High Performance, Hyper Energy Efficient Home

High Performance,  Hyper Energy Efficient Home

High Performance in the Hills of Vermont We had a lot of fun building this super insulated, high performance, hyper energy efficient home in 2012. Many unique design features both inside and out were incorporated into the construction many of which were designed by the owners Lisa and James themselves, so we developed a very close, collaborative relationship with them. The home presented some interesting challenges. The first was hitting ledge only 18 inches down when we started excavating, so we had to completely redesign the foundation. Ultimately, we elected to build a super insulated floating or Alaskan slab which has no frost walls. Instead of pinning the frost walls to the ledge, which would have created a huge thermal bridge, the Alaskan slab allowed us to create a foundation fully insulated from the ground with no thermal bridging, an important standard in high performance, hyper energy efficient homes. We used 8 inches of high density EPS foam board (two layers of 4″) to insulate under the slab and 6 inches along the slab edge to fully encapsulate the slab and eliminate thermal bridging. The foam panels were used as the concrete forms and were set up so that the edge of the slab was 12 inches in thickness while the rest of the main slab was 5″. All plumbing and wiring conduit was roughed in before pouring the concrete. We framed the house using a double 2×4 stud wall technique used on many super insulated homes. This creates a 12 inch thick wall cavity with a 5 inch space between the walls creating a substantial thermal break between the inner and outer walls. We used Igloo dense pack cellulose, our favorite insulation material, to insulate the walls. We designed the roof trusses with 18 inch raised heels to ensure the thick insulation was continuous from bottom plate to top plate and created a 20 inch deep cavity in the trusses so we could super insulate to R-70 all the way to the roof peak. This also created some attic space inside the thermal envelope for storage and the air exchange, heat recovery ventilation system. The owners wanted the house to have a post and beam look to it to match their barn. Because we used conventional engineered roof trusses, we elected to add custom milled rafter tails which we bolted to the trusses. Tongue and groove pine was run over the top of these to create a soffit. Since the rafter tails penetrate through the exterior sheathing of the house which is the air barrier, we air sealed these penetrations with 2 part spray foam from the inside. This can also be done with special European air sealing...

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Another High Performance, Net Zero Home

Another High Performance, Net Zero Home

This is another high performance (HP), low energy demand, super insulated, net zero home we built in 2013 in Charlotte, Vermont. This 3 bedroom, 2 1/2 bath home features many of the same details as the other HP, super insulated home we built that same year. The main difference is that this one  was built on a frost wall protected slab built with insulated concrete forms (ICF’s) whereas the other one featured a full basement. We also created a large insulated attic space for storage and the air exchange, heat recovery ventilator heat pump by using large attic trusses and super insulating all the way to the peak of this house instead of having a flat, standard trusses ceiling like the other one. The concrete slab itself, which is the finished first floor, is insulated with 8 inches of EPS foam to R-36. The slab was polished towards the end of the project and provides substantial thermal mass to hold cool in the summer and warmth in the winter. We used a double 2×4 wall framing system to create 12 inch thick dense pack cellulose walls (R-42) and dense packed the slopes of the ceilings with 18 inches of cellulose (R-64) all the way to the peak. We used the Schuco, German made triple pane tilt and turn windows using the 10% of floor area south facing glazing rule to make optimum use of the excellent solar exposure of this house. Finishes The outside of the house was finished with minimal door and window trim (Boral Exterior Trim). We created simple extension jams for the metal J channel to rest against and receive the vertical metal corrugated siding. The roof is standing seam. The front entry porch was built out of locally harvested hemlock timbers and tongue and groove white pine was used to finish the ceiling and red cedar decking on the deck. Interior finishes included a polished concrete first floor, cork and marmoleum floors on the second floor. There is a large custom tile two head shower with glass doors in the master bathroom along with lots of built ins throughout the house. Window sills are a simple maple design with drywall wrapping the remaining three sides of the triple pane windows and deep window wells. Kitchen cabinets and bath vanities were all custom made by a local cabinet maker. Mechanicals This home is one of the first houses in Vermont to have a CERV (Conditioning Energy Recovery Ventilator) which is a combines an air exchange, heat recovery system with an air source heat pump. This system is equipped with  CO2 and VOC sensors so that maximum air quality is maintained. This home also has a small...

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Super Energy Efficient, Custom Net Zero Home

Super Energy Efficient, Custom Net Zero Home

This new 3 bedroom, 2 1/2 bath home we built in 2013 for a young energy conscious family brought together all of the best elements that can go into a net zero, high performance, super energy efficient home in Vermont; double wall framing, simple, cozy and efficient design, heat pump heat, cooling and hot water, plentiful natural light through beautiful tilt and turn triple pane windows, thermal mass in the floor of the main living space, natural, renewable materials and efficient air exchange heat recovery ventilation and a full array of Solar PV’s on the roof. We took the best of what we had learned on previous high performance projects and applied them to this project and another, similar home we built concurrently that year (see Another High Performance Home in Vermont). Super Energy Efficient Foundation       We started this home by insulating under and around the footings with 4 inches of EPS foam so the home would have minimal thermal bridges from the ground all the way to the roof. We built our own foundation out of insulated concrete forms (ICF’s) and poured our own concrete walls. This gave us a super energy efficient full basement with R-30 walls with a 6 inch rebar re-enforced concrete core insulated on both sides. The rim joist of the floor system is also insulated on both sides with 2 inches of EPS set in the same plane as the ICF’s and then added 4 inches of air sealed polyisocyanurate foam board on the inside. The inside is finished with drywall which is screwed directly into plastic ties inside the ICF’s and finished on the outside with a fiberglass mesh re-enforced stucco/parging product called Sider-Crete. We used a typical double 2×4 wall framing system for the exterior walls with a total depth of 12 inches (R-42 insulated with dense pack cellulose). We placed the second floor framing on the inside 2×4 wall so that we could completely dense pack around the rim joist and eliminate the typical air leakage and low R- value issue that plague conventionally framed homes. We used regular roof trusses designed for a flat ceiling with 18 inch raised heels to allow for ample insulation over the top plates of the walls. Ceiling R- value is 85 with 24 inches of loose fill cellulose. When we set the trusses, we continued our 1/2 inch exterior zip wall sheathing up to the trusses, then under the trusses and across the entire ceiling. This enabled us to air seal the entire second floor ceiling before any interior partitions were built eliminating all the air leakage that is typically associated with interior walls and attics.  Because of the level of air...

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