I still remember using spray foam insulation in my early green renovation projects – it was almost magic! It sealed and insulated in one shot. It made it easy to finish attics and avoid most of the problems with fiberglass batts that were the common insulation on our jobs.I quickly became an advocate for spray foam, recommending it to clients regularly with excellent results. It was, and still is, a very good solution to certain problems in construction, particularly when used to create an insulated, semi-conditioned attic. This makes a big difference in building performance here in the south where almost everyone has an HVAC system in the attic.It was always fun to see the amazement of both homeowners and professionals checking out comfortable, insulated Atlanta attics in the summer. After they experienced this first hand, it wasn’t that hard to convince people to pay for spray foam.Beyond spray foamRecently, however, I’ve been revising my opinion on spray foam, as well as many other common and high profile “green” products. Not that I think spray foam is a bad product, rather that I have grown to see it as an easy way around bad design decisions, particularly in new homes.In renovations, particularly attic expansions, spray foam may well be the most appropriate insulation, but most new homes can have excellent performance with proper design and construction using more traditional materials. If we keep mechanical equipment out of attics and crawlspaces, avoid conditioned attics, and design building envelopes that can be simply air sealed and insulated, almost any insulation will work just fine. Spray foam is just one of many products out there that can be part of a high performance building, but it certainly isn’t the best or only solution.Tankless heaters and PEX aren’t the only answersMy evolution in thinking also includes products like tankless water heaters and PEX manifold piping. Tankless water heaters and PEX manifolds are both hot items in green building, and many people believe they are required in high performance homes. But as I have learned from both personal experience and industry pros like Gary Klein, the water heater is just one part of an efficient system, one in which the piping is at least as important as, if not more important than, the heater itself.And as Gary has demonstrated in articles and presentations, PEX manifold piping is not the panacea that many believe it is. Manifold piping can be installed just as badly as any other system, wasting lots of water and energy in the process. There is nothing wrong with tankless heaters or PEX piping, but just like any other good product, they must be considered as part of the entire house system, and be installed properly, to work efficiently.Why have we forsaken wood?Fiber-cement siding is common “green” product that gets a lot of attention for its durability, but this durability comes at a cost. It isn’t recyclable and won’t deteriorate for generations, if ever. Few installers take the proper safety precautions while working with it, putting them at risk from inhaling the dust created from cutting the material.Fiber-cement has been hailed as a green alternative to wood siding and trim products, but when we look at the pros and cons, it seems like wood offers a better, if sometimes more expensive, solution. Wood is renewable and reusable after deconstruction; it deteriorates in landfills, doesn’t create the same level of health hazards in manufacture and installation, and, when installed well and properly maintained, is pretty durable.Every day I learn something new about green building, layering the accrued knowledge over the months and years, and using it to come to new opinions on a regular basis. I enjoy what I learn from others in the industry and appreciate how it affects my opinions. Maybe, like many politicians, I’m just a flip-flopper, but I can live with that if it ultimately leads me to making better decisions.