Walls and Roof

The building envelope meets National Grid DER pilot house guidelines.

Subslab assembly

2 in XPS rigid foam (R-5/in) over existing concrete slab with drain mat below + 3/4 in plywood (R-1.25/in) flooring above.

Subslab R-value 10.9
Foundation wall assembly

2 in of XPS rigid foam (R-5/in) + 2 in of polyiso rigid foam (R-6.5/in), 3 in closed cell spray foam on rim joists, 0.4 in Spaceloft (R-10.3/in) used instead of polyiso near stairway to reduce thickness and maintain reasonable stair width

Foundation wall R-value 23.0
Above grade wall assembly

4 in of polyiso rigid foam (R-6.5/in) on exterior + 3.5 in of blown cellulose (R-3.4/in) in original wall cavities + 3/4 in plywood (R-1.25 /in) sheathing + 0.75 inch dead air space (R-1.0/in) + 0.5 inch gypsum board (R-0.9/in) + 5/16 in cement board siding (R-0.48/in)

Above grade wall R-value 40.2
Roof Assembly

Two 3 in polyiso rigid foam layers (R-6.5/in) + 5.5 in of blown cellulose (R-3.4/in) in roof rafter pockets + two 3/4 in plywood (R-1.25/in) sheathing layers + Asphalt shingles (R-0.44)

Roof R-value 60.0

Windows and Doors

Window Assembly:

R-8 Schuco SI82 U-PVC tilt & turn casement

Door Assembly:

2 First Floor Entry Doors - Fiberglass, Therma-Tru, R-4, R-5.3
2 Basement Entry Fire Doors - Fiberglass, Therma Tru, R-7.1 base door
On basement doors, added 0.4 in Spaceloft (R-10.3/in) + 2.0 in XPS (R-5/in) to achieve R-21.2
Door average Rval = 7.4
Door average U = 1/7.4 = 0.14

Average window U-factor 0.13
Solar Heat Gain Coefficient 0.50
Visible Light Transmittance 0.71
Door U-Factor 0.14
Door Area 72 sq ft

Mechanical Systems

Space cooling - Manufacturer & Model Mitsubishi Mini Split MUZ-FE09NA (Outside) / MSZ-FE09NA (Inside)
Space cooling - capacity 3 kW
Space heating - Manufacturer & Model Mitsubishi Mini Split MUZ-FE09NA (Outside) / MSZ-FE09NA (Inside)
Space heating - capacity 2 kW
Domestic hot water - Manufacturer & Model GE GEH50DEEDSCA, EFR = 2.4
Domestic hot water - capacity 50 gal
Ventilation - Manufacturer & Model Zehnder CA-350, 87% efficiency, measured balanced flow 61/95/155 cfm
Lighting Manufacturer and Model
Lighting Efficiency
Mechanical Equipment Installation Details and Comments

Blower door testing done both before and after DER completion to measure effect of air sealing measures.
CFM50 ACH50 EqLA(CFM/sq ft of enclosure)
Pre DER 2798 10.32 0.66
Post DER 434 1.43 0.09


Air Changes per hour, ACH50 1.43 ACH50
Air Changes per hour, CFM50 434.00