Understated Solar for Gray Winters
(Page 2 of 4)
The obvious response to an unpredictable climate is to stress insulation in preference to solar features. But does that mean solar technologies should be abandoned in the Midwest? Not at all. Kawecki's design still achieves approximately a 40% solar contribution to space heating. Let's look at how.
RELATED CONTENT
Want to know how to build your own photovoltaic system, how to construct a solar water pump, or eve...
It’s not every day that you get a chance to tour a green home. Well, here’s your opportunity! Every...
A string of new solar manufacturing plants are scheduled to open within the next few years....
From California to New Jersey, utilities across the nation are pursuing developments in solar power...
Rapid growth, declining costs: the future looks bright for solar energy....
First, the Pipics' house can definitely be called superinsulated. The walls are built from 2 X 6's (16" on center with 5/8" drywall for solid walls) and are filled with fiberglass and sheathed with 1 " foil-faced polyurethane on the outside—for an R-value of about 30. The ceiling has 15 to 16 inches of blown-in cellulose, giving it an R-value of roughly 50. The perimeter of the crawl space is insulat ed on the inside of the block footings with 1" foam, a vapor barrier, and foil-faced 6" fiberglass that laps a foot onto the floor. To reduce infiltration, electrical receptacles in the exterior walls were kept to a minimum, and no recessed lighting was used in the second floor ceiling.
Second, solar gain comes primarily from a sunspace, which functions as a large passive collector. The sun-room has little mass of its own (the brickwork on the walls is a veneer), an approach that until recently would have been considered quite odd. Here's why it was done: Using a mass (sometimes called Trombe) wall at the back of a sunspace to transfer heat to living areas doesn't work well in places where much of the wintertime solar radiation is diffuse. Mass walls require the intensity of direct radiation to drive heat through several inches of masonry on a daily basis. What's more, if the sunspace has a large amount of mass not linked with the living area, it would likely use most of the energy available on a cloudy day just to heat its own mass. (Problems with condensation during the humid Ohio summer also argue against extensive use of thermal mass.)
The best use of a sunspace in the Ohio climate seems to be to allow its temperature to float up during the day and down at night. The Pipics installed ample doors and windows on the ground floor, as well as a number of windows on the second story, to allow convection between the sunspace and the house. At night, or when the sunspace would overheat the house, the doors and windows can be closed. The high degree of control over gain and loss offered by this approach is a distinct advantage, in this climate, over directgain features that are largely at the mercy of the weather.
