HVAC and ERV Installed

The HVAC and ERV (energy recovery ventilator) have been roughed in/installed. The HVAC system and ERV was installed by McNutt Service Group and boy did they do a great job of sealing all the duct work. Mastic was used in great quantities and this should go a long way to achieving an excellent duct blaster test score. All the ducts in this prototype home were designed to be in the conditioned space or thermal building envelope. My goal from the beginning was to build a home that was orientated properly, very well insulated, and with an HVAC system that was designed and sized specifically for this home. With great southern exposure, Eco-Panels for the walls and spray foam for the roof and subfloor, I had achieved the first two goals. Every home should have the HVAC installer/company perform a Manual J (load calculation for heating and cooling sizing) that is verified by the Energy Star (HERS) rater prior to installation. After much contemplation, I decided to go with a high performance air to air heat pump for heating and cooling the home. At first I thought about installing a ground source geothermal system, but because I am attempting to build this home for less than $95 per square foot, many buyers in the affordable housing category may not be able to take advantage of these tax credits or afford the initial up front costs of a geothermal system. I have been asked by several people why I did not at least install a gas back up furnace for potentially better heating performance. My answer is simple--this home is being roughed in for future solar (photovoltaic) panels that will ultimately power the home. In my opinion there is plenty of evidence out there highlighting the fact that we need to significantly reduce our dependence on fossil fuels. If the heat pump and passive solar design are for some reason not able to heat the home effectively, I have designed it so I can add a wood stove or pellet stove in the future. The ERV was included because my goal is to build an extremely tight home. "Build it tight and ventilate it right" is a popular saying in the green building industry. The ERV provides continuous ventilation for the entire house, exausting stale indoor air and replacing it with fresh air from the outside. The ERV is rated to recapture about 75-80% of the conditioned air before it leaves the home. This means that in the winter when you are spending money to heat the home and bringing in cold fresh air--75-80% of that heat is recaptured or not lost. ERVs can also be fitted with different filtration systems depending on the homeowners needs for indoor air quality.

Windows Installed

The Marvin windows finally arrived after a lengthy delay. Part of this delay had to do with an additional 2 week lead time when ordering special glass or glazing from Marvin. As I mentioned in a previous post, I ordered these Marvin Integrity windows with Cardinal 179 glass for the south wall windows. The Cardinal 179 glass has a low U-Value of .28 and a high SHGC value of .70. That means that 70% of the radiant heat from the sun will penetrate through the glass into the home. The overhang for the second story windows was determined based on allowing the radiant gain to only be available from mid October to mid April--passive solar heating. Because the home was built on a crawl space, I reduced the overall size of the southern windows as I won't have much thermal mass to absorb the heat gain from the sun. We will have to build seperate overhangs/awnings for the main level south windows prior to installing the siding. I decided on Marvin windows for several reasons. The performance #'s of these windows are very good compared to the overall price (high quality for good value). Also, I wanted a window manufacturer that would integrate the Cardinal 179 glass into a fiberglass exterior cladding. Marvin now offers awning and casement windows in a full fiberglass frame, but the additional $1300 didn't make sense from a payback perspective. Fiberglass is much less susceptible to expansion and contraction from temperature changes, while also being very low maintainance. The interior of the windows is a high quality pine that I will eventually stain or paint to match the interior finishing colors. I chose only awning and casement style windows as my experience has shown me these seal much better than double hung windows for overall better performance. I minimized the amount of north windows and requested a very low SHGC rating for the east and more importantly west windows (.20). Having a lot of windows sure is nice, but finding that balance between aesthetics and energy performance is very important.

Front porch in place

As you can see from the picture, the front porch roof is a very simple shed design. The size of the front porch was limited based on county imposed set backs from the septic field (the far right post is the closest I could extend the front porch). The shed design is not only very affordable, it also simplifies flashing requirements and water collection for future landscaping. Unfortunately, the community I am building in denied my requests for using a metal roof on the main part of the house, but does allow metal roofing for the front porch. It is a bit confusing as it is the front porch roof that is by far the most visible. The windows finally arrived after a significant delay. I will share more about the windows in the next post.

Roof Trusses in place

We decided to work on a Saturday to lift the roof trusses in place. This process took us about 2 1/2 hours to complete. Once again, having the crane on site really helped reduce time and labor costs. Our crane provider (Gawain Mainwaring--Smart Builders in Asheville) was great to work with. Not only are his hourly crane rates very reasonable, but his crane operators were very flexible working with our schedule.

My preference going into this project was to build a vaulted hybrid timber frame roof with exposed rafters and beams and then place Eco-Panels 6.5" R-40 roof panels on top. After further research, I realized I needed to go with a different option. The two main reasons for this were cost and simplicity. As for costs, I estimated that the timber frame roof option would cost an additional $7,000-$30,000 depending on the truss design and wood species. As for simplicity, by switching to a basic 2x4 engineered truss, I could avoid additional load bearing requirments and create a prototype home that a future buyer could customize by changing room sizes and locations without additonal engineering. Basically, this prototype has only 1 interior load bearing wall for the staircase. In place of using Eco-Panels for the roof (which is a great option) I will have the roof deck and gable ends spray foamed to achieve an R-Value of around 30. I will have the insulation contractor spray foam the entire roof deck including the overhang area reducing the need for a vented soffit. I will use ZIP sheathing underneath the overhang and tape the seams prior to having the soffit material installed.

2nd floor panels erected

We were able to erect all the 2nd floor walls in just 2 hours. Although Eco-Panels recommends a crew of 3 to erect the panels, the 2nd floor panels on my prototype were erected by just a crew of 2. After just 2 days, from the time the Eco-Panels were delivered, we are ready to lift the roof trusses in place. Overall my experience with using Eco-Panels on my own home has been very positive and exceeded every expectation that I had going into this project.

The 2nd floor wall height is also 9' high, matching the main level. For most affordable homes 9' ceilings is an expensive upgrade. Although adding an extra foot of ceiling height increases the amount of conditioned volume in the home, this prototype's super efficient design created a great opportunity to add a typically very popular upgrade at a very affordable price.

1st floor panels and floor trusses set

The first floor perimeter is 124' and the walls are 9' high. Nailing the base plate, erecting the 1st floor walls, framing out the larger window rough openings, installing pre-dimensioned and insulated headers (provided by Eco-Panels) and adding a 2nd top plate took us only 4 hours to complete. We ripped down a 2x6 to 4 1/2" to run a second top plate around the perimeter. Eco-Panels integrated cam-lock system, pre-engineered corners and pre-engineered rough opening and headers, made completing the 1st floor wall system a breeze. Not only did using Eco-Panels save us a lot of time, labor and headaches, but I ended up with a wall system that is more than 2X stronger and almost 3x the affective R-Value (R-26) of a conventionally stick framed home.

The exterior skin I used on the Eco-Panels is the ZIP sytem from Huber---www.zipsystem.com---. I originally planned on ordering the Eco-Panels with integrated LP Smartside---www.lpcorp.com--(bypassing the need for additional siding) as the exterior skin. With a form--following--function mindset, one of the biggest challenges for me on this prototype has been taking such a simple rectangular design and giving it some curb appeal. Although I could have saved time and money by going with an integrated vertical (board and batten) siding option on Eco-Panels (like LP Smartside), aesthetically I felt a darker colored horizontal lap siding would end up being a more attractive option on this tall and lean prototype design. We'll see how it turns out!

The 2nd story floor trusses were ready to be set after lunch. We knew ahead of time that having the crane on site for the first few days after the panels were delivered would really speed up the process and get us dried in much quicker. We also used the crane to lift the 2nd floor Advantech subfloor sheets. By the end of the day, we had installed about 1/3 of the Advantech sheets and felt confident we would have the 2nd floor walls panels finished by the end of the next day.

Eco-Panels shipment arrives

Since I was having a lot of problems with my previous blog site, I decided to start a new blog and that is why it may appear that this prototype is being built extremely fast. No, this in not Extreme Makeover Home Edition, but we are very close to being on schedule for a 60 day build completion time frame.

Eco-Panels arrived as scheduled to the job site. As a disclaimer, I am the Regional Project Manager for Eco-Panels. My first experience with Eco-Panels was over 3 years ago at a local WNC Green Building Counsel function. The very first thing I noticed was the patented fully insulated corners--really cool. Then I noticed the internal cam-locking system and integrated electrical boxes and conduit. Once I was able to confirm that Eco-Panels use an injected, high density polyurethane foam, you could say that I was immediately very impressed with Eco-Panels. Most (about 95%) SIPS (structural insulated panels) are basically board stock EPS that are glued and pressed to OSB and use splines or studs to connect the panels. The obvious difference in quality, performance, options and integration between Eco-Panels and other SIP products was striking.

Prior to joining Eco-Panels, I performed certifications locally for the Energy Star and NC Healthy Built Homes programs. I had researched alternative building systems for years, but in every system I was able to find a flaw or weakness that I issues with. After spending several months learning more about Eco-Panels and taking a day off work to help erect walls panels on a job site, it was clear that I wanted to be a part of such an innovative company with the best overall solution for combining structural and thermal performance in the most integrated, user friendly and cost effective way I have ever come across.

I had scheduled a crane and operator to be at the job site to help unload the panels and this saved us a lot of time and hard labor. The first floor walls were bundled seperately from the 2nd floor walls and I was able to use the crane to transfer the 1st floor wall panels directly on to the subfloor and strategically arrange the 2nd floor wall panels on the site to be lifted up to the 2nd floor when needed. I made sure to have extra tarps on site to protect the panels from the weather even though we would be erecting the 2nd floor walls just 1 1/2 days later.