Heating Options, Part Three

In parts one and two, I talked about reducing heat needs and active heat sources. But as Anonymous pointed out in comments, there's also passive heat (I was getting there, really!)

For the most part, passive heat is best integrated during the design phase of new construction. This used to be standard practice until the wide-spread utilization of active systems. From the cooling courtyards of the Middle East and Mediterranean to the Pueblos of the American Southwest, the access (or avoidance) of passive solar heat was a primary consideration. Early American farmhouses were oriented to the climate effects of both wind and sun, but eventually the focus shifted to roads instead.

Many older homes can still utilize this advantage with strategic curtain use. In the cooler months the blinds are opened during the day and closed at night to keep the trapped heat inside. In warmer periods the process is reversed, blocking out the day's sun then encouraging cooling breezes at night. For several years I lived in an old brick bungalow that demonstrated the effectiveness of these methods quite nicely. Be careful of the chimney effect however – airflow along the windows behind the curtains can set up a cooling current instead of the desired heat retention. Thus the design of the magnetized edges of window quilts.

I knew a couple that built their home on the North Shore of Lake Superior in Minnesota who used solar awareness during their design and construction. The large South to Southeast windows captured much of the winter sun; in fact sometimes too much, necessitating opening windows and using ceiling fans to exhaust the hot air out in the middle of winter! During summers the overhang was designed to block the higher sun, and cooling lake breezes kept the house quite comfortable while the neighbors around the other side of the hill needed to use air conditioning units.

The main house of the property I live on now was also designed to be passive solar. The south side is nearly all patio doors opening to the black tile floor of the great room. In the summer, the overhang limits direct sun to just a few inches, while in winter it penetrates not only across the great room floor but even striking the back wall of the room! Unfortunately there is insufficient insulation below the slab, and as much of the gained heat dissipates into the ground below as into the room itself.

Quite possibly one of the most unique utilizations of passive solar is George Bernard Shaw's writing hut. It is a small 8x8 structure built on a lazy susan turntable! A simple push enabled the writer to utilize or avoid the sun as he desired. A door flanked by two non-operable windows are on one side, with one small operable window on the wall opposite. By turning the hut, he was able to optimize heat gain as desired; increasing the gain during cooler weather, or avoiding it during warmer weather. Minimal windows also translate to minimum heat loss, while the operable window opposite the door allowed natural ventilation. Being able to rotate the hut for natural light gain also reduced the need for artificial lighting.

The writing hut is also an excellent example of smaller spaces having lower heating requirements. Another example of this are the canopy beds frequently found in old stone structures. The heavy curtains closed off a small space better able to retain the heat exuded by the occupants. The raised sleeping shelves of the Inuit igloos served a similar function, as well as allowing the cooler air an area below the sleeping shelves to pool. And of course there are the three-dog nights, when the weather was so cold a person would bring three dogs to bed as personal heaters!

In a sense, utilizing passive solar is a method of reducing heating needs. But somehow it seems like more than just reducing – perhaps displacing would be a better word?