La Casa del Sol: a passive solar house – Mother Earth News


La Casa del Sol could loosely be called a renovation, in that it incorporates the frame of one end of a farm building.



Diagram of the passive solar house La Casa del Sol.


A self-proclaimed independent futurist, Sister Paula Gonzalez, has gathered 35 friends to realize the improbable passive solar house: La Casa del Sol.

April 29, 1985


At the end of August 1982, the first volunteer meeting for this “Saturday Project” convened to hear my plan to convert an old frame farm building into a sustainable home. In three years, some 35 people have been involved in one way or another, for varying periods of time. (Jerry Ropp, our de facto foreman, hasn’t missed a single Saturday since that first meeting.)

All the materials for the house you see in the photos were either [1] recycled, [2] purchased with money from recycling – especially garage and clothing sales, but also some scrap metal – or [3] donate. I do not have detailed cost figures at this point (since I am not only the accountant but also the sponsor, general contractor, soup maker and apprentice plumber, tiler, carpenter, partition finisher. dry, etc), but I know we raised about $ 12,000 or $ 13,000 and we still have $ 500 in the bank. This means that in anyone’s dollars, the 1,500 square foot super-insulated passive solar house that Sister Mary Bookser and I now live in – I call it La Casa del Sol, “the house of the sun” – costs less. $ 10 per square foot to build. In addition, our all-electric residence used less than 500 kWh of electricity (and some construction scraps in the woodstove) in February of this year.


Sister Paula Gonzalez

Sisters of Charity
Mont Saint-Joseph, OH

La Casa del Sol: a passive solar house

These are just a few selected excerpts from a letter we received from Sister Paula Gonzalez in response to the announcement of our low cost house building competition (see this MOTHER EARTH NEWS issue on page 90). We were impressed with what Sister Paula described, but the entry was also a problem. How would we equate the costs of a completely recycled house built entirely with volunteer labor to those of others built by conventional means even remotely? It would be a classic case of trying to compare apples with oranges.

For this and other reasons – just to begin with, we wondered what a Sister-Ph.D. Cell-biologist-professor was building a passive solar house – we decided that La Casa del Sol should have a full featured feature article. The more we heard and saw, the more fascinating the story of this passive solar house became.

From futurist to foundation researcher

The Sisters of Charity of Mount Saint Joseph, near Cincinnati, were founded by Saint Elizabeth Ann Seton, who aptly described the spirit of La Casa del Sol when she said: “Live simply, let others can simply live ”. La Casa founder Sister Paula believes that much of today’s global conflicts can be attributed to attempts by some to maintain (or achieve) a way of life our planet cannot (and cannot support). – at least not for all 4.7 billion charges. She asks, “What if, instead of fighting (until nuclear war) to extend the ‘good old days’ of the oil age, we start to use our limitless creativity and imagination?” to design the “best new days” “? La Casa is where the words stop and the action takes over.

La Casa del Sol could loosely be called a renovation, in that it incorporates the frame of one end of a farm building. Its 1,500 square feet extends far beyond the front of this humble structure (a former chicken coop for Mount St. Joseph College), and even the original concrete floor has been chiseled (by hand) to make room for a solar underfloor storage system.

The block diagram should give you an idea of ​​the thermal operation of the house (see the diagram of the solar house in the image gallery). Most of the solar energy is captured through approximately 250 square feet of quadruple insulated glass in the solar space. Part of this heat is stored directly in the concrete floor and soon covered with quarry tiles) of the solarium and the large room (the two rooms are connected by patio doors). At the same time, the heated air in the solar space rises to pass through the transom vents in the great room and the attic.

Another 96 square feet of Quadpane glass in a slatted attic helps solar gain. From the attic, some of the heated air is drawn by a fan into a stone storage floor: a heat storage system made up of washed gravel and concrete blocks lying on the sides, which function as plenums, like The detail of the rock storage section shows it. The rest continues its convective path through a passage above the bathroom and laundry room, into the east-west hallway, and through transom vents above the bedroom doors. The return path to the solar space is through the air floor, with additional thrust from another fan. The heat stored in the ground rises in the living spaces above.

Solar, as far as it goes

Does all of this work well? In autumn and spring, very good indeed. But the Cincinnati area can only expect five clear days per month from December through March. During the winter months, La Casa del Sol relies heavily on its highly insulated exterior to retain the little heat from the sun.

A typical wall section (see solar house diagram in image gallery) is double framed with real 2 inch by 4 inch planks as well as 2 inch by 4 inch lumber and contains a total of 5 -1/2 inches of expanded polystyrene (EPS) and another 3-1 / 2 inches of fiberglass – for a total R-value of about 32. Ceilings are framed 2 by 8, filled with 7-1 / 4 inch EPS, with another 1/2 inch of EPS used between the drywall and rafters for a total R-value of at least 32. The below-grade parts of the building have 2-inch extruded polystyrene on the outside, one layer of EPS on the inside and a 2 by 4 wall with 3-1 / 2 inches of fiberglass on the inside. The air floor is insulated with 1-1 / 2 ”EPS. The entire building is covered with a 6 mil polyethylene vapor / air barrier which, combined with careful caulking and airlock entrances with insulated doors and magnetic gaskets, should maintain the renewal rate. air less than 1/2 per hour.

Recognizing that conservation would be more important than pure solar gain, Sister Paula specified Quadpane glazing for the solar space and skylight. Although two layers of glass and two of Dow Sungain film transmit 25% less solar energy than conventional double-glazed windows, they lose less than half the heat – an interesting compromise. All other windows in the house are double-glazed with night-time insulation, and even the Quadpane slatted glazing is fitted with a quilted blind.

The Casa is so well insulated and waterproof that when the mercury dropped to an all-time high of minus 21 degrees Fahrenheit (with a wind chill of minus 64 degrees Fahrenheit) one night after a completely cloudy day in March 1985, the interior temperature set at 50 degrees Fahrenheit without backup heat.

That same evening, solar space hit a bottom of 38 degrees Fahrenheit and the geraniums continued to bloom happily. Normally, however, Sisters Paula and Mary turn on electric radiant heaters in the bedrooms when it is too cold. Once they have a catalytic combustor to clean their woodstove’s emissions, they hope to do without the small electric heaters altogether.

Although La Casa del Sol only receives about 20% of its heat from the sun in January, the solar features have additional benefits in terms of aesthetics and energy savings. The house is very well lit by daylight, which reduces the need for electric lighting. The glazing of the solar space lets in a lot of light into the large room, even on a cloudy day, and the skylight provides sunlight to the rear hall. A particularly clever feature of the building is the design of the skylights in the bathroom. Rather than having problem-prone (and expensive) roof glazing, the two-piece bath area has a non-structural ceiling that adjoins the air passage between the attic and the back hall. Light can pass through the slats in the back wall of the loft and shine onto the diffusing glazing (made by framing recycled shower doors) in the bathroom ceiling.

Water consumption (and the energy required to heat it) is kept to a minimum by a number of features. All faucets are fitted with water saving heads, the heater is on a timer that allows three 30-minute cycles per day, and the toilet has a jug filled with water inside to reduce the volume of the water. flush. It probably goes without saying that virtually all of these devices and accessories have been recycled.

Food for the sisters comes from the gardens behind the house and, again, recycling. Sister Paula discovered that an incredible amount of perfectly edible food is wasted for purely cosmetic reasons and brought in the major suppliers of products in the Cincinnati area. Part of lunch the day the MOTHER staff member visited was a crisp green salad made entirely of produce from the Sisters’ Garden and Cincinnati lettuce suckers.

Simplicity, not denial

This house is truly exemplary performance at around 2.5 Btu per degree-day per square foot for auxiliary heat, it uses half the energy that a new high-end conventional building does and between a quarter and an eighth. of the standard, but its genesis is at least as important: La Casa was built for a ridiculously small sum of money, which was generated entirely from the surplus produced by our wasteful society (albeit in this case generous). The construction was carried out by volunteers, most of whom were unqualified but skillfully led by Jerry Ropp and Sister Paula. They rightly call the accommodation the result of the La Casa community’s effort.

La Casa del Sol is just a first step; it shows that environmentally sensitive living is possible, and can even be delicious. Among Sister Paula’s plans is the conversion of the rest of the barn into accommodation for other Sisters of Charity. And yet to come are other energy saving features – two passive solar panels for domestic hot water are planned, an air-to-air heat exchanger is on the list, electricity coming from wind or photovoltaic panels is a possibility, and hybrid poplars for fuel are on the program – which will help La Casa residents live even lighter lives on the land.

Posted on May 1, 1986

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