Some materials made from plastic foam use expanding agents with very high resistance to heat flow thus, when manufactured, produces insulation with a very high R-Value. It is know that these agents disperse from the cellular structure until they reach an equilibrium level many years after it is manufactured. Because gases with a high R-Value disperse outside the cellular structure, the capacity of insulation can see a reduction of up to 30% from its original value. This phenomenon is known as "Thermal Drift".
Expanded polystyrene foams (EPS) do not use these types of agents; therefore, its thermal resistance remains stable throughout the product's life.
The following graph represents the thermal resistance behavior of polyurethane over the years:
The answer is NO. According to some studies, polyurethane R-Value oscillates between 6.25 and 5.56 Btu•in/ft²•h•°F; for practical purposes we are going to use a value of 6.00 Btu•in/ft²•h•°F and as is commonly known, EPS keeps its R-Value (3.85 Btu•in/ft²•h•°F) over time. When comparing both figures (6.00/3.85), for practical purposes, we can see that the factor resulting from this division is 1.50; that is, per every inch of polyurethane it is necessary to multiply it 1.5x in order to calculate the thickness of the expanded polystyrene that offers the same R-Value.
The R-values for various insulation materials can be found in the ASHRAE Fundamentals Handbook:
Expanded polystyrene is being recycled with success worldwide. Forecasts reveal that recycling of EPS will keep growing. There are four main categories of note concerning EPS residues, known as the 4 R's: reduce, recycle, reuse, and recover.
In many parts of the world, more than 50% of EPS is used for durable applications such as thermal insulation of buildings or as weight saving material in different construction projects.
EPS represents only 0.1% of total urban solid residues.
The use of EPS as thermal insulation in construction projects creates climate control energy savings in buildings and drastically decreases contaminant emissions (CO2 y SO2), contributing to the mitigation of the "greenhouse effect" and "acid rain".
Expanded or expandable polystyrene does not use, nor has ever used, foaming gases belonging to the CFC and HFC families. Therefore, its fabrication and use does not contribute to the degradation of the ozone layer.