RIP: Solar Powered Attic Ventilator’s

Welcome to a new series, based on putting numerous bad building practices and so-called green myths & misconceptions to rest. While I wish I could take credit for this idea, I do have to give the credit to this week’s – Let’s Blog Off. Needless to say, it was supposed to be based on writing one’s one obituary and limited to 208 words, but seeing there are not any real rules – why not change it up some? With that said, we will have a list of all the participating bloggers at the end and based on a few comments I have heard, they ought to be great.  

RIP: Solar Powered Attic Ventilator (aka SPAV)

SPAV, 1980’s – 2010, a key figure in costing the average homeowner $800 a pop died this day from complications brought on by Acute Respiratory Distress Syndrome (ARDS). While touted in some well known publications like the 2005 Building Products Magazine as one of the Most Valuable Products, it unfortunately never managed to live up to any of its hype.

SPAV is commonly touted utilizing such misleading messages such as its ability to cool an attic, prevent ice dams, and eliminating moisture problems. While the pages sound great and are filled with some well-known building science data, the problem is that the same science has never proven their worth. In many cases, these units are specified in leaky, under-insulated houses that can cause depressurizing causing possible combustion safety issues, radon issues, and sending that costly air-conditioning outside.

While many warnings of ongoing issues were provided as far back as 1995, the SPAV coolly dismissed them. Now it is commonly found being listed on many sites under the Useless Products List (#5). Unfortunately, rumors abound that this is not sitting well with those that have made fortunes off selling them and they are fanatically denying its death.  Ahhh well, I guess somebody will always chase after an easy dollar.

While this article is partly written in gist, there are major issues with simply believing the hype. For example, while I do not live up north, I really do have to ask – can anyone tell me how a solar powered fan (especially with a thermostat) buried in snow is going to help prevent ice-dams? Can anyone tell me how pulling in the hot humid air here in the southeast, will lower the moisture in the attic? I got news for you; in both cases, it does not and will generally exacerbate both of those conditions.

Now many people will argue the point that the test was compiled back in 1995 and we should do new testing. To some extent, they are right, but oh so wrong as the same issues listed in the original study still exist today even in newer homes. With that stated, there are a few areas where a fan like that does make sense; like a roof where one cannot add in the required ventilation at the upper section. If you have an existing house & are noticing that your attic is hot as you jump on a step stool and can feel the heat radiating down, notice weird melting patterns of the snow on your roof, or can just feel the heat or coolness before you go to open up the hatch, there are some places where your money will probably be better spent.

1. Have your house tested with a blower door and eliminate air leakage between the attic and living space.
2. If your attic hatch is extremely hot, it needs weather stripping and insulated with either a foam box covering or foam directly applied to it.
3. If you have air ducts or an air handler located in the attic, at minimum you should have your duct system tested, sealed and insulated.
4. Insulate the attic floor to a minimum of R-30 (or what the codes dictate for your area) after air sealing.
5. If you are replacing the roofing, look for ENERGY STAR® shingles or metal roofing & make sure the proper amount of ridge and soffit passive ventilation is installed.
6. If you are not replacing the roofing and an inadequate amount of venting is installed, bring in a professional to help evaluate and perform the proper retrofitting work.
7. Consider going with a hot-roof system

Ok, and now to see who played fully by the rules… (and for the record – 207 words for the actual obit)