I had a blower-door test done at my house and the result was 4.6 ACH50. ACH50 is a common standard for air infiltration and stands for Air Changes per Hour at 50 Pascals. Pascals are, like pounds per square inch, a measure of air pressure. 50 Pascals is about the pressure caused by a 20 mph wind. 4.5 ACH50 is equivalent to 1,035 CFM50 (cubic feet per minute at 50 Pascals). This means that the natural air exchange on my house (i.e., at 0 Pascals) is about 0.23 ACH (sometimes called ACH0). This means that the entire air volume of my house is replaced every four hours due to drafts around doors, windows, walls and chimneys. The natural air infiltration rate in my house is 238 CFM0.
This proves what I have long suspected, which is that it is absolutely not necessary to seal your house to the level of air tightness required by the Passive House (PassivHaus) Institute in order to cut your carbon emissions to zero.
The Passive House standard is often held up as the ideal standard for low-energy consumption houses. But I have never seen any financial analysis accompanying this conclusion. This data proves that you can cut both your carbon emissions and bills to zero (and I am making a 15% return on investment too) without the expense of creating a very tight building envelope.
Very few builders can build to a the Passive House standard of 0.6ACH50 and doing so often requires many hours of skilled labor plus the addition of an ERV (energy recovery ventilator) which, alone, can add $5,000 to the cost of the house. I know one contractor who recently did the air sealing on a Passive House project. He gets paid about 3x what a typical laborer on a construction site gets paid. Labor dollars add up real fast at those rates! Hence, the Passive House standard for air infiltration can only be achieved at considerable expense – an investment that will never earn a return.
Much like geothermal, solar hot-water panels and thickening your walls with insulation, a super-tight building envelope makes energy sense but does not make financial sense.
The highly-acclaimed book “Zero Carbon Home” by “Green Guru” David Green.
How we cut our home’s carbon emissions to zero.
How we cut our home’s utility bills to zero.
Solar panels on the roof of our house.
Our heat pumps.
Fiberglass and ISO board insulation on the roof of our house.
Triple-pane windows in our living room.
Useful links:
The Easiest Way to Calculate Your Home’s Carbon Footprint:https://greenzerocarbonhome.com/2018/07/what-is-the-carbon-footprint-of-natural-gas-heating-oil-propane-and-coal/
Written Answers to over 300 Questions about Zero Carbon Homes:https://greenzerocarbonhome.com/webinar-questions-and-answers/
Finance and Net Zero Energy Terms explained: https://greenzerocarbonhome.com/energy-and-finance-terms-explained/
Zero Carbon Home Website Home Page: https://greenzerocarbonhome.com
Database of State Incentive for Renewable Energy (DSIRE) https://www.dsireusa.org
Published articles on Zero Carbon and Net Zero Energy:
Department of Energy, EnergySage, “Zero Carbon Home”https://www.energysage.com/project/7230/zero-carbon-home/
Zero Energy Project, “My Zero Energy Retrofit beats my 401k”https://zeroenergyproject.org/2018/09/23/my-zero-energy-retrofit-beats-my-401k/
Cool Effect, “Mr. Green’s Zero Carbon Home” https://www.cooleffect.org/content/news/green-testimonial?utm_source=Cool_Effect_CRM&utm_medium=EMAIL&utm_campaign=20180814Engage_Testimonial&utm_content=green_CTA
Green Energy Times, “My Zero Energy Pool is a Great Investment!” http://www.greenenergytimes.org/wp-content/uploads/2019/05/GET_May-2019.pdf
Published Presentations on Zero Carbon Zero Bills:
To see a 3-minute interview of David Green by NBC Boston anchor Joy Lim Nakrin, please click here:TV interview
To see a 20-minute TED talk at Harvard Business School, please click here: TED Talk
You can watch a recorded version of my Zero Carbon, Zero Bills webinar here: Zero Carbon, Zero Bills Webinar
Reviews of my “Zero Carbon, Zero Bills” webinar included, “Minute-for-minute, point-for-point, one of the best webinars I have ever attended. Thank you!”, “David is a true inspiration and asset to our community. He inspired us to get solar panels and a new front door”, “This is like a masterclass in ZeroCarbon”, “Thank you soooo much for the sensible advice and your fabulous resources!!” and, although this next comment is a little flowery, it does express the sentiment of many other comments, “Your contribution to Greening America is great and will probably help our survival as a species a bit longer than expected”.
David – are you sure about your statement around Passive House. This goes differently with PassiveHaus published standards and performance .
Hi Michael, yes I am sure about the Passive House standard for air infiltration being 0.6ACH50. You can see a presentation on it here:
https://www.abaaconference.com/wp-content/uploads/2018/05/Scott-Pusey-and-Mike-ODonnell-Air-Tightness-Requirements-Of-The-Passive-House-Standard.pdf