Life Cycle Analysis

Like many of the concepts in Green Building, Life Cycle Analysis is conceptually simple, but difficult when it comes down to details.  As the name indicates, the idea is to look at the impact of a decision over the amount of time that it will exist for. For environmental impact, it means considering not just the impact of creating the material, but the impact it has during its lifetime and then the impact it has when it is disposed of.  There is also a life cycle analysis looking at costs: in addition to the purchase price, we must add the costs of operation and maintenance.

Life cycle analysis for environmental impact is a difficult task because you don't really know up front how long a material will last.  In addition, with new manufacturing techniques coming out, corporations have been slowing lowering their environmental impact.  In the meantime, debates about the relative impact of various choices will rage on and designers and consumers will be left using their instinct and personal preference to make the best choice possible.  Since the greatest impact decision one makes is how much space to build, one is better off spending time doing a good job there while avoiding the really bad materials than trying to determine the difference between two acceptable materials.

Cost is always a major decision maker for almost everyone, and typically is determined only by the up front cost.  In many cases this is a big mistake in the long run, especially if you will live in the house for a long time (and sometime even when you won't).  Admittedly everyone has a budget, and if a a loan is involved in purchase of the building or remodel, the bank will enforce a budget.  In this case also, building small is the biggest impact one can have.  Although the cost per square foot often goes up with smaller buildings, its because the owners have money left over to put in more quality materials.

As an example, consider low cost sheet flooring at about $4/sq ft versus hardwood or tile at $10 to $12/sq ft.  Depending on your pattern of usage, the more expensive products, costing about 3 times more can last 5 times longer while also increasing the resale value of your home.

Another example is to compare a standard washing machine with a low water use model.  The standard machine at $380 uses about $217/yr in energy for a ten year cost of $2550 while a low water use one is about twice as expensive at $700, but uses only $111/yr in energy, for a ten year total $1810, or a saving of $740. (These number were taken from the energy guide stickers on machines and were chosen in an attempt at a fair comparison: they aren't extreme numbers.  Every year new machines are introduced and prices and energy use changes so remember that actual mileage will vary!).  Note also that the new efficient machine often use less detergent and are gentler on your clothes resulting in added benefits.