Is Expanded Polystyrene (EPS) green?

Last time I mentioned that we (BuildFast) were selected as finalists in the California Clean Tech Open Green Building Category. Our elation lasted for about 2 seconds, until we saw the judge's comments, which were very critical of our use of Portland cement (the key ingredient to concrete) and expanded polystyrene (EPS) as insulation for our building materials. First, let me say I understand the judges' concerns, as it takes a significant amount of energy to make Portland cement, resulting in high CO2 emissions. And it's true that EPS is a non-biodegradable, petroleum derivative. But both of these materials do have a role in green building, if used appropriately . I’ll tackle Portland cement later and focus on EPS for now.

Good or Evil – its how you use it.

EPS, better know as Styrofoam, got its bad rap as a box designed to keep a Big Mac warm for few minutes before spending then next 1,000 years in a landfill. While some people are quick to criticize that all EPS is bad, I believe there is big moral difference between using it for a cup of coffee and using it to keep a family warm for generations to come. EPS is the most cost effective insulation (R-value/$) on the market, and it is readily available around the world ,eliminating transportation costs other products may require. How important is insulation? According to a study by consulting firm McKinsey, proper home insulation is the most cost effective way to reduce CO2 emissions, which reduces global warming.

Large EPS Blocks CAN be recycled

Even here in the progressive San Francisco bay area, it is difficult to recycle individual food containers, but large blocks of EPS can be recycled effectively. While this shouldn’t be an issue for the 100 years or so the building should last, it nice to know the home owner is a pickup truck drive away from recycling the foam blocks at the nearest EPS manufacturing facility. These large blocks can be cleaned, ground up, and added to the mix to make new EPS.

Doesn’t EPS produce CFCs?

Since the mid 1950s expanded polystyrene has not been produced with CFCs chlorofluorocarbons1. EPS manufacturing does use a small amount of pentane and EPS resin, the final EPS product is about 96% air. EPS should not be confused with extruded polystyrene (XPS), which is produced using CFCs.

We need a realistic solution today.

There are over a billion people in the world who lack adequate housing. And according to United Nations estimates, there are at least another billion on their way. While I am excited about some new technologies emerging, all of them are a long way from making a significant difference to fight global warming today.

What about straw bale or other organic materials?

There are people experimenting with straw bale and other bio-alternatives for panel in-fills, and I think this is something we will look at as well. There are two issues using bio-mass – lower insulation value and its risk of decomposing. Lower insulation can be solved by making the walls thicker or using them in more temperate climates, but the rotting & infestation issues could be harder to solve. Our vision is empowering people who are less skilled in buliding to build high-quality houses. The quality of the stucco around a straw bale home is very important. The straw must be kept both dry and breathable. Again, I am not saying we can’t do this, we just need to investigate it very carefully.

This is not the last post on this topic. I will try to determine the net C02 for our house and compare it to current building norms. In the meantime I am happy to hear any other building material recommendations.

References:

1 EPS Molders Association