Design - Sustainable Building Practices - Cont'd

The first post on this topic delt with site selection and house size.  Here the intent is to identify sustainable practice goals and see how well we are doing at meeting them.

Criteria for Selecting Sustainable Methods and Materials

From the outset, we tried to understand what we needed to do to employ carbon-phobic

methods and materials, based on my research in print and online that went back several years, well before we had even bought land.  Here are the major criteria for selecting sustainable methods and materials that I came to appreciate.  Most of them are covered in the two books shown here (click on images to enlarge).

• Embodied energy used in manufacture or extraction
• Embodied energy used in transport to building site
• Amount of finite resources in the material, like petroleum or old-age timber
• Amount of recycled content in the material, like in steel roofing
• Amount of toxic waste sequestered in the material, like fly ash in concrete and drywall
• Recycled material instead of new, like salvaged lumber and old limestone foundation stones 
• Minimal waste of materials during construction, like using dimensions that utilize off-the-shelf lumber sizes
• Advanced framing or better
• End-life disposal:  recycled (steel roofing) vs. landfilled (asphalt shingles)
• Amount of volatile organic compounds (VOCs) in the material, like in adhesives, finishes and floor coverings

Sustainable Practices Discussed in Other Posts

Sustainable practices that we have already employed or will be employing and that I have already or will be discussing in many other posts bear mentioning here again:

• Frost free shallow foundation
• Wall trusses that maximize insulation and minimize thermal bridging
• Hinged fiberglass windows and doors with insulated low-e glass
• Rice hull insulation; R-60 to R-72 walls and ceilings
• Blower door testing for air infiltration
• Slab edge insulation (in conjunction with frost free shallow foundation)

  

  Slab floor construction with slab edge exposed

• Fly ash concrete and drywall
• Framing with wall trusses made from recycled dimension lumber
• Steel roofing and wall cladding
• Passive solar conditioning; no energy-gulping conventional heating or air conditioning (references to the AGS system appear in many prior posts starting with first post on Annualized GeoSolar) 
• Airlock between living space and exterior doors
• PEX plumbing system
• Tankless water heater with underground "homeruns" to hot water faucets
• Low-flow faucets; dual-flush toilets
• Energy recovery ventilator
• LED lighting with motion activated switches and task lighting
• Kitchen cabinets, built-ins and casework from locally harvested hardwoods
• Retaining walls from recycled limestone
• Numerous rain gardens to capture surface runoff until it can soak in
• Landscaping with native plants

Striking a Balance

Unfortunately, we have found it impossible always to follow the best practices for sustainability due to circumstances beyond our control.  For instance, my original plan was to use gravel from recycled concrete for the sub-base under the slab-on-grade floor but the recycler did not have a slinger truck for spreading the gravel.  I thought we would use it also for the driveway but found out that it contains rebar fragments that puncture tires.  We may have trouble buying drywall containing fly ash and the floor was poured too late in the season such that the "winter mix" did not contain fly ash. And I am sure there will be instances when we will have to compromise for budget reasons such as giving up on using a damp-proofing material for the earth contact wall made from recycled asphalt shingles that was several times more expensive with less functionality, as it turns out, than the method we ended up with.

Impacting the Sustainability Movement?
I think most would agree that our project will still set a reasonably high bar for sustainability. As explained in an early post, we understand the limited impact of one little project like ours on the big picture but the chances are it will have some effect. At the time of this writing, (April, 2016) page views (hits) to this blog numbered over 6,000 with nearly a third coming from foreign countries.  The last check before publishing this post showed the following distribution among the top ten countries represented:

               -  U.S.                                              4,148         (69%)
               -  Russia                                             385
               -  Canada                                           147
               -  France                                             143
               -  Brazil                                               126
               -  Ukraine                                           114
               -  Poland                                              99
               -  China                                                67
               -  Germany                                           64
               -  United Kingdom                                 54

The other 700 visits originated from places all over the world like Indonesia, Japan, India, Scandinavia, Africa,  Australia, New Zealand, Turkey and the middle east.  Are we impacting the sustainability movement?  One can only hope that a modicum of folks somewhere have gleaned a few useful grains or at least have begun to think about sustainability.

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Update, summer of 2019:  the number of page views to the blog has grown exponentially until they number just under 100,000. 

Design - Sustainable Building Practices

Building green is not just about energy efficient windows, low-flow faucets and lots of insulation.  It starts with site selection, continues through construction and culminates with the owners enjoying a low carbon lifestyle indefinitely.

Site Selection

For site selection, an important issue is personal transportation -- by what mode and how far.  An urban in-fill location, such as ours, is preferable to suburban, exurban or rural because it reduces travel to infrastructure such as schools and churches, shopping, work, medical care and entertainment.  Proximity to public transit is also a plus; we are a few blocks from a bus line and a short bus ride from a light rail station.  And what an advantage is has been during construction to have the lumber yard, the rebar supplier, a home center, wholesale plumbing and electric dealers and a farm and home store -- all within a few miles.

Site Stewardship during Construction

Here the issue is minimal site disturbance -- limited excavation and respect for topsoil and trees. Our ranch design surrounded by an insulation/watershed umbrella unavoidably requires much more site disturbance than would a multistory conventionally-built house of similar size.  To our credit, though, the topsoil has been carefully removed and set aside for future use.  And erosion is being controlled by straw bales, silt fencing and a retention pond (which has had to be dredged twice during the first year and a half).

Erosion control with silt fencing, straw bales and a
retention pond.

Site Stewardship Is More Difficult When Working Alone
A distinct negative is that working alone takes a long time and site disturbance is protracted.  In an attempt to ameliorate this problem, construction was halted in late fall so I could use the track loader for some serious dirt work.  I was hoping that before the ground started freezing and thawing I could install the downhill portion of the insulation/watershed umbrella -- that part in front of the house -- so that the slope to the street could be returned to its original contour and native plants could a be started immediately for erosion control. So the considerable excess dirt in front of the house was moved to behind the north wall as the first 5-6' of backfill and the hillside was graded.

My intention was that, as soon as the proper contours have been established, erosion could be controlled with an erosion control blanket with native plant seeds sown under it for germination in the Spring. Unfortunately, unseasonably wet weather around Christmas interfered and we went into a crisis mode to make run-off from our property stay on our property using additional silt-fencing and another dredging of the retention pond. It is now May and pouring the footings, foundation and slab for the screened porch and pouring the garage floor has delayed installation of the umbrella to the extent that any definitive planting in front of the house will have to be delayed until Fall and may have to be annual rye grass as a temporary cover crop until it can be replaced by something better later.  We are committed to native landscaping but now recognize that it may have to be done more gradually than we would like.


House Size Matters
Of course, the larger the house, the more energy it consumes -- both during construction and during its life.  In my view, a McMansion that touts its structural insulated panels (SIPs), its geo-thermal HVAC system, its top-of-the-line windows and, even, its photovoltaic solar panels or wind turbine is nothing but sophisticated greenwashing.  True, such a home is better than a McMansion with no regard to sustainability, but size does matter. 

Each square foot of floor space has an impact on sustainability -- more concrete, more lumber, more drywall, more copper wiring and plumbing, more floor coverings, more insulation, more roofing, more furnishings, etc.  At a minimum, each additional square foot impacts sustainability by way of its embodied energy.  And window size and placement also have a bearing.  Ever notice the expansive windows that face north and west even in so-called "green" houses?  

However, the real impact on finite resources plays out during the life of the dwelling. More space requires more energy to heat and cool, regardless of how efficiently it is done (unless it is done strictly with renewable energy -- which is our case).

Our floor plan is essentially a 2,800 sq ft two bedroom/two bath ranch with a third bedroom piggybacked on as an abbreviated second floor giving total living space of 3,000 sq ft. About 450 sq ft of the 2,800 sq ft slab is non-living space that the principal author of the AGS system calls a "vertical basement" and we are calling "storage".  Another 110 sq ft comprises the entry air-lock which could be considered quasi-living-space. 

If our plan is overly consumptive, the master bedroom and the living room-kitchen-dining room "great room" might be considered somewhat generous. However, I rationalized this bit of extravagance to some degree in the following ways:

• Most of the lumber will be either recycled or grown locally
• The "extra" space impacts sustainability mostly via an increase in concrete for the floor, wood for the ceiling and metal roofing, but concrete does sequester industrial waste (fly-ash), wood ceilings come from plantation-grown trees less than 300 miles away and metal roof panels have recycled content and a recyclable end-life
• The extra space will have no impact on the amount of wiring because the longest circuits were shortcutted beneath the slab using donated wire; the same goes for the supply side of the plumbing
• At our age, we will not be the principal owners of the house -- either through inheritance or sale after we are gone, it will be occupied by younger folks with larger families who will appreciate and enjoy the roominess

However, the justification for the added space that is most defensible is that our passive AGS system will provide zero-energy conditioning year-round for the life of the house regardless of the size of interior space.

The next post on sustainable building practices focuses mostly on the construction phase.