Finish Details

When building the awnings over our south windows we were careful to allow winter sun and block summer sun.  This is a crucial aspect of the design that can make or break the heating and cooling passivity of a home.  To jive with IRS requirements for passive solar tax credits your south windows must receive full sun on the winter solstice and no sun on the summer solstice.

We were able to use wood from a wild cherry tree we felled from the house site for the bar top and backsplashes.

Not only do we love natural stone but the slate tile adds more "incidental mass".  This will help to smooth out our temperature "fly wheel" that much more.  It's also beautiful.

The lower 4' of this wall is actually 8" block filled solid with concrete.  The space between the block and stair treads is slate on backer board.  This vertical mass wall sits 3' from a big south-facing picture window.

We couldn't get enough slate!

A large ceiling fan above the staircase moves air between the floors.  This fan is extremely efficient for two reasons.  One is the large sweep (70").  The other reason is that the motor runs on direct current.  Fans have an efficiency rating based on cubic feet per minute per watt.  This fan is rated at 276.28 CFM/watt.  This is 121.28 CFM/watt higher than the minimum required for Energy Star compliance.

Concrete counter tops add more incidental mass, are highly durable, and provide aesthetic beauty while being more affordable than other solid state options.

All appliances are of course "Energy Star" rated.  When striving toward a net-zero (energy) home, one dollar spent on efficiency can save several dollars on a renewable energy system.  In other words, the less electricity you consume, the fewer photovoltaic panels are required to offset your consumption.

More concrete!

This brick surround for the wood stove will warm up, store, and slowly release heat back into the living space long after the fire goes out. 

Trim, finishes, and fixtures

We used solid pine for our trim.  This avoids all the formaldehyde glues used in most "paint-grade" trim.  These glues continue to offgas into the living space for years, negatively affecting indoor air quality.  This is a chief concern in a tightly sealed home.

We're using a variety of wood stains and sealers that have very "low" or "no" volatile organic compounds (VOCs).  Just like formaldehyde based glues, these substances continue to vaporize for years into the air you breath.  Many truly "green" "low" VOC products use plant-based oils that have some natural volatility but are not toxic like petroleum based products.  Our sealer is derived from waste products from the Vermont cheese industry.  They use the whey to create a natural sealer that's superior in performance to traditional toxic polyurethanes.

The cabinets are going in.  This is one area where it's difficult to avoid formaldehyde based glues without spending large sums of money.  Sealers are available that help "lock-in" the vapors to keep them from offgassing into your space.

Dual flush toilets have become very affordable lately.  They have two different buttons with two different flush volumes (all mechanical, no electricity required).  These save thousands and thousands of gallons of water over their useful life.

We chose a domestic hardwood for our upstairs floors.  This also avoids toxic binders that can negatively affect indoor air quality.  Unfortunately, due to the irrational nature of current world trade, trees felled in U.S. forests are often transported to China and India where they are processed into finished flooring and shipped back to us for purchase and use.  If only our trade policy encouraged Americans to process American resources our flooring choices would be far more sustainable.  While there are "safe" quality bamboo floors available they are also shipped from China and were unaffordable to us for this project.

Starting to feel like a livable space!

We varied the direction of the flooring material to make each room feel spacious and allow good energy flow.

Sheet Rock

The 2x6 construction creates deeper window sills.  Because of the deeper frame, we decided to "bull nose" the sheet rock.  This allows us to avoid using wood for window trim and create a smooth almost adobe-like appearance.

Tongue and groove white pine ceiling boards.

Laundry chute!

Busy, Busy, Busy!

Formaldehyde-free fiberglass batts.  By using fiberglass in our exterior wall cavities we saved a lot of money as we're able to do it ourselves and make certain it's done well.  Also note the lack of a vapor barrier.  We have 1" of foam board surrounding the exterior sheathing of the house.  If we used batts with a vapor barrier attached we'd be sandwiching material between two barriers and creating moisture issues.  This way the entire wall cavity can breath and wick moisture.  The formaldehyde-free designation is important so that the binders in the batts do not off-gas into the home.  This type of insulation is now widely available at certain home improvement stores.  We special ordered ours so we could get R-21 out of a higher density product as compared with the R-19 (performs at about R-17) on the shelf.  This improvement only added about $300.00 to the cost of construction.  Note that every cavity is 100% full, the batts aren't "squished" (it's the zillions of air pockets that insulate, not the fiberglass itself), and every wire, pipe, and box is cut around.

The wider stud spacing provided by 2x6 construction allows more space for insulation.  This means less "thermal bridging" through studs in the building envelope and a higher ratio of insulation to surface area.

Anywhere we have portions of the stud cavities that don't receive sheet rock we use foam board as an air barrier (as seen in the HVAC soffit above).  It's important to do this so that the insulation can actually perform as it's supposed to.

Every window sash is insulated with low-expansion foam (the yellow stuff in the picture).  This is one of the simplest and most cost effective things a builder can do when installing a window to make it less drafty.

Bathroom tile.

Master bath tile.  Masonry material like tile is not only very durable but adds a bit of "incidental mass" to the building.  These are surfaces with a high "specific heat" that take a while to heat up and cool down.  This helps to smooth out the temperature "fly wheel" in a passive home.

When building an economical floor plan (smaller, less consumptive) it's important to separate the spaces well.  In this case we used mineral wool insulation between the floors to dampen sound transfer.  This allows bedrooms upstairs to remain peaceful and useful while people play cards downstairs.  It also provides a level of protection against fire as it remains durable in very high temperatures.

The vaulted portions of the ceiling are covered in White Pine.  Because of the hips in our roof, sheet rock would have shown cracks and been very difficult to hang.  The pine is a beautiful and durable substitute.

Rough-ins, exterior paint, and finish grading

Framing materials that have been third-party certified by the Forest Stewardship Council are far more prevalent today than just a few years ago.

By buying domestic products we ensure our plumbing fixtures are made to American standards in regard to environmental laws, adequate wages, etc. 

Interior framing continues.

Professional staircase model.

As soon as the finish grading was completed we mulched and seeded the landscape.

Air handler for a 17+ SEER Heat Pump.  This HVAC system greatly exceeds energy star standards.  It does this with a 2-stage compressor.  We'll discuss this when we install the outside unit.

Our plumbing stack is roughed-in.  We stacked the bathrooms back to back and on top of each other which ends up being a mixed blessing.  We had a lot of waste and vent pipes, PEX supply lines, etc. crammed into one small space.  This is preferable as we're limiting material use, and ultimately limiting distances from the water heater. 

HVAC is roughed in.  By keeping all of the duct work and air-handler inside the conditioned space we ensure the system is exponentially more efficient.  All of the ducts are sealed with mastic and insulated.  We're anxiously awaiting the results of our duct blaster test.

Our bath fans are more efficient in three ways.  First we joined two fan's flex ducts together to limit the number of penetrations in the building envelope.  Second the fans have a back-draft stopper preventing outside air from backing into the building via the fans.  Third, the fans themselves have super efficient Direct Current (DC) motors.  Note the Energy Star label.

This is our Energy Recovery Ventilator (ERV).  All homes need fresh air for a healthy indoor environment.  Usually this comes from a thousand random leaks throughout the house creating an inefficient, uncomfortable situation.  Our home is so well air-sealed and insulated that we need to exchange outside air mechanically.  This may seem against the point but it offers several benefits, both for comfort and efficiency.  Fresh outside air is brought in, blown through a heat exchanger picking up thermal energy (without mixing the air) from outgoing interior air, and dumped into the HVAC's air return to be evenly distributed throughout the house.  This means every room in the house has a little bit of fresh air coming in throughout the day that's been pre-heated (or pre-cooled) closer to room temperature.  Energetically, this is all accomplished with a fan.

Exterior paint!

We are using a combination of insulation materials to get the highest possible thermal efficiency for the lowest possible cost.  This photo shows spray foam on the roof deck.  Spray foam offers two benefits: insulative value (millions of air pockets) and air sealing (fills gaps and cracks).  The roof is the most crucial part of a home to insulate.  It also has complex framing and penetrations that make other types of insulation unsuitable.  We applied 8.5".  The pros tell us that spray foam in our climate is 97% efficient at 6.5".  We went a couple inches thicker as a hedge against solar heat gain through the roof.  This may have been overkill but at least we'll sleep easy. 

The floor band was also a tricky area suitable only for spray foam.

Electric gets roughed in.

The project manager sleeps on a toilet.

Floors, shingles, and stairs

We acid washed the slab prior to interior framing so that the entire surface will have a uniform appearance.  We'll wait to seal it until the end of the construction process as this will be our finished floor.

It's important to leave the slab exposed as the finished floor in order to use it as thermal storage.  If we covered it with carpet it would defeat the entire passive design of the home.  Tile is an option as it's similar material though it would be far more expensive.  The acid wash gives the appearance of marble and can be done in numerous colors.  Carpet, wood, cork, etc. are options for the north side of the house where there is no direct solar gain though it's best to leave the mass as exposed as possible for passive cooling during the summer.

We're shingling our portico with hand split cedar shakes.  We love the beauty of natural materials so despite the long distance origin we opted to use these on the front of the house for a more rustic appearance.  They don't leach various chemicals like petrol-based asphalt shingles and they'll gain character with age.

Interior framing has begun!  Because none of our interior partitions are load-bearing we're able to be more frugal with our use of framing material.

The stair structure goes up around the vertical mass wall.

By using winding treads we're saving floor space and reinforcing the curved shape of the home.

Portico, mass wall, and roof

The portico comes together.

The disturbed area around the foundation was kept small by using a Bobcat for a "surgical" grading job.  The area around the perimeter is protected from erosion by a combination of temporary pea gravel and plastic left over from material deliveries.

We're incorporating a block wall into the staircase structure to increase the amount of thermal mass.  This wall faces south just a few feet from a large picture window.  Thermal mass like this block wall holds heat longer so that solar energy from the daytime is released into the living space throughout the night.  This concept is one of the big differences between the passive design of today and that of the 1970s.

The roof goes on.  This metal roof should last several decades, after which it's 100% recyclable.  In the mean time the relatively light "clay" color will conduct less heat through to the attic.  This is part of the passive cooling strategy.

The dome is in place for the tubular skylight.  Like it sounds, this skylight transmits sunlight through a highly reflective tube to the living space.  This results in natural daylight illuminating an interior space without the heat loss associated with typical skylights.  The finished look will be a light diffuser mounted flush with the sheet rock ceiling.  In addition to energy savings the tubular skylight connects you with natural events like clouds passing over the sun.