Archive for the ‘Thoughts’ Category

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.


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.

Can I raise goats on a roof?

Never thought about that until I saw a picture tonight.

We really like green roofs.   They provide a range of benefits.

1. Reduce Stormwater Runoff:

Simple, when rain hits a regular roof, it flows where gravity takes it, taking with it, all the debris, nutrients, etc. with it and go into the storm drains and into the waterways it goes.  When it hits a vegetative roof, it gets absorbed into the growing medium, the vegetation grows.  A typical green roof system retains from 70-90% of every inch of rainfall and you don’t need to water the plants.  It saves water.

2. Extends Roof Life:  The green roof sits on top of the actual roof membrane, shielding the roof membrane from UV radiation and temperature swings, extending the life of the roof membrane by 2-4 times.  It saves money.

3. Mitigates “Heat Island Effect”: When the sun hits buildings heat is retained making the surrounding space warm, then the heat re-radiates back when the surrounding space cools, basically, a negative thermal mass effect.  When you have a green roof, it insulates the roof from the sun and through the evapotranspiration (cool word for plants sweating), it also cools the space surrounding the roof.  It cools.

4. Green Space:  Instead of a boring old deck, you get a garden!  It Beautifies.

5. Reduce Heating and Cooling Loads: Essentially, you the green roof is insulation or as I like to call it, “outsulation”.

Here are a couple of cool ones:

Chicago City Hall

Photo courtesy of courtesy of DOE/NREL I Photographer: Katrin Scholz-Barth

Al Johnson’s Swedish Restaurant & Butik, photo Luanne Lozier

We don’t plan to start a goat farm but we plan to have a nice outdoor space above the garage (as much as I love it.  Maybe on my own house:)

What we decided to do was to strategically place about sixty 2’x2′ green roof trays above the roof terrace.  We believe the effect will be pretty awesome.  Stay tuned.



APHN: Passive Passion not Passive Aggression

The American Passive House Network (APHN) is two weeks old!  See

See for the two week birth announcement 🙂

I personally am extremely glad that such a platform exists now for PH designers, architects, engineers, builders… on the ground just doing their work.  Passive House/Passivhaus no matter how you spell it and no matter how you measure it (metric or imperial) it, is something that needs to be nurtured.  If PH is to become the mainstream building standard as it has become in Europe, people involved in PH in the U.S. and internationally need to work really hard and in solidarity to make it happen.

“The Americans will always do the right thing… after they’ve exhausted all the alternatives.” — Winston Churchill

We simply cannot and do not have time to waste on the alternatives.

I am sure many others feel the same way I do about the break up.  We were the children of two divorcing parents who continue to be aggressive against each other.  The good thing is we really should not feel the need to choose sides, in fact, it probably benefits us the most if we continue to talk to both sides.  More importantly, we have each other.  I benefit loads everyday from all the PH individuals I correspond with.  It a great community of people who share knowledge and experience freely, so let’s continue to share as generously as possible with each other.  It’s a movement that should not be slowed down because of petty disagreements.

For those who are just getting into PH and not familiar with the breakup, don’t bother.   Just skip ahead and know that there are people out there building homes/schools/apartments for the future and join our efforts.  I did not know about APHN until about two weeks ago but I am really psyched!

I think a visual of why PH folks are such an obsessed, fanatical lot is helpful here.  This is a trailer to Charlie Hoxie’s Passive Passion, the official selection from the 2011 NY Architecture and Design Film Festival: check it out!  You should really buy the movie for the full effect.  I did.


Barcroft and Columbia Pike

A simple fact about real estate is that its value is dramatically impacted by the condition of the immediate area where the property is located.  This is especially true in the case of the Arlington Passivhaus.  This whole journey started with Eric and I driving around in Arlington neighborhoods looking at properties listed for sale.  We came to this  neighborhood to look at another piece of property a block down. We were not familiar with the neighborhood at all except that it “felt like a nice place”.  We decided to drive around every block hoping to learn a little more about the area.  That’s when I chanced to turn my head and saw a small hand-written sign inside of a dusty window of a house stating, “For Sale.”

That “it felt like a nice place” sensation has a lot to do everything in the neighborhood.  We are not from Arlington and will not pretend to be Barcrofters.  We can’t help but appreciate the beauty of the neighborhood.  8th Street is a relatively wide (for Arlington), tree-lined street with cute, distinct and largely well-maintained historical homes.

Our neighbor and award-winning landscape designer Scott’s home has the most amazing masonry walls and of course one of the most elegant gardens I’ve seen.  I don’t think you can get someone to build walls like that anymore.

Scott's Masonry walls

Scott's Front Yard

Scott's Front Entrance

Half a block down sits the Barcroft Community House, which dates back to 1908, a building designated in the National Register of Historical Places.  I love the Gothic windows!  The Community House is currently undergoing restoration.  I can’t wait to see it when the work is complete.

Barcroft Community House

Here’s a map of the Barcroft Neighborhood

Barcroft Map

Columbia Pike is the main drag in the area.  For the last decade exciting developments have been coming down the Pike.  Other than the glitzy new condo/apartment buildings, there are several high-impact developments in progress.

I think the three most exciting developments are

1. Wakefield High School:

S. George Mason Entry

Rendering of the new building from Arlington Public School website

The $91 Million school broke ground last June.  The building is to be completed in 2014 to boast 403,940 gross sqft on four floors, enough to accommodate 1900 students.  The building will be going after LEED Silver.  Although we are are not huge fans of LEED, we like some of the features being included at the school.

  • Solar hot water
  • Rain gardens
  • Low VOC materials for better indoor air quality
  • Using mechanical waste heat to heat the pool
  • Reforestation

For more information on this project, see

2. The New Arlington Mill Community Center

Rendering from

This $24 Million project broke ground last August.  It is expected to be completed early 2013 to feature a 5-story main building (57,000 sqf), an attached Gym (8,700 sqf), a public plaza and two levels of underground parking.

See here for more information:

3. Pike Transit

Future streetcar scenario

Image from

This is a 5 mile modern street car project to connect Pentagon City, Arlington to Bailey’s Cross Road, Fairfax.  This five mile long corridor was slow to develop because it isn’t metro accessible.  With so much development going on on Columbia Pike, the Pike Transit will transform Columbia Pike from a car based growth to a much more sustainable public transportation based one.

I envy the folks who live in Barcroft, with so many positive things going on just a stone’s throw away.

Here is an Emmy nominated video created by the Columbia Pike Documentary Project ( that captures the diverse heritage of the Pike and the changes happening.


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