2019 Idaho Real Estate Blog

Home ventilation Main The Durable Green Home
So what is the requirement for ventilation for homes? ASHRAE 62.2 standard is 7.5 cfm/person plus .01 cfm/ft2 of conditioned floor area. so for 2000 ft three bedroom home with 4 occupants means 4 x 7.5 = 30 cfm (people load) and 2,000 ft x .01 cfm/ ft2 = 20 cfm (house / furnishing load) so 30 + 20 = 50 cfm. so there is the standard. but what else should we think about? indoor air pollutants? furnishings? smokers? Condensation problems? hobbies? unvented combustion appliances? the list goes on and on, and How do we ventilate? Is ventilation required?

Well I will not go into the code and the contradictions there, and as far as Energy Star homes are concerned they refer back to code for ventilation, specs are at http://www.northwestenergystar.com/ But for this conversation lets talk about a few methods, not that these might be the only ones, just points to consider whether new construction or remodel. There are all kinds of ways to ventilate a home I would recommend  reading the PDF at http://www.buildingscience.com/ titled Read this Before you ventilate, or the Ventilation Guide by Armin Rudd available at http://www.eeba.org/ these are great resources to help figure this out. Also it looks like ASHRAE is going to redefine the standard or at least they are talking about doing that this coming year to require ventilation in new and older buildings alike, Article in Home Energy magazine March or February issue. could this produce some durability problems? you bet. So briefly how do you ventilate? Well to start I don't like the "dump air into the building approach" this method brings a vent into the home and relies on the furnace to pull outside air into the home. Who wants outside air introduced and dumped? can you control this? Maybe but I don't think so, can you damper it to control Thermo-siphon loops? is the heating contractor getting the right damper? could this be uncomfortable? YES, could there be pollutants? do we have months with poor outdoor air quality in the summer (fire season, spring) or months in the winter (inversions) YES. But this is a way to introduce air. There are also ways to do the same thing but filtering the air through a tempered passive vent that has a filter, still outside air and not a good filter. Then there is the vent into the return side of the furnace controlled with different methods that brings fresh air (calculated  controlled ventilation) and feeds it through the forced air system and into the home Tempering and filtering the fresh air. We are getting better, but still not the best. So what about HRV or ERV units? these are becoming more and more popular and readily available for the price of a latte a day, we can have controlled, calculated, purified, balanced fresh air for our homes with the capacity to increase the ventilation on times when we might need it, say those parties we like to have once in a while, or the cleaning people who have not caught on to more healthy, low VOC cleaning products (Yuck). you can research these at the American lung association web site, Canada gives tax credits for Venmar units http://www.venmar.com/ and Broan, Honeywell, etc have all come out with like units that are affordable. Another reason a person may want these units are  allergies or asthma. what about just building a leaky home? do you know where the air comes from (crawl, attic) do you really want to rely on air infiltration to supply your fresh air? Do you know or can you control how much? A home I was in recently (new cheap home) blows a match out when the wind blows outside if you hold it next to the window casing and the wall, do you want this much fresh air? do you want the pollutants, moisture, pollen, smoke, noise, etc that comes with it?or would you like to control the fresh air and filter it? Do you think there are durability problems with leaky homes? talk to one of our preferred Heating contractors on our website if you want to know more about your ventilation strategies. you can also call On Point for a indoor air quality test and report for your home 229-0292. There are also some heating companies out there that test indoor air quality, ask for one that tests VOC's, Particulates, Carbon monoxide and dioxide, and hopefully Radon, and others. This will at least give you a place to start in addressing ventilation. but this is not the only thing you should consider, you will also want to address your lifestyle, and furnishings, floor coverings etc if you really want good indoor air quality. A resource for this is Sharon Patterson at www.omyourhome.com for a Holistic evaluation of your home.

 
Posted by Tad Duby at 3/31/2007 3:15:00 PM
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