The envelope of the house is insulated with R40 value upper walls, R27 value lower walls, and R60 value roofs. The upper walls are double 2x4 at 24” on center, wood stud walls separated by a 3.5” cavity. The outer wall and cavity have 7” of dense pack cellulose insulation and the inner wall is insulated with 3.5” of rockwool insulation. The lower walls are 8” Logix ICF concrete walls with 2-3/4” of high density foam on each face and extend fully up to the first floor level 3/4" engineered floor decking. First floor framing is located between and attached to the ICF walls, not on top of the ICF walls. The roof trusses have a minimum of 24” of blown-in cellulose insulation. Under the lower level 4” slab-on-grade is 6” of EPS foam insulation which is R22+.
Radiant floor tubing on the upper floor is an Uponor staple up system with an insulation barrier, while the lower floor is a 4" thick concrete floor with embedded Uponor tubing.
The roofs are all pitched using prefabricated roof trusses that allow for a minimum of 24" of blown in cellulose. The top chords are extended using supplemental on-site lumber to create a standardized 24" overhanging soffit for summer shading and continuous air flow to the ridge vents. Likewise, the gable ends receive similar treatment to provide a 24" overhang.
Given the use of double wood stud wall (R40+) exterior wall construction on the upper level and Logix ICF (R27) concrete on the lower level walls, any type of exterior door was a significant drop-off in thermal performance, so it only made sense to use the french style doors (5 total) as daylighting features as well, which allowed a reduction in the total windows required for great natural light. Including features like the operable sidelites to the two main entry doors added to the natural ventilation options. Additionally, placing a large (8’x8’) french slider door on the lower level directly below the (12’x8’) NanaWall folding/sliding glass door assembly above on the upper level leading into the 3-season room, permits the lower level to be completely protected from summer rains, allowing it to be open even during inclement weather, just like the entry sidelites. The large slider also floods enormous amounts of light into the lower level.
-4" Reinforced concrete w/radiant floor tubing
-6" EPS foam insulation
-Taped and sealed vapor barrier.
-12" sand bed which houses both the glycol filled gound loops from the solar hot water panels (upper layer) and the water filled ground loops (lower layer) from the geothermal heat pumps.
-Natural grade or compacted fill
Slab edge assembly
The lower level walls are 8” Logix ICF concrete walls with 2-3/4” of high density foam on each face with an R27 insulation value extended down past the edge of slab to the frost line and wall footing. No further slab edge treatment is required.
Slab edge R-value
Foundation wall assembly
The lower level walls are 8” Logix ICF concrete walls with 2-3/4” of high density foam on each face with an R27 insulation value extended down to the frost line and wall footing.
Foundation wall R-value
Above grade wall assembly
The upper walls are double 2x4 at 24” on center, wood stud walls separated by a 3.5” cavity. The outer wall and cavity have 7” of dense pack cellulose insulation and vapor barrier. The inner wall (inside the vapor barrier) is insulated with 3.5” of rockwool insulation.
Above grade wall R-value
Flat attic assembly
The roof trusses have a minimum of 24” of blown-in cellulose insulation. All flat ceilings areas (cosmetic only) are insulated above as part of the roof truss assembly. Penetrations for down lighting fixtures occur through the cosmetic ceilings, not through a vapor barrier. The roof trusses have a minimum of 24” of blown-in cellulose insulation above the ceiling vapor barrier. All penetrations through the vapor barrier occur at predetermined locations between the trusses that are fitted with a pre-made insulated box to allow for proper sealing of the vapor barrier. Blower door testing was conducted both before and after installing of the interior drywall.
Flat attic R-value
Cathedral ceiling assembly
The roof trusses have a minimum of 24” of blown-in cellulose insulation. All flat ceilings areas (cosmetic only) are insulated above as part of the roof truss assembly. The roof trusses have a minimum of 24” of blown-in cellulose insulation above the ceiling vapor barrier. All penetrations through the vapor barrier occur at predetermined locations between the trusses that are fitted with a pre-made insulated box to allow for proper sealing of the vapor barrier. Blower door testing was conducted both before and after installing of the interior drywall.
Cathedral ceiling R-value
All roofs are pitched using deep roof trusses. The roof trusses have a minimum of 24” of blown-in cellulose insulation.
Uplighting: Philips eW Fuse Powercore LED, Under cabinet: Philips eW Profile Powercore LED, Closets: Philips eW Profile Powercore LED, Downlighting Cans: Standard cans w/LED replacement kit bulbs
Lighting Power Density: 0.38 watts/sf with >95% LED
Mechanical Equipment Installation Details and Comments
An experienced commercial grade mechanical contractor was hired for the mechanical install. Rigorous inspections were conducted and installation was guided/coordinated with the manufacturer's (Bosch/Buderus) assistance . Blower door tests were undertaken both before and after drywall installations. Flow hoods used to balance and adjust.
A dedicated make-up air system (exterior hood, duct, gravity damper and floor level diffuser) was designed and installed in the mechanical room for negative pressure associated with the use of the range hood. The range hood is served by an in-line Fantech fan located in the mechanical room that discharges directly to the exterior (not to the ERV). Intake hoods (2) are located on the west wall. Discharge hoods (2) are located on the north wall.
Two floor inspection/measuring ports are installed in the 4" concrete floor in the mechanical room using 4"dia PVC tubes with screw caps. Sensors are located within the tubes to measure ground (sand bed) temperatures at the geothermal tubing level and the solar thermal glycol tubing levels in the ground.
Hand control dampers are installed in the air supply ducts for the master bedroom wing to allow reduction of heat to create cooler room temperatures in the winter months, if desired.
Heating and cooling are provided by two Bosch 2 ton ground-source heat pumps connected to a horizontal ground loop system. One heat pump is a Bosch water-water model and the other a Bosch water-air model. The water-water unit is solely devoted to heating the ten zone radiant floor system on two floor levels, a Runtal hydronic towel warmer/radiator in the master bath, and the 198 gal Bosch/Buderus PL750/2S Solar DHW/Space Heating Combi Tank (i.e.-12 zones total). The solar tank is kept at a minimum of 100 deg F by the heat pump during periods of poor weather when the on-demand Seisco electric heating then boosts the water temp to 130 deg F for domestic distribution.
The water-air heat pump serves a single upper level ducted distribution system located within the lighting soffits. The upper level air system is controlled by a centrally located “smart” Ecobee thermostat and a mechanical room Ecobee control panel, which is also accessible on-line via a PC or smart phone app, to provide both heating and cooling control at all times. Nine of the ten radiant zones are controlled by simple heat only wall thermostats, and the largest open space 1st floor zone is controlled by the Ecobee thermostat which decides how best to heat that large living area (i.e. - capable of running both heat pumps simultaneously), to supply both hot air and a radiant warm floor if required during severe cold conditions.
A simple PVC under slab ventilation loop with 4" dia vertical exit stack was installed for potential Radon mitigation, but later testing proved to not require radon mitigation. The stack dead head is accessible behind a drywall access panel for any possible future need.
On both the east (laundry room and 2nd bath) and south (kitchenette) walls of the lower level, the interior finished walls were bumped out from the ICF using 2x4 studs to create a 12' wide continuous access chase to run wiring and plumbing with permanent access and cleanouts.
In addition to the HVAC systems (heat pumps) and the fresh air system (HRV), there are three isolated in-line Fantech fans that can be manually controlled by adjustable fan speed wall mounted dials at the first floor level. They each consist of an intake louvre near the ceiling of the vaulted space on the upper level, ductwork, in-line fan w/access hatch, and discharge box located near floor at the lower level. Each can be used to move warm air (den, livingroom, and master bedroom) from upper level spaces to add heat to the lower level at times of the year (swing seasons) when daytime temps may be higher than desired at the upper level, but outside night time temps might otherwise call for heat (i.e- storing the heat internally to the building).