Completion

Completion date
06/01/2016

Occupancy

Occupied year round by 4 family members
Home is occupied during the day as home office
Home is occupied by house rental guests when on vacation

Days per year Building is fully occupied:
360

Scope

Type of Construction
Number of buildings 1
Floor area of each building 1,500
Bedrooms 3
Bathrooms 2.0
Stories 2
Conditioned Building Volume 18,323 cu ft
Conditioned Floor Area 1,500 sq ft
Semiconditioned Floor Area 2,600 sq ft
Historic significance

Home is within the Old West Side Historic District on the National Trust for Historic Places. Home received historic renovation tax credits from the Michigan State Historic Preservation Office. Home was built in 1901.

Location and Climate Details

Single-family residence

Address
217 S. Seventh St.
Ann Arbor, MI 48103
United States
Location Type Urban
Climate Region Zone 5
Köppen Climate Type Dfa
Lat. / Long. POINT (-83.758223 42.280251)
Elevation 840 ft
Solar Insolation 3.66
Annual CDD and Base Temp 883 | 65 deg F
Annual HDD and Base Temp 6084 | 65 deg F

Site

Site conditions:
previously developed land
Site description:

It is within the Western Great Lakes forests is a terrestrial ecoregion as defined by the World Wildlife Fund. It is within the Temperate Broadleaf and Mixed Forests ecozone / biome of North America, in the United States. The home is sited near a tributary of Allen Creek, but well above the flood zone. The soil is categorized as Fox Sandy Loam.

In keeping with the ethos that the greenest building is the one that already exists, the Grocoff family sought to restore a historic home to the highest energy efficiency standards achievable today. This achievement emphasizes the feasibility of deep-green renovations of our existing housing stock.

Materials and Design Strategy

Materials:

Home was restored using the U.S. Secretary of the Interior Standards for Historic Preservation. Few new materials were used. Wood was sourced locally from dead and downed trees from local sawyers or from Forest Stewardship Council (FSC) sources. Whenever available reclaimed or salvaged materials were used.

Special architectural measures:

Efficiency Measures
The Grocoffs’ renovation was achieved within the tight restrictions of the Secretary of Interior Standards for Historic Preservation. In keeping with these guidelines, they wanted to preserve the heritage, story of place and the beauty of the home without expanding the footprint. Therefore, they did not consider changing the structure or layout of the walls or windows. In addition, when the Grocoffs purchased their historic home, it already; had good solar orientation; eaves that provide summer shade for the second floor windows; a natural passive stack effect as a result of operable basement and attic windows; and large south-facing windows. These features were restored to their original functionality. Practically speaking, there were minimal improvements that could be made to the home’s thermal envelope. To achieve Net Zero Energy, attention was focused on optimizing energy use in the home through the introduction of efficient systems, appliances and controls.

Insulation and Sealing
Windows: The original windows are single-pane assemblies with wood framing. To improve the energy efficiency of the house, a wood window repair expert restored and weather-stripped the original sashes and hardware. Trapp low-e storm windows were added to the exterior. Air Changes per Hour @ 50 Pa (ACH50) were reduced from 15.70 ACH50 before the window restoration to 4.75 ACH50 after restoration and installation of exterior storm windows.

Wall Insulation Retrofit: On the exterior, the asbestos siding, installed in 1947, was removed to reveal the original wood clapboard siding. Two rows of clapboard were carefully removed. Holes were drilled through the wood lathe to allow for filling the above-grade balloon-frame walls with R-13 dense-pack blown cellulose insulation. The clapboards were replaced and the original exterior wood was restored and painted. Limited by the 2x4 width of the original framing, the walls achieve a value of only R-15 including the plaster walls and exterior wood clapboard.

Basement: The basement foundation walls are made of cut stone block and is are partially below grade. The rim joist cavity was filled with spray foam. However,though the stone foundation walls were left uninsulated. The basement is partially conditioned and used for laundry and storage.

Attic: The attic was converted from an uninsulated, poorly-ventilated space (vented with gable windows) to a cathedralized, unventilated space using open cell Demilec Sealection 500 spray foam, achieving approximately R-29. EcoSmart Insulated cellular shades are used on the interior of the windows.

The Michigan State Historic Preservation Office first denied the request for historic preservation tax benefits. They based their decision on the use of spray foam on the underside of the roof deck of the attic. The denial was reversed on appeal. The appeals officer determined that the since the foam was open-cell foam it was reversible. They stated that the “adoption of “new” technologies is problematic because of the possibility of irreparable damage or complete destruction to elements of a historic resource’s fabric that are irreplaceable.” However, they determined that it was demonstrated that after considering all forms of insulation, “that the use of open cell spray foam was the most appropriate choice for insulation of the Property in that it provides the best performance for contemporary use while maintaining the historic character of the Property.”