We as a society — as a species — are well on our way toward climate catastrophe. To avoid the worst-case scenarios we need to drop worldwide greenhouse gas emissions to zero by 2050. Retrofitting existing buildings is a crucial part of meeting that challenge. Buildings are responsible for 40% of wordwide greenhouse gas emissions; and 50% of the building stock will be new or retrofitted by mid-century.
But construction itself is also an energy- and carbon-intensive activity. The manufacture of materials such as insulation can itself release significant greenhouse gases (11% of worldwide emissions and growing). An analysis of insulation by Building Green showed that certain types of insulation could take over a century to provide a positive return on carbon. Existing “deep energy retrofit” practices have been criticized for incurring more carbon debt than they can possibly repay.
We urgently need a simple, replicable, climatically sound, cost-effective model for retrofitting houses like mine.
So, yes, this project is about reducing my family’s carbon footprint and creating a safe, durable home for the coming decades. But it’s more than that. I hope this can be a model for sustainable retrofits of the many similar buildings throughout the Midwest.
With that in mind, the following are my goals for this project:
1. Minimize 30-year carbon emissions.
A few important notes:
- 30-year emissions includes BOTH the embodied carbon (or “upfront carbon“) from the manufacturing and transportation of building materials (incurred at Day 0) AND the operational emissions of the house projected from now through 2050. Why 2050? Because that’s when we need to be at zero emissions. Carbon emissions after that point are almost moot: If our electric grid is still emitting carbon in 2050, we should start looking for a new planet.
- “Carbon” as I use it throughout this blog is shorthand for “carbon-equivalent greenhouse gas emissions.” So, it includes emissions of all greenhouse gas, calculated in terms of carbon equivalent impact.
- I hope to achieve Net Zero Energy — producing as much energy as my household consumes on an annual basis with rooftop solar panels — BUT ONLY IF that approach aligns with the top-line goal. In other words, it’s possible that the scenario that minimizes 30-year carbon does not get the house to Net Zero, because Net Zero may require more insulation, or more PVs, than the operational carbon savings justify.
2. Design for durability & long life.
Because construction is a carbon-intensive activity, we must (a) build new only when necessary, opting to retrofit whenever possible, and (b) when we do build, make sure we’re building for the long term, so as not to require another major carbon investment in a few short decades. So in this sense, the second goal is a logical extension of the first.
My house is already 150 years old. How can I make sure it will last for another century? There are a few parts to this:
- Durability: Do no harm to the brick bearing walls. This house consists of 12″ thick brick walls sitting on a 16″ thick stone foundation. It sounds neigh impenetrable — but it turns out that insulating brick the wrong way can do severe damage over time. Improper insulation can prevent the brick from drying out, can exacerbate freeze / thaw damage, and can create condensation that can rot the wood joists and break apart the soft clay bricks themselves. This retrofit seeks to avoid these issues.
- Long life: Design for aging in place. The current house has steep stairs, with no bedroom or full bath on the first floor, and laundry in our 6-foot-tall cellar. I intend to explore adaptations that would accommodate aging and improve accessibility.
- Long life: Adapting to future climate. The home must be livable, even as our world changes. (More on this below.)
3. Create a healthy home.
This is a home for a family, including two growing boys. Creating a healthy home should be a no-brainer; unfortunately, that’s not the status quo. This retrofit aims to improve health in 4 ways:
- Remediate the known toxins (namely lead paint).
- Avoid new materials with known toxins. “Toxins,” of course, is a broad and problematic term, so in practice I will aim to avoid the “red list” materials identified by the International Living Future Institute.
- Manage moisture carefully. When adding insulation in a mixed-humid climate, the risk of condensation is high — and with condensation comes mold, rot, air quality issues, and other problems. This home will be designed to avoid condensation in assemblies; will be detailed to keep bulk water out; and (to paraphrase building science guru Joe Lstiburek) will allow water out when it gets in anyway.
- Provide excellent indoor air quality. This is a combination of avoiding contaminants like VOCs, providing plenty of fresh air for occupants, and having excellent filters to screen out particulates and other pollution (which are expected to get worse …).
4. Prepare for climate-related disruptions.
We are committed, at the very least, to 1.5 degC of warming (and more likely 2 or more degrees). But even these “best-case” scenarios comes with a plethora of disruptions, both major and minor — from power outages to heat waves to more intense downpours.
The Fourth National Climate Assessment outlines predicted climate-related risks for the Midwest region, including:
- Higher temperatures in both summer and winter (including higher night-time temperatures)
- Increase in extreme heat waves (days over 95 F)
- Degradation in air quality (increase in ground-level ozone, sulfur dioxide, and VOCs)
- Intensification of heavy downpours and flash flooding
- Increased risk of disease carried by insects and rodents
- Decline in drinking water quality (result of flooding & increased agricultural runoff)
- Increased frequency of drought, especially in summer
- Reduction in agriculture productivity (5-25% by mid-century)
The retrofit should enable the house to continue to provide shelter, comfort, and safety through as many of these eventualities as possible.
5. Be a model for others.
Part of my motivation for starting this blog is to create a replicable model that can be utilized on similar buildings in this climate zone. Retrofitting one building, while it might give me warm fuzzies, won’t solve the problem. But inspiring others — and creating a scalable model for retrofits — could make a meaningful impact.
To that end: please feel free to reach out to me with questions or comments — especially if this is something you’d like to take on yourself.