Archive for June, 2011

No SRECs in New York yet

I’ve mentioned Solar Renewable Energy Credits in previous posts and comments. It’s a great way to shorten the payback period for solar producers and encourage more solar production. Also encourages power companies to purchase more renewable energy from the little guy.

But it requires each state to pass legislation to authorize an SREC market in the state. Several states around us have SREC markets. New York had a bill that did not get voted on this session. Looks like it will be another year before it comes up for consideration again.

Maybe next year.

ERV installed

Our HVAC contractor was busy at the site two weeks ago. He completed the install of the ERV unit in the basement. I hope he enjoyed the challenge. It was a tight space, but in the end everything fit fine.

The only casualty is our pantry area. We lost another few square feet to ducts. This is because we originally planned to run the exterior vents through the rim joist area, but later decided to move them up 4 feet from ground level to avoid snow accumulation issues in the winter. Moving them up higher meant penetrating the first floor space above the unit in the basement.

The unit is hung from the floor trusses above and flexible ducts connect the unit to the metal ducts in order to dampen the vibration from the unit. The unit itself is very quite, but we’re not moving to the country to listen to a ventilator.

The ducts to the exterior are insulated to R8. The pre-heat unit is installed close to the unit on the intake side. It is only used when the intake air is below 10 degrees F. It warms the incoming air just enough to prevent rotary lockout on the unit.

Click on the ventilation category on the right to learn more about how we chose this unit and why we’re using an ERV in the first place.

More siding progress…

Just wanted to share a few pics of the siding to date. We’ve finished half of the west gable end, half the south side and half the north side. There is a crazy logic to all the skipping around but I will spare the details for once. We’re planning to finish the north side before deciding what’s next.

Warren made a great mockup of the brackets we will use for the ‘roofets’ (small shade roofs for the south facing 1st floor windows). The actual brackets will be made from Douglas Fir. We will have to frame out the roofets and add the metal roof before we can continue with that side.

On the west gable end, we have to frame out the porch before completing the siding there. Same for the east gable end. We have a small entry porch that needs to be attached with it’s own roofet before that side can begin.

Mega Watt a month?


We generated our first half megawatt hour (500 kWh) this Sunday, roughly 11 days since we turned on the system. Weather depending, we’re on track to generate our first megawatt hour before the end of the month. We might have to have a first megawatt party July 4th weekend. Kick-ass!

Green Building Open House and National Solar Tour

Mark October 1, 2011 on your calendars. We’ve signed up for the Green Building Open House (sponsored by the Northeast Sustainable Energy Association) and the National Solar Tour (sponsored by the American Solar Energy Society). Consider yourselves invited.

Solar update

In our first week of operation our array generated roughly 230 kWh of electricity. We used 25 kWh and sent 205 kWh back to the grid. I love that.

Siding progress

The weather report appeared to be clear for a few days in row last week so we decided it was time to start the siding. The first day was half sunny and half stormy with a brief spat of hail. This was the same storm that spawned tornadoes in Massachusetts. Despite this initial setback, we were able to work steadily the last few days.

We looked at a few different siding materials when we started the project. Affordability was a big factor, but so was sustainability and durability. Cedar is the most durable natural product but also very expensive. We rejected fiber cement because we just didn’t like the look and it seemed out of place in our woodsy setting. Vinyl looks cheap and it is certainly not an environmentally friendly product.

We settled on hemlock wood siding. It is durable, looks good and is cheaper than cedar. It is factory stained with one coat of Cabot’s (Thicket solid) water-soluble stain.

We are installing the siding over 3/8″ Sturdi-Strips furring and 7/16″ screened Cor-a-Vents at the top and bottom of the wall and above windows and doors. This provides a space behind the siding for air to circulate and aid in the drying process. We’re using this rain screen approach because the ZIP panels are OSB and we have 12″ of cellulose next to it. OSB and cellulose perform best if they can dry easily. We want to make sure they can dry as easily as possible.

We’re using metal flashing at any location water has a direct path to the wall, anytime siding meets trim, frieze or baseboard and between lengths of siding. All siding and trim is attached with stainless nails.

Here’s some snapshots with descriptions of the details.

Window detail.

We wrapped the window with furring strips then nailed flashing on the outside edges on top of the furring. Window trim was then installed over furring and flashing. Drip cap on top was taped to sheathing using Zip tape. Cor-a-Vent was nailed over drip cap, then the siding was notched 3/8″ over the drip cap to allow for drainage and air flow.

Gable detail.

Frieze plate is nailed over furring. We forgot to notch the frieze trim plate before we nailed the furring and frieze, so we custom folded a J-channel below it. This detail prevents insects from getting under the frieze and shields rain from directly entering the gap. We then nailed Cor-a-Vent strips over the bottom edge of the J-channel, then slid the siding into the channel, with a 1/4″ gap at the gable edge for air circulation. We’ll notch the frieze plate for the other gable end so we don’t have to use the J-channel flashing detail.

Bottom corner trim detail

Two strips of furring at the edge, and two more offset from the edge to support nailing of the corner trim, then flashing over the furring. Screened Cor-a-Vent at the bottom for air circulation. Corner trim is nailed over this, then base trim is nailed over the Cor-a-Vent.

Corner trim with base trim installed

You can see the flashing behind the corner trim. The base and corner trim extends about a 1/2″ below the bottom of the sheathing. The base trim is notched to accept the fist layer of siding. The layer of siding above the base will be hidden by the first two courses of siding.

North side

The first 5 courses of siding up on the north side of the house. You can see the vertical furring strips spaced at 24″ on center. We’ll pause here until the ventilation ducts are installed 4 feet above finish grade. Then we’ll continue the siding around the vent in/out-takes. The outdoor unit of the ASHP will also be installed on this wall with brackets. Then we’ll figure out how to install the siding around the brackets.

Siding begins

I took a few days off to help Warren get started with the siding. Just wanted to post a quick photo to show our progress. I’ll update with more details later this week.

Bath Time

Last week the plumber roughed in the waste pipes and venting. Soon he’ll begin the hot and cold water supply lines. He asked what faucets we’re using to make sure he has all the right connections, specs, etc. This prompted a mini bath shopping spree, and an opportunity for me to share our bath plans.

Faucets: We really like the old-fashioned cross handles, and starting looking around for an updated, streamline version. We eventually settled on the Grohe Arden line as they are less expensive than similar models from Kohler and Berclay and got great reviews. We ordered the Watersense versions (low-flow 1.5 GPM) in chrome last Friday. Unfortunately it will take 2 weeks for delivery.

Bathtub: We are doing a separate soaking tub and shower. We bought the 6′ Kohler Archer drop-in tub before we closed in the house. Larry started working on the the framing for the tub surround over Memorial Day weekend, and I put a deposit on a Carrara marble slab for the tub surround yesterday.  Once the framing is done, we will make a trip to the stone yard to pick out our slab and the installers will come to the site and create a template. It will take about two weeks to cut, edge and polish the slab after templating. The tub drain was ordered with the faucets, so all the plumbing should be in place before the slab is ready for install.

Shower: We are looking into using the Schluter-Shower System to waterproof the shower area. It’s cool because you install it over regular drywall and it keeps everything water tight. We will be using a frameless glass door instead of a curtain to allow more light and help make the space feel bigger.

Tile: We were originally planning to tile the walls in the bath, but to save money we are now just tiling the shower enclosure and front of the tub surround. We are considering Lucian glass tiles from Ann Sacks and Optix from Waterworks. We have chosen a light gray porcelain tile for the floor and are looking at a flat pebble for the shower floor in either a blue/green mix or white (similar to Carrara.)

Vanity: Next big sale day, we will be ordering the Hutton washstand in dark espresso with Carrara marble top from Restoration Hardware.

Heat: We will be heating the bathroom (and our towels) with a Runtal Radiator Electric Omnipanel.

Attic access detail, the ‘cork’

I started working on the details for our attic hatchway a few months ago. The internet is fairly void of super-insulated air-tight attic hatchways. I found this curious considering all the net zero and Passivhaus work going on to date.

The problem is how to insulate and air seal the attic access to the same standards as the rest of the ceiling. Our ceiling will be insulated with 24 inches of loose cellulose (R-75), so I wanted to make sure the hatchway was at least equal in R value and air tight. The trick was to find a way to achieve this and still be able to open and close the hatchway with relative ease.

Our solution is nicknamed the ‘cork’. Essentially it’s a 24″ deep hatchway filled with 2 insulated components. The first component is air sealed to the interior drywall. It is a piece of plywood screwed to the ceiling within a gasket and 8″ of left over rigid insulation (R-40) glued to the top of it. This is a fairly standard approach to sealing the attic hatch. The second component (the cork) is 14″ of rigid insulation (approx. R-70) held in place by a hinged top plate.

To gain access to the attic we will first remove the lower panel from inside the house, then we pop the top barrier out into the attic. To close the access we reverse the process.

The total insulated value is R-110, but that is misleading. Due to inefficiencies of sealing the insulation to the hatchway, air can circulate inside the hatchway in tiny gaps at the edges and between the two insulated components, so I just tried to cram as much insulation as possible into the hatchway as tightly as possible but still be able to pop the cork to gain access to the attic. Only an inferred camera will tell if my efforts have been successful.

I hope this is helpful to others out there building super insulated houses with attic access from the inside. If you have a simpler detail, please don’t tell me. I feel silly enough spending 2 days building the cork. But please do post your solution to make it easier for the next person.

One last word, the code requires attics be accessible, but I don’t believe it specifies whether it has to be from the inside or outside of the house. Assuming you have an attic that needs access and your local code allows outside access, I would recommend exterior access based on my experience building a super-insulated air-tight attic access hatchway. Interior access can be done, but it’s a lot of tedious work.

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