More Progress....

Summer vacation is over and the kids are attending their new school.  Since we haven't moved yet, our morning routine consists of getting up early and driving the boys to the new house where they are picked up by the school bus to ride with our new neighborhood's children. That gives Paul and I, well mostly Paul, an early start on the day's projects like painting or working on his solar hot water system.

Painting the staircase stringers

Coatings

Since the envelope of a Passive house is tightly sealed, creating a healthy indoor air environment is very important.  We have focused on no or low VOC paints, stains, and clear coatings for the walls and wood work.  Paul found an interesting product from Vermont Natural Coatings for the wood doors and trim. http://www.vermontnaturalcoatings.com/ This low VOC product uses whey protein, a natural byproduct of cheese making and renewable resource, in place of chemicals commonly used in other finishes like benzene and formaldehyde. As Paul and I primed and painted the stringers and risers for the staircase with low VOC paints, we commented on how the paint smelled like Wrigley's spearmint gum. A far cry from the last time I painted an apartment in NYC in the 1990's and was practically asphyxiated by the fumes. I'm so glad that environmental health awareness is improving.

Power

Another milestone was reached two days ago when CL&P came to connect the power to the house.  We have been running power from a temporary box at the street but now we can plug a drill or a saw, even a light into an outlet in the house. Shortly the solar array will be completed and connected. A special 2 way meter will then be installed to  monitor our production and usage of electricity.

Kitchens and Bathrooms

The kitchen cabinets have been installed and the templating date for the stone counter tops is scheduled for next week. The bathroom tile is being installed and it looks beautiful.

I took another bold step today and scheduled an appointment for an estimate by a moving company and a potential moving date.  I'm not telling what the date is yet, Murphy's law.

Solar Panels Here and There

Most of the PV panels are up

A large part of our energy efficient home design is related to solar energy.  Passive, photovoltaic, and solar thermal.  Our high efficiency European windows located on the south side of the house help with the passive part.  We are in the process installing the other two.  We have contracted with Aegis Solar to purchase and install a 10.8kW array of photovoltaic panels on the south side of the roof which will generate about 12,500 kWh of electricity per year.  Folks often ask if we will be "off the grid".  The answer is no. The simpler and less expensive way to set up a solar PV system is with a grid-tied system.  We are connected to the electric grid, selling CL&P the power we generate and buying from them what we need to use. We estimate our annual electricity consumption to be around 8,000 kWh per year (which at this time is a very rough guess).  We should generate more electricity than we use for the house each year and have enough leftover power an electric car.

The other solar component is a DIY solar thermal hot water system. Paul researched online others who have made similar systems and shared their designs and ideas at builditsolar.com. Paul's system is taken from the design at builditsolar.com. It's a drainback system with a 16' x 8' collector mounted on the ground behind the garage and a 230 gallon home-made tank in the basement.



Paul surveying his work on the frame of the collector

Tank in the basement





We hope that this system will provide most of our hot water during the year.  It remains to be seen exactly how much it will produce.



We spent several hours wrestling PEX tubing into a three layered coil
for the heat exchange element which will be submerged in the tank.





The competed coil

Other areas of progress; The interior walls are up, closed and primed. Wood flooring that acclimated in the space over the holiday weekend has been installed. Kitchen cabinetry will be delivered this week and the bathroom tile has arrived. 

All of the ventilation hoses haves been attached to the ERV.







The exterior siding is mostly finished with a beautiful cedar ceiling on the front and screened porches.  The septic system has been installed.

The garage door is installed and preliminary grading and landscaping is underway.

I mentioned in a prior post about the illusion of time during construction.  We've hit a period of fast forward where the interior is quickly changing the look from a construction zone to a home.  A warm beautiful home.

Lots Of Progress

The south side off the house. Notice the perfectly shaded windows.

 Our friends often ask us "How's the house coming?"  I'm thrilled to report that the answer to that question is "It's coming right along." During the building process there are times when things appear to be moving faster and slower.  For example, when walls go up it appears to be faster progress than when, say the electrical wiring is being done. Some changes are just more visually obvious so they give an impression of speedier progression. All part of the illusion of construction.


The siding is up on the west side of the house and garage.

When I arrived at the site this past Friday after a few days vacation there was noticeable progress. There were 5 crews at the house all working on different things.



1) Putting up the siding, 2) Drywalling the interior, 3) Ventilation system work, 4) Concrete being poured for the porch, and 5) The excavator preparing the site for the septic system.

The place was abuzz with activity. So much has happened recently that it has been hard to keep up in our blog. Not being a daily blogger, items have been stacking up.  Here is a brief  list to bring you up to date:

• The interior wall insulation (see "walls like a sandwich" post) is completed on the first and second floors. The downstairs will be finished pending the completion of the placement of the ERV (Energy Recovery Ventilation) tubing and heat pump vents.

Ventilation tubes for the ERV

• All ERV vents and air flow vents are placed on the first and second floors. (more about our ERV in another post.)
• The drywall is mostly up on the first and second floors, 25 buckets of joint compound wait patiently stacked in the living room.

• All the electrical wiring, outlets, lighting locations, switch boxes,and random other electrical equipment is installed including the big gray breaker box on the wall downstairs.

Electrical panel and the ERV, the lungs and power of the house.

• All the plumbing pipes are installed in the proper location in the laundry, kitchen, and bathrooms, including the late addition of a wet bar in the game room downstairs.
• A drain water heat recovery system has been installed. (More about that in another post.)
• Paul has run all the speaker wire for the various sound systems including the screen porch.
• Paul has been constructing the DIY Solar Thermal water heater. (That certainly deserves it's own post)

In addition to all of that, we have been busy selecting fixtures, counter tops, cabinetry, tile, flooring, lighting, and all of the other things that go into the house. There is still lots to be done to finish the interior as well as the exterior like the solar panel array on the roof and landscaping. Certainly it feels more tangable now than when it was our patch of dirt. Seeing the daily progress is really exciting and I joyfully anticipate living in our wonderful new home.

A bit about our windows



Turn function of the window

In a Passive House the windows are like an appliance that performs a specific task efficiently. They are an integral part the passive solar function of the house. The windows capture solar energy into the house and then must help the house retain that energy,  i.e. not let all that good heat go right out the window, a one way valve.  We decided on Intus Eforte windows manufactured in Lithuania, http://intuswindows.com/passive-house-window.html

While the windows are not officially certified by the Passive House organization, their performance metrics are comparable to windows that are.

There are 3 main metrics for analyzing window performance.  U-value is a measure of a window's ability to keep heat from escaping the house, lower is better.  It is the inverse of R-value, a metric commonly used with insulation.  SHGC is Solar Heat Gain Coefficient, a measure of the fraction of heat from the sun that makes it into the house.  VT is visual transmittance, a measure of the amount of light from the sun that makes it into the house. 

The eastern and western windows have U-values of 0.088, an SHGC of 0.4 and a VT of 0.58.  The northern and southern facing windows have U-values of 0.105, an SHGC of 0.5 and a VT of 0.74.  Originally, the SHGC of the southern facing windows was going to be higher, but there was concern about too much solar gain in the spring and fall when the sun is lower in the sky. 

Why did we choose Intus?  There are no American-made windows that meet the performance requirements of our Passive House, so we had to look at European manufacturers.  Wood framed windows were too expensive.  That left us with UPVC.  We looked at Intus, Shuco and Unilux.  Since we have no idea which if any of these companies will still be in business in the US 10 years from now, it ultimately came down to cost.  Intus was 25% less expensive than the second place finisher, Shuco.  We ended up paying about $50/SF of glass, but that includes a large slider and two doors.  I was surprised at how affordable these windows were. 

You can see the "tilt" function in the top left window. The windows are nicely shaded in June.

 We're very happy with the windows.  They seem to be really well made.  The windows are a little different that what we are used to in the US.  They are in-swing windows which are popular in Europe.  They have a really cool tilt-turn function that enables you to tilt the window in just a little for ventilation (see top left window in the picture above) or swing the window all the way open like a door.  They seal up very tightly when closed.  We were able to get some really large panes of glass for an uninterrupted visual frame of the trees and beautiful garden I'm still dreaming about.

Our architect Jamie also designed a beautiful curved overhang like the brim of a hat on the south side of the house to provide just the right shading for the first floor windows for the time of year and position of the sun.  We have been at the house during these hot summer days and have seen the upstairs windows perfectly shaded by the roof overhang and the large slider in the dining room perfectly shaded by the hat brim as well.  I  look forward to feeling the sun shining in brightly in the colder months to warm our New England winter bones.

Finishing the wall insulation

The insulators were back last week putting in the final layer of dense pack cellulose between the studs of the inner stud wall.  This completes the EPS/Polyioso sandwich with dense pack cellulose bread.

The video below shows the cellulose being blown between the studs and the cloth batting.  Behind the studs, you can see the aluminum foil cover on the sheets of Polyiso from the middle layer of insulation.

This brings the total wall insulation of our 1' thick double stud walls to R 48.  Is this a lot of insulation?  The framer has commented that we could have insulated standard 4 houses with the amount of insulation in our Passive House and that was before this last layer of dense pack went in.  The CT Energy Efficiency Fund gives rebates for "High Performance Insulation".  Their minimum requirement is R 21.  We have more than double the insulation of what is considered a very well insulated home.  One of the fundamental principles of Passive House is super insulation.  We're definitely meeting that requirement.

The basement walls (where we'll lose less heat) are insulated with 2 inches of Polyiso up against the foundation walls and dense pack cellulose in between 2x6 studs.  These walls have a combined R-value of R 32.  Underneath the basement slab is 5 inches of EPS at R 28.  The slab doesn't meet the foundation walls creating a thermal break that prevents heat from being conducted from the slab to the foundation.

The attic is going to be insulated with loose pack cellulose to R 83.  This should do wonders for keeping the heat from escaping to the roof during the cold months and infiltrating from the roof during hot months.  Again, the CT Energy Efficiency Fund requirement for ceilings is R 40, so again, we have more than twice this amount of insulation.

According to our builder all this extra insulation costs about $10K more than insulation would on a standard house.  We think that the upfront cost will more than pay for itself over the house's life.  In addition the extra insulation will provide a more comfortable place to live.

Walls like a sandwich, Insulation Information

The wall construction of a passive house is one thing that makes it very distinct from a standard building.  Our architect Jamie Wolf told us when Passive House "geeks" get together, their line is "What are your walls?" meaning what are the materials and construction you use in the Passive Houses you build. In my last blog entry, I described the first blower door smoke test to check for air leakage in the outer wall structure. We have come to the next step in wall construction, the insulation.  Jamie describes his walls as a "Sandwich Wall".  Basically, it is a double stud wall with several layers of insulation. Outside to in, an outer stud wall with dense pack cellulose blown in between the wall studs retained by a mesh batting (the bread). 

Dense pack cellulose being blown in between the wall studs

Next is a 4" thick layer of EPS, then a 1" layer of Polyisocyanurate (Meat and cheese).



Three layers out of the four done

Finished off with an interior stud wall with dense pack cellulose blown in between the studs and the interior wall board (bread again).  Insulating and appetizing. Great care is taken to eliminate air leakage and thermal bridging which is heat loss through conduction.

I have been a little remiss about blogging in real time. A lot of progress has been made at the Green Box.  I'll catch up in the next couple of entries.

Currently, the interior stud wall is partially constructed but will not be closed in with wall board until all the electrical, plumbing, ventilation, and heating/cooling lines are finished being installed in all of the interior walls so they can all be closed up together.  In addition, the windows are in, the roof shingles are on, and the screen porch and front porch are in the works.  More details and photos soon to come.



I love our windows

In other news, our green box is an official participant in the CT Zero Energy Challenge for 2012. Check out our entry and the competition at www.ctzeroenergychallenge.com/.We are entered as WolfWorks - Harwinton,CT.

Smokin' - The first Blower Door Test

A couple of weeks ago we had our first blower door test.  A blower door test tests air leakage in a building.  This test, the first of several we expect, was meant to see how tight the frame of the house is.

The builder next to the blower door

 

Since the windows and doors haven’t been installed, window and door openings were all sealed, either with house siding (i.e. they haven’t been cut out yet) or taped shut with plastic.  A special blower was placed in the front door.  First, the blower pulled air out from the house, depressurizing it to 50 pascals.  Air pressure inside the house was less than air pressure outside causing air outside to be sucked into the house.  A meter then measured how much air entered the building.

 

The passive house standard requires that air leakage in a building be limited to 0.6 ACH  (air change per hour) at 50 pascals.  This means that when the house is pressurized to 50 pascals pressure differential between inside and outside, 0.6 of the volume in the house will leak in or out each hour.  For a house the size of ours we were looking for a reading of 350 (not sure what units) from the meter to meet the Passive House standard.  The meter reading was 220 or less than 2/3 of the Passive House threshold.

 

For comparison, our builder told us he performed the blower door test on his own home, a typical leaky home, and got a meter reading of 4000.  At another client’s home where they took a leaky home and did some energy efficiency work, the meter reading after the energy efficiency work was 1900.  This illustrates that it’s much easier to build a house that’s air tight than it is to take a leaky house and make it air tight.

 

Air leakage is measured when a building is pressurized because it’s much more difficult to measure under normal conditions.  The pressurized readings can then be mathematically converted to normal condition readings (by dividing by 16 or 17).  The Passive House standard of 0.6 ACH at 50 pascals converts to about 0.035 ACH without a pressure differential.  This means that under normal conditions only 3.5% of the air volume in a house will leak out per hour.  Compare this to our builder’s leaky home where more than 50% of the volume of air will leak every hour.  Much of the energy that a building loses is through air leakage.  We can see here that our house will lose a small fraction of the energy that a typical leaky house loses.  This is a clear example of how putting a little thought and energy into the early stages of construction can make a home much more energy efficient without a big expense. 

 

 

Fogging the seams inside the building

 

After the air leakage readings were taken, the builder broke out a fog machine.  This time, the blower door fan was reversed to pull air into the building and create higher pressure inside.  Fog was blown against all the seams inside the building while the framing crew looked for escaping fog outside the building.  The few areas where leakage was found were marked and sealed with silicon or tape.

Here's a quick video showing the fogging from outside the building:

The next blower door test will probably take place after the windows and doors have been installed.