Scionwood Retreat
An Alternative Approach to Net Zero Energy Home
Walls and Roof
This is an on-frame HUD Code doublewide. It measures 28' x 64' = 1792 sq. ft. Concrete footers were poured for all the concrete block piers that carry the weight of the home from the I-Beams and for the parameter brick curtain wall that totally encloses the properly closed crawl space. Prior to pouring the concrete for the parameter footer the tie-down anchors were augered into the footer trench. Following construction below grade foundation water-proofing and a drain to daylight parameter french drain was installed. The finish grade of the soil drains all surface water away from the foundation.
The home uses 2 x 6 wall framing and a 2 x 4 roof truss system with cathedral ceilings throughout the interior and approximately a 3/12 roof pitch.
Insulation values are: Ceiling R-30, Walls R-19, Floor R-22
The windows are intentionally simple. Single-hung, none treated, single-pane glass in an aluminum frame plus and interior single-hung of the same materials. The two windows are separated by the wall framing leaving a 5 inch space.
Space conditioning is provided by a standard heat pump and an energy recovery ventilator. Separate airtight ducts systems were site installed for each.
The properly closed crawl space has a continuous and sealed poly vapor retarder for the ground and walls - leaving a 3 inch view strip at the top of the foundation wall. A dehumidifier with gravity drain to outside manages the minimal water vapor that migrates into the space.
Foundation wall assembly
Concrete footers were poured for all the concrete block piers that carry the weight of the home from the I-Beams and for the parameter brick curtain wall that totally encloses the properly closed crawl space. Prior to pouring the concrete for the parameter footer the tie-down anchors were augered into the footer trench.
The single brick width curtain wall foundation is not insulated. Its height ranges from 3.5 to 4.5 feet tall.
The home is 28 feet wide and 64 feet long.
Above grade wall assembly
2x6 wall assembly with R-19 fiberglass batts. The interior surface is 1/2 inch sheetrock and the exterior is 1/2 inch OSB with vinyl siding
Above grade wall R-value
19.0
Cathedral ceiling assembly
100% of the ceiling is a cathedral assembly using a 2 x 4 truss system
Because it is HUD Code, the ceiling assembly for each half is fully constructed and then placed onto each half of the home as a unit which substantially reduces the wall to attic air leakage paths. The ceiling is 1/2 inch sheetrock and the insulation is blown cellulose.
Cathedral ceiling R-value
30.0
Roof Assembly
2 x 4 truss system
The home is 28 feet wide and 64 feet long.
each section is 14 wide and 64 feet long.
The attic has soffit and ridge venting and the decking is 1/2 inch OSB with shingles.
Windows and Doors
Window Assembly:
Intentionally inexpensive aluminum frame single-hung windows with non-coated single-pane glass.
Interior single-hung storm window of the same materials with the two windows separated by the wall framing leaving a 5 inch space between them
No record of U-factor, SHGC, etc.
Cheap windows
Door Assembly:
foam core filled steel door [3' 0" x 6' 8"] with one third of its area being an insulated glass sandwich fixed window light
Door Area
20 sq ft
Mechanical Systems
Space cooling - Manufacturer & Model
Rheem RPRL 024JEZ 2-stage heat pump
Space cooling - capacity
7 kW
Space heating - Manufacturer & Model
Rheem RPRL 024JEZ 2-stage heat pump
Space heating - capacity
7 kW
Domestic hot water - Manufacturer & Model
Intertherm 20RTOE3JNC - electric
Domestic hot water - capacity
50 gal
Domestic hot water - efficiency
92 kW
Ventilation - Manufacturer & Model
Venmar AVS Duo 1.2 with TRE = 75%
Lighting Manufacturer and Model
multiple
Lighting Efficiency
all lighting is cfl [80%] or led [20%]
Mechanical Equipment Installation Details and Comments
Manuals J,D, S, & T were used in design and selection. With room by room calculations present, air distribution was balanced with air flow measurements. The complete air distribution system including the air handler was tested with a duct blaster and found to have less than 5 CFM25 Total air leakage. System performance was achieved by establishing correct air handler air flow and then establishing proper refrigerant charge. The 7KW heat strip is locked out until outside temperature drops to 20 degrees F.
The ERV ventilation system has a separate sealed air distribution system that was tested with a duct blaster and found to have less than 5 CFM25 Total air leakage. Balanced air flow into and out of the home was achieved by using through the cabinet pressure taps and the resulting air flow measurements at the ERV and then making adjustments to the balancing dampers. There is a simplicity to using a separate duct system for the ERV that avoids a lot of installation mistakes that we find where space conditioning and ventilation equipment are connected to the same duct system.
Walls and Roof
This is an on-frame HUD Code doublewide. It measures 28' x 64' = 1792 sq. ft. Concrete footers were poured for all the concrete block piers that carry the weight of the home from the I-Beams and for the parameter brick curtain wall that totally encloses the properly closed crawl space. Prior to pouring the concrete for the parameter footer the tie-down anchors were augered into the footer trench. Following construction below grade foundation water-proofing and a drain to daylight parameter french drain was installed. The finish grade of the soil drains all surface water away from the foundation.
The home uses 2 x 6 wall framing and a 2 x 4 roof truss system with cathedral ceilings throughout the interior and approximately a 3/12 roof pitch.
Insulation values are: Ceiling R-30, Walls R-19, Floor R-22
The windows are intentionally simple. Single-hung, none treated, single-pane glass in an aluminum frame plus and interior single-hung of the same materials. The two windows are separated by the wall framing leaving a 5 inch space.
Space conditioning is provided by a standard heat pump and an energy recovery ventilator. Separate airtight ducts systems were site installed for each.
The properly closed crawl space has a continuous and sealed poly vapor retarder for the ground and walls - leaving a 3 inch view strip at the top of the foundation wall. A dehumidifier with gravity drain to outside manages the minimal water vapor that migrates into the space.
| Foundation wall assembly |
Concrete footers were poured for all the concrete block piers that carry the weight of the home from the I-Beams and for the parameter brick curtain wall that totally encloses the properly closed crawl space. Prior to pouring the concrete for the parameter footer the tie-down anchors were augered into the footer trench. |
|---|---|
| Above grade wall assembly |
2x6 wall assembly with R-19 fiberglass batts. The interior surface is 1/2 inch sheetrock and the exterior is 1/2 inch OSB with vinyl siding |
| Above grade wall R-value | 19.0 |
| Cathedral ceiling assembly |
100% of the ceiling is a cathedral assembly using a 2 x 4 truss system |
| Cathedral ceiling R-value | 30.0 |
| Roof Assembly |
2 x 4 truss system |
Windows and Doors
Window Assembly:
Intentionally inexpensive aluminum frame single-hung windows with non-coated single-pane glass.
Interior single-hung storm window of the same materials with the two windows separated by the wall framing leaving a 5 inch space between them
No record of U-factor, SHGC, etc.
Cheap windows
Door Assembly:
foam core filled steel door [3' 0" x 6' 8"] with one third of its area being an insulated glass sandwich fixed window light
| Door Area | 20 sq ft |
|---|
Mechanical Systems
| Space cooling - Manufacturer & Model | Rheem RPRL 024JEZ 2-stage heat pump |
|---|---|
| Space cooling - capacity | 7 kW |
| Space heating - Manufacturer & Model | Rheem RPRL 024JEZ 2-stage heat pump |
| Space heating - capacity | 7 kW |
| Domestic hot water - Manufacturer & Model | Intertherm 20RTOE3JNC - electric |
| Domestic hot water - capacity | 50 gal |
| Domestic hot water - efficiency | 92 kW |
| Ventilation - Manufacturer & Model | Venmar AVS Duo 1.2 with TRE = 75% |
| Lighting Manufacturer and Model | multiple |
| Lighting Efficiency | all lighting is cfl [80%] or led [20%] |
| Mechanical Equipment Installation Details and Comments |
Manuals J,D, S, & T were used in design and selection. With room by room calculations present, air distribution was balanced with air flow measurements. The complete air distribution system including the air handler was tested with a duct blaster and found to have less than 5 CFM25 Total air leakage. System performance was achieved by establishing correct air handler air flow and then establishing proper refrigerant charge. The 7KW heat strip is locked out until outside temperature drops to 20 degrees F. |