You may be surprised to learn that right across the United States, the days when our electric supply runs closest to its capacity are not the coldest days of winter, but the dog days of summer, when the air conditioners are set at maximum and it still feels too hot. The worst offenders, and the greatest energy consumers in this stressful time, are office buildings built -- one might be tempted to say designed, except that wrongly implies intelligence on the part of the architects -- to stack workers in configurations that could scarcely be better conceived to waste coolness and trap heat: solar ovens for cooking people. Energy theorist Amory Lovins, who will be heard from in Chapter 16, has called these curtain-wall monstrosities "all glass but no windows."
The same vain and sloppy architectural practices, applied to residential construction, produced a generation of once-fashionable, cheaply-built, flat-roofed, poorly insulated, glass-walled buildings habitable only because of their massive heating and cooling systems. Owners of these artifacts are reminded of their misfortune every month when they open their heating and cooling bills. Little can be done: increase and cherish shade trees, abandon and close off poorly ventilated southern rooms in summer, seek and encourage any nighttime cross-ventilation opportunities. Costlier remedies include replacing old glass with high-tech glass, installing or extending overhangs to block summer sun, increasing interior thermal mass in the cooler and more-easily ventilated areas of the house, replacing old floors with massive hydronic floors, adding a second roof or a cooling tower, and retiring the original air conditioning unit in favor of the most advanced and efficient model available. With energy trends as they are, you may expect any of these measures to pay you back within your lifetime.
The gracious houses built before architects and mass-production housing spoiled the American vision of a sensible dwelling may handle summer's heat well. In areas with hot summers, stately deciduous trees may already be thriving; whole neighborhoods often enjoy temperatures several degrees below those reported at the treeless airport. Remember that it is best to keep the heat where you want it, indoors in winter, outdoors in summer. For older homes, employing the common-sense measures intended by the original builders and the best modern means can be very effective, will be quickly repaid in energy savings, and will improve thermal performance in summer and winter:
[[photo: blower door
- Install radiant barriers and beef up attic and, if possible, in-wall insulation.
- Add or increase attic ventilation with a solar-powered fan.
- Replace single-glazed windows with the best possible modern fenestration; do not buy cheap windows. Minimizing infiltration of outdoor air with weather stripping and caulking windows is a stop-gap.
- Maintain storm windows and sashes, cross-ventilate in summer, close off unused rooms in winter, and use door-snakes (those long, bean- or sand-filled socks that block the crack below the door).
- Renovate and use the shutters provided by wise old-timers on the south side in summer.
- Improve window shades, especially on the north side, to retain winter heat and reflect summer heat.
- Install efficient new cooling and heating units before the old ones are worn out. If you have all the preceding measures in place, you may be surprised to find you can get by comfortably with a smaller unit than you had before.
If in doubt about where your home is hemorrhaging energy, a home energy audit might be warranted. In addition to documenting all energy expenditures -- follow the money -- comprehensive audits employ physical measurements of the home's energy integrity using blower doors and infrared cameras to identify leaks and weak spots in your home's defense against the frigid outdoors. Since most of us must heat as well as cool, improvements in wintertime performance often apply as well in summer, when the house's thermal behavior must be inverted to keep heat outside. The results of such diagnostic tests may help you decide which measures will be most cost-effective. In many states, audits are now being used to "energy rate" homes for bank financing and government-sponsored renovation programs. A typical finding will be that heat loss is occurring primarily through single pane windows, and therefore all the caulking and weather stripping in the world will make a very small impact. Based on this finding, it may be possible to justify, and perhaps even finance, rewindowing a whole house, or at least the most wasteful windows. (You are invited to conduct your own home energy audit in chapter 5.)
Whether planning a new structure or a retrofit, consider the dwelling's entire heating envelope. Here is a nightmare scenario: two o'clock on an August afternoon in a Lodi, California subdivision, where summertime electric bills for a normal dwelling average more than $200 a month. Or worse, if you are very brave, imagine a house near Houston, where cooling bills are typically in excess of $300 a month. The sun boils down on the shallow-pitched roof, and attic temperatures (if there is an attic) get high enough to bake bread. The single-pane windows, especially in the late afternoon, are a misery, permitting solar gain as well as radiating the heat from outdoors, which may easily reach 120°F, and so the tenants have covered the windows with aluminum foil. Of course this renders the indoor space dark, and so incandescent lighting adds to the cooling load which has long ago overwhelmed the inefficient air conditioning unit roaring like an injured bear in full sun on the roof. Just home from school, the senior child dutifully washes the dishes and starts preparing dinner. Every time he runs the hot water, he unintentionally heats the slab beneath him as the water travels in transit through pipes buried in the slab from the water heater located conveniently (for the original builder) in the service room at the opposite end of the house; the heat radiates gently into the interior space, further taxing the air conditioner, and wilting the people. Were any of these perversions anticipated or considered by the house's builders? A more urgent question: What can we do to salvage this valuable housing stock and make it more livable?
For new commodity housing, improved techniques are just coming in to use for collecting hot water and storing the heat for future use -- please see the sidebar on Solar Space Heating. For some existing homes, like the tract home described in the last paragraph, we may reasonably conclude that no remedies will suffice, and the building should be demolished.