Guest guest Posted May 21, 2004 Report Share Posted May 21, 2004 Don't be too impressed. I didn't write it, I'm just trying to understand it! I look forward to meeting you too. Tim Toburen RE: Re: Building leakage > > > > > > > > Does anyone know of an economical way to test if a building has > > leakage to the building envelope.(the outside walls)This may be > > required to see if a building could sustain a wind blowing directly at > > > it which contained a CBR agent. The HVAC system is turned off so there > > > is no positive pressure due > to > > possible ingress through the system. > > > > One system I thought of was using SF6 a decay trace gas, released in > > side and with AHUs and entrance doors sealed. Log how long before it > > leaks out, but the gas will decay anyway so pointless.May be a > > pointless excercise anyway because the wind pressure acting upon a > > building may be far greater than what could be developed inside? > > > > Another question is, are there clearance criteria for buildings > > decontaminated from cbr agents ? > > > > Thanks for any input > > Jeff Charlton > > in London > > > > > > > > > > > > > > FAIR USE NOTICE: > > > > This site contains copyrighted material the use of which has not > > always > been specifically authorized by the copyright owner. We are making such > material available in our efforts to advance understanding of > environmental, political, human rights, economic, democracy, scientific, > and social justice issues, etc. We believe this constitutes a 'fair use' > of any such copyrighted material as provided for in section 107 of the > US Copyright Law. In accordance with Title 17 U.S.C. Section 107, the > material on this site is distributed without profit to those who have > expressed a prior interest in receiving the included information for > research and educational purposes. For more information go to: > http://www.law.cornell.edu/uscode/17/107.shtml. > If you wish to use copyrighted material from this site for purposes of > your own that go beyond 'fair use', you must obtain permission from the > copyright owner. > > Quote Link to comment Share on other sites More sharing options...
Guest guest Posted May 21, 2004 Report Share Posted May 21, 2004 There are a number of ways to estimate the leakage of building enclosures, rooms or cavities within buildings, elements of assemblies and even through sub-grade soils, exfoliated rock materials. The simplest and most repeatable methods use fans (like the Minneapolis Blower or fans used to provide ventilation for the building) to induce pressure differences between different nodes of the connected cavity network, map the pressure differences and measure the airflows creating them. Given enough pressure-flow data calculations of connecting leakage (areas or flows@some pressure difference) can be made. A number of researchers have applied these methods for years (in the US: Grimsrud, Harje, Persily, Lstiburek, Sherman, Turk, Cummings, Moyer, Tooley, Blasnik among others - a literature search on any of these names should find some good papers). CONTAM, which can be downloaded from the NIST website can be used to model these dynamics. There is a fat document on the NIST website that provides the results of many of the research projects for use as inputs to CONTAM models. The only systematic study of non-residential buildings was conducted by FSEC in the mid 1990's on 86 buildings in Florida. Of course if you are thinking of new buildings the task is reversed - you do calculations to see how airtight you have to make things, plan airsealing details you believe can achieve that airtightness and then do on site supervision to ensure good execution and finally pressure test to demonstrate compliance. Hugh and I are currently working on a NYSERDA/DOE project to characterize the unplanned and planned airflows in small non-residential buildings in central New York. We are using fan pressurization methods. For a primer on this topic I suggest an article Jim Cummings and I wrote for ASHRAE Journal last year on unplanned airflows and moisture problems or either of two papers I wrote with Jim, Joe Lstiburek, Bill and Mike in on unplanned airflows in commercial and residential buildings for the ASHRAE healthy buildings conference at the National Institute of Medicine in the mid-1990's. Terry Brennan on 5/21/2004 11:19 AM, Mark R Stroup at Mkstroup@... wrote: Tim, I'm impressed, very good document. I owe you a drink at some future convention. What's you poison? Mark R Stroup CGC, CMR, Pres. Five Star Hospitality Services, Inc. Orlando, FL Re: Re: Building leakage Here is a resource that might help you, although it probably won't directly answer your question. It's from an article dealing with airtightness of building envelopes. Some interesting information about effectiveness (or lack of it) of poly vapor barriers under real-life conditions. http://www.fpl.fs.fed.us/documnts/pdf1998/tenwo98a.pdf Tim Toburen RE: Re: Building leakage > > > Does anyone know of an economical way to test if a building has > leakage to the building envelope.(the outside walls)This may be > required to see if a building could sustain a wind blowing directly at > it which contained a CBR agent. The HVAC system is turned off so there > is no positive pressure due to > possible ingress through the system. > > One system I thought of was using SF6 a decay trace gas, released in > side and with AHUs and entrance doors sealed. Log how long before it > leaks out, but the gas will decay anyway so pointless.May be a > pointless excercise anyway because the wind pressure acting upon a > building may be far greater than what could be developed inside? > > Another question is, are there clearance criteria for buildings > decontaminated from cbr agents ? > > Thanks for any input > Jeff Charlton > in London > > > > > > > FAIR USE NOTICE: > > This site contains copyrighted material the use of which has not > always been specifically authorized by the copyright owner. We are making such material available in our efforts to advance understanding of environmental, political, human rights, economic, democracy, scientific, and social justice issues, etc. We believe this constitutes a 'fair use' of any such copyrighted material as provided for in section 107 of the US Copyright Law. In accordance with Title 17 U.S.C. Section 107, the material on this site is distributed without profit to those who have expressed a prior interest in receiving the included information for research and educational purposes. For more information go to: http://www.law.cornell.edu/uscode/17/107.shtml. If you wish to use copyrighted material from this site for purposes of your own that go beyond 'fair use', you must obtain permission from the copyright owner. > Quote Link to comment Share on other sites More sharing options...
Guest guest Posted May 24, 2004 Report Share Posted May 24, 2004 Jeff Charlton wrote: > > One system I thought of was using SF6 a decay trace gas, released in side > and with AHUs and entrance doors sealed. Log how long before it leaks out, > but the gas will decay anyway so pointless.May be a pointless excercise > anyway because the wind pressure acting upon a building may be far greater > than what could be developed inside. The pressures are orders of magnitude different. However, building components, such as a window, a door, or a wall section could be tested with the same equipment used for water leak testing with a pressure differential representative of design wind speeds. I would think CO2 would make an effective tracer for a short term, small volume test. CO2 could be added from a cartridge, outside air could be measured before an after the test, and air inside the test chamber could be logged with a Q-Trak or equivalent. With those results, the rooms and the house as a whole would have to be modeled with assumptions with respect to degree of mixing and segregation of the spaces. Don Schaezler, Ph.D., P.E., CIH ETC Information Services, LLC Quote Link to comment Share on other sites More sharing options...
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