Are there low carbon bio-based structural insulated panels (sips) commercially available in the U.S.? Most sips use foam for insulation. Are there any that use cellulose, straw or other carbon sequestering materials?
I have heard that Ecococon (straw) is working on building capacity for the US (https://ecococon.eu/us/).
Also Phoenix Haus in Colorado is offering a prefab building panel system with cellulose insulation and wood fibre boards (https://www.phoenixhaus.com/). Both systems are certified Passive House components. Hope this helps…
Thanks Jens. Greatly appreciated! I have another question you may be able to help me with regards to offsetting embodied carbon in a building.
After you have reduced embodied carbon in your building plan and once you have done a life cycle analysis and have the kgs of embodied carbon for the building. What is the best formula for determining the kWh of solar panels needed to offset the embodied (as well as or separate from the operational) carbon? I have not seen anything written about this even from organizations that certify net zero carbon buildings. Please let me know if you have some info or a lead to someone who may. Best wishes, Joe Emerson
Check out the Smart Wall - a collaboration between Havelock wool and 475 Building Supply. https://havelockwool.com/smart-wall-insulation/
Thanks Cathy. Very helpful! Joe
Hi Joe. Not exactly a SIP, but you might have a look at BamCore.
Thanks! Very helpful. Joe
Please reach out if you need further details regarding calcs of renewable energy to offset embodied impacts.
Thanks for this. I appreciate it. What I really trying to pin down is this:
If you have done a full life cycle analysis and know the kg or metric tons of embodied carbon in your building, how do you determine how many solar collectors you will need to offset both the operational and the embodied carbon?
This is especially complicated when we consider that if your utility is using coal to produce electricity, you will get MORE credit for the renewable energy you send back to the grid, compared to sending renewable energy to a grid that is supplied with a fair amount of renewable energy. I do not see anybody, including eTool, addressing how to make this calculation.
Unless it is part of the eTool analysis. Is that possible?
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I am happy to share information on B.PUBLIC’s panels. Our system is a complete envelope based on PassivHaus performance. We offer a variety of R-values for climate appropriate applications. Wood and dense-pack cellulose. We have standard sizes and offer details for foundations, roofing, siding, etc. (http://www.bpublicprefab.com) BIM will be available soon. Please email or message for a tech intro.
Thanks for the information Edie. When our new panelized home directory is ready, we will contact you to give you an opportunity to be listed. I will also be writing a blog on low carbon panels and will include your company. One suggestion: On your website it was not very clear what your panels are made of. It might be good to have a section on the use of cellulose and how it helps reduce the embodied carbon footprint of the panels. Thanks, Joe
another great resource for what Zero Carbon / Zero emissions can mean comes out of Norway:
I am visualizing building emissions along the life-cyle phases and right now it feels to me somewhat feasible to cut off the tally at 2050 as we are trying to avoid imminent emissions to avoid climate change feedbacks. Something like the diagram attached. Depending of where the “Zero” definition is coming from there might be different life-cycle stages included or totally ignored…
After passively optimizing your envelope you can find out what your building is emitting in regards to operational carbon buy running an energy model via a tool like PHPP, WUFI, EnergyPlus, Sefaira etc. Typically these tools have the electricity grid factors (gCO2e/kWh) for different locations built-in and can convert from energy use intensify to carbon intensity. Be aware to include the PV array in your LCA as this can have quite high emissions by itself.
To estimate the electricity offset from a certain size panel array you can use a tool like PVWatts. https://pvwatts.nrel.gov/.
This article (https://www.lowtechmagazine.com/2015/04/how-sustainable-is-pv-solar-power.html) seems to suggest that assuming China as the manufacturing origin for the PV the life-cycle carbon for solar electricity is around 70gCO2e/kWh assuming optimum yield. If your PV array’s latitude, orientation and angle is not perfect this might up to double.
Do you know the electricity grid emissions for your buildings location already?
From this (https://circularecology.com/solar-pv-embodied-carbon.html) and other sources I found the embodied carbon for crystalline PV arrays to be in the range of 2200 to 2600 kgCO2e/kWp installed. (equals ca. 6.5m²)
There is another active thread on PV and solar hot water impacts on this forum: Upfront Embodied Carbon of PV and Solar Hot Water Systems
I hope this helps,
Below are the links with details on calculations and a case study. We include the embodied impacts of solar panels and simulate the carbon credit for feeding renewable energy back to grid by assuming today´s grid coefficient or a grid decarbonisation scenario. EN15978 says to report export energy (D1) only after all annual on site demand (B6) is met by renewable supply. Happy to organise an online chat to run through an example together if you like.
There are a surprising number of manufacturers making wood/cellulose SIPs. Some have already been mentioned, but Bensonwood https://bensonwood.com/building-systems/panelized-enclosures/ is a leader in the field. Barrette https://www.barrettestructural.com/en/prefabricated-walls/, Factor https://www.factorbuildingpanels.ca/, Tooke Tree https://www.tooketree.com/ and Simple Life http://www.simplelifehomes.ca/ are among those offering customizable, carbon-storing panels.
As others mentioned in regards to offsetting embodied carbon with solar panels, it’s not too straightforward because of the regional and temporal differences in electricity generation sources. In some markets already saturated with solar energy, there is a possibility that someone’s PV system won’t even be displacing any more fossil fuels than is already happening for various reasons. That said, you could use the average grid CO2 emissions intensity per kWh (like from the EIA for the United States) and compare it with the intensity of a kWh generated with PV - the difference is your “offset”. LEED and Living Building also provide resources for calculating this.
An alternative is to purchase actual carbon offsets which then fund initiatives like afforestation, carbon capture, and research into decarbonaztion of the materials we use in construction in the first place. The value of installing PV versus pursuing other carbon offsets for decarbonization is whole another discussion though.
Thank you Chris!
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