In last week’s column about shifting from combustible wood-frame home construction to fire-resistant concrete home construction, I reported that an Australian company has developed a “green” concrete which reduces the large carbon footprint of traditional concrete made from Portland cement. Concrete manufacture and deployment reportedly is responsible for 8% of global CO2 emissions.
A reader shared with me information about the Portland Cement Association’s release of its “Roadmap to Carbon Neutrality” in October 2021, suggesting that the industry is aware of its carbon footprint and wants to reduce it.
Here’s an excerpt from a press release published online:
“The PCA roadmap involves the entire value chain, starting at the cement plant and extending through the entire life cycle of the built environment to incorporate the circular economy. It recognizes five main areas of opportunity: clinker, cement, concrete, construction and carbonation (using concrete as a carbon sink). Each phase of the value chain is integral to reaching the goal and can unlock unique and specific pathways to carbon neutrality, including actions such as reducing CO2 from the manufacturing process, decreasing combustion emissions by changing fuel sources, and shifting toward increased use of renewable electricity.
“The association is committed to gathering a coalition of industry experts, researchers, policymakers and companies along the value chain to make the roadmap a reality. ‘PCA is actively engaging with organizations beyond the industry to bring the right people to the table to accelerate and advance solutions to reach carbon neutrality,’ said Massimo Toso, PCA climate and sustainability council co-chair, and president and CEO of Buzzi Unicem USA.
My previous two columns about reducing your home’s vulnerability to wildfires generated a lot of reader response, providing even more to write about on this important subject.
Fire resistance is personal for Rita and me, since we live in a wood frame home backing to open space which would be ready fuel for a wildfire.
I’ve been told that following an 1863 fire, Denver passed an ordinance requiring masonry construction. Somewhere along the line, that requirement was dropped. I wouldn’t be surprised to see building codes changed once again restricting wood construction.
While there’s a trend toward requiring fire suppression systems inside homes, they are designed to suppress fires which originate inside a home. If a fire originates externally, such systems may be of limited effectiveness in saving a structure.
Last week I wrote about ICFs — insulated concrete forms. Concrete is poured into a form which has insulating EPS (expanded polystyrene) on each side. This produces a concrete wall which has insulation pre-installed on each side of it.
A couple readers made me aware of the opposite approach, a concrete wall in which the “sandwich” has concrete on the outside and the expanded polystyrene on the inside.
Reader Lynn Greene invited me to visit her home in Perry Park (see picture below), southwest of Castle Rock, which was built with Thermomass® walls and concrete floors developed by Composite Technologies Corporation of Boone, Iowa.
Lynn’s tenant told me that the energy costs peak out at about $70 per month to heat the house with radiant floor heating built into the concrete floors. That heat is provided by a high efficiency boiler using natural gas. Large south-facing windows provide a lot of free winter time heating. (Notice the large overhangs shading the south-facing windows in summer but not in the winter.)
The Thermomass walls were poured in place, less expensive and more attractive than walls built of uninsulated concrete block. It also allowed electrical and other conduits to be built into the walls instead of surface mounted afterward.
Another “sandwich” approach is sold by a company called RSG 3-D, but they create panels which are assembled onsite instead of being poured in place. Also, their polystyrene interiors (which are wider) have steel connectors instead of the plastic connectors used in the Thermomass walls. That reduces the insulating quality of the wall, since metal is a conductor.
Another reader reminded me that the making of concrete is a major source of carbon dioxide, a greenhouse gas. According to Wikipedia, “The cement industry is one of the two largest producers of carbon dioxide (CO2), creating up to 8% of worldwide man-made emissions of this gas, of which 50% is from the chemical process and 40% from burning fuel.”
Click here to read an article from The Guardian about the development of “green concrete” in Australia that sounds very promising. As you may know, “concrete is made from approximately 10% Portland cement, 3% supplementary cementitious inclusion (for example fly ash), 80% aggregates (such as gravel and sand), and 7% water.” Then it is reinforced with steel, which has its own huge carbon footprint. By replacing the steel with recycled plastic, that impact is mitigated, and, according to article from The Guardian, the Australian company Wagners has created earth friendly concrete using blast furnace slag – an industrial waste from steel production – along with fly ash, a waste from coal power generation, as a replacement for Portland cement.
To make a concrete home truly resistant to wildfire, it is necessary to make the windows and doors and other openings fire resistant too. There is glass (with frames) rated for 20 to 180 minutes of fire resistance. See www.fireglass.com.
Lastly, one must deal with roofing. Another reader made me aware of the synthetic roofing by CeDUR which was installed on her Wheat Ridge home and which is also on Woody’s Wood-Fired Pizza:
It looks just like a wood shake roof and is installed the same way in individual shakes, but it has the highest rating of fire resistance (Class A), earning homeowners a substantial discount on their homeowners insurance. Learn more at www.cedur.com/fire-safety.
There are vents of all kinds not only on your roof but on soffits, foundations, eaves and gables, and they need to be protected from flying embers. Vulcan Vent sells vents for all those openings, “built to create a barrier against wind-blown embers and flames in the presence of intense heat.” Learn more about them at www.VulcanVents.com.