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/
I was on-site last week (Jan. 9-10) for the installation of Zola windows. This was both exciting and nerve-wracking for a few reasons:
- Installing the windows correctly is critical to both the water management strategy and air tightness of the house. I wanted to make sure the details I had drawn actually worked out in practice.
- The windows are massive. Each panel of the large lift-slide doors weighed 1000 lbs., and the second floor study window was 800 lbs.
- The windows are one of the most expensive line items for the entire house. The possibility of damaging them was a bit scary.
Further complicating the process were extremely cold temperatures, and one day of rain (just enough to cover everything with mud).
In charge of the installation was Harry Schilling of Schilling Construction. I was incredibly pleased with Harry’s work and would highly recommend him for other projects. He and his team were fast and efficient while also paying close attention to detail. Harry also taught the owner and his assistant how to perform the installation, so they could help out with many of the steps, thereby reducing the labor costs.
Here’s how the windows were installed — both in theory and in practice.
I incorporated energy and daylight analysis as part of the conceptual design for the Iowa Nest Residence. This meant that early design discussions encompassed both traditional topics like floor plan layout, siting, and aesthetics, as well as performance criteria. The addition of analysis added a trivial amount of time, but proved incredibly valuable. Here’s how I did it — and what I will do differently next time.
Iowa, like much of the American Midwest, has a treacherous combination of deep, cold winters and hot, humid summers. Could we overcome this with good passive design? Could shading, natural ventilation, earth berming, and the like obviate the need for air conditioning?
Here’s how I went about answering this question. This analysis was done in early design so that the answer could inform basic design moves.
We knew we wanted a Net Zero Energy house — but was this a feasible goal? What would it take to deliver? Here’s how I investigated this question before we even had a design in hand.
In my post on passive strategies and simple box modeling, I showed how sensitivity analysis can be used to identify the most important passive strategies while still in the pre-design phase. In this post, I’ll show in depth how I did that analysis.
For reference, here is the end product: graphs showing the potential impact of a number of individual strategies.
Before I ever put pen to paper for this project, I wanted to answer a deceptively simple question: What passive design measures are most important? What basic strategies did the design need to employ to be successful? —to maintain human comfort with a minimum of added energy?
It’s important to answer this question before design begins in earnest for two reasons:
- With a limited budget, it’s important that we invest in the right things; and
- If we know the most important strategies before we start designing, we can incorporate them into the DNA of the design—often more effectively and at lower cost than if they were afterthoughts. For instance, if thermal mass or natural ventilation is important, these things will begin to dictate the construction or interior layout in ways that are difficult to “add on” later.
This webinar from December 2015 provides an overview of the design processes and analyses that were used to set the project on track toward Net Zero Energy during Conceptual and Schematic Design. The studies include “simple box” energy modeling to determine the best passive design measures, comparison of design options, analysis of shading strategies, and optimization of envelope parameters like R-values and glazing. I used a variety of tools including Climate Consultant and the CBE Thermal Comfort Tool — but mostly I used Sefaira Architecture. (Full disclosure: I worked for Sefaira for nearly five years; that’s where this webinar comes from originally.)
I’ll be going into more depth on these studies in future posts, but this webinar is a great overview.
The Iowa Nest is a Net Zero Energy-targeted residence in rural Iowa. It is designed to supply 100% of its energy needs; to be comfortable without conventional air conditioning; to fit into the landscape; to last for hundreds of years; and to do all of this on a conventional construction budget.
This blog will be run jointly by me (Carl), the primary designer, and by the owners, Peter and Jen. Our hope is to share our experiences designing and building this house so others can learn from our mistakes and re-create our successes. Our experience has shown us that it is possible to achieve remarkable performance (and great design) with a reasonable budget — and we hope to show others how they can do this, too.
You can subscribe to our mailing list to get regular updates: just send an email to firstname.lastname@example.org.
Let’s start by taking a closer look at the project’s design goals.