Archive for June, 2011

Bethesda Passivhaus Grand Opening

Went to the grand opening for the Bethesda Passivhaus.  It was a good turn-out.  The house was indeed beautiful with very nice finishes throughout.  More importantly, it was very comfortable.  It was about 95 degrees when I arrived, the house felt cool but no blasts of cold air anywhere, just cool throughout.  Instead of hearing an outdoor air-conditioning unit laboring away, I heard the quiet whisper of the ERV blending the air slowly.  The house is cooled by a small mitsubishi mini-split that is integrated into the ventilation system, which delivers the conditioned air to the entire house.  A different approach from our HVAC design but definitely effective.  In fact, their HVAC design integrated both heating and cooling with the ERV, which I believe is unique in all passive houses.

Here are the specs of the house

Chelsea Lane stats020

For those who aren’t as interested in the building specs, be sure to look at the last few $ numbers.  For $600 you can heat and cool the house for a whole year! The projected total energy cost is $1738/yr.  Remember, this is a 4400 sqft house.  A conventionally built home of the same size would cost $7,531/yr to operate.  Move in and save some money.

Great passive house!


Indoor Air Quality

I was reading Dr. Wolfgang Feist’s 8 secrets behind the success of Passivhaus, one of which is “Best indoor air quality”.

I think no one will dispute the importance of good indoor air quality (IAQ).  However, to what lengths do builders actually go to make the indoor air healthy for the occupants? In the industrialized world, people spend about 90% of their time indoors, but according to the EPA, indoor air quality can be 10 times worse than outdoor air on warm days in large smoggy cities.  What are the contaminates to our indoor air:

1. Biological contaminates:  these include pet dander, dust mites, mold and bacteria that originate either indoors or outdoors.

2. Chemical contaminates: these include formaldehyde, VOCs (Volatile Organic Compounds) both of which are ingredients in solvents and adhesives used in a whole dost of wood products, paint, caulk, carpets, finishes.

3. Radon: naturally occuring but carcinogenic gas

4. Combustion by-products: carbon monoxide and other gases caused by incomplete burning in gas appliances and car exhaust that migrate into living space from attached garages

Let’s not go into the nasty health problems we can get from all these and straight to the solutions that the Passivhaus approach provides.

A Certified Passivhause must have an air-infiltration rate of 0.6 ACH at 50 Pascal or less.  This means the house is virtually air-tight.  A conventional house breathes through the cracks in its walls and windows and doors frames, this is sort of like using your skin to breath without a filtration system for the air coming in (your air-handler typically has a filter but that only filters the airs that gets sucked into the duct work).

A Passivhaus actually has a respiratory system like us with a dedicated intake and exhaust and a lung (Energy Recovery Ventilator) with very good filters, to filter the air that gets into the indoor living space.  This is one of the reasons it is important to build the house air-tight, so no air is intruding into the house through an accidental pathway and even more important that when you build the duct system for the ERV, it be air-tight too.  In a Passivhaus, the air enters into the intake duct which is filtered through the ERV before it is taken to the living space, that same air is breathed by the humans and animals in the house goes through the ERV again and it is exhausted to the outside.  The process continues 24/7, which means fresh air all the time.  Like my friend David Peabody says, it is a “one way” path for the air to circulate.

Day 4: Thirty Tons of Gravel (Actually 50)

Just ordered 30 tons of gravel.  It actually turned out less than I thought. We are using it to build a compacted crushed stone footing.  Our basement walls are made up of pre-fabricated concrete panels.  These precast walls will not use a conventional poured concrete footing system to bear the weight of the house, they will sit right on top of a bed of gravel.  Taking our soil type into consideration, in order to support all the loads of the house, we need to build a 4 ft wide and 8 in deep gravel trench using 1/2 in gravel around the home’s footprint.  Once laid down, the gravel will need to be compacted down to achieve the bearing strength required.

This crushed stone system was advocated by Frank Lloyd Wright back in the day. He observed that roadways and railroads all over the world did not have poured concrete footings, they experience much more concentrated loads than houses, yet they were “perfectly static” with no sign of heaving.  He called them “dry wall footing” or “rubble trench footing”.  FLW went on to build several of his projects supported by this footing system.

The benefits of this system:

  • A “static” foundation with excellent drainage
  • Greatly decreases the use of concrete in the foundation
  • No messy concrete pours
  • No waste
  • Speed! As soon as the gravel is compacted the walls can be set
Here are some pictures of Leon Home Improvement folks helping us place and compact the crushed stone footing.
We ran out to gravel!  Ordered another 20 tons and this is what it looks like now with 8″ of gravel all around.

Day 2,3: Fancy Foot Work

Note: Previously posted on FB Page, migrated to wordpress to maintain completeness of our journal.

With unpredictable weather, work has been stop and go for a few days.  In the past week, our concrete contractor North Star Foundations Inc. has been working hard to excavate and build two footings on the two sides of the house.  On the west side (down for you) we have a 4’x4’x12″ footing that will help hold up the garage and the green roof (which you can’t see from the picture).  On the east side (up), we have a gigantic 6′ wide footing about 10′ from grade for the areaway to ensure that the areaway stairs are structurally independent from the foundation walls.

Here’s our beautiful areaway retaining wall by North Star Foundations Inc.

Day 1: Put that thing back where it came from!

Note: Previously posted on FB page on June 3, 2011.   Migrated to wordpress to maintain completeness of our journal.

After receiving permits last month, the construction of the Arlington Passive House started today! Today, the work was to put build up the area that will eventually become the garage by backfilling and compacting some of the dirt that was taken out.  Sounds silly but trust me, we had to do it.

Piles of Dirt

A bobcat was used to carefully dump the dirt back in.  After each 8 inch lift and after the organic matters and large chunks were removed, the excavators used a remote-controlled compactor to temp down the dirt.  The thing is basically a gigantic remote controlled car.  Eric and I wanted to play…


After each lift is compacted, a geotechnical engineer used some sort of nuclear seismic testing thingy (I swear, there was a radioactive sign) to test the density, moisture and bearing strength of our dirt.  The dirt was compacted to 95% with less than 13% moisture and the bearing strength exceeding 3000 psi.  I am not sure what that means other than a few weeks from now, we can set a crane on it to set our foundation walls. After 8 hours of backfilling, compacting and testing, we have a nice flat platform to work with.  Also, much of the 6ft tall dirt mounts are gone.

Dirt Piles Gone

Lesson 2: How to turn ashes to gold

Previously posted on our FB Page:

I couldn’t believe it when I received the county real estate assessment notice a couple of weeks ago.  A miracle had occurred!

As some of you know, we donated the house to the ARL Co. fire department for a controlled burn exercise.  Now, the house before the burn was definitely uninhabitable.  I think back then, you could potentially argue that the parts, if taken apart and sold for scraps, may be worth $48,700 (Assessed value 2010).

The FD burned it in October 2010 and therefore, turned it into a heap of burned remains of a house.  I actually think it should have a negative value due to the various potential liabilities this heap now represents.  The RE assessment department turn my ashes to gold!  The assessment for the improvement (house) actually came out to be $52,200.  That is a $3500 increase. Amazing!

Lesson 1. Donating a House

We purchased the property in the summer of 2010.  This is what it looked like:

There was really no way of saving it.  This house sat on a charming, pristine, tree-lined street in Arlington.  We thought this is a great property to redevelop.  There was no question about tearing it down.  One of our friends heard that you could donate tear-down homes to the fire department for training exercises.  We thought, “great! if we are going to get rid of it, we might as well do something useful in the process.”  We called the Arlington FD to donate it.  They were very happy to get a house to train in.

The FD told me they will probably not burn the house due to the closeness of the houses in Arlington.  It was about one week before the actual exercise, they told me that they plan to burn the house, but “just a small portion of it”.  I thought maybe they can just burn a small portion of the attic or something.  I asked two questions: 1. Do you have permits to burn?  2. Do I need to contact the neighbors?  They told me a permit was pulled and they will contact the neighbors.

At the appointed time I showed up as a spectator and of course as the homeowner.  The street was blocked off and the entire neighborhood was out.  I spoke with several neighbors and found out that they had just been notified of the burning 16 hours before!  I was quite shocked by this.  One of the neighbors asked me if I got the TV crew to come.  I asked, “what TV crew?”  There was a camera crew which I thought were just part of the FD filming it for training purposes on site getting ready to film. I spoke with the FD and was told that they were a national network news team filming the burning as part of their October fire safety month program.  I was a little disturbed that no one in the FD let me know about this or asked my permission to film but I kept quiet.  I do believe in fire safety and was hoping the program will benefit from this.

Here’s the footage of the burning that I filmed:

When it was all done. I asked the FD if I needed to do anything to secure the house.  They told me they will take care of it.  I waited around to see what they do to secure it.  When I saw a truck pull up with a bunch of OSB boards, I felt good that they were going to board up the place and left.

The very next day, this was posted on a local blog:  I commented that I had no knowledge that CBS was filming the burn and it wasn’t burned “for TV”.  Then I heard that the neighborhood got together and petitioned that the FD never burn in Barcroft again.

With some much negative ramifications that resulted from this.  We decided that we needed to move our demolition permit ahead of schedule.  Truth be told, after the burning, the boarded house was more secure than the state that it was in pre-burning with most windows broken (the house was in this state for years).  However, we knew neighbors probably didn’t want to live next to a burn-out house, we decided to make a separate demolition permit application ahead of our building permit application.  At the time we were about three months away from finishing up with the design.  The demolition permit still took about 2 months to get.  We removed the house as quickly as we could.  We also had to excavate out the old basement foundation, which left a large hole on the lot.  We did neglect to fence off the lot for a few weeks.  However, as soon as one of the neighbors voiced his concern, we installed a fence to secure the lot.

During all this time, we completed out designs and submitted our building permit application for plan review.  The process took another 2 months.

Lessons learned:

1. Donating a house is fine but make sure they agree to NOT burn it

2. Always be sure to secure the site

3. Talk to neighbors

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