And Another Thing about Residential Ventilation

Now that the ASHRAE 62.2-2010 residential ventilation standard is so much in the fore front of residential energy efficiency, I have been trying to explain some of the more complex parts like the Infiltration Credit and the Existing Building Deficit from Appendix A.  I got so fed up with all the bits and pieces of this process that I have developed a spreadsheet that is available on our website.  All you have to do is plug in the state or province where the house is located, select a city, enter the floor area, the number of bedrooms, and the number of stories.  The spreadsheet can then calculate the basic whole building ventilation rate from that, give you an ‘N’ factor based on the ASHRAE 136 weather tables, and give you a target ACH50 for .35 air changes per hour.  If you enter a starting CFM50, it will then use that information to calculate the adjusted whole building ventilation rate including the infiltration credit, and provide the ACH50 and the ACHnatural.  You can then plug in a Finish CFM50, and will give you the readjusted whole building ventilation rate.

If it is an existing building, you can plug in information about the kitchen and bathroom windows and fans, and it will give you a further adjusted whole building ventilation rate that will allow you to leave the existing fans in place.  It will also calculate the house depressurization based on the fan airflows.

And since the whole building ventilation system can be used intermittently, I have added a tab that can be selected to determine either the size of the fan required or the run-time depending on the desired operating cycle.  This spreadsheet is free because I want people to be able to apply the standard effectively without spending a huge amount of time on the math.  Check it out.

Also available on our website is a ASHRAE 62.2 checklist for analysts and auditors that will allow you to go through a home and determine what needs to be done to meet all the elements of the Standard.  It’s sort of like the whole Standard on one page.  There is also a system documentation sheet that will allow the designer of the system to meet the documentation requirements of the Standard and provide really useful information to anyone that comes along afterwards to check the system as well as information for the homeowner to know what their system is supposed to do and maybe understand why they should shut it off and stuff it full of socks!


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