Steam Oven

The Steam-Convection Oven is my favorite of all the kitchen appliances at Midori Haus.  At our previous home we had a gas cooktop and gas oven.  I’ve been cooking on gas stove top for over 20 years I liked cooking with gas a lot.  That is until we started taking energy efficiency classes at PG&E.  Let me paint a picture of what used to take place at our condo.

We learned that backdrafting occurs when there is negative pressure in the house.  This can happen when the volume of air removed by the exhaust fans (kitchen vent hood, bathroom exhaust fans) is greater than the volume of air that can easily enter the house such as through open windows.  At our condo we had all the windows and doors closed in the winter time because we didn’t want the 47 degree air coming into the house.  When we turned on the vent hood for cooking the make up air would need to come from some place that has the least resistance.  At our condo this was the gas wall furnace.  When the kitchen vent hood is sucking up the air above the gas oven to remove the combustion byproducts and cooking odor the make up air is coming into the house from the outside via the flue of the gas furnace on the wall dragging all the dust, particles stuck in the flue into the house.  Yuck.  After we learned about backdrafting we started this drill of opening the windows before we turned on the oven and vent hood to avoid bad air coming into the house.  In the winter this brought in cold air and the house never seemed to get warm.

Fast forward to present where we don’t have any gas combustion appliance in the house at Midori Haus where the Heat Recovery Ventilator provides constant fresh air.  We no longer have to do this routine of opening the window while kitchen vent hood is on.

Kurt gets credit for finding the Gaggenau BS 270610 Steam Oven on eBay.  Yes, we bought an expensive piece of kitchen appliance on eBay to save thousands of dollars and it’s working great.  With this oven I can control both the temperature and humidity separately and cleaning the oven is a really easy.  For baking coffee cakes I set the temperature to 340F and 30% humidity.  For making boiled eggs or steamed rice I set the temperature to 210F and 100% humidity.  It took me a while to work up the courage to make rice in the steam oven because I just could not imagine rice turning out well in an oven.  And I’m happy to have overcome that mental block.

Cooking rice in the steam oven requires the unperforated tray to be filled with 1/2 pound of rice with 2 cups of water and cooked in the steam oven at 210F at 100% humidity for 30 minutes.  Here are some photos:

Basmati rice with some water in the steam oven tray

The tray is inserted into the rails in the steam oven

Temperature is set to 210F at 100% humidity

Timer is set to 30 minutes

The oven is plumbed with filtered water and the steam fogs up the cavity

At about 10 minutes left in cooking time I throw in a bowl of leftover chili

Rice and chili is done!

This method of cooking rice works well with short-medium grain rice (aka sushi rice) too.

I’m sad to say that we’re not cooking rice much these days.  Why?  Because we want to minimize exposure to arsenic.  Consumer Reports came out with a study that showed rice products (brown rice, white rice, organic baby cereal, brown rice pasta, etc.) contained arsenic, many at worrisome levels.  If you follow the link above and read the report you’ll see a chart that lists products and levels of arsenic detected.  For example, Trader Joe’s Organic Brown Rice Fusilli pasta contains total arsenic level of 347 to 384 parts per billion (ppb).  We used to buy that often and liked it until we found this report. The thing I found curious is that although the level of arsenic found in the rice pasta is high there is no standard for arsenic levels in food.  If you look at the EPA standard for arsenic in drinking water its 10 ppb.  Strange, isn’t?

Lighting

According to U.S. Energy Information Administration (EIA) estimate 461 billion kilowatt-hours were used for lighting by the residential and commercial sectors in 2011.  This is about 17% of the total electricity consumed by both of these sectors and 12% of total U.S. electricity consumption.  This government website contain interesting data.  For example, looking through some of the tables on this site I noticed that 1995 was the year when electricity use by the residential sector exceeded the electricity use by the industrial sector.  But I digress.  This post is not about historical electricity consumption data but about lighting choices we’ve made at Midorihaus.  For those who want to explore the rabbit warren of historical energy data I invite you to look at this report from EIA.

We wanted 3 outcomes for lighting at Midorihaus: (1) good light quality that is functional and pleasing, (2) energy efficient performance of the materials, and (3) aesthetics of the lighting fixtures to match the overall Arts and Crafts style of the Bungalow architecture.  These 3 outcomes were equally important so naturally Kurt drove this area.  Not only does he have the gift of easily juggling and synthesizing different aspects and ideas all at once he also has over 2 decades of analog photography experience which trained his eyes to notice different qualities of light plus the science background to tie it all together.

The Arts and Crafts aesthetics part was fun.  Looking at books on Arts and Crafts style and visiting lighting stores to look at fixtures were enjoyable.  Our neighbor turned us on to The Bright Spot website and we were delighted to find reasonably priced Arts and Crafts style lighting fixtures.   We bought most of our lighting fixtures from The Bright Spot.

Researching and buying the light bulbs took a bit more time.  The light quality and energy efficiency aspects were challenging because evaluating light quality is subjective and the technology, especially with LEDs, is changing rapidly.  We’ve heard leaders in this field talk about how in 2 years the LEDs will be much better performing at lower cost than it is today.  But we can’t wait 2 years — we need to put some kind of lighting into the house now.  So, here are the steps we took to figure out what light bulbs to use:  1) Visited lighting retail shops to check out what they had in stock and compared them on their display board with dimmers; 2) Bought a number of CFLs and LEDs that looked good at the store; 3) Put the sample light bulbs in the fixtures in different rooms to note what we liked and didn’t like; 4) Measure actual performance of the light bulb (rather than trust the printed stuff on the box).

1) Visiting lighting retail shops.  We started locally at Riverside Lighting & Electric in Santa Cruz.  After identifying few different types of Compact Flourescent Lamp (CFL) and Light Emitting Diode (LED) bulbs we asked the salesperson if we could use the display board with a dimmer to see the lights side by side.  By putting different things near the light, such as your hand or paper with color, you can judge with your eyes what looks pleasing to you.  Since we specified dimming switches in several of the rooms it was important to have a bulb that performed well in dimming function.  Some of the bulbs had a noticeable color changes or reduced sensitivity when dimmed.  Other shops we visited were City Lights in San Francisco,  Bay Lighting Supply in Santa Clara, Light Point in Menlo Park, and Rejuvenation in Berekely.  City Lights in San Francisco had a wide selection of light bulbs and separate departments and staff for lighting fixtures and light bulbs.

2) Buying CFLs and LEDs to try at home.  We bought the CFLs and LEDs below to try out in the fixtures in our home.

CFL Bulbs:  GE, TCP 850 lumens, TCP 750 lumens

LED Bulbs:  Green Creative, Energetics, Philips, LEDwiser

3) Try the light bulbs in the lighting fixtures.  Seeing the bare bulb in the lighting store is nothing like seeing the bulb in the fixtures in the actual room in the house.  It was amazing to see how many different things can affect the overall light quality — the paint colors of the wall and ceiling, the direction the lighting fixture, the type of material used in the lighting fixture (colored glass, metal borders, etc.), furniture in the room, and time of day.  We found that while the labels on the boxes (color temperature, lumens, watts) contain information that will guide you on narrowing down the initial selection, the actual “feel of the light” in the rooms determines the best fit.

Below are some pictures of our lighting fixtures in various rooms.

Bedroom:  Sconce with Green Creative bulbs.

You may have noticed that we used quite a bit of LEDwiser bulbs.  Kurt met the entrepreneur behind this up and coming company in San Jose through Cleantech Open and we were impressed with their product.  LEDwiser’s product had the best lumens/watt ratio and had good directional coverage.

4) Measure actual performance.  We used the Kill A Watt to measure the watts drawn by the light bulb.  This was an interesting exercise to see if the actual electricity consumption measured on this device is what’s advertised on the box.  We plugged in the Kill A Watt into the electrical outlet on the wall then plugged in a table lamp to the Kill A Watt.  Then different light bulbs were screwed into the lamp to measure their electricity consumption.  We found that all of the LEDs we tested measured below the watts advertised on their boxes.  The TruDim CFL from TCP had the characteristic of shooting above the advertised wattage when warming up then settled near the advertised number.

Performs as advertised

Overshoots while warming up

If you’re interested you can check out the summary of our test.  Once we decided which bulbs we liked we totaled up the numbers and placed orders with the respective companies.

…And then there’s Title 24

One area where we felt “handcuffed” in our lighting fixture selection was the kitchen.  Lighting in kitchen is subject to energy efficiency standards specified in California Code of Regulations, commonly known as Title 24.  Instead of using the Arts and Crafts style ceiling mount fixtures with LED bulbs we had to get a very specific kind of lighting fixture that forced you to using a specific type of high efficiency lighting.  Perhaps this code was meant to prevent homeowners from using 100 watt incandescent light bulbs all over the kitchen. The intention is good but it makes it harder for those of us who want to have better energy efficiency than code minimum.  Because this is part of the code where building inspectors check and there are limited number of manufacturers and models we had little choice.

If you’re curious about what Title 24 details take a look at this website, Title 24 Express, which seems to have the layman’s explanation of Title 24 in an easy to read layout.

If you are really into government regulations and want to read more about Title 24 then enjoy this government site.

Floor

The house we bought in September 2010 had several different flooring materials:  wood, vinyl tiles, linoleum and carpet.  We were confident that the white oak in the living room and the dining room would refinish nicely and wanted to have Marmoleum in the bathrooms.  The other rooms were unknown.  As the deconstruction progressed we saw that the other rooms had fir floors.  Taylor, our general contractor, convinced us that we should attempt to refinish the original fir floor before deciding to replace it with new wood or cover them up with Marmoleum.  Well, he was right.  The refinished floors are beautiful!

During the deconstruction phase (December 2011) asbestos abatement specialists came in to remove materials containing asbestos, including 9-inch vinyl tiles in various rooms.  Then the floors were covered with cardboard paper while construction went on for the next several months.  As the project neared the finish stage the floors were sanded 4 times:  twice using medium grit sanding material (60 and 80) then twice again using fine grit sanding material (120 and 150).  The numbers refer to the CAMI grit designation.  Then waterborne wood floor finish called Bona Mega was used to finish the floor, applying and drying 3 times.  This product is GREENGUARD certified for indoor air quality.

Before:  Living room floor was in decent shape.  There were some termite damage on the south east corner and some staining from prior floor covering.

After:  Termite damaged pieces were replaced with new white oak that blended well.  Wood was sanded and stained.

Before:  The floor in the dining room was also white oak and in decent shape.

After:  Dining room floor was sanded and stained.

Before:  The kitchen floor was a light pink and brown vinyl tile.

During Construction:  This is what the kitchen floor looked like after the tile was removed and mastic scraped off.  At this stage it was difficult for us to imagine what the refinished floor would look like.

After:  The fir floor under the tile sanded down nicely and works well with the cherry cabinets.  Amazing!

Before:  The mudroom floor was the same type of light pink and brown vinyl tile that covered the kitchen.

After:  The fir floor under the tile was sanded down and stained.  Few pieces that were badly stained were replaced.  The result is a “distressed wood” look that is popular with homeowners.  We were told by the floor subcontractor that people pay extra money to get the distressed look!

Before:  The middle bedroom had a linoleum floor.

After:  The fir below the linoleum refinished beautifully.

Before:  The south bedroom had light brown carpet.

After:  The fir floor under the carpet has the distressed look after sanding and refinishing. Note the closet opening is wider now and you can see evidence of the smaller opening on the floor.

Before:  This room had a very colorful vinyl tile.

After:  The floor under the colorful vinyl tile was also the old tight-grained fir that refinished nicely.

Before:  The master bathroom was covered in white vinyl tile.  Termites had a feast in this bathroom and a good portion of floor had to be replaced.

During Construction:  The floor of the master bathroom was badly termite eaten.  In fact, we saw some live termites in this area.  Most of the floor in the master bathroom was replaced.

After:  We selected Marmoleum (this is a linoleum product brand name from Forbo) to cover the bathroom floors.  Marmoleum is made out of renewable, sustainable materials.  This is another material you can buy at GreenSpace in Santa Cruz.

If you’re interested in learning about other flooring material, I invite you to take a look at Green Remodel Forum.

Before:  The kitchenette was covered in brown vinyl sheet flooring.

After:  The kitchenette will become the master closet.  The fir floor under the linoleum refinished nicely.

Before:  The hallway floor was covered in red and brown vinyl tiles.

During Construction:  This is what the hallway floor looked like after the tile and the mastic was removed.

After:  Like other rooms the fir floor was sanded and stained after the vinyl tiles were removed.  There were few damaged areas that needed replacement.  It was quite fortunate that our contractor was had old fir he removed from another job that could be re-used to patch the floor in the hallway.

Before:  The hallway bathroom had a white linoleum floor.

After:  We used a white Marmoleum to cover the hallway bathroom floor.

Kitchen and Mudroom

We kept the same total footprint of the house — interior usable space of 1,569 square feet.  The room layout stayed the same, with the exception of the kitchen where we knocked down the wall between the kitchen and the mudroom and took the space from the bedroom closet.

Old layout

The original house had an exterior door into the mudroom that held the washer and dryer.  The kitchen had 3 openings.  One opening between the kitchen and the mudroom, a door leading to the hallway and another door into the dining room.  The sink faced the west windows and at the left end of the countertop was the ventilated vegetable storage (aka California Cooler) where the exterior wall had vents.  The gas-fired water heater was in the south-east corner next to the gas stove and range.   A ceiling fan vented to the outside could be operated by pulling the chain.  The north wall had a cute built-in cabinet.

The new layout

The new layout still has a mudroom, but there is no longer a wall separating the mudroom from the kitchen.  The door into the mudroom extends out to a small deck where we’ll have a outdoor gas barbecue.  A bench and cabinet is placed on the south wall and this is where we’ll hang out coats and take our shoes off.  Looking straight in from the mudroom door you’ll see a little desk area where we intend to do paper mail sorting, recipe lookup and such.  Pantry is next to the desk.  The breakfast bar wraps around the outside of the sink, countertop and cooktop.  There is no longer a door to the hallway and the cabinets cover the east wall.  We have 2 sinks in the hopes of having 2 cooks in the kitchen working side by side in peace.  The door to the dining room changed from the swinging type to a larger pocket door.

Here are some “before photos” of the original kitchen.

Mudroom:  As viewed from the kitchen.  Washer and dryer took up most of the space in the mudroom.  Note the bead board wall behind the washer and dryer.  Speaking of wall, the kitchen had the lovely funky plastic fake brick thing above the wainscoting.

Kitchen sink:  The kitchen sink and the countertop was a little taller than the standard countertop height I’m familiar with.  The windows above the sink and countertop provided pretty afternoon light.  On the right side of the sink is a vegetable storage space known as “California Cooler.”

California Cooler:  The upper and lower vents next to the lattice fence provided the cool breeze to flow through the wire mesh shelves to keep the fruits and vegetables fresh.  If you’re curious about the California Cooler, read what another blogger wrote about them.

Fridge, Stove, Water Heater:  The gas water heater in the kitchen was literally placed in the center of the house.  The seismic strapping prevented the use of the cool “ironing board feature,” (we think).  The gas stove/oven was a O’Keefe & Merritt from the 1950’s.  It was very cute but we didn’t want to have any gas combustion appliances in the house so it was sold on Craigslist.  The refrigerator was only about 5 years old and it too got sold on Craigslist.

Hidden Chimney:  When our designer took measurements of the house there was a small amount of unaccounted space between the closet and the kitchen.  This mystery was solved during the deconstruction where a chimney was revealed in the wall cavity behind the water heater.

Upper Cabinets:  A cute glass door showed what was stored in the cabinets.

Lower Drawers and Bins:  Below the upper cabinet was a countertop covered in blue linoleum.  These bins in the kitchen must have been used to store flour or some grains back in 1920’s.  As charming as these were we chose not to keep them.

Here are the “work-in-progress photos” of the new kitchen:

Mudroom Bench and Cabinets:  The door to the mudroom is to the right of the bench and we’ll probably use this door 90% of the time.  So, we’ll come in through the door and kick off our shoes then place them under the bench.  Next hang the jacket on the hook.  If we were riding our bikes and we had helmets and gloves they may go in the upper cabinet.

Desk and Communication Center:  The little desk in the corner of the mudroom will be used for day-to-day household paper and communication.  The slots above the desk will be used to sort mail.  Under the desk will have network devices and the desk will have a small computer that will display the house monitoring data (energy consumption, temperature and humidity).  To the left of the desk is the pantry.

Pantry:  Next to the desk is the pantry with pull-out drawers.

Upper Cabinets:  The kitchen cabinets are made of cherry wood in Shaker style with soft-close mechanism for doors and drawers.  Crown moulding a the top that bridge gaps between the cabinet and the soffit adds just the right touch to make the kitchen have the arts and crafts feel without being too fussy.  Loughridge Cabinets of Scotts Valley made these and we’re really happy with their workmanship.

 Countertop:  In these two photos you’ll see Taylor applying adhesive to the top of the cabinet then fitting the carefully cut PaperStone countertop with Jacob’s help. We looked at various materials for the countertop and the breakfast bar.  Going to a retail shop where you can see green product samples as well as get information from knowledgeable staff made a big difference.  We shopped for the countertops and breakfast bar in the spring of 2011 by going to Ecohaus in San Francisco (now closed) and GreenSpace in Santa Cruz (still open!!) and looked at many different green countertop products.

There are many different types of materials and color choices within each product line.  If you’re considering the pros and cons of different materials I invite you to take a look at the Countertop page of Green Remodel Forum where there is a detailed description of various materials by attributes.  Our selection criteria came down to 2 key points:  sustainability of the material and aesthetic fit with the California Bungalow style.  We chose a product called PaperStone in mocha color for the countertop.  It’s a sensible product that is made with FSC certified post consumer paper product held together with petroleum-free resin.  Details of the PaperStone material can be found here.

Tile:  For the kitchen backsplash we used the Debris series from Fireclay Tile which is made with 60% recycled material in the Bay Area.  While many distributors carry Fireclay tile we liked visiting the showroom in San Jose.  Picking out a dozen different sample tiles and taking it back to our kitchen to see which best matched the color scheme was very helpful.

Re-using the bead boards:  Remember the bead boards on the wall of the original mudroom?  They were re-used to surface the breakfast bar.

The Outside Layer

People wear different clothing depending on where they are and what they are doing.  What you see on them, whether it be a banker in New York or mountain climber on Everest or a surfer in Hawaii, reflects both the function they’re engaged in as well as their personal taste.  The mountain climber will likely wear several different layers such as the base layer to wick moisture away from their body, some middle insulting layers to keep warm and some outer layer that serves as wind and moisture barrier to stay dry.  All of them expressed in whatever color, style, and material to be fashionable.  You can think of the house in the same way where different layers serve different purpose and the styling and color reflects the owners’ taste.

In this post we’ll cover the exterior look of Midori Haus.  We’ll continue the story from the exterior mineral wool insulation.  You may recall from the insulation post of this blog that 3.25 inches of rigid mineral wool insulation (Roxul Toprock DD) was nailed on to the outer surface of OSB sheathing.  Over that Tyvek Home Wrap was applied.  This is the layer that protects the home from wind and rain that could penetrate the exterior siding. 

Tyvek Home Wrap over mineral wool insulation

Then furring strips were nailed over the Tyvek Home Wrap. The furring strips are used to fasten the sidings.  If you would like to see example of furring spacing, number of screws and other details for attaching furring strips have a look at this article from Green Building Advisor.com.

Furring strips

Screws used to attach furring strips

Extra care was taken around the windows to prevent water damage.  For details on why windows flashing are important and how this is done, see article in Fine Home Building.  (Note: this article doesn’t describe what was done on our house)

When we were asked about the details of trim around the windows and doors Kurt and I looked at each other and said, “Let’s look at examples in the neighborhood and agree on what we like.”  So we took a walk down our street as well as some of our favorite local streets with Arts and Crafts style homes.  We showed David, the lead carpenter, the style of trim we liked and he mocked up a window trim.  This was really helpful in getting the decorative detail in a way that felt subtle and classic.

Is the flared skirt look on the side of the building called “Battering” or “Flared Siding”?  At one point someone told us that it was called battering but I can’t seem to locate a source that calls this battering. Anyway, the original house did not have the cute flared skirt but Kurt really liked the look of having this flared siding to give a a bit more of Arts and Crafts look.  So the crew of Santa Cruz Green Builders cut many pieces of wood to shape the flared skirt look for the house, including the trim of the door.

Cement fiberboard siding product called, HardiePlank, was used as the lap siding material for the body of the house. We selected this material because it is durable (resists rot, won’t burn, termites won’t eat it) and the company has a sustainable manufacturing practice.  While we could have chosen different types of surface that simulates different wood grains, we decide to go with the smooth surface.  For the top area above the belly band we used the Hardie Shingle product.  

Hardie Plank Lap Siding

Installing Hardie Plank Lap Siding

Hardie Plank Lap Siding with the flared skirt effect

Hardie Shingle siding

Installing Hardie Shingles

One of the outcomes we want for our house is the aesthetics and curb appeal of the 1920’s Arts and Crafts look of a California Bungalow.  We chose to reflect these in the grill pattern on the windows, trim around the windows, lap siding, front porch, the hint of flared skirt effect on the siding, and keeping the original footprint of the house.  A slight deviation from the Arts and Crafts aesthetic is the decks outside of the kitchen and bedrooms but this adds the indoor-outdoor connection we wanted for our lifestyle.  For reading on bungalows, I invite you to read The Bungalow: A Short History on the Arts and Crafts Home page.

Walls and Ceiling

We’ve removed asbestos and lead based paint in the original house.  So we should have safe and healthy indoor air in the house, right?  Not if you don’t pay attention to the material you introduce into the house.  Earlier this year we read a book by Bill Bryson titled, At Home: A Short History of Private Life.  A curious and well-researched book containing facts about homes in England and US, there were many astonishing examples of the rooms, materials used for homes and how people lived.  In Chapter 14 he mentions ways in which how our houses can hurt us.  One example is wallpaper.  After 1775 a popular shade of green was made by soaking the wallpaper in a compound containing copper arsenite invented by a Swedish chemist, Karl Scheele, and the color was known as Scheele’s green.  Use of wallpaper increased after the wallpaper tax was lifted in 1830 in England and by the late 19th century 80% of English wallpapers contained arsenic.  Today most of us know that arsenic is toxic.  But back then they didn’t and the rich green color containing arsenic was used in candles, clothing and even food coloring.

A more recent example of walls in your home causing harm is the reactive sulfur gasses coming out of certain drywalls manufactured in China.  According to CDC report the people who lived in US homes that were built between 2001 and 2008 containing imported drywalls experienced headaches, eye irritation, difficulty breathing and other health problems.  The Chinesedrywall website appear to have collection of information related to this issue.  By the way, the term drywall, sheetrock and gypsum board appear to be used interchangeably.  For a quick overview of the history and manufacture of drywall see this video.

We know that people made decisions based on information available to them at that time.  Some of these, like asbestos, has beneficial qualities like fire-resistance and sound absorption that made it attractive to use in various building materials at one time.  It’s only later when the side effects of these materials that caused serious illness, such as lung cancer from inhaling asbestos fibers, that made these materials fall out of favor.  So, in 2012, we’ve chosen materials based on what we know today to be benign and promote good air quality.

Our house was built in 1922 so the original walls and ceiling were made of lath and plaster.  Here are some photos of the original wall taken during deconstruction.

Plaster above the door chipped away to reveal the lath underneath

“Lath” is the narrow wood strips nailed horizontally across  wall studs.

Plaster oozing through the lath holds it in place

Below are the “after” pictures of the new walls.

We chose to have fiberglass batts installed in the interior wall cavities between rooms.  The purpose for this is not for thermal insulation but for sound attenuation.  We noticed that the hardwood floor over a crawlspace seem to carry the sound throughout the house, perhaps similar to how a sound reverberates within a guitar. We were told that another way to dampen the sound is to use different thicknesses in the drywall, for example using 5/8″ and 1/2″ on either side of the wall studs.  We didn’t do that.  Hopefully the fiberglass batts will dampen the sound of me playing my flute to prevent annoyance to others in the house.

AirRenew drywall from CertainTeed was selected.  This drywall product promotes indoor air quality in two ways — 1) Traps volatile organic compounds (VOCs) such as formaldehyde in the air and makes it inert and traps it inside the drywall; 2) Resistent to mold and mildew.  You can watch a short video of this here.

Ceiling and walls installed using AirRenew.

Lydia Corser from GreenSpace advised us to be selective of the plaster used to texture the drywall.  Her store, located next to Habitat’s ReStore on the west side of Santa Cruz, is a great place to get get paint, flooring, countertops and various interior materials for your home.

We selected M-100 hypo-allergenic powder compound from Murco to be used to texture the wall.  This product is formulated with no VOC’s, preservatives, mildewcides or fungicides.

The compound is mixed with water.  I was told that this product is a little bit harder to mix than the usual texturing material.

Though harder to mix application is the same effort.

Insulation

We want to be comfortable in the house.  There is a narrow band of temperature and humidity range we human beings are comfortable at.  The temperature-humidity chart below show the comfort zone to be in the low 70’s to 80 degrees Fahrenheit, which is about the ambient temperature in Hawaii.  Since less than 1% of the population of the U.S.A. live in the 50th State most of us encounter climates where the outdoor temperature is either too warm or too cold.

So to keep the inside of the house comfortable the shell of the house would need to slow down the transfer of heat between inside of the house and outside of the house.  This (either keeping the interior cool when it’s blazing hot outside or keeping the interior warm when it’s frigid outside) is what insulation does.  What type of material to use for insulation and how much to use depends on where you live and the goal you’re trying to achieve (performance and cost).

US EPA’s Energy Star site has this insulation map and accompanying table that shows different climate zones and the recommended level of insulation.  You’ll notice numbers preceded by “R” on the table such as R30, R25, R60, etc.  The R-value is the unit of measure for resistance to heat flow.  The higher the R-value the less heat flows between the inside and outside of the house. Different materials performance as insulators and you can find a table of R-value for different materials in this Wikipedia article.

Rather than use a generic table of recommended R-values we had our Passive House consultant and designer, Graham Irwin, perform the analysis and calculation using the Passive House Planning Package (PHPP) from Passive House Institute.  When all the details of the house (climate data for our zip code, house orientation, materials used etc.) are entered into the PHPP software it will calculate the amount of energy needed to heat and cool the house.  We have specific energy target we want to achieve for heating the house to meet passive house standard: 15 kWh/square-meter/year or 4.75 kBTU/square-foot/year. The same target exists for cooling demand for the year but since we live in a temperate climate that doesn’t require air conditioning it’s not a big concern for us.

Using the insulation specifications below our heating demand for the year to keep the house at comfortable temperature of 68-degrees Fahrenheit (20-degrees Celsius) is 8.75 kWh/square-meter/year.

Attic – 12-inches of blown-in cellulose; foam was applied to the tight corners along the wall-roof line (~R35)

Floor – 5.5-inches of fiberglass batts in the floor joist cavities and 2-inches of expanded polystyrene (EPS) board under that. (~R26)

Walls – 3.5-inches of dense pack cellulose (wet spray) in stud bays and 3.25-inches of rigid mineral wool (Roxul TopRock DD) on the exterior wall (~R28)

We had many discussions with the insulation experts, contractors, energy efficiency specialists and architects before deciding on the materials we chose.  One key learning for us was when we heard Alex Wilson speak at PG&E’s Pacific Energy Center in San Francisco.  He shared a story of a well-intentioned homeowner wanting to save energy and reduce greenhouse gas emission was horrified to learn that the spray foam product he used to insulate his house would take 60-years to payback — this is not financial payback but the time it would take his energy savings to offset the amount of greenhouse gas released into the air from the blowing agent used for his spray foam product.  So we decided to stay away from spray foam products.  You can find one of Alex Wilson’s article on insulation at Green Building Advisor.  The chart below is from that article.

Attic

Here are some before and after picture of our attic.

Before:  Very little insulation in the attic

You can see from this “before photo” that we did have some attic insulation, if only to barely cover the ceiling joist.

After:  over 12 inches of blown in cellulose

In this “after photo” you can see the measuring tag sticking up from the sea of cellulose to indicate that between 12 and 14 inches of cellulose filled  the space.

The insulation sub-contractor, Ponzini Insulation, did the cellulose insulation in the attic and in the wall cavity.  Applying blown in cellulose in the attic.  They had a big truck with special attachments to pump the cellulose through the long hose to apply the insulation.

Insulation Truck

Installer applying blown in cellulose into the attic

Floor

Crew from Santa Cruz Green Builders did the insulation and air sealing below the floor in this cozy crawlspace.  Fiberglass batts filled the 5.5-inch deep cavity between the floor joists.  Then sheets of 2-inch thick EPS board was applied under that.  The seams of the EPS boards were meticulously taped using Siga tapes.  Because the EPS board serves dual purpose of insulation and air barrier the edges of the board coming in contact with other material (wood, concrete) were foamed to prevent air leakage.

Crawl space view of the floor after completion of insulation

Walls

Our 90-year old house did not have any wall insulation!

Before:  No insulation between stud bays

As you can see from this deconstruction photo, the space between the exterior skip sheathing (horizontal board) and the interior wall made of lath (small strips of wood) and plaster was empty.

After:  wet spray cellulose filled the wall stud bays

Wet spray insulation was applied to the open stud bays in the interior wall cavity.  This took almost one week to dry fully but it allows for visual inspection of cellulose application.  Speaking of inspection, we had Quality Insulation Inspection (QII) performed by Bright Green Strategies for the California Advanced Homes rebate program.

Mineral wool material applied to exterior sheathing

Sheets of rigid mineral wool were applied to the exterior wall.

We used TopRock DD from Roxul

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.

Mid-Construction Tour

Join us for a mid-construction tour of Midorihaus this Saturday!

Beginning of Air Sealing

Why Air Sealing?

We want our house to be comfortable, durable and energy efficient.  So air sealing is an important element in meeting those criteria.  You know that air can pass through small cracks, spaces and even pin holes, right?  For example, if you see daylight in the door frame when it’s closed you’ll feel a draft standing next to it when it’s cold outside and warm inside.  Then if you put weather stripping around it to prevent air flow the house feels more comfortable, right?  So, stopping air leakage leads to comfort.

Air sealing also leads to durability of the building because air can transport moisture.  You might ask, what’s the connection to durability?  Well, remember the pictures of rotted skip sheathing due to rain water intrusion?  Prolonged water exposure can cause wood to weaken and also invite mold to grow.  Not good for durability of the structure nor the health of occupants.  Let’s imagine a hypothetical example for illustrating why moist air passing through cracks in the walls is bad for durability.   Say there’s a lot of cooking going on in the kitchen and the indoor temperature is 80 degrees with 50% humidity and the outside temperature is 40 degrees.  The dew point (the temperature that vapor in the air changes to liquid) is 59 degrees.  Warm air can hold more moisture than cold air.  So for a given relative humidity, the the surrounding air temperature will determine if it will stay in the air as moisture or condense to liquid and become water.  For an explanation of using simplified psychrometric chart have a look at this guide on air properties from NebGuide.  In this hypothetical example the warm air leaking through the kitchen wall will to the outside will encounter drop in temperature along its path and when the temperature drops below dew point the moisture vapor will change to liquid water.  If the cold surface happens to be the insulation layer it will get soggy and dampen the wood around it and if it doesn’t dry out over a period of time there will be rot and maybe mold.  So, stopping air leakage leads to durability.

Air sealing is good for energy efficiency.  Imagine driving in your car with the windows open in the winter.  The heater is on in the car but the hot air is escaping through the window.  When you close the window it’s warmer because the heat is no longer escaping through the window and you can use a lower temperature setting to stay comfortable.  Same thing with the house.  If you have the windows open you use more energy to heat the house than if you had the windows closed.  The opening and closing of the windows are something we can do voluntarily to control and minimize the use of energy to heat the house.  The air sealing of small cracks and spaces are like having lots of tiny miniscule windows that we can’t close.  Some of these cracks are buried under layers of building material and homeowners can’t get to them easily.  So we rely on the builders to ensure that these miniscule uncontrollable windows in the house at different stages of construction.

Air Sealing Examples

When we’re talking about air sealing for passive house standard the builder is taking steps to mitigate air leaks from tiny spaces like gaps between two pieces of wood on a top plate, mudsill, etc.  To refresh your memory, we are striving towards Passivhaus certification and the airtightness goal is 0.6 air changes per hour (ACH) at 50 pascals.  If you recall our baseline blower door test came in at 22 ACH.  This means we are targeting the house to be 3600% more airtight than the original house!

By the way, you may want to take a look at this page for a brief overview of Passivhaus.

Air sealing work on the wall framing was done prior to sheathing.  These guys examined the places were unintended airflow could occur, like the junction of mudsill and studs, corners, etc.  Below are some pictures of air sealing examples.