Archive for October, 2014

Designing and building your own net zero home

We wrote this article in June for the Fall 2014 issue of BuildingEnergy Magazine. Edited by Mark J. McCourt.

Designing and building your own home can be a huge challenge. It can be even more daunting if you set your sights on a high performance home that will produce more power each year than it uses. Thankfully, there are a ton of resources online—at times too many—that can help make those challenges more manageable. I am not, however, suggesting that any homeowner can do this without considerable learning or prior design build experience.

Jill and I are both designers. Jill works in graphic design and I work in the technology industry to make online applications easier and more intuitive to use. I studied architecture in school and paid for college in the early years by working for builders and a mason. It wasn’t out of concern for the budget that we did not hire an architect; in fact, an architect experienced in high performance homes would have likely saved us time and money. We simply wanted to do it ourselves because we enjoy the challenge and we had confidence we could do it well. We also knew when to ask for help.

We hired DEAP Group to estimate our peak heating load, specify our ventilation requirements and estimate how much solar we would need to achieve net zero. They also offered a number of recommendations that boosted our efficiency further. Please do not rely on anyone without experience in high performance homes to do this type of work for you; our energy star rater had zero experience with homes of our type. Based on their calculations, the heating load would have been half DEAP’s estimate, and our total usage would have been twice DEAP’s estimate. If we had followed our energy star estimate, we would have needed a 12 kW system to net out. Our first year actuals came very close to DEAP’s estimate.

One of our most important decisions was picking a contractor. Ideally we wanted someone that had experience building a net zero home, but there was no one in our rural area. We found W.R. Coolidge and Co., an experienced builder next door, that was interested in high performance homes and was eager to learn with us. Most importantly, he was willing to let us do as much of the work as we felt comfortable doing ourselves, and show us how to do it right.

Since we were involved in every decision and I had built detailed 3D models of almost every house system and detail, it was easy for us to coordinate the work of the contractors responsible for the foundation, electrical, plumbing, HVAC, cellulose insulation and solar PV installation. All of this required a great deal of time, research and planning; it is one of the reasons it took us more than 18 months to complete the house.

Throughout the process we posted much of our thinking and analysis in our blog, uphillhouse.com. The technology community places a great deal of value on open-source work. Sharing your work has several benefits: it creates opportunities for others to comment and make suggestions for improvements; it makes it easier for others to follow in your footsteps with less risk and more confidence; and most importantly, the act of sharing requires you to explain what you’re doing and why, in simple and clear terms. This forces you to think things through much more carefully. If your logic or calculation has a flaw, you want to make sure you find it before you tell the world about it.

After we moved in, we installed sensors to track the performance of our home. All our data is posted online at netplusdesign.com, for anyone to view and analyze. We collect and post our data for several reasons. We believe data should be open and accessible so that others can benefit from our experience. We want to know how the house actually performs, as compared to the estimates. We want to prove whether we have met our goals or not; if we have not, then we need to understand why.

We have been extremely lucky. It is a very comfortable home even in the deepest, coldest days and months of an upstate New York winter. In our first two years living in the house, we produced more energy than we used, despite the addition of a barn, dairy goats, chickens, turkeys, other assorted critters and a plug-in hybrid vehicle. This year, winter temperatures were much colder, and we are attempting to raise more of our own food, both of which use more energy. Last year, we passed into net positive territory in early June. This year we were still 1,121 kWh short at the end of May, a 1,000 kWh difference from 2013. We still expect us to generate a surplus in 2014, but it will be close.

So don’t go it alone unless you’re prepared to invest a significant amount of time researching and learning the nuances of high-performance building. If you don’t have 100 percent confidence in what you’re doing and why, it’s too easy for contractors to convince you that it’s too hard or too expensive to do it that way. Your house will suffer from a thousand small decisions that will ultimately undo your original goal: to live more sustainably in a net-zero home.

Larry & Jill

We’re on the cover of BuildingEnergy magazine!

Pic of BuildingEnergy Magazine

We’re on the cover of Building Energy magazine, Fall 2014.

There is a description of the entries to the 2014 Zero Net Energy Building Award, and an article we wrote to go along with our entry.

It’s not available online yet, but when it is, it should be available from the NESEA BuildingEnergy Magazine page.

* Note to magazine editor, the last name is Burks, not Burk. The home is in New York, not New Hampshire. CFM stands for Cubic Feet per Minute, not Cubic Feet per Meter.

Entry door lock sets replaced

Pic of corroded door lock mechanism (closeup) Pic of corroded door lock mechanism

Why am I writing about our entry door locks? We’ve had problems with our entry door locks every winter. They freeze up and it’s impossible to get the key in the key hole. Now they are so corroded inside that the lock mechanism barely works the rest of the year. They are less than 3 years old. I was surprised to see the amount of corrosion inside.

I’ve spoken to a few people about our frozen door locks in the winter. The issue seems to be that the house is so tight, that warm moist air inside the house only has one place to get out, through the key holes. One other consideration. Our ERV is set by default to produce a very small increase in internal air pressure. I believe their thought is that you want to be pushing clean air out the leaks, rather than pulling unconditioned air in. But I believe this may be one of the sources of our problem.

I’ve installed new door entry sets and will be setting the ERV to fully balanced to see if this solves our problem this winter.

I haven’t seen anyone else mention this problem, so I thought I would post here and see if anyone else with a passivhaus-level tight home has had this experience.  Please comment below if you have, and what you did to fix it.

Update January 2017

lockset-2014

The original lock sets were manufactured by Schlage. The new one are from Kwikset. I like the style better and the push button lock better than the turn mechanism. They seem to be holding up well, but as I mention in the comment below, we now have an HRV which lowers the amount of moisture in the air in the winter. We also haven’t seen the same cold temperatures that we did in the first 3 years.

3rd quarter 2014

Since we’re coming up on the solar tour this weekend, I wanted to post the numbers for July through September.

We turned net positive in August and now have a surplus of 851 kWh. Last year at this time we had a surplus of 1,749 kWh. Looks like we’re in fairly good shape to generate more than we use this year, unless we have more cold snaps. We’ve already had our first frost in September. Last year we turned the heat on October 27. Can’t wait to see what the next quarter holds for us.

Happy October and go see some homes on the solar tour this weekend!

2014 Usage Solar PV Net usage
or (surplus)
Avg.
daily usage
HDD
Total 6,246 6,997 (851) 22.9 TBD
Jan
1103 472 631 35.6 1,380
Feb
994 511 483 35.5 1,174
Mar1 1060 743 317 34.2 1,170
Apr 751 889 (138) 25.0 550
May 662 834 (171) 21.4 231
Jun 413 869 (456) 13.8 64
Jul 432 950 (518) 13.9 X
Aug 440 919 (479) 14.2 x
Sep 391 911 (520) 13.0 x

1 Transition from eMonitor to eGauge data begins March 8. Missing data for about 4 hours.


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