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Choosing Insulation for Carbon Value – Why More is Not Always Better Part 1

SWA’s Enclosure Group is acutely aware that insulation is the most important single material choice to maximize the enclosure’s thermal resistance over its operational life. Many of us in the building industry believe that, combined with a good continuous air seal, the highest insulation value makes the greenest enclosure, helping to reduce a structure’s carbon footprint and combat climate change. It may come as a surprise, then, that some of the most commonly used insulation materials are so carbon-heavy to manufacture and/or install, that for many decades they wipe away the carbon-energy savings they are supposed to provide.  The following is a detailed discussion of how and why this is, and what the industry is doing to change the equation.

Embodied vs. Operational Carbon

The built environment looms large in the climate picture, because almost 40% of the total carbon put into the planet’s atmosphere each year is attributed to buildings. Over the past 30 years of green building, we have overwhelmingly focused on operational carbon – the carbon that buildings emit as they are being used. Only recently have we begun to focus on embodied carbon – the carbon that goes into constructing buildings, which is typically far greater than the energy saved in the first decades of operation. Changes in energy codes are aimed at operational carbon, and even those organizations and standards that have been at the forefront of promoting sustainable building [LEED, PH] have not been quantifying or limiting embodied carbon, although they bring attention to it.

The Time Value of Carbon

Assuming that a building stands for many decades, or even centuries, its operational carbon will eclipse its embodied carbon over its lifetime, and therefore when the building’s carbon Life Cycle Assessment (LCA) is calculated, operational carbon savings will be more important than embodied carbon saved/spent in the long run. Why does embodied carbon deserve equal weight with operational carbon? Because of the total global carbon emissions from buildings, 28% is pegged to embodied carbon. That’s already a large percentage, but when you consider the near term, the first 30 years of a building’s life, the percentage jumps to about 50%. In effect, every new building is in carbon debt upon completion due to the huge amount of carbon emitted  in order to construct it., And in order for the climate to benefit from the energy savings provided by a well-insulated and sealed enclosure and a high efficiency energy system, the building needs to last and be used for a very long time. The problem is that we may not have 30 years, let alone 60, to pay off that carbon debt.

In the first 30 years of a building’s operational life, 50% of its total carbon emissions are still due to embodied carbon (Source: Architecture 2030)

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Electric Cars: Are They Better for Your Pocket and the Climate Right NOW?

Last week, I read a blog post from Connecticut Fund for the Environment President Curt Johnson, and he reaffirmed what I already expected: my next car will likely be an electric vehicle (EV). I currently drive a Toyota Prius hybrid, but when I bought it in 2013, the price to purchase and to operate an EV did not work out, so I chose the Prius, which has very reliably achieved 50 mpg over the last six years.

As an engineer who admittedly knows nothing about cars, I feel like the information out there on EVs is either slightly biased (i.e., published by EV manufacturers) or not transparent enough with the math to convince me. So I set out to create a blog post that was unbiased and transparent. I liked this one from Tom Murphy, an associate professor of physics at the University of California, San Diego, so hopefully I’m making it a bit more user-friendly and applicable to your current/local situation.

I just wanted to know two simple things (and admit to ignoring a long list of other factors that influence the type of car most people will choose to drive):

Number 1: At what gas price is an EV cheaper to drive per mile?

Number 2: While EV tailpipe emissions are zero, is my local electric grid clean enough that it’s a good idea, right NOW? I know my next car will be electric, I just don’t know WHEN the grid will be clean enough that it’s better for the environment for me to switch.

When I began writing this article, I had no idea what the answers would be.

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Buildings to Cool the Climate

The Intergovernmental Panel on Climate Change (IPCC), viewed as the most credible source of climate change research, issued an alarming report on October 2018 removing all doubt – absent aggressive action the atmosphere will warm up by as much as 2.7 ° F above preindustrial levels by 2040, inundating coastlines and intensifying droughts and poverty. The significance of this report is that the effects of climate change will occur in our lifetime.

The building construction sector has a critical role in drawing down carbon emissions by 2040. As nations all over the globe tackle operational emissions from buildings, we must now address our total emissions impact.

Estimated cumulative carbon emissions from new buildings 2020 to 2070

Life-cycle emissions resulting from buildings consist of two components: operational and embodied. A great deal of effort has been put into reducing the former as it is assumed to be higher than the latter. Studies have revealed the growing significance of embodied emissions in buildings, but its importance is often underestimated in energy efficiency decisions.

According to the Embodied Carbon Review 2018 by Bionova Inc, embodied carbon is the total impact of all the greenhouse gases emitted by the construction and materials of our built environment. Furthermore, during their life-cycle, the same products also cause carbon impacts when maintained, repaired, or disposed of.

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Low-Carbon Concrete: Reducing the Embodied Energy of a Notorious Emitter

It is safe to say we are in a climate crisis. Of the last 17 years, 16 have been the hottest on record.[1] Sea level is expected to rise by as much as eight feet by the end of the century.[2] And by 2050, as many as 140 million people will have been displaced by climate change.[3] The time to act is now, and a major area of impact is buildings, which account for 40% of carbon emissions in the United States. Better envelopes, lighting, and mechanical systems are helping buildings become more efficient, which means an increasing proportion of carbon—up to 68% of a building’s lifetime emissions—is locked up in materials.[4] This “embodied” carbon gets released during a material’s extraction, manufacture, transport, maintenance, and, eventually, disposal.

If our industry is to meet the 2030 Challenge of carbon neutrality by the close of the decade, we will need to reevaluate building materials and select low-carbon alternatives.

Embodied carbon life-cycle

Figure 1: Courtesy of Faithful+Gould

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