Save Money by Insulating Your Home

Learn ways to save money by insulating your home, includes new insulation techniques, information on materials used for home insulation and reasons for insulating your house.


| October/November 1997



Save Money By Insulating Your Home

The incorporation of insulation as a means to retard energy flow is a relatively recent idea that wasn't generally used until after W W II.


PHOTO: FOTOLIA/MAKSYMOWICZ

This revolution in insulation techniques will help you save money by insulating your home. 

It has long been accepted that the best way to reduce energy use is to conserve it. In America, as well as in western Europe, we use a disproportionate share of the world's energy as we rapidly diminish the fossil supply. In the northern latitudes, above 35 degrees or so, we have to supply a titanic amount of energy to heat human spaces, but in recent decades, we use a near equal amount of energy to cool these same spaces as we move south of the 35 degree latitude. One's energy bill in mid-Florida for cooling closely parallels that of someone in Wisconsin or New England for heating.

In order to substantially reduce this energy waste, we must learn to construct residential and commercial spaces that are more resistant to energy flow. The incorporation of insulation as a means to retard energy flow is a relatively recent idea that wasn't generally used until after W W II. We measure insulation in units, called R (which stands for "Resistance" to heat flow). If a substance has R value it doesn't know if its stopping cold or heat but simply that it is resisting the passage of energy through it. Crudely, one R is about equal to a 1 inch thick piece of softwood. One generally has a feeling for wood, and most everyone can envision having a piece of 1 inch pine wood on their hand with a block of ice on top (or a small fire) and realize that it would be some time before one would "feel" the heat or cold. One R is quite a lot of resistance. It is therefore easy to understand that two pieces of 1 inch pine would have twice the R-value.

Also bandied about in the insulation books is the term "U value." This latter term is a measure of overall heat transmission, which is the reciprocal of R. It is best understood by the equation 1/R = U. My apologies for bringing algebra into this discussion, but it is useful in energy calculations because "U" is the number of Btus transmitted in one hour through one square foot of insulation, assuming that there is a one degree Fahrenheit temperature difference between the outside and inside air temperatures. Now take a breath. The hard part is almost over.

It's obvious that we want to surround human spaces with a lot of R value to conserve heating and cooling energy. Real world application of this basic idea, however, is a subject that is debated and misunderstood by many people who, frankly, should know better. Naturally, the most commonly used insulation material tends to be one of the most highly advertised, aggressively marketed, and by all appearances, economical home building products in America. This material's dominance is such that you have it in mind before I even print the word—fiberglass. Though it is being replaced by a newer fiber, Miraflex, which doesn't have undue health implications, fiberglass is still the hulking presence in the marketplace.

So how do we get the most effective "R" value for our money? You have no doubt seen numerous charts listing the R values of all kinds of materials. Trouble is, the goal of achieving a good assembly is not quite as simple as picking various R's from a chart and adding them up. We must understand the interaction of the various parts, the correct assembly, their cost, and, most importantly, moisture movement. Following this reasoning leads us, surprisingly, to different methods than those which are commonly employed.





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