete frost walls were used for the house or garage. The lack of frost walls prevented at least 4,000 kg CO₂e from concrete on that build.
In another build, helical piers were used instead of a foundation for the garage. The use of helical piers allowed for no concrete to be used on this part of the build. Since no concrete was used, the project saved itself from around another 4,000 kg CO₂e, effectively making its MCI 120 which is low. The key thing I have found that makes a house rank high or low on the MCI scale, is the concrete usage or lack thereof.
My final thought I will share is the importance of a tool such as BEAM getting incorporated into building. As BEAM models or an equivalent get wide-spread I believe construction will become a ‘greener’ industry. There needs to be focus on reducing impacts from all aspects of building. BEAM allowed me to understand the extent of carbon released from one building based on materials alone.