It occurs to me that I never did post the final architectural drawings that we are now using for construction. So here, along with a brief explanation, are some of the most prominent ones. Click on an image to open it in a separate window. I will add additional drawings as needed. And thanks to our architect Chris Briley for permission to post them for information only.
Site plan: The basic shape of the house fits the unique characteristics of the site. The long axis is perfectly oriented due south, perched 35′ above the 200′ of frontage on the Saco River. A land swap with the city of Saco was a key enabler in siting the house. The building footprint hugs the north and west zoning boundaries, which keeps it as far from the steep slopes on the south and east sides of the lot as practicable. That also shortened the distance to water, sewer, and electrical services. The site plan complies with Saco zoning restrictions, as well as those of the Saco River Corridor Commission.
Main Floor Plan: The main floor is about 2,100 square feet, excluding the garage and the 3 Season room, which are both outside the thermal envelope, i.e., are neither heated or cooled. The master bedroom and laundry on the main floor make for one-level living. The floor plan has living areas along the long south facing axis, which, not coincidentally, is also the prime view to the Saco River and our marina neighbor. (One of our key land purchase criteria was to align southern orientation with a picturesque view.) All the utility spaces e.g., closet, bathroom, stairs, laundry, garage are on the north side. The home incorporates “universal design,” i.e, there are no steps to enter the home from either the front door or garage. Interior pathways are a wheelchair friendly 42″ wide. All doors are 36″ wide. Showers are barrier-free.
Lower level Floor Plan: The lower level will have 2 bedrooms (we will use one as an exercise room), a bathroom, storage areas, a mechanical room, and a rec room that I will use as a woodworking shop. There are 4 large below grade venting windows facing south to let in lots of natural light and fresh air. Bilco Scapewels provide emergency egress. We were able to conceal all but one lally column within a wall. For better energy efficiency and security, there is no direct access from the lower level to the outside yard. Access to the lower level is via either an interior stairwell from the main floor, or from the garage.
Front and rear facades: Most homes built to the Passive House standard that we have seen or read about have been, well, rather plain-jane rectangular boxes. We wanted a bit more style than that, but remain consistent with the neighborhood. The street view is a one-floor wedge shaped ranch. The exterior will have a stone base topped with fiber cement shingles. There’s a sheltered porch with a distinguishing elliptical-shaped roof leading to the front door, stone planters, and craftsman-style tapered columns. The primary heat source for the house will be the sun, so it makes sense that the south facade features a large expanse of windows. There’s plenty of roof real estate to mount the 5 – 6 Kw solar panels to get us to net zero energy use.
Wall X-section: Any home built to the Passive House standard will have thick exterior walls and lots of insulation. We are using Logix Platinum series insulated concrete forms for the foundation with embedded graphite particles that provide a 23% increase in R-value for the same size block. The exterior walls are a double wall 2 X 4, spaced 9″ apart, with exterior Advantech sheathing that combines traditional sheathing with a Tyvek like air barrier. The walls are being built in a factory and will be trucked to the site. The 14″ deep wall cavity will be filled with dense pack cellulose. We will pay particular attention to air sealing the exterior wall, and will use an air-tight drywall approach on the interior wall. R-values are as follows:
- sub-slab: R-40
- foundation: R-41
- double-stud wall: R-53
- ceiling: R-84
Window details: We selected a Passive House certified triple-pane, wood core, aluminum clad European style tilt-turn window made by Bieber in France. European windows do not have a nailing flange like north-american style windows, so the installation details are different. We opted for an “outtie” vs. “innie” installation, meaning the windows are near the outside plane of the house. Our architect Chris Briley, and energy consultant Marc Rosenbaum agreed innie windows have better energy performance, but they are much more difficult to seal against water intrusion. Water management trumps energy, so that windows are outties. We have splayed the interior vertical wall opening around the windows to improve daylighting.
HVAC plans: While the sun will be the primary heat source, sometimes, the sun don’t shine on Maine. We abandoned plans for radiant floor heat as too expensive, and too many BTUs. We will use 3 mini-split cassettes on the main floor and one on the lower level to provide heating AND cooling. These systems are very energy efficient, producing 3 times the heating or cooling for every unit of energy consumed and are effective when outside temps plummet to well below zero. If there’s a profound cold spell, we will either light our pellet stove, or book an immediate flight to the Caribbean!
3-Season Room: We wanted this room to have an entirely different feel than the rest of the house. Otherwise, it’s just another sitting area. It is designed with non-structural post and beam, knotty pine walls and ceilings to give the room a classic maine cottage feel. The pine logs were harvested from our site and milled nearby. Though outside the building envelope, this room is built with the same double stud wall and levels of insulation. There are but two difference: no HVAC, and double vs. triple pane windows. With a majestic view of the river, I expect we will spend lots of time relaxing here.