Solar Panels as a Financial Investment

Net-Zero, a house that produces all the energy that it uses

In 2012, we built the first certified Passive House in the state of CT.  Since a Passive House is an ultra energy efficient house that requires very little energy to heat and cool, we knew that through the purchase of a solar PV system, we'd have the opportunity to also be a net-zero house, i.e. one that produces all the energy it uses.  The idea of our home having a zero carbon footprint and zero energy bills was very appealing, but would the expense of the solar panels be worth it?

Solar panels are a financial investment

I spent much of my 22 year career in the financial services industry analyzing fixed income investments.  When you purchase a solar PV system you make an investment upfront to pay for the system and you receive investment returns over the next 25 years in the form of savings on your electricity bill.  The cashflows here are very similar to that of an annuity or long-term bond.  Furthermore, the savings are after tax savings, so it's comparable to a tax-free annuity or a long-term municipal bond.  It makes sense then to analyze the investment in a solar system the same way you would a financial investment, by discounting future cashflows and computing a yield on the investment.

One complication is that we don't know exactly what the future savings will be.  In order to estimate the future savings we need to make some assumptions.  Solar providers are pretty good at estimating the amount of  electricity a system will generate over its life.  Using the average annual generation provided is a reasonable place to start.  But, the future price of electricity is much more difficult to estimate.  The best we can do here is to look at history and analyze the yield of the investment using several different assumptions for the energy inflation.

When I bought my system in 2012 the net cost after state rebates and federal tax credits was about $3 per watt for our 10.78 kW system.  I created a spreadsheet (borrowed from somewhere on the internet) and figured out that the yield on my system was about 1.1% plus whatever I assumed for annual electricity inflation.  If I assumed electricity inflation was 4% the yield was 5.1%.  If assumed 6%, the yield was 7.1%.  If I assumed 1%, the yield was 2.1%.  Historically, I think that energy inflation has averaged around 5% per year for the last few decades.  Back in 2012 yields on long-dated municipal bonds were in the 2%-3% range.  The investment in solar PV seemed like it would return more even under very conservative assumptions for electricity inflation.  When I bought my system our utility charged $0.14 per kWh.  Now they charge $0.17, an increase of more than 23% over just 3 years.  Unless there is a persistent and significant decline in electricity prices going forward, this will have been an excellent financial investment.  It's a bet that I'm happy I made.

Prices have dropped dramitically and investment yields have gone up dramatically

Prices for solar PV panels have decreased dramatically over the last 3 years.  Additionally, our town is part of CT's Solarize program enabling residents to get bulk purchase discounts.  With the Solarize Harwinton pricing residents can get a solar PV system installed for less than $2.00 per watt.  Even if you have a partially shaded site and you assume zero electricity price inflation, a solar system through this program today yields 5.8% and again, that's an after tax return.  If you add in modest electricity price inflation of 4%, the yields are closer to 10%.  If you have a site without a severe shade problem with modest energy inflation you could see yields close to 12% and again, these are after tax yields.

In conclusion, solar PV panels seem like an amazing investment today.  Where else can you get after tax returns of 6%, 10% or 12% for 25 years?  Stocks?  Bonds?  I don't think so.  And, as a bonus you get to do something good for the environment.

I've attached the spreadsheet I used for the analysis if anyone's interested in playing around with it.

Energy Consumption for 2013 and 2014

Happy New Year everyone!  We've been living in Our Connecticut Passive House for a little more than two years now.  I began detailed electricity monitoring in January 2013.  Now we have complete information for all of 2013 and 2014.  In these two years, our 10.78kW solar panel system produced 24,113 kWh of electricity while we used 23,384 kWh.  So, we produced 729 kWh more than we used.  Yippee! The house is completely electric.  No oil, gas, wood or any other fuel is used. 

One of the great things about living in a net-zero house, i.e. one that produces all the energy it uses, is that our total energy bill consists of the CL&P (our electric utility company) fixed charge of $16 per month for being connected to the grid.  This is a pretty impressive result given that we have a decent size house (2800 sf of finished floor space) and live in a cold climate.  We're looking forward to reaping the benefits of our investment in energy efficiency and solar power for entire lifespan of the house.

The charts below show electricity production and usage for calendar years 2013 and 2014 respectively.  You can see that in 2013 we produced more than we used (by 1266kWh), while in 2014 we used more than we produced (by 537 kWh).

Our usage in 2013 was 11,136 kWh.  Usage increased by 1112 kWh to 12,248 kWh in 2014.  This entire increase can be explained by the increased heat pump and HRV consumption in the very cold months of January and February 2014.  The average temperature during Jan and Feb 2013 was 27 F while in 2014 it dropped 4 degrees to 23 F.  Another factor influencing the additional consumption was turning up the indoor thermostat from 68 F to 70 F during 2014.  There also may have been a decrease in sunshine heating the house indicated  by the less impressive performance of the solar hot water heater in Jan 2014 compared with 2013.  Solar PV performance was also weaker in 2014 during Jan, but it's difficult to say how much of the performance difference is due to snow covering the panels on the roof.  The solar hot water panel is on the ground, so it's easy to clear the snow off it.

Electricity production was down 692 kWh in 2014 compared to 2013.  In 2013 we produced 12,403 kWh and in 2014 we produced 11,711 kWh.  Most of this difference is probably due to a snow covered roof in January and February 2014.

So, two years into the journey, it looks like a Passive House's energy efficiency combined with solar energy generation can produce a house with a zero net carbon footprint that costs almost nothing to operate.  It's not just hype.

Radon and a Passive House

Let me start out by stating that I am neither a radon expert, Passive House expert or a builder.  That said, I do have experience with radon gas in a Passive House that I'd like to share.

According to The Passive House Institute US FAQ, Passive Houses are by design, well-protected from radon.  They attribute the radon-preventing attributes of a Passive House to its rigorous air tightness metrics and balanced ventilation.  Our home is a certified Passive House that had a radon problem until a conventional radon mitigation system was installed.  I don't believe that achieving the Passive House standard did much to reduce the likelihood of our having a radon problem.

According to the EPA's A Citizens Guide to Radon, radon occurs naturally in soil and rocks in which home foundations are placed.  Radon can be found all over the country.  In our area, northwest CT, there is approximately a 40% chance of radon existing on the site of your home according to a local expert.

Radon gas enters a home through gaps in the structure (typically a foundation) that separates the below grade interior of a home from the earth that surrounds it.  The local expert we saw explained that even a tiny gap the size of a dime can lead to elevated levels of radon in a home.  The atmospheric pressure in the ground tends to be higher than the atmospheric pressure in a house's interior.  As a result, a basement can act as a sort of vacuum cleaner motor that sucks in radon in soil air through any of these small gaps.  Radon gas can then accumulate to levels that according to the EPA can lead to increased risks of lung cancer.

In houses without balanced ventilation this vacuum cleaner effect can be exacerbated by exhaust fans, dryer vents and mechanical heating and cooling systems.  As air is forced out of a house unconditioned air enters through gaps in the lower portions of the house.  Although a Passive House has a balanced ventilation system, the pressure in the soil around the foundation still tends to have higher pressure than the house's interior. I conclude this based on the fact that my house has a balanced ventilation system as well as a radon problem isolated in the basement.

A Passive House's balanced ventilation can also reduce the level of radon in a house by exhausting the air with elevated levels of radon from a basement and supplying fresh air with lower levels of radon found in outdoor air.  Doubling the rate of ventilation cuts the radon level in half.  In our house, I saw short term (7 day) radon levels range over the course of a year from 3 pCi/liter up to 12 pCi/liter using a Safety Siren Radon Gas Detector.  We would have had to quadruple the rate of ventilation in order to reduce the highest detected levels below 4 pCi/liter as recommended by the EPA.  This was not possible they way our ventilation system was designed.  So, while our continuous exhaust of basement air reduces the amount of radon in our basement, it doesn't reduce it nearly enough to mitigate our moderate radon problem.

A Passive House's balanced ventilation has two seemingly positive characteristics with respect to radon infiltration and exhaust which, at least in my case, fell short of preventing elevated indoor radon levels.  So, the question now is why don't the air-tightness requirements of a Passive House prevent enough soil air containing high levels of radon from entering the building?  Our house beat the Passive House standard by more than 35%.  It had an air-tightness measure of 0.38 ACH50 (air change per hour at 50 pascals) with a corresponding reading on the blower door test of about 180 cfm.  This means that under normal unpressurized conditions air leaks into our house at a rate of about 300 liters/minute.  I'll assume that the air entering our house through the balanced ventilation system has radon levels of 0.5 pCi.  Soil air in the US typically has radon levels of 200 to 2000 pCi.  I'll assume that our soil has a radon level of 750 pCi which is considered in the middle of  an average risk area (270-1350 pCi, according to A Living Radon Reference Manual) for radon.  If the source of air in our basement were a mixture of 99.5% 0.5 pCi air from the ventilation system and 0.5% 750 pCi soil air, then we'd see radon levels of 4 pCi in the basement.  Our basement contains about 300,000 liters of air.  0.5% of this is approximately 1500 liters.  If all the air leakage in our house occurred below grade with soil air, it would take about 5 minutes to leak 1500 liters of 750 pCi soil air.  If only1% of the leakage in our house occurred below grade it would take 8 hours.  The entire volume of air in my basement is exhausted out by the ventilation system every 16 hours, so 1500 liters leakage in 8 hours should be enough maintain radon levels at 4 pCi in the basement.  I don't know the actual soil air radon levels (although our well water tested at 2500 pCi and 5000 pCi, so 750 for the soil seems reasonable to me) or the percentage of our house's leakage occurring below grade, but nonetheless, I'm not at all comforted that the Passive House air-tightness requirements have any meaningful effect on preventing radon infiltration.  In fact, our house exceeded the Passive House standard on the initial blower door test under conditions that were ideal for radon infiltration, with a gravel basement floor prior to the concrete slab being installed. 

To prevent radon from infiltrating a house through air-tightness requires close to 100% effectiveness below grade.  Our house was designed and built with an elaborate air and vapor barrier surrounding the foundation (although based on our initial blower door test this barrier was not at all necessary to achieve the Passive House air-tightness standard).  I suspect that others who build Passive Houses have similar below grade air and vapor barriers.  The barrier was designed to be continuous with both penetrations (well and septic) sealed with spray foam.  My expectation was that this air and vapor barrier would keep all soil air with its high radon concentrations out of the house.  Unfortunately, it seems to have at least one dime sized gap as evidenced by the elevated radon levels in the basement.  Here is a photo album with pictures of the foundation and barrier for anyone interested.

Fortunately, we were able to prevent radon from entering through the small gaps in our air and vapor barrier through  a conventional radon mitigation system.  The conventional system was built by drilling an 8" diameter whole through are basement slab and removing about 5 gallons of the gravel found there.  A 4" PVC pipe was inserted into the hole and the hole was sealed back up.  The pipe travels out of the basement and into the adjoining garage and then out the garage wall.  A 20 watt fan was placed in the pipe and run continuously to create negative pressure underneath the slab.  Because the pressure under the slab is now less than the pressure indoors in the basement, there is no longer a vacuum effect and soil air is not sucked into the basement through existing gaps.  Fortunately, we were able to achieve the desired result with a small fan drawing only 20 watts to keep electricity usage to a minimum.

4" PVC pipe penetration through basement slab for conventional radon mitigation system

So, while a Passive House's balanced ventilation and air-tightness sound like they'd be helpful preventing elevated levels of indoor radon, they don't do enough to make a difference.  In particular, air leakage permitted by the Passive House standard can allow substantial amounts of radon to infiltrate a home.  I don't believe, unfortunately, that achieving the Passive House standard significantly reduces the risk of having a radon issue in your house.  On the positive side, if you have a Passive House with a radon issue, it can be addressed with a conventional radon mitigation system.

A year in Our Connecticut Passive House

  

Autumn through the screen porch

We moved into OCPH in October of 2012. It's hard to believe that a year has already passed. We had a wild weather autumn and winter with several major storms followed by a wet spring with some late frost, then a humid but beautiful summer. It's autumn again and the cool nights and gorgeous New England foliage make this one of my favorite times of the year. I know I have mentioned this before but living in a Passive House makes you feel more connected to the weather conditions as they dictate how you "drive" your house. The heat exchange ventilation system, the lungs of the house, allowed us to keep the windows closed on the hot humid days of summer. We had the thermostat set to 76 degrees and even in daily 80+ degree weather, Due to great insulation and shading, the AC only kicked in occasionally. The engineered overhangs on the south side of the house shaded the windows beautifully to prevent unintended solar heat gains while keeping the windows unobstructed by curtains maintaining a bright open living space.

Now the sun's angle is becoming lower in the sky and the sunlight is once again streaming into the house in the cooling weather. The night temperatures have been in the 40s and the house stays comfortably in the 70s with the heat pump turned off.

Diane's Fire Pit

Energy wise, we are still on track to be Net Positive for the year. Paul the graph master will post some data on this soon.

On October 5th OCPH will be participating in the NESEA Green Buildings Open House tour organized by the Northeast Sustainable Energy Association. This is the 14th year of the event and there are 373 participant sights throughout the northeast. We are proud to join the tour and share what we have learned and lived.

Running the house on Prius Power

 

On Sunday morning June 30th, we experienced our first prolonged power outage since moving in.  A tree came down on one of the power lines around the corner and power was out for about 6 hours. It was time to see the inverter that we bought from Converdant Vehicles to turn our Prius into a backup generator in action.

The inverter works by taking energy from the big hybrid battery in the Prius and converting it to a pure sine wave 240/120 AC current, no different from what we typically get from the power grid.  We parked the car in front of the garage and connected it to the inverter with a cable we had professionally installed into the hybrid battery. We then turned on the car, turned on the inverter and flipped the switch on the generator sub-panel we had installed in the mechanical room that contains our critical circuits. Instantly, our well pump and ventilation system were back up running.

When I turned on the car, I noticed that it was almost out of gas, down to the last bar on the display.  Fortunately, this setup is very efficient. The inverter takes as input the DC current from the hybrid battery. As the hybrid battery loses it's charge, the Prius' gas engine turns on to recharge the hybrid battery. If there is only a small appliance load on the inverter, the gas engine turns on infrequently.  We only had a few hundred watts of power being drawn, so we used little gasoline.

Another cool thing is that the only noise this set up makes is the sound of the Prius idling. We could hear our neighbors' loud gas generators from hundreds of feet away, but most of the time we were pulling electricity from the Prius in silence because there was plenty of charge in the hybrid battery without the car even idling.

Perhaps the most impressive aspect of this setup is that the inverter generates 240/120 split phase pure sine wave AC power. With it, we can operate both 240 volt appliances (well pump, HRV) and 120 volt appliances (fridge, lights, computers). Because it's pure sine wave power, we don't have to worry about the generator frying our computers, TVs, etc. I was able to watch recorded TV on an LED flat panel using a signal from our Windows Media Center PC we use as a DVR while the family took hot showers (complements of the sunny day prior to the outage). All this while the Prius either sat silently or idled in the driveway.

Energy Consumption at Mid-Year

We've made it through half of our first calendar year in the house and have some additional energy usage information to share.  First off, on May 6th, we became net producers of electricity for the calendar year.  From January 1st to June 30th, we produced 6580 kWh of electricity and consumed 5220 kWh, a net surplus of 1360 kWh, which at $0.14/kWh is worth $190.  Our HERS rater estimated that we'd produce about $400 surplus of electricity for the year.  We seem to be on track to realizing that.  The chart below illustrates our experience.

In the beginning of the year we consumed more electricity than we produced.  There were two drivers of this.  One, fewer daytime hours means less electricity produced by the PV panels on the roof.  And two, colder outdoor temperatures means that we need to consume more electricity running the heat pumps.  You can see in the chart above that this trend was reversed in March as evidenced by the orange "Net" line in the chart above starting to slope upwards.

In April, May and June we produced significantly more electricity than we consumed.  We see the same two drivers at work again.  One, more daylight hours means more electricity produced by the PV panels on the roof and two, warmer outdoor temperatures means we consume less electricity because we need to run the heat pumps less frequently.

It'll be interesting to see how often we need to run the heat pumps for cooling in July and August.  We have seen the house heat up pretty quickly to 83 or 84 degrees when it's 95 outside.  Fortunately, there have only been a couple of days like that and as a result, we've hardly used the heat pumps for cooling.  They seem to use 10 to 15 kWh per day or $1.40 to $2.10 at $0.14/kWh.  We've had them on the last couple of days more for dehumidifying than cooling.  It's been so wet and humid around here lately that turning on the heat pumps has been a better option than opening the windows at night for cooling the house.


It'll also be interesting to see how our PV panels perform the rest of the year.  So far they are performing very close to the estimates we received from the company we bought them from, Aegis Solar.  You can see from the chart below that we produced more electricity in April than in June.  This probably has something to do with the 34 degree angle to the horizon of the panels on our roof being better suited to the sun being somewhat lower in the sky.

Stay tuned to see what our stats will be in July and August, the hottest months of the year.

Outside

Recently we have turned our attention and efforts in a big way to our landscaping. We have hydrosseded (a spray on combo of grass seed, fertilizer, fiber mulch and water) over an acre of property and are in the process of putting in foundation plantings and a large garden bed in the front of the house. Paul and I built and installed raised beds for my vegetable garden and we have put in some fruit trees and a blueberry bush patch. With all of this new growth at once we find ourselves spending lots of time digging holes and watering. We have developed a complicated relationship with the weather, wanting a balance of energy generating sun and well water relieving rain. Connecticut is still in a bit of a drought so I'm sure no one will mind that I am doing a rain dance.

A hydroseeded slope in "surreal green"

My raised bed veggie garden labyrinth.

We have also been communing with the rocks on our property of which we have tons. We have put them to good use creating old style pile rock walls and in the dry stream bed which directs rain water away from the foundation. Paul and I have worn out several pairs of work gloves hauling rocks. What a workout.

Pile rock wall. The grass is starting to grow

Dry stream bed in progress

Right now I am sitting in a lounge chair on the back patio. I'm blogging while I rest my barking dogs and aching back from garden/yard work for 5 hours this morning. What a luxury to sit in such a beautiful and peaceful location. I'm inspired to get up and do a little vegetable seed planting.

A misty morning with young fruit trees in the distance

What we gave up

We made it! Our first winter in OCPH. A winter with several snowstorms and a major hurricane. We were warm and comfortable without a furnace or fireplace or radiators. Just a small heat pump system and passive solar gains. There are signs of spring in Southern New England as the last of the snow piles on our property have melted. We are coming into our second season living in OCPH and I am excited to see how the house performs.

Spring on the back patio

The media storm has continued with several great articles in the Avon News, the Waterburry Republican, and the Green Building Advisor. I'm waiting with baited breath for a call from the New York Times, who was our original inspiration for building a Passive House. Heck, as long as I'm putting myself out there, Paul and I would love to go on the The Colbert Report. C'mon Stephen, you know you wanna.

One common question of most of the interviewers was "What did you have to give up? What design compromises did you have to make to build a house like yours?" We really only came up with three, and they are not biggies as far as I'm concerned.

1) No fireplace - A fireplace and chimney is a huge heat sink and breaches the sealed envelope of a house which is a Passive House no-no. I plan to build a beautiful stone fire pit circle in the side yard so all our fireside gatherings will happen outdoors. I enjoy a good song circle by the fire even in warm weather so I don't consider no fireplace to be a sacrifice at all.

2) No direct entry from the garage to the house - The indoor air environment would be compromised by having auto and other fumes from the garage vent into the house. The garage shares one wall with the house but has no un-sealed penetrations making it outside the building envelope. We have a side door from the garage that exits onto the covered porch and have to walk about 10 steps to the front door. Not having a direct garage/house connection is a good building practice for any house concerned with clean indoor air.

3) Ventless clothes dryer - A vented dryer not only is a breach in the envelope but the rate at which it sucks air out of the house throws off the air pressure balance. The ERV (energy recovery ventilation unit) is "tuned" so the incoming air volume matches the out-vented air. We use the combination of a spin dryer and a condensing dryer. That, my friends, is another post altogether. Again, a minor compromise that I have come to appreciate and love.


Now that the interior of the house is basically done, we are shifting our focus to the outdoors. Gardens need to be designed and planted. I've started my vegetable seeds in flats in my little outdoor greenhouse. It's going to be a busy spring at OCPH.

Barrel composter and seed starter greenhouse

The Media Storm

There has been lots of buzz about OCPH in the media. It started when reporter Christopher Hoffman happened upon this blog.  He told me he had been interested in Passive House design and wrote a lovely story that landed on the front page of the Hartford Currant. Thank you Chris. Several other media outlets have picked up the story also including Fox CT 61 News and Chanel 3 Eyewitness News Ct. Thank you to the news media for helping to share our story. We hope to inspire others to explore alternative building methods as we have been inspired by folks who have built and shared before us.

Jim Altman from FOX CT News
 

Yesterday we attended a lovely ceremony hosted by the Energize Connecticut and CL&P to present the awards for the 2012 CT Zero Energy Challenge. OCPH won the overall first prize as well as three of the four sub categories, lowest overall HERS Index, most affordable, and lowest annual operating costs. They screened the videos about the winners that were filmed in January (see post 1/30/13) and spoke a bit about the 2013 participants. I can't wait to follow the new crop of energy efficient projects this year including a couple of net zero working farms in Litchfield. Check out our 2012 ZEC video. They did a great job with the production and editing and we had a blast making it. I think we nailed the power pose. Beat that Real Housewives.

Enoch Lenge of the Connecticut Energy Efficiency Fund presented the awards

One thing I have discovered personally by doing these 90 second television news segments is that I need to perfect my elevator speech. It is tough to encapsulate into two sentences what a Passive House is, especially with a camera and microphone in your face. What gets aired is an edited down sound bite sacrificing technical details, often for dramatic factoids. Good entertainment. My favorite example so far is the article in the Huffington Post, who we did not even speak to, and after publication sent in a correction which they did publish. (I still love you Arianna)

We read, researched and digested tons of information about energy efficient building and Passive House, living the process from the ground up for the past few years. Most of the reporters, as most of the population, have never heard of a Passive House. In general the reporters have done a terrific job of fitting lots of information into a short and interesting segment or article and getting it out there. We have been contacted by some great people who are interested in doing similar projects and we are happy to share our experience. Pay it forward.

Energy Consumption for Jan and Feb

In building our home we took a bit of a leap of faith that this stuff actually works.  So, the question is does a Passive House really use only a small fraction of the energy of a code built home to heat?  Well, we have some results from January and February to share.

On the left behind the garage, a solar hot water collector and 2 air source heat pumps.  On the roof, solar PV panels.

The house is heated by 2 Mitsubishi SEZKD09NA4 ducted air handlers and 2 Mitsubishi SUZKA09NA outdoor heat pump units (see the 2 tiny rectangles to the right of the large solar hot water collector in the photo above).  These are small units that ordinarily heat a room or two in a typical house.  The heating load for the building only requires one of these units, but the ducting runs would have been too long for a single unit to handle.  With the thermostat set to 68 F the whole time, they did an admirable job keeping us warm.  Indoor temperatures on the main two floors where these units service ranged from 67 F to 74 F depending on how sunny it was.  The basement which isn't heated was cooler.

I bought an eMonitor electricity monitoring system that provides circuit by circuit electricity usage information.  The electricity charges for these Mitsubishi units at the current CL&P rate of $0.14/kWh were $66 in January and $58 in February.  Compare this to the $300/month in kerosene it costs to heat our smaller empty condo to 53 F so that the pipes won't freeze.

So how does electricity usage in January and February compare to projected usage?  It seems a little on the high side, but it's hard to tell.  We used 469 kWh in January and 412 kWh in February.  The PHPP (Passive House Planning Package) determined that the heating demand for January and February was 877 kWh and 555 kWh.  Our usage was substantially below the demand, but that is because heat pumps extract heat from the outdoor air and produce more indoor heat in kWh than they consume in electricity.  The COP (coefficient of performance) of these units is 2.4 at 17 F and 3.1 at 47 F.  A COP of 2.4 means that the heat pump will produce 2.4 units of heat for each unit of electricity consumed.  The average low temperature for the month in both Jan and Feb was about 17 F.  I'd expect a COP of at least 2.4 for Jan and Feb.  If the PHPP was correct in computing our heating demand, our effective COP was about 1.9 for Jan and 1.4 for Feb.  Both months seemed very cloudy, so it's also possible that the amount of sunshine captured did not match what PHPP assumed causing a higher demand for heat and the Mitsubishis to run more than expected.

One thing I found interesting that you can see in the graph below is the wide variation in electricity consumed by the heat pumps.  The range is from 2kWh to 25kWh per day.  The amount of sun coming into the house really makes a difference in the amount of heat the heat pumps need to produce.  There was a very sunny stretch for 4 or 5 days around Valentine's Day where the average consumption by the heat pumps was 4 kWh per day.  I can tell that this was a sunny stretch because the solar hot water tank got up to its limit of 160 F for several days in a row here and electricity usage for hot water was pretty close to zero.  Hopefully, we'll see the electricity usage on these Mitsubishi's go to zero soon with warmer temperatures, more daylight hours and fewer clouds.

The Zehnder HRV used more electricity than expected in Jan and Feb, with costs of $20 and $17 respectively. It turns out that there is a resistance coil to keep the unit from freezing when outdoor temperatures get very low that draws electricity relatively frequently.  When temperatures are above freezing the HRV should cost $7/month to run.

On the hot water front, I'm very pleased with the performance of the DIY system I built from the design on Gary Reysa's www.builditsolar.com website.  Running the supplemental/backup on-demand Stiebel Eltron Tempra 24 Plus heater cost $10 in January and $7 in February.  I estimate that our family of 4 uses about 75 gallons a day of hot water.  I expect electricity usage here to also approach zero soon as we transition into spring and summer.

In January we used $76 worth of electricity for heat and hot water and in February we used $65 worth.  The great thing about using this little electricity for these two major energy categories is that it means that the solar electric panels we have on the roof should be able to provide all the electricity that we use in the house over the course of a year.

"We're Rolling"

Tuesday 1/29/13

Well, today a film crew from the CT Zero Energy Challenge came to video document OCPH. They are actually filming me right now. Camera over my left shoulder showing me diligently working on my Blog. Riveting b-roll footage.



The video cast and crew

Thursday 1/31/13

For the video Paul and I were asked questions about our process of deciding to build an ultra energy efficient house and how we went about making it a reality. Also on hand to answer questions were Jamie Wolf of Wolfworks, the designer of our home, and Peter Harding of Home Energy Technologies, our HERS rater. More about our HERS rating in another post. For a primer on what a HERS rating is, peek at Peter Harding's website. The film will be posted on the CT Zero Energy Challenge website soon.

Icicles on the rain chain

Life in OCPH

Last week we had an arctic weather blast. I awoke to low single digit temps every morning. Along with the arctic air came bright clear skies and our PV and Thermal Solar Systems were cookin'!  When the sun came streaming into the windows at about 10:00am the passive solar gains warmed our house to 72 degrees. With the thermostat set to 68, our small supplemental heat pump got a daytime break even though the outdoor temps remained in the teens and low twenties. Paul's solar hot water system was really cookin'. The panel heated up to 180 degrees and the tank temp rose to a simmering 147 degrees. In this case our anti-scald mix valve was a good thing.

Three weeks ago Paul installed energy usage monitoring software called E-Monitor which gives us an hourly breakdown of the energy consumption of our different systems (heating/cooling, mechanical ventilation, lighting, entertainment systems, kitchen, etc.) We are starting to compile data and recognize usage patterns which help us further minimize our energy consumption. It will take an entire year to get the complete story of our energy usage.



Sunrise through our screen porch


One of the questions we were asked during the video interview was "What motivated you to build this type of home?"  90 minutes of footage will be edited down to a 3-4 minute video. I am going to take advantage of this platform to add to my answer.

Paul and I first learned about Passive House from an article we read in the New York Times in 2008. We thought it made so much sense. The concept of Passive House solved many of the gripes we had about our current domicile which was drafty and dark with uneven temperatures throughout the house. We paid too much for heating fuel and electricity and I have kids with indoor dust allergies. Passive House addressed all of those issues. A couple of years later we started to plan for a move in 2012. There were many beautiful houses on the market. I saw several listings in great communities in move-in condition at a good price. The problem was I knew about Passive House. My home search was steered by the fact that I knew the possibilities that existed in Passive House and I lost my appetite for the gorgeous houses already on the market. It was a strange phenomenon when it occured, like loosing your taste for chocolate. That is when I sought out Jamie and Wolfworks. Turns out my real dream home is ultra energy efficient and environmentally responsible. It also has a condensing dryer and a stainless steel apron front sink.

My first 100% Solar Heated Shower

My Beautiful Master Bathroom

I just took the best shower ever! Please allow me to explain. Paul has been puting the finishing touches on the Solar Domestic Hot Water system he built. The last few details included securing the heat exchange coil inside the tank and insulating the outside of the tank. We have been getting some great numbers with the collector (solar panel) reaching temperatures of up to 156 degrees and the tank reaching 106 degrees uninsulated. We held off on insulating the tank until we saw that all the components worked consistently and there were no leaks. The system has been inline and producing hot water for a couple of weeks but the uninsulated tank was allowing most of the heat to escape, effectively heating our mechanical room. This required us to rely on the hot water on demand backup system to heat the water to the desired 111 degrees. Today Paul put 3 of the 5.5 inches of polyiso insulation onto the outside of the tank. Just that much allowed the tank to retain so much more heat that I was able to for the first time switch off the breaker for the on demand water heater and take a purely solar hot shower.

Copper pipes hold the coil in place in the tank

Paul seals the pipe penetrations in the tank

The well water comes into the house at about 50 degrees and first runs through the drain water heat recovery coil. As I shower, the heat from the water I am using is transferred to the incoming well water. We are solar-heating the water and then recycling the heat through the drain water heat recovery pipe. Then the water makes its way to to the heat exchanger coil inside the tank at about 85 degrees. It takes 5 minutes for the water to run all the way through the 300 feet of PEX tubing of the exchanger, all the while absorbing heat from the tank. Today the tank temperature was at 115.5 degrees. The water was nice and hot for my entire 7.5 minute shower. (It takes a while to rinse and repeat with my long hair)  Mind you today was a 40 degree mid winter day with only about 4 hours of good sun. We anticipate that during the longer days of the year, Paul's DIY DHW system should provide 100% of our hot water needs.

The Insulated Tank

The good news keeps coming at OCPH. Although it is not published on their website yet, we received a heads up phone call a couple of weeks ago from the 2012 CT Zero Energy Challenge.Apparently we are the 2012 Overall Winner as well as winner of 3 of the 4 sub categories. Once again, a huge thank you to Jamie and everyone at Wolfworks for helping us realize our vision of building an amazing energy efficient home that we love to live in. Jamie beat me to the punch and wrote a post in his own blog about this accomplishment.

Building OCPH gave us the opportunity to walk the walk and be responsible energy consumers. We are certainly not the most earthy crunchy people you will ever meet but we care about the environment and are mindful of our personal impact upon it. We chose to build a house that we could live with, as well as live in. It would have felt wrong to do it any other way.

It's Official!

Today we received official word that we have achieved Passive House standard which makes us a Certified Passive House. This has been the keystone of our goals as we set out on this adventure to build our dream home. Our Certification is from the Passive House Academy which is accredited by the Passivhaus Institut in Germany. To learn more about the Passive House standard you can explore the above link or rewind to Paul's blog entry from April 28, 2012. I would like to thank Jamie Wolf, designer, and Janet Downey, builder, and all of the cast and crew who have made this moment possible. I apologize for divulging into my Oscar fantasy but honestly, we are really grateful for your creativity and expertise.

What else is new? Paul has been busy completing his solar thermal hot water system. It is currently up and running. All of the plumbing is connected and the domestic hot water is running through the system. After about two weeks of partial system testing, final waterproofing of the home made 220 gallon tank, and modifying plumbing fittings to control water flow and air bubbles in the pipes, the system is online and contributing to the heating of the domestic hot water. With the cold temps outside and the days being the shortest of the year at the winter solstice, the thermal gains we are achieving with the system are significant. In the warmer weather and longer days we might produce close to 100% solar thermal hot water. Yes, I just made that prediction publicly. (knock on wood) Paul will write a post soon to describe in detail the system he built and post some stats on the DHW production.

Painting with special solar absorbent paint

Installing the glazing

The exchange coil in the tank

The system is running

What have I been up to? Well, I have been decorating and hanging art and family photos which, in a different way, is also contributing to the warmth of of the house . I have also completed my part of the wonderful custom staircase, the centerpiece of our home. I had the pleasure of designing the pattern for and hand lacing the rail guard with 700 feet of galvanized stainless steel cable. The skin on my hands in growing back and the railing looks great.

Another favorite design feature is the George Nelson mid-century modern bubble lamps that float in our dining room's vaulted ceiling. I love their timeless style and the soft light they cast.

 

Other favorite nooks include my kitchen cook book shelf.

Artwork by Andrea Cutler

We are blessed with many friends and family members who are artists including Paul's mom Gloria Honig whose work is displayed throughout the house.

Artwork by Gloria Honig

 

 

As we get into the colder weather we will truly experience the function of OCPH.  Meanwhile, we plan to enjoy the holiday season and warm our home with friends and family, literally.

Happy Holidays Everyone!

Life in OCPH, so far...

First impressions

It has been about 2 weeks since move in day. A whirlwind of activity has my head still spinning but the initial verdict is in. I LOVE MY NEW HOUSE! It is super quiet. I've been sleeping like a rock. The walls are so thick, you hear no outside noise. Good riddance to my old weekly 5 am garbage truck wake up call. We have been experimenting with the temperature in the house. We had our first snow storm two days ago. Our supplemental heat system is a heat pump that supplies both heating and cooling seasonally. Even with sub freezing temps outside, if I don't turn on the heat, the indoor temperature settles at about 66 degrees by morning. On a sunny day the house heats up by solar gains alone to about 71 degrees. Yesterday was cloudy so last night I set the thermostat at 68 degrees and the house is really comfortable this morning. I'm going to turn off the heat pump now. As the sun rises on this sunny day, the house should stay warm through tonight. Now you may think 68 degrees is a little lower than you set your thermostat but let me say something else about Passive House. The house feels warmer because there are no drafts or cold spots and the wood floor feels the same temperature as the air. The ERV (energy recovery ventilation) circulates the heat evenly in the house so it's a warm 68 degrees. It's kind of like Arizona being a cool 100 degrees because it's a "dry heat".

What have we been up to

Paul has been working hard to finish up his DIY solar hot water system. With all the other tasks required to ready the house for move in, closets (woodwork, flooring, not to mention packing and moving) the solar water system was temporarily sidelined. Back on track, Paul has completed soldering the copper piping that sits in the collector panel and we moved it into the frame on the back of the garage. The collector (solar panel) will sit in a sunny spot against the back of the garage where the pipes have a short run down into the basement to the tank containing the heat exchanger coil.

We mounted the copper piping to the insulated frame and wrapped aluminum fins over the top of each pipe creating a conductive contact to collect and transfer solar heat into the water filled pipes. Paul used special clamps to crimp a good contact while he secured the fins with screws. The next step has been slightly foiled by the weather. Next he has to paint the fins with a special solar absorbent black paint that requires a minimum warm temperature for application. Although there is still snow on the ground, It is supposed to warm up to the 60s in the next few days so we will strike while the aluminum is hot.



Wednesday afternoon

Thursday sunset
 

My goal is still to have most of the detailed finishing work in the interior finished in time for Thanksgiving. It still seems like we are on track and will be ready for turkey day. I have so much to be thankful for this year. Most of all my family.

We Are In

We did it. Our move went well and we have been residents of OCPH for 4 days now. We are still unpacking and finishing constriction details but we are so glad to be here. And just in time for hurricane Sandy to blow through. School has already been canceled for tomorrow and they are predicting downed trees and power outages. Unfortunately one of the details left to be finished is the installation of our back up generator. Ironic. I'm still happy to be here. I'll post more later about Passive House life. For now, here are some photos of the new digs.

Good luck to everyone during the storm. Stay safe.