Whole Systems Thinking Leads To Efficiency

As the guest speaker at the monthly meeting of a sustainability organization in Newburyport, I listened to the post talk discussion among its members.  I overheard a builder present at the event sharing his efforts to build green with a commonly expressed concern – “it just more expensive to build green”.   It is a concern frequently expressed in the building community, but not necessarily grounded in fact.  Others present questioned his assertion; not the validity of it, but the ambiguous nature of the statement.  “How much more expensive,” an architects.  “Ten percent, twenty percent?  Or less.  When you just say more expensive it translates to the general public as a significant cost increase.”  The builder couldn’t put an exact number on it, but his guess was 5 to 10 percent.  According to studies done by McGraw Hill, a major publisher of building and construction magazine and texts, the actual cost of building a LEED certifiable residence is + or – 2% compared to conventional built homes.  This builder, new to green design, lacked a sense of whole systems thinking while his heart was in the right place.  His experience was that if you simply swap out the fiberglass insulation for spray foam or paper cellulose, then the cost will rise dramatically.  Indeed it will.  Simply swapping these materials will at least double the cost of insulation.  But green design demands whole system thinking.  One common element of green design is a more open floor plan that leads to less labor and building materials, as well as a reduced demand for heating energy.  With whole systems thinking, more money spent on one facet, such as insulation, is offset by the design that allows much smaller heating systems.  Perhaps a wall hung boiler will be used in a first floor closet, eliminated the need for a complete utility room in the basement.

That whole systems thinking is a process that continues step after step.  Since I began with an example of heating equipment, let me continue on the same subject.  Assuming you have designed your house for super-efficiency, you may find that your houses heating and cooling demands are so low that more common heat systems such as a furnace or wall hung boiler don’t accurately enough match the btu requirements of your home.  Such systems use a single unit to cover all of the homes demand.  In contrast, an air source heat pump may allow you to better tailor fit your house’s energy demand by adding the heating heads (elements) that work in increments of 8kbtu to 15ktu.  All of this leads to potential savings in the overall heat system.  The the  same efficient unit such as the Mitsubishi Mr. Slim will also provide summertime cooling.

The same thinking can be applied to windows.  Granted, it would be great for all of us to have windows with thermal values of R-9, but few of us can afford that.  Does it make sense to spend $80k on R-9 windows that meet passive house standards or when you can go with a $40k package of high quality R-6 windows from LePage.  Windows are the weakest part of your thermal wall.  Doubling the cost for an increased r-value of 3 just doesn’t add up.  And there are other factors to consider.  Does the R-9 window have an equal fenestration rating for air infiltration as the R-6 window?  Is the R-9 window built as well, and thus as durable as the R-6 window?

Ultimately, the way to get people to understand the value of green building design is to get them to understand whole systems thinking.  It’s easy to appreciate and it just make sense in the end.

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