Here is a first pass, can't quite drop the country detailing but it's a transition with the flat roof on the master bedroom wing with raised bed planters for safety railing and a brick floor for grilling and second floor outdoor living.
Beth and I have been feeling inspired by some of the homes we've seen in Ashville, and San Francisco and we thought it would be great fun to design an affordable home with a modern spin that had high performance and green elements but would not be out of place on an infill or high density lot. We've dubbed this our "affordable green" project and want to present a couple versions of it here in hopes that it will inspire someone to ask us to incorporate some of these ideas into their new home.
This concept is for a small and narrow footprint that could be oriented east-west and we have a flat roof (San Francisco style) version that could be oriented north south without compromising the solar potential. We realized that in a high density situation we wouldn't be able to count on passive solar design for solar thermal heating so we resolved to use rooftop solar collectors to collect solar hot water for radiant floor heat. This east-west orientation can use ridge mounted panels on a pitched roof whereas a flat roof version would use frame mounted panels.
We're using a slab floor so we can take advantage of slab-type radiant heat and the thermal mass of that. But there are a couple of refinements. We've done a couple of homes with partial radiant slabs recently where even though only the kitchen, entry and a few bathrooms had radiant heat we still had clients report that they rarely use the heat pump back-up. It seems that with the well sealed and insulated building envelope the heat dissipated throughout the home evenly enough that they stayed comfortable in the bedrooms even with no direct radiant heat in those locations. I've also been hearing through the building science community about builders in the Midwest who are using extreme high thermal mass strategies, insulated rock and sand beds etc, to get enhanced thermal performance. In summer cooling season we may tolerate 78 to 80 degrees in our homes and in winter be happy with 68 to 72. If we can use the summer months to elevate the temperature of a well insulated thermal flywheel to 78 degrees we can harvest that energy in the winter months when 68 is not so bad. Our general pattern with radiant floor systems is to have zones of 500 to 700 sf that are linked together. Often the zone with the most glass ends up triggering its thermostat the most leaving the others to stay warm from the residual heat left in the radiant floor system from the water being displaced from the zone that is calling for heat. I've been thinking that we could design an insulated radiant slab that was partially covered by resilient flooring that would not emit heat into the home but could serve as an extended thermal flywheel for the home. This proposed project would have 1176 sf of slab on the first floor but only one 500 sf emitting zone with tile flooring and the rest would be passive thermal flywheel with resilient flooring. Heat would rise up the stairwell to the second floor as well as be linked through the cross connections of the return air grills on the zoned bypass HVAC system. If the temperature imbalance got uncomfortable on cold winter nights the owners could put the HVAC on fan and automatically engage the 15 SEER heat pump if the interior temp dropped below 68 degrees.
1176 sf on the first floor. Entry, dining, kitchen and first floor bathrooms have radiant floor heat on a single zone t-stat. the heat flows under the resilient engineered wood flooring in the living room and master bedroom.
The first floor is an "aging-in-place" design, all functions are walker accessible (not wheel chair accessible but not far from it.) With the narrow lot program we chose to place the kitchen in the center of the building and to tuck the laundry into the mechanical room adjacent to the staircase. We have an (optional) energy efficient wood stove in the corner of the living room and left room for a flat panel TV to the right of it. There is outdoor living space behind the house with the potential for alley parking as well as off street parking to the side of the front porch in front of the master bedroom. Two awnings visible on the second floor plan provide sun shelter to the south facing dining and living room windows.
Upstairs plan 756 SF. Two small bedrooms connected by an 11x11 study area. By using a zoned bypass heat pump we can put keep all ductwork out of the roof and cross connect the return air ducts between the floors for better air balancing.
The outdoor living area behind the house is enhanced by a 20 x 18 roof garden on the second floor above the master bedroom. This is not what is commonly referred to as a "living roof" but shares many of its benefits. The roof membrane is a Schulter system applied directly to ¾" Advantech subfloor on graduated 16" to 24" flat roof trusses with pitch strips applied over the trusses to throw water off rain scuppers on the north wall in case of a hurricane. Above the water proofing a layer of brick tile acts as a wear layer and fire proofing to make the roof garden the location for the Weber and outdoor dining. Wrap around planters sit on skids that hold them up off the brick. The planters are 22" tall and 36" wide so they act both as seats and as safety railing. To meet code there will be a 14" tall trellis rail in the center of the planter to support the tomato plants and keep toddlers from crawling through the plants to fall off the precipice.