When most people hear the words “green home” they mostly think of new construction, super-insulated homes. But what about all the homes that are already standing, some for more than a century? In our opinion it’s where the true advancements in energy efficiency can be made, not to mention the potential for starting a wildfire of thriving business for contractors, architects and all the support fields now surrounding green building. We’ve been looking for a green remodel to cover on this site, and I think we may have found something that just about anyone can relate to, but one that takes a serious approach to materials and the net output of the final product.
Charlotte’s Retro is a deep energy retrofit project nearing completion (at the time of this writing) in Northport, Maine. The homeowner, eco-designer and master house-wright Christian Corson of EcoCor Design & Build, is midway through a deep energy retrofit (DER) on his 1965 classic Maine cape. In the standard building practice of that era, 2×4 exterior walls insulated with R13 fiberglass bats, 2×4 and 2×8 in the roof with fiberglass bats, Anderson double hung wood/wood windows and a surprisingly bone-dry basement made up the original construction. An oil fired hydronic heating system (forced hot water) with base board supply was the original heating system, but no record of the original boiler is available. As Chris noted to us “for it’s time, the home was well built. The walls are still plumb, the basement is dry and overall it’s in great shape”.
Jump to 2000 when Chris’ in-laws, then owners, remodeled the home and added a kitchen bump-out to the back of the home. It was built atop a 4′ frost wall with an earthen crawlspace below. Both dormers (see images) where added to the front roof and a non-attached garage was built. The new kitchen walls were done with 2×6 and the roof with 2×8, both insulated with fiberglass bats. A major upgrade of that remodel was a Weil-McLain boiler, a plus then, and as tested earlier this year still performs at 87% efficiency. When looking at the home as a candidate for a deep energy retrofit, Chris said it was perfect. “Sub-par electrical, decent plumbing, structurally sound, dry basement, enough room for a family of four and an energy pig all calculated to a sum that equalled DER”. Not to mention the beautiful 9 acre lot and good southern exposure we couldn’t help but noticing when we visited.
The goal of the retrofit is to meet the German EnerPHit standard, which is the Passive House standard for retrofits of existing buildings. So you may be thinking that in order to make this happen, the family had to move out of the home while the long, arduous retrofit takes place. Not so. In fact, the family has managed to virtually live without disruption during most of the construction. Other than window replacement and a new entry way addition on the front of the home, the inside has been untouched. Remember, this is a Deep Energy Retrofit, not an interior cosmetic remodel. Something to keep in mind if you’re considering and efficiency upgrade to your home. So how can a 1965 home become a Passive House? Let’s find out.
To begin with the basement a decision had to be made; let the basement stay a part of the main house or to thermally break it apart. Chris decided to create a thermal barrier and separate the main living space from the basement. Insulating and air sealing the basement ceiling (main floor) was done with 4 inches of water blown, open cell Icynene LD-200 with Roxull mineral batts underneath equalling R27. The staircase leading to the main floor was insulated with Polarguard Type 1 EPS and the door with Polarguard Type 1 EPS air sealed to the door. As for the crawl space beneath the kitchen addition, the earthen floor was covered with 6mil. poly-ethylene vapor barrier and sealed to the concrete foundation. This acts as moisture management for the kitchen and rest of the house.
The exterior walls where approached with the PERSIST method, or Pressure Equalized Rain Screen Insulated Structure Technique. Corson started by removing all shingles and 30# felt paper that was used as a water barrier. He also removed all the eves and soffits where he cut off the rafter tails, insulated with cellulose and replaced with a smooth continuous surface. To replace the old felt paper method, all exterior walls where wrapped with peel and stick Grace Ice and Water shield, which applies a continuous air barrier and drainage plain behind the insulation. Next the building received 5.5 inches of upcycled, aged Polyisocyanurate for more insulation value. Followed by rain screen and then resided with reverse board and bat completed the wall detail. The roof was a complete strip of asphalt shingles and felt paper, then a recover with the same Grace Ice and Water shield the walls received. In addition, an 8″ layer of Polyisocyanurate was installed and then covered with standing seam metal roofing.
For windows Chris chose Intus uPVC tilt/turn passive house windows. The whole window U-value is .14. Intus windows perform incredibly well (the passiv haus certification should be a hint as to how well) and they have a high visible transmittance as well as improve the auditory comfort significantly. Increasing window size was a huge factor as well. When vying for solar gain, great windows placed in strategic areas is key. Charlotte’s retro has great southern exposure and Chris has taken full advantage.
As this project moves forward, we will release our second article with the final details, images and techniques used to achieve EnerPHit. Ventilation, exterior wall finishes, window performance, PHPP comparisons and more to come. Stay tuned!
Please let us know what you think or any questions you have by posting comments below!