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There was once a time, not that long ago, when a main street shopkeeper would just roll down the awning if the store got too hot -- a practical solution to an almost daily problem.
But now it's 2006, and the odds are good that the store's awning is fixed in place, not retractable. In fact, the awning is probably just decoration, or maybe it's advertising. If the shopkeeper wants his store to cool down, he doesn't mess with the awning; he turns up the air conditioner.
He also inadvertently damages the environment.
Like many buildings built before the advent of air conditioning, cheap electricity, and suspended ceilings, traditional main street storefront buildings were designed from the beginning with energy conservation in mind. From their materials to their physical orientation, main street buildings were planned to make the most of the natural environment. For example:
- Retractable awnings protected storefronts from excessive heat gain during the hotter parts of the day but let sunlight warm the air inside during cooler hours.
- Storefront windows flooded the front of the storefront with sunlight; concrete and masonry floor aprons inside the storefront windows absorbed heat, radiating it back into the storefront when the temperature dropped.
- Transom windows filtered sunlight deep into buildings (sometimes intensified by small panes of prism glass), while white tin ceilings reflected sunlight far into store interiors, further minimizing the hours needed for artificial lighting.
- Long, shared party walls between storefront buildings minimized heat loss, with only the narrow front and rear facades exposed to the weather.
- On-roof water tanks collected rain water, and gravity carried it down into the building for flushing toilets and for other non-potable uses.
- Fans in the high first-floor ceilings recirculated sun-warmed air back into the store space below.
But that's just the beginning of the story of energy and historic main street buildings.
The materials used to build main street buildings represent an enormous amount of encapsulated energy. On the heels of the energy crisis of the mid-1970s, consulting firm Booz Allen Hamilton measured the amount of energy inherent in various building materials. They found, among other things, that the amount of energy required to manufacture eight bricks, haul them to a construction site, and place them in a wall is equal to the amount of energy in a gallon of gasoline.
Why is this significant? Because it tells us that our existing downtown brick buildings -- the heart of many of our main streets -- represent a huge energy investment; an investment that is lost when these buildings are torn down. For example, the amount of energy inherent in the bricks alone in a typical three-floor, 20-by-100-foot brick bearing-wall main street building is equal to the amount of energy in more than 3,700 gallons of gasoline -- enough to keep the average American driving for almost eight and a half years.
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