Hidden Carbon: A Closer Look at the Building Lifecycle
When most people think about a building lifecycle or lifespan, they tend to think of it in a very linear fashion, where it spends a couple years in design, a couple years getting constructed, and then 60 years or more in the standard operation phase, where people are heating the building it, cooling it, turning the lights on, et cetera. Then, eventually, it gets demolished.
The challenge from a carbon calculation perspective is that buildings don't operate in a consistent, linear fashion. Buildings are much more like living things. Their needs change, their uses change, and they're constantly readapting to what the needs of their occupants are.
Case Study: How a Building Changes Over 150 Years
Let’s look at The Dryades Market in New Orleans. It was built in 1849 as sort of a grocery food market where people could come and get fresh produce, meat, et cetera. It operated in that capacity for over a hundred years. In the 1970s it was readapted into a big box retail store. While it was still a retail use, the building had very different space needs, not to mention major systems updates.
Then, about 40 years later, the building was readapted again and went through a major renovation to become the New Orleans Jazz Market. This LEED-certified entertainment space features state-of-the-art technologies and amenities throughout the 350-seat theater.
This building is a shining example of how a building can be reimagined and redesigned. It avoided demolition, but there are still carbon costs.
Buildings are Living Things
The idea that a building gets built once and then just operates in that standard format doesn't really make sense with how we see buildings used today.
Instead, the idea is that buildings are living things. There are a lot of products and materials that go in during the construction phase - Product stage A in the chart below. In the operational phase, or Use stage B, you can't negate the fact that there are still material carbon changes happening that you need to consider as well.
A true carbon calculation of a building must include the carbon impacts of those materials all the way up until its end of life (stage C and D), whether it's either recycled or disposed of.
Requirements for a complete carbon calculation: Scope A1 through D
Measuring the True Carbon Impacts
Embodied carbon and operational carbon are two things that you need to be looking at all points in the design construction process.
Before we go on, let’s level set on what we mean by embodied carbon.
Embodied carbon is the carbon dioxide associated with the emissions of all the manufacturing, transportation, installation, maintenance, and disposal of the building materials.
Forecasting During Design Phase
When we look at carbon impacts by phase, for example, during the design phase, you should really be looking at both embodied in operational carbon in terms of forecasting.
The embodied carbon is heavily driven by what materials you're evaluating, what you're specifying, what you're putting into your design as your basis for what the contractor should be using to build that building.
For operational carbon, you’re forecasting what do you think it's going to use in terms of its energy and water once the building is up and running and people are occupying that space.
Materials Evaluation and Specification
When you move into the construction phase, it's when you start getting into those real actuals, checking your work and your assumptions.
For embodied carbon, this is heavily driven by your materials. Material procurement is a big one, and this is really when you want capture that actual A1 through A3 scope.
As we know, a lot of times what we specify and select is our basis of design doesn't always make it into our construction projects. We've all had the case of a contractor substituting some product or material for something else. So, it's really important when we get to that construction phase to back and check what materials have been put in and what that carbon impact is.
Because it might be higher, it might be lower. Additionally, you should be really paying close attention to what the installation process looks like for your contractor. The A4 and A5 scope can vary widely depending on where your project is located, what sort of equipment your contractor is using, what are their standard practices for reducing waste and things like that. So that's something that really needs to be carefully tracked at your job site as you're going through construction.
What about Construction Waste?
A lot of people tend to think about waste in terms of just diverted from landfill percentages and how much could be recycled? What many fail to think about or account for is the fact that even waste that is recycled has carbon impacts associated with it. We need to look at C1 through C4 and D1 scope.
When you're hauling that waste away, you're going to have all those transportation emissions, whether it's going to a recycling plant, whether it's going to a landfill.
If you're hauling off concrete that you're going to reuse, it needs to be ground up. You have all that energy associated with that equipment that grinds it up and turns it into a new product that could be reused.
There are carbon impacts for diversion methods. You know, every, every diversion method, whatever that might be, does have a carbon impact. We need to evaluate, not just is it getting diverted from landfill or not, but how am I diverting it and what's the carbon impact of that process? Or might there be alternative options available to me in my location that might be more carbon effective or efficient.
Getting Our Arms Around the Ever-Growing Operational Phase
When we get to the operations phase, operational carbon becomes the thing that everyone kind of thinks about. They understand it that the building is now up and running. You'll be tracking your energy consumption in terms of water, waste, fuels, et cetera, at that operational level, scope B1 to B5, C1 to C4, and D1. What does it take to actually use the building?
The challenge is that embodied carbon keeps progressively growing the building’s carbon footprint.
The initial impact of what you spent in terms of carbon cost to build the building does decrease on a year-over-year basis as the building lifespan ages, and that is tracked in A1 to A5 scope. However, material replacements – upgrades, new tenant fitouts, new construction work, and even just painting, carpet replacement, and other maintenance – all of those have material carbon impacts (B1 to B5 scope). This really changes the embodied footprint of the building.
The calculation is not a static one-and-done process or evaluation when the building's completed initially.
Demolition: Even Diversion Has Carbon Costs
Now let’s look at the final stage or end of life for our buildings. That’s covered by C1 to C4 plus D1 scope. We have to look at our holistic carbon impact for that project throughout its entire lifespan. Is the building being disassembled and recycled, or going straight to landfill? What is the embodied carbon of that materials based on how did we divert them?
Not how did we think we could divert them or what might have been recoverable, but what did we actually do with those materials when we took that building down so that we can come up with that full scope holistic look and how much carbon did that building use across its entire lifespan?
We can only improve what we measure. Accuracy in our carbon calculations is essential. When we measure how our buildings perform against initial predictions, we are able to make improvements.
In a future blog I’ll talk about embodied carbon analysis, how it currently works and why it needs to have a reboot.
Where do you see gaps in carbon emissions calculations on your projects? Email us at info@blueoceanaec.com.