Super-low-energy rehab with flair

Posted Wednesday, April 18, 2012 in Sustainable Maine

Super-low-energy rehab with flair

by Paul Kando 

PORTLAND — The impressive energy savings of Passivhaus may not be in the cards for every older home. Still its principles — super-insulation, absence of thermal bridges, air-tightness, heat/energy recovery ventilation and super-energy-efficient windows — apply in improving the energy-efficiency of any building, often with spectacular results. This attractive house in a quiet Portland neighborhood, rehabilitated by Jesse Thompson of Kaplan & Thompson Architects and his artist wife, Betsy, is a case in point.

They started with a neglected and leaky 1960s ranch house, with poorly insulated 2x4 walls and 1,100 square feet of living space linked to a two-car garage by an open breezeway. In the basement a gas-fired boiler struggled to keep it warm and provide the occupants with hot water. Today the house, with its dark stained hemlock siding, salvaged slate base and massive tapered chimney, has a striking, contemporary presence in a neighborhood of modest older homes,.   

Just past the Euro-brown entry door, a new mudroom with a vivid blue wall and coat hooks fashioned from birch plywood off-cuts welcomes the visitor. It opens into an open living area with a dramatic curved plaster ceiling over the kitchen and dining area. It rises to 12 feet over the sunny main living room, where the custom steel fireplace surround provides a visual focal point. The wood stove heats the whole house, which uses only 3.81 kWh of energy per square foot of floor per year for heating. At the opposite end of the living room, a broad, bright stairway leads upstairs to the children’s rooms. They are airy, bright, and feature natural-finished birch plywood floors and creative touches by a resident artist mom. They make one wish to be a child again.

To begin the renovation, the Thompsons stripped the building down to the outside plywood. They enclosed the breezeway, which became part of the heated envelope as the new entry foyer. For the children they added two bedrooms on a new second floor. Outside, over a continuous air barrier, 6 inches of salvaged rigid-foam insulation were added all around. The original windows were replaced with R-5 triple-glazed fiberglass casements, sealed to the continuous air barrier with tape. Because of the thick exterior insulation, the new windows are deeply set. Augmented by slatted exterior sunshades, this prevents summer overheating while allowing full solar gain in the winter.  

In the basement, R-10 rigid-foam insulation was added on top of the existing concrete floor to isolate the building from the ground. On top of that a new basement slab was poured. The existing natural-gas boiler was left in place to provide hot water and serve as back-up to the new, compact Scandinavian wood-burning stove in the living room, which heats the whole house for only $350 per year. Air-tightness was increased by 90 percent. It now meets the “EnerPHit” standard for Passivhaus retrofits, one air change per hour at 50 Pascals pressure, as tested by blower door. A Swiss heat-recovery ventilator provides fresh air year-round to all rooms.

All building materials were carefully chosen for low toxicity. Salvaged goods used throughout the renovation include the existing red-oak floor, stained black with "Liquid Nightmare" ebonizing, the ceramic tiles, and the recycled slate roofing used as siding on the lower part of the exterior.  

This LEED Platinum 2012 house meets the Architecture 2030 Challenge goal of 70 percent carbon reduction by 2015. Average electricity use is only about 350 kWH per month, thanks to efficient appliances and LED/fluorescent lighting throughout. The renovation expanded the original 1,100-square-foot footprint of the home to 1,900 square feet on two floors. Costs came to just $85/SF, in spite of the home’s classy architectural flair.

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