|Re: Energy demand is the problem - CO2||<– Date –> <– Thread –>|
|From: Norman Gauss (normangausscharter.net)|
|Date: Sat, 16 Jul 2011 10:55:43 -0700 (PDT)|
Sharon: Here is an excerpt from the Wikipedia website on carbon dioxide: "In indoor spaces occupied by people the carbon dioxide concentration will reach higher levels than in pure outdoor air. Concentrations higher than 1,000 ppm will cause discomfort in more than 20% of occupants, and the discomfort will increase with increasing CO2 concentration. The discomfort will be caused by various gases coming from human respiration and perspiration, and not by CO2 itself. At 2,000 ppm the majority of occupants will feel a significant degree of discomfort, and many will develop nausea and headaches. The CO2 concentration between 300 and 2,500 ppm is used as an indicator of indoor air quality." Your community's goal to minimize heating fresh air before it enters the building's circulation means that a compromise must be reached between maintaining indoor air quality and keeping the temperature within the range of human comfort. In the process of pumping in fresh air, there also must be a consideration of getting rid of stale air. Buildings situated in areas with extremely cold winters frequently have special devices known as heat exchangers. In some tight buildings it is necessary to pump indoor air to the outdoors because it is stale. Before this happens, the stale air is routed to heat exchangers so that the heat of the stale air can be used to heat the incoming fresh air. For very tight buildings this is essential because of the back pressure that stale air can present when fresh air is trying to enter the building. In our common house, we have continuously running exhaust fans in our restrooms and shower which also pump air out of the rest of the building so that there tends to be a partial vacuum. We have vents that supply makeup air for these exhaust fans. Since our climate has mild winters, we have no need for heat exchangers. It is important not to confuse the concept of exhaustion of combustion gases with air quality in the occupied spaces. Upon installation, furnaces and water heaters have efficient ways to avoid mixing combustion gases with indoor air. Norm Gauss -----Original Message----- From: Sharon Villines [mailto:sharon [at] sharonvillines.com] Sent: Friday, July 15, 2011 1:47 PM To: Cohousing-L Subject: Re: [C-L]_ Energy demand is the problem On 15 Jul 2011, at 1:22 PM, ehrbar [at] greenhouse.economics.utah.edu wrote: > The heat which a CO2 molecule prevents from escaping from the earth > through the greenhouse effect is tens of thousands times more than the > combustion heat generating this molecule. > One can say carbon combustion is a gift that keeps giving. Well, it isn't directly off topic since we all make energy consumption decisions and redesign plans for our communities. I have a related question related to CO2. We have two fresh air ducts on our HVAC system for the large dining room and kitchen of our commonhouse. The dampers were always open but we only needed that much fresh air when the room was fully occupied. We asked the HVAC engineer to wire the dampers and put a switch upstairs so we could open the dampers when we were expecting a large crowd but otherwise not be heating and cooling outdoor air. He said that was against code and instead put a CO2 sensor on the vent that is supposed to open the damper when the CO2 is above 1000 (we think). The other night, with no one in the CH and no cooking going on, it was 954. Some of the numbers I've found say that outdoor air is 300-400 and that people start complaining at 600-800. CO2 itself isn't highly toxic but is used as indicator of other toxins that might be present. On TED there is one lecture from a man in Delhi who lowered the levels in his building and saw a dramatic reduction in sick days and productivity. He used plants to improve the air quality. What levels do you consider optimal? Not compared with "this won't kill you" but with healthy air. Anyone out there can answer, I just noticed that Hans raised CO2 and thought he might know. Sharon ---- Sharon Villines Takoma Village Cohousing, Washington DC http://www.takomavillage.org _________________________________________________________________ Cohousing-L mailing list -- Unsubscribe, archives and other info at: http://www.cohousing.org/cohousing-L/
- (no other messages in thread)
Results generated by Tiger Technologies Web hosting using MHonArc.