Thursday, December 8, 2022

Design - Sustainability Inventory - Part II: Living Quarters

 By now, our 8-year journey to energy independence has been documented with nearly 150 individual blog posts.  For those who may be curious about our project but not enough to wade through myriad posts, perhaps the previous Part I and this Part II will suffice.

Click on picture to enlarge for better viewing

Part I covered the non-living spaces of our passive solar home -- the grounds, the exterior shell of the house, the screened porch, the garage, the airlock and the vertical basement. This post outlines how the interior living spaces contribute to the advanced  passive solar design.

This report posts during early winter 2022 after having taken occupancy in late March.  

Common Features

            The windows are double-thickness with two kinds of glass – transparent on                  the first floor and translucent on the second

The transparent first story windows are backed up by thermal mass – the concrete floor and the soil beneath it. The solar gain through the windows warms whatever it shines on -- the floor primarily but also the furnishings which have minimal thermal mass but still contribute to warming the air.  And, the medium shade for the floor hits the sweet spot -- a dark color would overheat and a light one would reflect, rather than absorb, solar energy.


                         The fact that the windows on the
                      second floor are not backed up by thermal mass and are more                                    
numerous than on the first floor requires a different strategy for                                    maximizing solar gain during the winter.  The glass in most of the                                second story windows is translucent (frosted).  Unlike transparent                                 glass through which sunlight enters uninterruptedly and heats                                    whatever it shines on, translucent glass diffuses or scatters sunlight                            so that, in the absence of thermal mass, it heats the interior contents                            randomly and without overheating. 

The most prevalent wall color in the house is rated at 65% reflectance which is the sweet spot between reflectance and glare.  The reflective paint works in tandem with the translucent glass to scatter winter solar energy. 

Our windows, in addition to transparency vs. translucency, have three additional energy-saving features – low-e coating, fiberglass frames and swing design.

Low-e coating for a double-glazed window blocks up to 90% of the heat loss on winter nights and cloudy days.

Fiberglass frames are “greener” than the more ubiquitous vinyl frames

             Less embodied energy (made from sand rather than                         petroleum).

Co-efficient of thermal expansion matches window glass for better seal of double-glazing as well as minimizing air leakage between frame and glass; contrastingly, vinyl expands (summer) and contracts (winter) much more than window glass.  

All windows are casement or awning (both swing style) that, on closure, create a compressible weather-proof seal.  Sliding styles (double- or single-hung or side-by-side), need greater tolerances for sashes to slide freely within frames and, as such, have more potential for leakage.

Polished and stained concrete floors, in the absence of tile and carpeting, maximize the flow of heat from the mass in winter and into the mass in summer; in a few years, after the mass temperature reaches equilibrium, tile would probably work without compromising the thermal performance of the house. 

Handicap accessibility, e.g., 36” doors with lever-type door “knobs",                           elevated wall  receptacles, no grade changes between drive and house.  

Combination fire and CO alarms for sleeping areas hardwired (with battery backup).

Numerous through-the-wall ventilators that allow stale air accumulating at the high point of the sloped ceiling of the first floor to escape to the second story. 

         Continuous ventilators at the top and bottom of the tall north wall, i.e., the one           separating the living space and vertical basement, allow air to move back              and forth through the wall and either deposit or extract heat from the thermal              mass (concrete vertical basement wall and the earth behind it) depending on              the season

Entryway / Kitchen / Laundry / Dining Room

Entryway wall veneered with handmade bricks salvaged from 19th century farmhouse.

Salvaged kitchen and laundry cabinets are Facebook Marketplace finds; laminate (Formica) countertops instead of natural stone with its embodied energy (long distance importation or energy-intensive manufacturing).

            All appliances, range hood and ceiling fans are Energy Star rated.

Lowered countertop area that doubles as lunch counter and ADA-compliant work surface.

Supply and return vents for ERV system.

Living Room / TV Area

Continuous ventilators at the top and bottom of the tall north wall (mentioned above).

Wall switches for all TV and computer receptacles to control phantom loads.

Guest Bathroom

            Salvaged wainscoting for one wall

            Porcelain tile for tub surround gifted by contractor (left overs from a job)

            Recycled ceramic (rather than fiberglass) bathtub (Craigslist)

            Wash basin mounted on treadle-type sewing machine

            Low-flow faucets and shower

            1.2 GPF handicap height toilet

            Exhaust vent for ERV system

South Bedroom

            Energy Star ceiling fan

            Supply vent for ERV system

Master Bedroom / Walk-in Closet

            Energy Star ceiling fan

            Supply vent for ERV

            Repurposed closet organizer (Facebook Marketplace)

Master Bath

1.2 GPF handicap height toilet

Low flow faucets and shower

Exhaust vent for ERV

Recycled vanity with manufactured stone countertop rescued from dealer’s “bone yard” (laminate is no longer recommended for bathroom vanities)

Handicap accessibility

                        Wheelchair accessible shower with controls reachable before                                       entering spray

                        25 sq ft  of floor space in middle for wheelchair turning

                        One sink is handicap (and child) accessible

                        Numerous grab bars

Second Floor Balcony (Catwalk)

            Vents from first floor to syphon off warm air accumulating at high side of                       cathedral ceiling.

Click-together composite floating floor; composite is more sustainable than vinyl and, by being manufactured from pulp wood, is even more sustainable than conventional hardwood flooring; medium color for a balance between absorption and reflection of solar energy.

“Green” windows

Translucent window glass vs. transparent glass for better thermal performance in the absence of any significant thermal mass on the second story

Windows inset 11” from exterior wall plane to reduce heat loss due to “wind washing”

Only enough operable windows for adequate ventilation (fixed windows have a much higher Energy Star rating than identical windows that are operable)


Second Floor Bedroom / Bathroom

            ERV supply vent (bedroom) and return vent (bathroom)

Corrugated roofing for bathroom wall cladding (long-lasting and recyclable end life)

            Recycled wall cabinet (Habistore)

            1.2 GPF toilet

Unfinished projects

Custom stairway and railing system from rough sawmill lumber:  stair steps from hackberry; balusters from hackberry and red oak, railings from red oak

Interior casework (baseboards, trim around doors and windows, etc.) from rough sawmill red oak

Once the interior is finished, a certified consultant using a blower door tester will ascertain the tightness of the house – a major criterion for either a HERS rating (Home Energy Rating System) or NAHB rating (National Association of Home Builders) that we will seek.

ACKNOWLEDGMENT

We will be forever indebted to the government of Collinsville, IL, particularly the Building Director and his staff for their forbearance during nearly a decade of construction.  If the folks at city hall had not taken genuine “ownership” for the town's first "green" project, it would never have been built.

RECOGNITION 

At Collinsville's 2022 Awards Night, the local chapter of the Cool Cities Committee recognized our project with its "Cool Cities Sustainability Award".  (The nationwide network of Cool Cities Committees was birthed by the Sierra Club.  As ambassadors for sustainability, the club's members serve as advisors to the City Council as well as to civic committees, schools, organizations and citizens.)