Hopper Design, LLC

Toward Healthy and Sustainable Homes

Designs - Solar Cape 20x40

1 bedrooms, 1 1/2 bathroom

 Download plans: $175.00

Cape footprint 20' x 40' (total 800 square feet)
A heated basement is included at 800 square feet.

This Solar Cape has entrances on the south and east and provides all the conveniences for living on one floor. A bathroom is located off the master bedroom and a half bath near the entry. This design has a full heated basement suitable for use as a workshop, office, or guest room.

The long glazed side of this home faces south and has a compact single story scale. It is designed for efficient use of space and is economical to build, substantially lowering construction costs. This design has several important features that allow significant reduction of non-renewable energy needs, making it possible to achieve net zero energy usage.


View of south and east elevations at 11 a.m. in mid-October.

The south facade has substantial glazing to allow passive solar gain in winter. Active solar systems are planned for the south facing roof. This combination of passive and active solar use is critical for achieving zero net energy usage. Active systems are only practical after major steps to conserve energy have been taken first. Roof mounted active systems can be added later but must be planned for in construction.

A typical house of this size would consume 14 to 35 MBTU1 of heating energy per year. Everett Barber's new QuikCheck Energy (QCE)2 program indicates that this Cape can perform near to the standards of "Passivhaus" at 3.8 MBTU/yr. If we used today's super insulated construction techniques QCE indicates a 6.1 MBTU annual requirement for heating energy. With three more advanced construction and insulation strategies for this Solar Cape, annual heating energy needs can be reduced to 4.5, 2.2, or 0.7 MBTU. Each strategy requires a higher degree of conservation measures to be built into the home. The plans for this Solar Cape are designed for a 2.2 MBTU/yr heating energy requirement which, with the active systems shown, can attain net zero energy usage.

This home provides all essential living needs conveniently on one floor, making it suitable for folks of all ages. The living, dining, and kitchen are designed as open adjoining spaces. The kitchen is highly functional, has a window facing east for morning light, and is accessible from the east entrance.


Solar Cape first floor plan showing entry, kitchen, dining, living, master bedroom, bathrooms, closets, and stair to basement. Four water filled copper tanks for thermal capacitance may be added as shown.


Solar Cape basement floor plan showing optional study/guest room, bathroom, utility, and open area for family play room, hobby, workshop, and storage. Basement windows mounted high may be added (not shown).


View of Cape in spring. Welcome sunlight enters the home on a cool day.


Site Plan with drive entries possible from northwest through east to southwest.

Three active solar systems

The roof of the Solar Cape supports three separate active solar systems. On the roof two solar thermal panels are dedicated to the production of domestic hot water and four thermal panels are dedicated to the production of space heating. A 5.1 kW photovoltaic system is planned as grid-tied to feed the utility via a net-meter. This approach for the production of electricity is essential for achieving a zero net energy design. Note that all this equipment is mounted above the roof drainage surface and allows air to cool and increase performance of the PV's while shading the roof in summer. The net solar load impacting the roof is thus greatly reduced. This also makes servicing of these systems simple.


View of the west and south elevations at 4 p.m. in fall with a 5.1 kWh photovoltaic array and six thermal collectors for domestic hot water and space heating.

More images

Interior views stretched to include items of interest.

View looking southeast through living to dining. The east entrance is to the left (not shown).


View to east with dining and kitchen beyond. An optional wood or pellet stove can provide supplemental heating in winter.


View of master bedroom with entry to walk-in closet and bathroom.


View of Solar Cape on June 21 at 11 a.m., summer solstice. Note how little solar energy enters the home.


View of Solar Cape on December 21 at 11 a.m., winter solstice. Note how well the south windows allow solar energy deep into the home.