“Hold somebody's hand and feel its warmth. Gram per gram, it converts 10,000 times more energy per second than the sun. You find this hard to believe? Here are the numbers: an average human weighs 70 kilograms and consumes about 12,600 kilojoules / day; that makes about 2 millijoules / gram.second, or 2 milliwatts / gram. For the sun it's a miserable 0.2 microjoules / gram.second. Some bacteria, such as the soil bacterium ‘Azotobacter’ convert as much as 10 joules / gram.second, outperforming the sun by a factor 50 million. I am warm because inside each of my body cells there are dozens, hundreds or even thousands of mitochondria that burn the food I eat.”
Gottfried Schatz, in "Jeff's view on science and scientists", 2006
El Niño is in full swing, and most of the country is about to undergo the kinds of temperature extremes (not to mention precipitation events, many of which will be white and fluffy, or clear and slippery) which inevitably lead to discussions of weatherproofing one’s home, and finding ways to save on heating costs.
We at Myrtle’s place, of course, live in the sliver of Texas which is just north of subtropical, so we don’t actually have to deal with the white or slippery stuff very often (snow on average falls in the lower Brazos Valley about every four years, and hardly ever sticks for more than a few hours), but it does get cold enough that many of our neighbors flip their thermostats from “cool” to “heat” – we are not among them, as we throw open the windows and put the heating blankets on our beds. (Few pleasures match that of sleeping warmly in cold air, but we digress.)
This seems an excellent opportunity to discuss the global effects of exceptionally local actions – most of the time, when winter heating costs are discussed, it is in the context of personal housekeeping, and this is appropriate. The immediate impact of heating (and cooling, the summer equivalent of this discussion) on household budgets are not only in and of themselves important microeconomic considerations, but they also impact thousands of other decisions made by individual consumers which, in turn, have a great impact on the overall economy and (what we at Myrtle’s place consider more important) on the environment.
The usual suggestions involve things like weather-stripping around doors and windows, making sure attic and wall spaces are properly insulated, etc. We do not disagree with any of these suggestions. They are all good and proper (there are some ways to do each of those items which are more environmentally conscious than others, but that is another topic altogether).
What we are concerned with today is more of a theoretical understanding of how weatherizing one’s home works, and how that fits into the broader scheme of maximizing the philosophy of the 3 R’s (reduce, reuse, recycle).
There are two distinct concepts from the world of physics at play in heating or cooling one’s home which have a direct impact on how much energy we expend and how costly it is to do so.
Efficiency and effectiveness are sometimes compatible, and sometimes not. The best practices in the home or business space involve that happy conjunction between these two ideas.
When discussing power transference for a particular use, efficiency is defined as the useful power output divided by the total power consumed. Expression of this concept is very common in all branches of engineering; the formula is typically denoted by the Greek letter small Eta (η - ήτα). Efficiency = Useful power output / Total power input.
Effectiveness, on the other hand, refers to the capacity to produce a desired result. Since the desired result is a subjective concept, effectiveness may be represented in logical terms, but not mathematical terms.
This, of course, makes it impossible to objectively decide on the best possible system to use in pretty much any household application, whether weatherizing, cooking, cleaning, lighting or entertaining, just to name a few of the activities in which we all engage.
In terms of heating and cooling, this means that one must first decide what temperature range one wishes to maintain in one’s home (or office), and that frequently must be a consensus reached among many people with opposing desires.
Most often, the range in question will vary greatly. Fortunately, the efficiency involved in strategies to keep within that range involve a large set of common tools (the aforementioned weather-stripping, insulation, etc.) However, some clear variations exist in terms of personal aesthetic preferences, tastes, and the width of tolerable range.
For example, one of the most effective strategies in heating and cooling very directly impacts the look of one’s home. We have written before about the advantages of painting one’s roof white. It drops the ambient temperature of one’s attic spaces by a huge percentage (in our case, the temperature of our roof dropped from 150° F to 108° F immediately after painting it in a Brazos Valley May several years ago). Similarly, planting vines along one’s western or southern exposures can vastly reduce the amount of heat in summer reaching one’s home.
However… both of those strategies leave one susceptible to slightly more heat loss in winter. That could, of course, be mitigated by use of extra insulation in those areas, but the point is that in isolation, one strategy or another might require some tweaking in order to maintain balance between efficiency and effectiveness. And some home-owners associations might not look kindly on certain strategies, more’s the pity.
For our northern counterparts, winter is an especially good time to consider this balance, as the very choice of heating method involves a wide range of efficiencies, and not all engineers agree on the best choice of formulae to determine that efficiency anyway. Just to give you an easy to understand anecdotal idea, the single most efficient form of heat transfer is that of simply burning any carbon-based fuel source with minimal water content (fossil fuel, wood, paper, mummies, you name it). Typically 100% of the convertible material is consumed by flames. So, theoretically, if you want heat, a fireplace is the best possible option. Except… while it is extremely efficient, it is usually not very effective, because most of the heat goes straight up the chimney, or into the bricks and mortar right around the fireplace. That’s usually not the desired outcome.
So, most people go with some kind of HVAC (heating, ventilation and air conditioning) system, utilizing either electricity or some kind of fossil fuel (typically gas, heating oil, or coal) for the wintertime heating functionality.
Calculating the efficiency of such a system is a nightmare, given the number of variables involved of which the manufacturers could not possibly be aware, so believe the BTU (or other) calculations at your own risk. Typically, though, if they are claiming a higher efficiency than others, there’s a fair bet that they are correct.
The effectiveness, on the other hand? That’s an entirely separate question. The delivery method can directly affect bothefficiency and effectiveness, but then… the effectiveness being far more dependent on the delivery method, it can impact howefficient a system is required in order to achieve cost-effectiveness, measured only by how much one must spend compared to one’s budget.
To give you some idea, perhaps heat is only required at a certain time of day, in a certain part of the building. In the frigid north, a lone radiator rattling away in one’s sitting room in relatively inefficient manner (but utilizing only a fraction of the fuel necessary to heat the whole house) would be much less expensive (and much less ecologically damaging) than an extremely efficient system which heats the whole house.
In our cozy home on the Gulf Coast, a small electric space heater might achieve the same result, at much less cost than running a full household heater that only has to be turned on three or four times a year.
The same principles, as we mentioned, may be applied to all other home activities – lights, in particular, have recently become a focal point for such concerns – one of the federal government’s greatest achievements of the 21st century, actually, has gone relatively unheralded: light bulb labeling has switched from emphasizing wattage (a measure of the total input) to lumens (a measure of the total output). We may make a posting about that some time soon, actually, because in addition to the output quantity of light, there are vast differences in the output quality of light, which make the comparison of efficiency and effectiveness particularly interesting.
The bottom line for each activity, though, is to synthesize strategies which fit into the overall theme of reducing the amount of input necessary to meet particular goals (choosing not to heat or cool certain rooms in one’s house, for example), reusing any materials which might assist in meeting those goals (hanging old quilts on walls provides a surprising amount of extra insulation, and that’s just for starters – Google “decorative insulation” and see just how cool modern temperature control can be), and recycling whenever possible (using cellulose pulp insulation, for example, frequently means using recycled materials, though check with the manufacturer to be sure).
The calculations can be complicated to an inconceivable degree if one wants to get picky with absolute goals (zero carbon emissions, most efficient heat distribution, etc.) but if one keeps in mind just the broad concepts (efficient is different from effective; reduce, reuse, recycle when possible), the minefield of consumer angst when it comes to the seasons of extreme discomfort (“The hell with it, just turn on the bleepity-bleep heater!”) can be avoided.
Remember, just being alive is an exercise in temperature conversion and energy expenditure. Being conscientious does not have to be a chore; it can be a game.
Plus, in winter, there’s hot cocoa.