What’s New? What’s Old?

“Is this part of the original house?” is one of the questions people ask when they visit Midori Haus.  We feel complimented when people ask that question because we did put fair amount of effort into re-using materials to give it the look and feel of a vintage house that was originally built in 1922.  When we didn’t have any specific old looking items to re-use we bought new items that were made to look in the old style.

An example of this is the push button switch for the lights.  The house did not have push button switches when we bought it in 2010 but we are pretty sure that the orignal house did.  So to give it the original look we bought push button switches and switch plates in oil-rubbed bronze finish from Rejuvenation in Berkeley.

Most are simple on/off switches where you press the top button to turn lights on.  To turn the lights off you press the bottom button.  Some of the switches have a dimming function where you press the bottom button for on/off and the top is an adjustable dial to control the light intensity.  We chose to use these antique looking switches for pure decorative purposes.  There are no energy efficiency advantages.

Let’s look at the hallway bathroom door for a good mixture of old and new items.  The frosted glass on white door with the glass door knob has a vintage look.  When friends saw this door before the renovation they would say, “That looks like the door in my grandmother’s old house,” or “My basement door in my old bungalow has a door just like that.”

 We added the stained glass window above the door to let more light into the hallway.  People often perceive this to old but we got this new from The Bright Spot.

The door, the knob and the trims are original with fresh paint.

 We kept the built-in storage unit in the hallway.  These front got some fresh paint and the inside was simply cleaned.  It smells of old wood when you open the drawers and it’s part of the charm.

Most of the floor is original.  We removed the floor coverings (tile, carpet, linoleum) and had the original wood floors refinished.

The windows on the front of the house retained the same positions and size.  The triple-pane, Argon-filled fiberglass windows have a much better performance than the old single pane leaded window.

We did re-use the trims around the windows.  Santa Cruz Green Builders did a great job of matching the wood covering the deep window sill with the original window trims.

Notice the patched marks of nail holes on the window trim.  This is evidence of prior homeowners  installing curtain rods multiple times on this window trim.

  The mudroom bench and cabinets are new.  This practical set of built-in furniture was made by Loughridge Cabinets in Scotts Valley.  When you walk into the mudroom/kitchen area from the side door you can park your groceries on the bench, hang your hat and coat on the hook, and sit on the bench to take your shoes off.

Speaking of the mudroom, we did use a piece of the old mudroom in our new kitchen.  The breadboard on the wall was re-used on the breakfast bar in the kitchen.

In our old kitchen the gas water heater was next to the stove, strapped onto the wall.  The gas stove and the water heater shared a flue going up through the ceiling to exhaust above the roof.

As you enter the front door you’ll see this tidy shoes storage to your right.  We ask all visitors to take their shoes off in our house and this is one of the places where you can store them.

Also made by Loughridge Cabinets, the concept of the Japanese “getabako” is expressed in the arts and crafts style.This is built back into the wall and protrudes through the dining room. In the dining room the back side of the shoes storage cabinet looks like a nice stand.

 The buffet is the original built-in furniture that stayed in place during construction.  It was covered up for 13 months while the crew worked around it.

French door between the dining room and kitchen is also original piece of the house.

 Finally, I added a touch of Japanese influence in this arts and crafts house by re-using my other’s old kimono as cushion covers.

First Interim Blower Door Test A Success!

Good news!  The first interim blower door test passed the passive house criteria of 0.6 ACH at 50 Pascals!

This was very happy surprise when we stopped by the job site on Wednesday, 8/1/2012, after returning from a long vacation.  Riding our bikes into the fenced area we saw that the “blower door” (the red plastic lining fitted into the door frame with a large fan hugged by the elastic band on the plastic sheet) was placed in the front door.  Just as we were saying, “Hmm… They’re doing the blower door test today, I don’t think we can get in,” we saw the blower door being dismantled by our air sealing consultant, Terry Nordbye.  He was very happy and pleased to tell us that the house passed the blower door test.  Yeah!

Then we saw Taylor Darling of Santa Cruz Green Builders, our general contractor, walking out of the house with a big smile on his face and showed us this picture:

 
This means that the house, at this mid-construction stage, has met one of the most difficult criteria of passive house certification, air tightness test of 0.6 ACH50 maximum.  Our approach to air sealing is to do few interim blower door test during construction rather than wait until the very end so that air tightness is ensured along the way.  You may ask, what does 0.6 ACH50 maximum mean?  Well, ACH stands for Air Change per Hour.  The target of 0.6 ACH means 60% of the air volume in the house exchanging with the exterior of the house (leaking) each hour.  So, for our house with 1,569 square foot of interior space and 9-feet ceiling, the total volume of air within the house is 14,121 cubic feet.  60% of that is 8,472.6

ft3, which is the maximum allowable air leakage per hour at 50 Pascals (equivalent to having 20 miles per hour wind blowing outside of the house).  Now let’s convert the per hour figure to per minute figure to get to a familiar term of CFM (cubic feet per minute) by dividing by 60 (1 hour = 60 minutes).  This gives us a target of 141 CFM.  As you can see from the above picture (135 CFM at 52.2 Pascals) Taylor and his crew managed to exceed the air tightness criteria!  Excellent job, guys!

Taylor said that in the morning the very first blower door test result came in at 0.96ACH and they knew they knew their work for the day would be a quest for air leaks and patching them with foam and tape.  Fortunately it turned out to be only few large leaks rather than lots of tiny leaks.  One was the drain in the hallway bathtub where it didn’t yet have the p-trap and water in place.  Another was a set of penetration made for solar thermal plumbing.  The third was a penetration in the top plate that wasn’t visible from the bottom that leaked air into the space between two beams in the ceiling.  Here are some photos from Taylor on the examples of air sealing:

Solar thermal plumbing

Sealing around the windows

Foam sealing at the perimeter foundation

EPS foam board under the floor insulation in the crawlspace

Taylor and his crew, in addition to being good builders are air sealing rock stars.  This cannot be emphasized enough because they’ve managed to make this 90-year old house VERY airtight.  I’ve often heard that an average new construction today is about 5~6ACH.  What Taylor and his crew managed to do was to get this old house to be 10 times tighter than an average new construction.  It’s much harder to get to this level of air tightness with a retrofit because we’ve reused many of the existing structure (foundation, framing, roof, floor) from 90 years ago and therefore less control compared to a new construction.  You may also remember that the baseline blower door test for this house was 22 ACH.  We kept the vented attic and vented crawlspace so the air sealing was done at the ceiling and the foam board below the floor joist. 

Advice and help from our air sealing consultant, Terry Nordbye, was very helpful.  At one point during our visit David asked Taylor and Terry about which smoke pens belonged to whom.  After they sorted out their tools I asked Taylor, “So how did those smoke pens work in detecting leaks?”  His reply was, “We didn’t use the smoke pens.  We just listened.”  Apparently they boosted up the blower door fan to 180 Pascals and at that pressure they could hear the air leaks quite clearly.  One thing that leaked air more than expected was the window hardware.  We have lovely triple pane tilt-turn windows from Cascadia and the hardware on the windows leaked air quite a bit.

You may wonder with such air tightness of the house envelope what the indoor air quality will be like.  That will be another post on Heat Recovery Ventilator.

Framing

The wood frame of the house is like the skeleton of the human body.  It forms the shape and size of the house and provides the strength.  For our project, the roof framing for the house will stay in tact, since we are not changing or replacing the roof.  Floor framing had to be addressed where water or termite damage was present.  But it was the walls that needed lots of reframing.  If we’re not adding any living space and keeping the layout of the rooms the same why do we need re-framing?  Reasons are changes in openings, water damage, termite damage and durability.

Changes in Openings
Though we were hoping to reuse most of the original framing, much were replaced with new wood because of the changes in the size and location of the openings.  The total number of windows was reduced by 4 — original house had 22 windows and the remodeled house will have 18 windows, half of them are different size from the original.  The total number of exterior door openings remain the same at 4.  The difference is the size and location of the 2 doors.  In the interior we removed (closed off) one door, widened another door (from a swing door to a large pocket door), re-positioned the opening of the hallway door (to accommodate book shelf) and widen the kitchen by removing the wall between the mudroom and the kitchen.  So these interior walls needed to be reframed too.

Before (old framing)

Here are pictures of the South-East corner of the house where you can compare before and after reframing for new windows.  (Note:  left side is south and right side is east.)

In this South-East bedroom the south wall had one door and no windows.  The east wall had a large opening for 2 double-hung windows.

After (new framing)

After reframing you can see the south wall now had a large window and the east wall now has 2 small windows.

Water Damage
You may recall that we had rotted skip sheathing on the east and west ends of the house.  These were caused by water leaking around the window opening and spreading down.  In some places the wall studs, floor joist, mudsill and subfloor needed to be replaced.

Note the skip sheathing is rotted at the bottom

Floor joitsts sistered and a portion of subfloor replaced

Rotten floor joist sistered

Termites
We found many evidence of termite damage during the framing stage as you can see from the photos below.  But did you know that only a small percentage of the 2600 species of termites are pests?  Lots of interesting tidbits are found on the Termite Web site.  Fascinating….

What we care about in our project is to prevent termites from eating our house. We also care about minimizing the use of harmful synthetic chemical pesticides on the property so we are choosing to use Bora Care.  The active ingredient, borate, go directly into the wood, not into the soil and kills the termites (and other wood eating insects) by starving them to death.  Borates, once inside the insects’ digestive tract poisons the microorganisms that break down the wood’s cellulose.

This stud was well-feasted by termites

Girder with termite damage

Last week we saw a live termite crawling around the bathroom!

Bora Care will be applied to all wood surfaces

Durability
We decided to have the ceiling joists replaced with sturdier ones.  The initial reason was to replace the termite eaten joist.  Then we thought beefing up all the ceiling joists would give us the option in the future to convert the attic space.

2×10 ceiling joists

Sustainable Lumber
As a consumer we can provide incentive for the industry to pursue responsible forestry by buying FSC certified lumber.  Forest Stewardship Council (FSC), a non-for-profit organization, has principles and criteria that describe how forest have to be managed to meet the social, economic, ecological, cultural and spiritual needs of present and future generations.  You can read about these 10 principles here.

FSC certified wood

Sustainable Forestry Initiative is another standard promoting sustainable forestry practices.  You can read about their standards here.

Sustainable Forestry Initiative certified wood

Tidbit
Sometime in the last 2 years I came across some curious tidbits about why building codes have 18″ as the minimum crawlspace height (because that’s how high termites jump) and why traditional framing uses 16 inches on center (because a larger span would cause plaster to crack).    But I haven’t found a source to quote!   If you have a link to a website that mentions either of these tidbits please comment.  Thanks!

Midorihaus Passive House Windows

We also see that after the investment in high performance windows, increasing the insulation of the exterior shell and employing a heat recovery ventilator (HRV) or energy recovery ventilator (ERV) are the next wisest dollars spent.

Yes, investing in high performance windows is a good investment provided they can provide a lasting energy savings over less expensive but lower performing windows. However the coastal climate of Santa Cruz involves wide swings in outdoor relative humidity levels, precipitation, drizzling fog, and extended intense direct sun & UV due to generally high ambient air quality. This is a stress factor for wood window frame materials and necessitates more frequent resurfacing/repainting even though wood frames are the most sustainable material for window frame fabrication from the perspective of embodied energy. Termites need also be considered as a risk factor with wooden windows.

This is a graph from the Canadian manufacture of pigmented fiberglass windows (Cascadia) we ultimately chose for the project. It is vendor-formatted data you have to take it with a grain of salt but I believe is in general faithful to the facts. It compares many performance attributes of the four different windows frame material types commonly available.

So why did we choose this vendor Cascadia over the rest? This can be seen from the graph below which compares cost and various performance criteria for several vendors:

Simply put, energy efficient buildings minimize reliance on artificial lighting. To achieve this they maximize the amount of natural light admitted into the building interior through their windows. As a result energy efficient buildings enjoy high natural lighting efficacy. Energy efficient buildings also need to retain interior heat very efficiently at night and during cold seasons. For windows to accomplish all this at once requires special optical coatings which transmit in the light we see (visible light) while controlling or reflecting invisible heat energy (short wave infra-red) from the inside out and from the outside in. Different vendors offer different solutions but generally a thin layer of metallic silver is deposited onto the inner surfaces of the outmost glass and the cavity is filled with an inert gas such as Argon to prevent future tarnishing of the silver. One exception is Serious Windows whose products offer good thermal performance but rely on an inner polymer film to control Solar Heat Gain Coefficient (SHGC). SHGC is the measure of the amount of short wave infrared that passes through the window from the exterior. If the SHGC is too high and there is no effective roof overhang or shading this can contribute to high summertime HVAC loads, especially in climates with a high CDD (Cooling Degree Day) load. You learn more about HDD and CDD here: http://en.wikipedia.org/wiki/Heating_degree_day. Maps for the US are here: http://en.wikipedia.org/wiki/File:United_States_Heating_Degree_Day_map,_1961-1990.jpg and here: http://en.wikipedia.org/wiki/File:United_States_Cooling_Degree_Day_map,_1961-1990.jpg.

In the case of the Serious Windows approach, the windows were dimmer that other vendors with comparable SHGC. In quantitative terms this means they are lower in natural lighting efficacy due to lower Visible Transmittance or VT, which is the ratio of the light ultimately getting through the window expressed as a fraction of the total visible light reaching the exterior of the window. Serious Windows uses internal, non-ceramic thin films between the outer glass panes, which are also absorptive in the ultra-violet band. Ultra violet light chemically alters many hydrocarbon-based materials over time. This approach may not prove as durable as triple glazed with all ceramic glass although, however in all fairness, Serious Materials offers a life warranty on their windows. The Marvin triple glazed windows are not as well performing as either the Cascadia or the other European triple glazed offerings. The Cascadia windows offer a higher Solar Heat Gain Coefficient, higher VT (more light gets indoors), and somewhat better thermal performance (lower U value) than the Marvin Windows but to not quite attain performance the European vendors. It should be mentioned the Marvin Windows had some nice features such as optional built-in bug screens and SDLs that looked very nice in the show room.

The European windows we saw on tours were, as expected, beautiful and extremely well built. Many offer an aluminum cladding over the wood frames. The Sorpetaler windows were quite impressive as seen in two other Bay Area Passive Houses. However, all of the European windows would have been burdened with very high embedded shipping energy. Since we also considered global warming potential when selecting our insulation materials we thought being consistent with the windows too would serve the overall desired project outcomes. The Cascadia windows were the best overall balance of desired outcomes at the time of our project. However this will likely change and hopefully more domestic alternatives for Passive House projects will become available domestically. The American made wooden H and H windows were very cost competitive to Cascadia. From a sustainability perspective H and H seemed an ideal choice with lower transport embodied energy (made in the US) and lower embodied manufacturing energy (wooden frames). But at the time of our project H and H had no NFRC certification. That was too high of a risk to assume since we would only learn of any shortcomings in air sealing after installation. A final vendor comment..the Inline window rep kept trying to steer us away form triple pane and towards a high performance double pane option.

This brings us to a final discussion point. Why triple paned in the comparably mild climate of Santa Cruz CA? Three reasons (1) enhanced street noise attenuation (2) enhanced winter comfort due to higher indoor glass surface temperature (3) best bang for the buck in energy savings. The fact of the matter is that once you are working with a vendor who can satisfy the air tightness requirement and window frame R values needed for a Passive House you are in a price range where much of what you are paying is for the overall build quality and engineering. The marginal savings of a few thousand dollars do ‘downgrade’ to double pane glass didn’t seem with it when considering the ancillary comfort benefits.

Getting your Passive House windows right will be an in depth exercise for the homeowners and designers requiring tremendous attention to detail and patience in working with the vendors. It is critical to ensure that the correct coatings are incorporated in each window to ensure that window’s performance relative to its compass orientation NSEW. Customer service is sometimes lacking. Be fore-warned! Our issues involved trying to avoid the ‘grilles between glass’ or GBG with our SDLs. We were unable to get a different color SDL adhesive (which adheres the SDL bar to the exterior glass surfaces). This meant using aluminum bars between the #2 and #3 glass surface to avoid the awkward visual gap when looking though the windows from an angle. The Cascadia GBG bars are thermally broken as they intercept the divider at the edge of the glass. We have been told the thermal performance as modeled by the glass unit manufacture (Cardinal USA) is not appreciably affected. We have yet to receive the exact modeling for our project..story continued.

Glass and Windows

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