Introducing IntelliStructures Blog

Dear All,

Since the Arlington Passivhaus is now at an end.  We will be moving our new content to a new blog for IntelliStructures Inc.

If you enjoyed what we wrote about here, please visit us here for discussions on Passivhaus, high performance enclosures, SIPs structures and more.

Thanks for reading!


We are keeping it!

Okay, I admit getting emotionally attached to a house is not a great thing for a builder.  Let me just lay out other perfectly logical reasons for keeping it.


Looking at this home from an investment perspective, we should keep it.  Columbia Pike is undergoing some very serious changes as we speak.  We talked about some of this in a previous post  Changes are already underway, the Columbia Pike Documentary Project has been doing a great job documenting the changes along the corridor for years.  We think that recent developments will really add to the value of properties in the area.

During the early hours of July 24, after a marathon of a board meeting, the Arlington County Board approved two very important initiatives.  First, the Columbia Pike Neighborhoods Area Plan and second, the County accepted a modern fixed-rail street car as the preferred mode of public transportation through the Pike Transit Initiative  Revitalization of the area has been underway for quite some time and there are already several large scale mixed-use developments along the pike.  However, without an adequate public transportation system and a good plan designed for transit-oriented growth, I feared that the Pike was just going to be a congested road with expensive stores on the two sides.  With these two initiatives in place, the future of Columbia Pike is bright.  The Neighborhood plan would allow for higher-density development along the corridor while the street car system will give this corridor an opportunity to enjoy “smart growth” development, creating walkable mixed-use neighborhoods.  I think that is very smart and have faith in what is to come on the corridor.

The Arlington Passivhaus benefits by being only four blocks away from the pike, giving whoever lives here the connectivity to all the good things a mixed-used community has to offer while still enjoy the single family home, the 2-car garage, the garden and the immediate neighborhood.

More to Learn

In the past two years,  we learned so much from designing and building of this home.  It’s really only been operational for a little more than a month.  There is still a lot to learn about this house as an operating home.  I think anyone who has built or lived in a PH can tell you, it just behaves so differently from a typical home.  I believe there are plenty of things to improve upon for our next project but we need more information.  Short of moving in ourselves, leasing it out to a family of four is the next best thing for us to know how the home functions.  We’ll also be able to visit our baby from time to time.

We officially took the home off the market on Friday and signed a leasing contract with a very nice family of four.

Signing off for now…

Here’s a video that takes the project from the beginning to end, a sort of birthing story of this brand new home that we hope will be here for a long long time.


Edison marries Tesla

I am not suggesting they were gay.

As you all know that the D.C. region experienced a lengthy power outage last week.  This really got me and I am sure, other local energy geeks to think about backup power.  The traditional backup power is a generator that burns either gas or diesel.  Generators pollute and frequently lead to combustion gas poisoning (Some people are really that dumb).  People who have off-grid photovotaics (PVs) do not need to worry about outages but in the D.C. area most of us grid-tied folks will still experience loss of power even if we had PVs; the power company won’t let you charge up the lines when they are down for safety reasons.

Well, one elegant solution that is already available combines PVs, electric vehicles (EV) and ideally, a Passivhaus.  Imagine, Arlington Passivhaus with a PV array that wipes out its electric loads, so, a net zero energy home.  The garage also comes equipped with an electric car charger and the owners drive EVs or Plug-in Hybrids.

Under normal circumstances, the PVs will generate enough juice to power the house and charge the cars.  Whatever electrons left over go into the grid and the neighbors get to use and owners get to net-meter.  In a power outage situation, even though the PVs stop generating, the car batteries are already fully charged to power at least the most essential part of the house.  In a prolong outage like what we had recently, the batteries will eventually be depleted, at that point, if you have a Plug-in Hybrid, you can take it out for a long spin to charge the battery, then you have some juice again to power the house.

Here is a system that Toyota is testing that optimizes this scenario:

Now, let’s take this one step further.  Imagine if entire neighborhoods, towns, cities have this, we would’ve achieve a level of energy security that no oil, gas, coal or nuclear company can promise.  Utility companies will continue to play a very important role, they can focus their efforts on supplying power to the biggest consumers of energy, i.e. manufacturing, data centers, etc.  Utility companies really should be the ones building this network of home-generated power and the ones that maintain it.  Economic development is inevitable, energy consumption can only continue to grow, so, the utility companies need not worry about having enough customers.

I think of the War of Currents in the late 1880s between Thomas Edison and Nikola Tesla needs to be revisited.  Perhaps instead of battling over whose current was superior, the two geniuses should have married their technologies.



Monitoring and power outage

We’ve been monitoring the temperature and humidity in the Arlington Passivhaus for about a week now.  As part of a long stretch of heat wave a storm hit (they haven’t come up with a name yet, but let’s just call it the Big One for now), along with the PH, more than 1.5 million homes in VA/MD/DC area lost power, some areas are still recovering from a multi-day outage without air-conditioning.  This actually provided us with an unique opportunity to monitor and report what happens in this situation.

Let’s start with monitoring.

Here are a few constants:

MiniSplit setting: cool 67 F

ERV: Low (approximately 75 CFM)

Transfer Fans: ON


A note on humidity: we noticed the indoor humidity has been consistently high (60s), since we’ve been monitoring.  We attribute this largely to the moisture still in the building materials, especially that giant basement slab and seasonal factors.  However, we also noticed the relative humidity level has about a 7% swings if several windows or doors are open and it is humid outside.  This let us to consult the Bethesda Passive House team (David and Brandon JR.) since they probably experienced something similar.  The advice they gave us was to turn the ERV down while the house is “drying out”.  Because while the ERV dehuminifies the air that comes into the home, it does not take all the moisture out, so in effect, operating an ERV makes the humidity problem worse.  See for more explanation on this.  By turning down the ERV, we’ve been able to consistently drop the relative humidity levels a few percentage points a day from high 60% to mid-50%.  It still likes to go back up on very humid days though…

Temperature Results:

On a Normal Summer Day

We don’t have a large enough data set yet but we can report our observations so far.

We’ve observed the following on a typical summer day (June 27, 2012 Outdoor Temp: 62-89F, Humidity: 23-40%)

At 12 pm when the outdoor temp was 88 F, the indoor temps were: 68F/70F/70F (Basement/1st Floor/2nd Floor)

At 3pm when the outdoor temp was 94 F, the indoor temps were: 68F/70F/72F (Basement/1st Floor/ 2nd Floor)

Two Degree Temperature Differences Between Floors

This experience was consistent with other days with similar levels of humidity and temperature.  The temperature differences are typically about 2 degrees.  Heat rises up so, the 2nd floor usually is the warmest.

Effects of Solar Screens

We have motorized solar screens on the 1st floor south-facing windows.  This picture was taken around noon time and it is illustrative of the need to shade first floor south-facing glazings, the sun hits directly on it, while the 3ft roof overhang protects the 2nd floor windows from the sun.  By the way, shading needs to be on the outside of the windows, or they just become radiant heaters!

Solar Screens

One day, we wanted to see the effects of not shading, the result is that initially, the 1st floor becomes warmer than 2nd floor, then a few hours later, both 1st floor and 2nd floor are 2 degrees warmer than they would normally be.  This makes sense because the lack of shading makes the 1st floor 2 degrees warmer, then as heat rises, the 2nd floor eventually gets 2 degrees warmer too.  The basement is most consistent, the lack of shading on the 1st floor has no noticeable effect on the basement temperature. However, not shading creates a temperature difference of 3-4 degrees between basement and 1st floor.

On an Extra Hot and Humid Day (Outdoor Temp 71-103 F, Humidity: 50-66%)

At 12 pm when the outdoor temp was 95 F, the indoor temps were: 68F/70F/72F (Basement/1st Floor/2nd Floor)

At 3pm when the outdoor temp was 103 F, the indoor temps were: 70F/75F/77F (Basement/1st Floor/ 2nd Floor)

As you see, at 95 F, the indoor temperatures are still able to keep a nice two degree temperature difference between floors.  However, when it hit above 100F, temperature differences widen between basement and first floor to 5 degrees.  However, the difference between first and second maintains 2 degrees.  Also keep in mind, conditions are never perfect.  On this day, we had workers opening and leaving doors open all day long bringing in large amounts of hot and humid air.

Solar screen close-up

3ft Overhang

After the Storm

The storm devastated Northern Virginia, Mayland and D.C.  Here’s a picture of what we are seeing around town.

Crews restoring power

After the storm, the heat wave continued to rage on.  We were curious how Arlington Passivhaus performs in a heat wave with no active cooling.  Here’s what we observed on  after 40 hours of power loss on another scorcher day:

While the outdoor temperature was 92 degrees, the basement was a comfortable 73 degrees.  First floor was a warm but not unpleasant 81 degrees.  Second floor was 79 degrees.

This tells me two things:

Insulation Really Works

First, all the insulation in the walls and roof is effectively isolating the indoor environment from the outdoor elements, slowing down the effects of extreme outdoor temperature changes, i.e. after 40 hours of power loss, the first floor only warmed up by 6 degrees (75F -81F) and second floor by 2 degrees (77F-79F).

Shading is Crucial

I think the 6 degree increase in temperature on the first floor can also be attributed partially to the lack of shading on the French door on the middle of the wall (see first picture above), which explains why the second floor only increased by 2 degrees.

We still have no power…

We anxiously await the power to return.  This would be an opportunity to monitor how quickly a system like this recovers to desired indoor temperature and relative humidity level.

Hopefully, the next time we post, there will be power and interesting observations to report.


On Market!

With a slightly heavy heart, we are here to announce that the Arlington Passivhaus is on the market.  The blog will continue because we are still going to be testing and monitoring this home’s performance while the home is on the market and will continue to report our findings.

We will also continue to hold tours for anyone who is interested in learning about the Passivhaus and how to actually build one.

This is not the “end of an era” but we want to drop a quick “Thank You” to all our readers, advisors, advocates, neighbors, friends, family, the Arlington County, the Passiv House community and everyone who had a role in making this project possible for their support up to now.  We will continue to need it as we move forward.

Here’s our virtual tour slide show

See here for the full listing

Here’s D.C. Curbed’s article on our house

Oh! Almost forgot.  OPEN HOUSE this Saturday (6/16) 1-4pm

4616 8th Street S., Arlington VA 22204

Sneak Preview

The landscaping is almost complete.  We are almost done inside too.  Eric and I are seriously having mixed feelings.  We are relieved that this home is built but at the same time, we are getting really attached to it….  Well, it’s almost time to let it go.  We plan to put it on the market next week and have our official Open House on Saturday June 16th from 1-4pm, so if you are in the area, be sure to stop by.

Here’s a sneak preview and some highlights of our landscaping.

Front View

Front view 2

Our extensive landscaping, carefully designed and installed by Scott Brinitzer and his team really help accentuate the modern design of the home.  The trees soften the hard/straight lines of house while the hardscape reinforces the orientation of the different parts of the building.  Using little bamboo plants and sedums as ground cover, he created connections with the extensive interior use of bamboo and the sedums on the green roof.  Scott’s design also incorporates a very smart storm water management technique by guiding excess storm water through various parts of the yard and allows the soil to soak up storm water along the way.  By slowing water down and absorbing it as much as possible, this yard significantly reduces storm water runoff.

Here’s a full frontal:

Full Frontal

Here are some nice landscaping details:

Pea Gravel Path

Using trees as fencing, the boundary with the neighbor is softened.  The pea gravel walkway offers a path to slow down and truly enjoy the garden.  Plus it really gives you that Zen feel.  The steel edging around the path gives the path a very crisp feel.


Pea gravel path

Views from the top

From the Green Roof


From the Green Roof 2

It’s only been a couple of weeks but the sedums on the green roof are really thriving.

Green Roof

Green Roof 2

Here are some new interior shots


Living room

Stair Case

MBA Shower

Foyer “Genkan”

Arlington Passivhaus Art Gallery

Today, we are not featuring energy performance, mechanical systems, or building science.  Those things are what makes a house operate but they do not make it a home.  We believe a truly good home is one that stands in the intersection between art and science.  This is not a new idea, Apple’s entire product line is based on that concept. We need the science for the performance but we always need the art to evoke our imagination and feelings.

We’ve decided to feature art work that we have a strong connection to.  If you come visit our project, you will see these oil paintings done by Dr. Jesun Lin, a prominent physician and increasingly noted abstract painter living in Taiwan.  He is also our dad.

Hmm, perhaps that’s where our contemporary taste came from…

Upper Gallery

With these paintings, the space really comes alive.

“Sunshine” in the kitchen

Lower Gallery

Dad practices medicine in Changhua Taiwan, he is most well-known for his innovative surgical techniques in hypospadias repair.  His paintings have exhibited at the Salon d’Automne and Salon du Printemps in Paris, France.

We got Gold!

This past Sunday, we had the great honor to host the Arlington Green Home Choice Program’s annual awards ceremony at OUR house!  It was an awesome success.  Arlington County uses this opportunity every year to recognize the home owners, builders and the homes that voluntarily participate in the program to build and retrofit homes to a high performing level that is “healthy, comfortable, cost efficient and reduces energy and water usage and protects the environment.”  Helen, the manager of the Green Home Choice Program works tirelessly to engage builders through the entire process from design, construction to commissioning.  She certainly kept us going through the hard times with her encouragement and her frequent site visits tell us how serious she and the county are about promoting green homes.

We really like the program because of its prerequisite that the home be Energy Star qualified.  Even though Energy Star isn’t the most stringent standard out there, it is a great starting point and more importantly, it is performance based.  This also means a Green Home Choice building will perform significantly better than a conventional home.  Additionally, as Energy Star continues to tighten its standard, Green Home Choice homes will also improve in energy performance.  Modeled after the EarthCraft program, Green Home Choice uses a score card to determine other sustainability features of a home, such as water use, site design, etc.  Here’s the 72 page score sheet.  It’s also good to look for ideas in during the design process.

For this year (2011-2012), twelve homes were certified in the Arlington Green Home Choice program.  Out of which 6 received”Certified”, 3 “Silver” and 3 “Gold” awards.   This is the first year, Arlington has given out the “Gold” awards.

GHC Certified Homes

Here’s our gold!

Matt Fine and Jake (Zavos Architecture and Design), me, Jay Fisette (Arlington County Board Member), Charlie Byrd (Intellistructures), Ricardo Leon (Leon Home Improvement), Helen Reinecke-Wilt (Manager of GHC)

Special thanks to Helen Reinecke-Wilt,  Joan Kelsch for organizing this successful event.  To Jay Fisette for his support and commitment to a sustainable energy future.  Congratulations to all the other Green Home Choice participants.

Stay tuned and be sure to come visit us on June 3rd for the 10th Annual Arlington Green Home and Garden Tour.  For more information, click below.

Does Your House Breath Air or Drink Water?

Andy from Elysian Energy came out to do our final blower door test.  We knew that we had a 1 ACH 50 from John’s test at the Meetup event with 30 people walking around and playing with the windows and doors.  After taking some significant measures to air-sealing the windows and joints, Jim and Andy came for a second test which had a result that I thought was too good to be true but we felt comfortable enough to proceed with drywall and everything else.  I think there was a discrepancy in how the total air volume was calculated…

Last Friday, Andy did our final testing the ACH at a number of different pressure levels and our final number was 0.52 ACH 50!  The number is not 0.33 but we think it is a very respectable one for our first attempt at Passivhaus.

Final Blower Door Test

Air-tightness really is a difficult thing to achieve if you do not plan ahead.  I think to get the air infiltration number even lower, air sealing must be done in conjunction with construction, i.e. tape as you build.  I know of a builder that tapes up each nail hole right after the nail is hammered in so as to not miss any.  It is obsessive but I am not sure if that effort is really excessive.  Air-tightness is a quality of construction issue.  We’ll never get to a 0 ACH 50 unless you build a house with a balloon but we can certainly get darn close…

The Importance of Air-Tight Construction

I know this is a huge topic but in an effort to share information and help me articulate the issue I must dip into the importance of air-tight construction.  We had previously talked about this but we only talked about what we need to achieve but never explained why.  Here are some of the “why”.

1. Energy conservation:  Did you know that you can have all the insulation in the world and the build can still perform poorly? A leaky building envelope means “uncontrolled ventilation”.  This means conditioned air can leak out and hot/cold air can leak in; thus decreasing the effectiveness of the insulation.

This is an illustration of air-infiltration from

As you can see, air can leak in and out at a variety of places.  This is “uncontrolled ventilation” or what some typical builders talk about when they say, “You don’t want a tight house, your house needs to breath.”  Our retort is, “Your house does not need to breath, you do!”

2. Indoor Air Quality: Air can carry pollutants, moisture, odor and other undesirables into the building through these leaks.  If you cannot tell where the air is leaking in from, you have no idea what pollutants are being carried into the indoor environment.  As I like to say, “you are breathing like a frog.”  I love Kermit the Frog but we are mammals, so let’s have a tight skin (air-tight building envelope) and breath through a dedicated respiratory system (an Energy Recovery Ventilator or Heat Recovery Ventilator) that brings in fresh air through a controlled path and filters it before we consume it.

Do you want to breath the air that passes through this window?

3. Vapor Penetration

Air carries a large amount of vapor or moisture.  Each air leak has potential to cause water intrusion which in turn causes mold and structural damage if the moisture does not dry out.  In well insulated buildings, this problem can get worse because there is so much material that can trap moisture.  Therefore, air-tightness becomes even more important as building envelopes get tighter to keep water out in the first place.

This image from  Building Science Corporation paper RR-0412: Insulations, Sheathings and Vapor Retarders gives us a dramatic visual of how moisture laden air behaves with air-tight building envelopes and leaky building envelopes.  Over just one heating season in a cold climate, 30 quarts of water enters into a 1in sq hole in a building envelope whereas in an air-tight building envelope, only 1/3 quart of water enters into the envelope through diffusion.

Water is the biggest enemy of buildings, keep it out.  By building an air-tight envelope, water intrusion becomes water diffusion.

So, we’ve concluded that a house does not need to breath and does not need to drink water either.

Planting a Vegetative Roof

We placed an announcement on facebook to see how effective FB is at turning virtual connections to real life ones  In the end my fellow Passivhaus designer Bokyung and her husband Min and their lovely daughters came out to our green roof planting event.

Ready for planting!



We have eight different varieties of Sedums, some are deciduous and some are evergreen.  Some of them will disappear completely on the surface when winter comes and reemerge next spring.  All of them flower and should be really beautiful in a couple of months.


Here’s Bokyung planting the Sedums.

All planted

All planted.  It took eight of us (4 adults and 3 kids and 1 baby) about 2 hours to plant it all.  It was a great time and now we can all say, “we’ve planted a green roof.”

Thanks Bokyung and Min for coming out!




%d bloggers like this: