Budget Solar Retrofitting

Image Gallery

Article Tools

Image Gallery

Print

E-mail

Comments

RSS

Energy And Environment

We take the sun for granted as it lights, warms and measures our lifetimes in precise 24-hour segments. This free, high-quality light and its attendant energies can enhance our lives by the manner in which it interfaces with the various structures we inhabit. This light-space relationship has reached a critical, often unrecognized importance during the last century as most of us have moved indoors in the workplace.

In the past the sun was taken more seriously with the best body of "solar law" belonging to the ancient Romans. In their cities, they carefully controlled building size and location to enable each space to receive its maximum ration of light and heat. In America, most farmhouses in the early colonies were oriented with the long wall facing the sun's benefits. By the mid 1800s we began to forget the sun's benefits. The mass production of cast iron wood stoves in Troy and Albany, NY worked so well as a heater that a home's position to the sun seemed virtually unimportant. The common use of the light bulb found us further from the need to properly employ the sun.

Today, over two decades removed from the 1970s' energy crisis, we are again returning to the solar knowledge our forefathers embraced. The sun is even available to most suburban and rural homes which may not have one wall oriented near south. To determine the "solar window" of the structure in question for its potential to deliver energy to the inner spaces, check your own shadow at noon standard time (1 P.M. if it is daylight savings time) and find solar south to be opposite your north body shadow. If one wall or a portion of your structure is within +/-10 degrees of this, you have good orientation. You will have a nearly desirable situation, however, if the wall with the most windows is within 30 degrees of solar south (beware of westfacing glass, as the summer sun, low in the sky from June-Sept at 5:30 - 8:30 P.M., can lead to overheating).

How do we use this basic knowledge of your own "solar window" to best enhance the home' s energy efficiency? There are a number of inexpensive steps that one can apply to every structure to substantially improve it's performance.

First: Remove the largest north-facing window possible as it always loses energy. Most homes can afford the loss of one or more non-sunny windows with the wall that replaces it insulated (R12-R20) much better than the window (R1-R4).

Second: Install a larger south-facing window or enlarge one or more existing units. Remember, the sun needs to "see" those windows for the majority (5-6 hours) of the day. Choose windows having modern high-efficiency glass rated at R3R4, and in most cases they can be non venting Axed units because the typical home already has enough venting windows. You now have the opportunity to receive up to 250 Btu's per sq. ft. per hour at midday ...free. For six hours facing near south during winter in the northern United States, the average availability will be 175 Btu's per sq. ft. Each 10 sq. ft. of glass which will transmit about two-thirds of this energy will therefore yield 700 free Btu' s to your space on a sunny day in addition to the daylighting benefit. The value of this energy can be compared to one thousand watts of electric heat, or 1 kilowatt, which for one hour yields 3414 Btu's and costs from 10-20¢, depending on where you are. This does not count the fact that a window would probably also reduce lighting electrical usage. A 100-watt bulb burning for 10 hours also uses a kilowatt.

RSS | Comments | E-mail | Print