A green roof is roof covered with a growing medium and plants. Obviously, a lot of thought and effort is needed to create a roof that can take the additional load and not leak after decades of use. But what you achieve is a structure that has exceptional thermal characteristics. And, in cases like this, can be seamlessly integrated into its native environment.

From the sidewalk you go down to enter the house, which is almost completely below street level.

Built in 1979, this home is located almost entirely below street level, on the side of a hill. From the front sidewalk, you can walk up a gentle slope covered with drought-tolerant plants. Only the skylights give away the fact that you are walking on the roof of the house. At the edge of the “roof” are rows of solar panels that actually provide more hot water and electricity than the house needs.

But the house is unique in another way: it’s built of concrete block, from top to bottom. Even the floors and ceilings of this multi-level structure are poured concrete. In addition to providing a rock-solid, termite-proof, nonflammable structure, the concrete provides both acoustic insulation: if the windows and doors are closed, the house is very quiet.

A view of the house from down-slope shows how it is tucked into the hill.

But more significantly, the concrete – and the green roof – both add significantly to the thermal mass of the structure, buffering it from changes in temperature. Summer cooling is achieved by opening downstairs windows and roof skylights at night. Double-paned windows on the south-facing slope provide a primary source of heat, with the very occasional use of fireplaces. Combined with San Diego’s moderate climate, the net result is that the house requires neither heating nor cooling.

Now, a concrete home isn’t for everyone. A lot of planning is needed since it isn’t easy to move walls or run new electrical service in concrete! Nevertheless, this particular implementation has created a comfortable zero-energy home. And who wouldn’t like to live in a home with no utility bills?

The house during construction in 1979. Note that, in addition to the concrete walls, the ceiling is poured concrete. Special care was taken to ensure that the wood forms used for the concrete pour could be used multiple times.

Your hosts for the tour will be Don and Ann, who not only planned this unique home but did much of the work on it themselves. Don’t miss this opportunity to visit one of San Diego’s few green roofs – and zero energy homes.