A Net Zero Energy Home at Conventional Cost
The 13th edition of Mechanical and Electrical Equipment for Buildings (AKA “MEEB”) has just been published by Wiley. Chapter 1 on Design Process prominently features the Iowa Nest Residence as an exemplar of high-performance design — incorporating much of the material that has been discussed in detail on this blog.
Continue reading “The Nest Residence is Featured in the New Edition of MEEB”
We set out to design a Net Zero Energy house at conventional per-square-foot costs. We got pretty darn close. Sans solar panels (which will be installed after two years of operation), the house came in at 8% less than a conventional new home. With solar panels, the house is still 2% less than conventional.
Here’s a full cost breakdown, and the seven strategies we used to get there.
Continue reading “Seven Strategies for Net Zero Energy at Net Zero Cost”
Things have to come through the walls, roof, and floors — even in an airtight house. How do we detail these elements in a way that (1) keep bulk water out, (2) meets our ambitious (Passive House level) air-tightness goals, and (3) avoids risk of condensation? Here are my details.
Continue reading “Penetration Details: Puncturing the Envelope of an Air-Tight House”
How should you design and detail a wood stove in an airtight Passive House? Here are some of the considerations, and the approach we used on this project.
First off: should you even have a wood stove in a Passive House? This is rightly a matter of some debate. It’s certainly not necessary, as our temperature data have shown: this particular house has proven it can stay habitable even through the coldest of cold snaps—maintaining ~55 degF even in -20 degF outdoor temperatures without mechanical heating.
And, a wood stove in a Passive House comes with downsides and risks:
We were pleased to host the Iowa Building Enclosure Council (BEC) once again to show our progress on the house and review the design process we used to meet our ambitious energy and cost goals.
The group toured the house previously in 2017, and we were delighted to be able to show our progress.
This past weekend was a big milestone: we passed our initial blower door test, exceeding our airtightness target of 530 CFM @50Pa (a target based on Passive House standards as well as early energy analysis). Here’s what we learned about our air barrier.
Continue reading “Blower Door Test: Two and a Half Weak Points in Our Air Barrier”
Below is the slideshow I presented on April 20, 2017 to the Iowa Building Enclosure Council, and to a sustainable construction class from Hawkeye Community College.
The version below is slightly edited to make it easier to follow online. (I tend to avoid text in my presentations, which can make them difficult to follow without accompaniment.)
Continue reading “Slideshow: Achieving Net Zero Energy at Conventional Cost”
We were pleased to host the Iowa chapter of the Building Enclosure Council (BEC) for a house tour and presentation, as well as a sustainable construction class from Hawkeye College. Many thanks to everyone who came out — including for the many excellent questions and kind words about the house.
It’s now been a little over a month since we’ve been gathering temperature and humidity data from the still-not-complete and still-unconditioned house. I previously wrote that the early data seemed to show more stable, and generally warmer, indoor temperatures. That story is now even clearer.
We’ve added temperature and humidity sensors to the house in three locations, so we can start to track the home’s actual measured performance. While these sensors will be most useful once the house is complete, the data that’s coming back now is already interesting, and is already showing the effectiveness of the passive design measures.
For those interested, you can track the live data here: http://www.iowanest.com/monitor/
Continue reading “A House That Maintains Its Own Temperature”