Today, we ran the first blower door test at the MinnePHit House in Minneapolis. The EnerPHit building standard prescribes maximum air-leakage for a retrofit Passive House of 1,0 ACH50 (air changes per hour at 50 Pascal pressure). Converted to CFM50 (cubic feet per minute at 50 Pascals), we were shooting for a magic number of 300 or less. Immediately, the house outperformed this with a reading of 285 CFM. We spent the rest of the morning with help from the Energy Conservatory, Ryan Stegora (builder) and Paul Brazelton (owner) identifying leaks. Some were patched right away—others marked for later improvements. At the end, we measured a steady 267 CFM50, which corresponds to 0.88 ACH50.
We are excited to see that even a 76 year old home can be made virtually airtight, and we are confident that the builder can improve on the performance of this rough-in result for the final test. The Passive House recommendation for retrofits is at 0.6 ACH50 (about 183 CFM50). This means that the home is currently one “Passive House in the Woods total air leakage” from achieving this reach goal.
To put things into perspective, this home started with a blower door result of 8.5 ACH50 and a corresponding 2,100 CFM50 of air leakage. Since then, it grew by almost 40%. Many existing homes we tested over the years in the TwinCities range from 7 to 15 ACH50. According to the Energy Conservatory, average new construction is in the range of 3 – 7 ACH50, with exceptional builders getting down to 1.5 ACH50 on occasion.
We are very pleased with the performance, which also reflects positively on our detailing and specifications.
Minneapolis – The free, self-guided 16th Annual MRES Solar Tour Saturday, October 1, includes open houses at about 50 Minnesota homes, businesses and organizations that have solar and other renewable energy installations. Organized by the Minnesota Renewable Energy Society (MRES), the tour includes open houses in the Twin Cities and several other Minnesota communities from 10 a.m. to 5 p.m.
For the first time, this year the online guide to sites at www.MNSolarTour.org will list each site’s additional eco-friendly features. Besides the usual pictures, maps and details about alternative energy technologies for each site, the guide will list eco-friendly features such as urban chickens, electric cars, rainwater storage systems and the like. Tour guests must register at www.MNSolarTour.org to obtain addresses of the tour sites.
“The solar tour is popular with people who are thinking about purchasing some kind of renewable energy technology because it gives them a chance to see lots of systems and talk to lots of owners,” said Laura Cina, managing director of MRES. “The lists of other eco-friendly site features this year should draw even more people to the event.”
The owner, representatives from TE Studio, as well as representatives from Energy Concepts will be on site during the day to answer your questions.
The 8th international Passive House Days are coming up in November. Once again, the gracious homeowner of the Passive House in the Woods is allowing us to open it up to the public. Join us on November 11 and 13 for two distinctive events.
11/11/11: 6.30-9.00 pm: Friday Night Social: One year in the Passive House, a guided tour, meet the designers, and social gathering.
11/13/11: 10.45-Noon: Public Tour
On Saturday, the owners of the MinnePHit House are opening their doors to visitors to showcase the first EnerPHit project in the country. We are going to showcase the process of what it took to take this 1935 home to the Passive House level of performance.
A conversation on the MinnePHit website inspired me to write a quick summary of why airtight buildings are a good thing. You can find my response to the thread on the MinnePHit website. I will maintain this article on Google Knol going forward.
At TE Studio we are fortunate enough to attract some pretty incredible people. Most recently, we were commissioned by a couple from South Minneapolis to bring their mid-30s home into the 21st century of performance. A brief description of their family reads like this:
Two grown-ups, three girls, two dogs and eight chickens. A 1935 neo-Tudor in Minneapolis, MN. A passion for the planet.
You can see where we are going with this. With ground-breaking in sight, we are looking to make a Passive House retrofit. “Ze Germans” call it EnerPHit—as in energy efficient passive house retrofit.
This means some significant changes—most noticeably to the building envelope, or those bits that separate inside from out. TE Studio is providing the design for this winter coat. We are looking to sustainable materials in an effort to cut the heating demand to about 12kBTUs, or about three hairdryers going at the same time. 9-1/2″ i-Joists will be screwed to an air-tightened sheathing layer on the outside of the current shell, and dense-packed with cellulose insulation for an R-value of 44. Since we are also adding to the back of the house we decided to design a new “hat” for the home. A trussed hip-roof will provide R-77 of cellulose insulation. Even the basement will be insulated to R-values in the 30s. Combined with an airtightness goal of 1.0 ACH50 or better, this retrofit will meet the requirements set forth in the current draft of the EnerPHit standard. According to the German Passiv Haus Institute, this is the first EnerPHit project in North America.
Mechanical ventilation is a good idea for most buildings, but it is essential for any high-performance building. We designed an ERV-based whole house system with an efficiency rating of over 90%. This means that the precious heating energy will remain inside the envelope while the occupants are supplied with outside air year-round. We are able to recycle the home’s existing boiler and continue to heat the home with in-floor heat. The same boiler will also provide hot water. This project demonstrates the amazing potential of a high-efficiency design for existing homes in a cold climate through a great amount of recycling of what is existing—paired with carefully selected sustainable materials and methods for the retrofit and what is new.
The design is complementary to the building’s origins and surroundings. An open first floor plan will provide much needed space for the family, and offer a connection with the backyard. On the second floor we are adding bed rooms for the kids and an additional bath. At just over 2,000 finished square feet (counting the basement), this is no mansion for 5 people and two dogs, but with its well organized layout, it will be incredibly functional.
We are very excited about this project. The owners are offering updates on the project at http://www.minnephithouse.com
Only one question left to ask: What do the chickens think of this?