The Davis House Somerville, MA

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This renovation transformed this building from an energy guzzler to a resilient and healthy spacious 2-family, designed to use less energy than it produces. Careful planning resulted in high efficiency of the building envelop, of the heating, cooling and ventilation systems. The solar panels provide the energy needed to run this two family.

This is important because:

  • Existing structures, outnumbering new housing nearly 300-to-1
  • “The greenest building is the one that’s already built, in almost every case.”
  • There are 130million housing units that already exist. 80 % will still be here in 2050. This is where many of our efforts should be.

The goal was to reduce the energy use and increase the usability of the building within the same footprint by:

  • New envelop: Roof R-60 to 62.5, Walls R-48, Bsmt-Walls R-23, Slab R-20 3 pane windows: (SW, NW,NE) U 0.21, SHG 0.19, VLT 0.32
    (SE) U 0.25, SHG 0.31, VLT 0.34
  • Retained 60% more solar gain on the SE for passive solar heat.
  • Windows added by 50% to South, removed by 50% to North
  • Provided solar shading ACH .85 to 1.2 @ 50P

Equipment:

A hybrid solar system with 56 Sunpower solar panels for PV combined with 12 Sundrum panels attached under the PV panels provide power and hot water. The hot water is for
both domestic use and for the basement radiant slab. 3 minisplits per unit provide both heating and cooling. Each unit has a HRV which provides preconditioned air to all rooms and works with booster fans to exhaust bath and kitchen air. The condensing washer-dryers don’t require an exhaust fan. With these strategies we minimized the number of exterior envelop penetrations from the mechanical equipment and provide for a much healthier indoor environment with constant fresh air supply

Each unit has a HRV which provides preconditioned air to all rooms and works with booster fans to exhaust bath and kitchen air. The condensing washer-dryers don’t require an exhaust fan. With these strategies we minimized the number of exterior envelop penetrations from the mechanical equipment and provide for a much healthier indoor environment with constant fresh air supply.

Layout:

Redesigned layout with combined rooms for spaciousness. Expand interior to exterior with decks and added windows. Expand living space to basement & in attic by lowering floors and adding daylight.

Minimize visual clutter, use transparent materials (see stairs).The sustainability of the design is enhanced by resource efficiency: many of the building materials used are reused or recycled, for example bathroom floor tiles are the former slate roof. The floors were reinstalled. Demolished chimney bricks were reused. One staircase was rebuilt, a stair and cabinet built with wood from a nearby demolition site, recycled ceramic tiles and recycled tire decking etc.

The healthy indoor environment is due to using no or low off-gazing building materials and a continuously operating ventilation fan supplied preheated out door air. The redesigned room layout assures the spacious feel for the interiors. Although the apartments are small, about 1360 SF, with a lot of daylight and transparent adjacencies between the non-private rooms, the space feels generous. New decks also expand the interior spaces to the exterior.

Recycled furniture in both apartments complete the sustainability of the project.

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Project TypeZero Energy Renovation
Sq Footage 3130
Annual Renewable Energy Generated 8586
Energy Source Photovoltaic
Climate Zone Zone 5
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