Alternatives to CFCs and Global Warming: A Systems Approach to Evaluating Net Contributions

Conclusions

Two major conclusions can be drawn from this information. First and foremost, incorrect decisions can be made if entire systems are not considered carefully in evaluating impacts of alternative technologies. Expanded polystyrene bead board and resinated mineral fiber boards are alternative insulating materials that could be used in place of CFC blown foam insulation in commercial buildings. Neither of these materials employ greenhouse gases so, on the surface they may appear preferable to foam insulation. However, neither of them is as effective in blocking heat transfer as HCFC blown foams and their total equivalent warming impact is higher than that of some insulating materials that do use greenhouse gases. This is illustrated clearly in Figure 1. A second conclusion that can be drawn is that in some cases there are no significant differences between alternative technologies, even when the entire system is considered. Figure 2 shows that there are very minor differences between the TEWIs for HCFC-123 and HCFC-141b as foam blowing agents in refrigerators using either HFC-134a, HFC-152a, or the ternary blend as refrigerants. There is not a strong basis for preferring any of these compounds as refrigerants or blowing agents on this criteria. Again, however, one would reach a very different conclusion based solely on comparisons of the GWPs of these compounds.