Another problem of most product-based LCA systems is the assumptions that they must often make about the use of a material. In many LCA systems, the use phase is the area of most uncertainty. This is partly because the impacts involved are so specific to the building and situation. Obviously this is a big deal for building materialswhich have such a long use period. The problem is a bit different for individual products, for building assemblies, and for whole buildingsand thus the solutions can be quite different. For buildings, operating energy is the biggest factor. But for individual products, cleaning and maintenancewhich may generate substantial emissionsmay be bigger considerations. Does a flooring product, for example, require frequent cleaning? What kind of cleaners must be used? The indoor air quality (IAQ) impact of maintenance may be far greater than some products production impact, especially with such a long-life product. The final challenge to LCA is, of course, generalizing its use throughout the building industry, including manufacturing. Solving the problems discussed above will help, but conversely increasing the popularity of LCA will help solve those problems. LCA is not something that the non-specialist can do. However, it is not something that the average designer, manager or regulator would want to do. What is needed are intermediary tools that make the results of LCA studies available in practical forms that can be easily used. The explosion of life-cycle awareness in the last decade has in fact resulted in the emergence of just these kinds of toolsfor use by architects, engineers, product designers, managers, etc. Some of these are programs, like BEES, that designers can download (sometimes for free) from the Internet and then use to plug in numbers and weightings for their particular projects. Others are directories or guides that designers