Why Did We Choose to Build a Passive House?Before I get into the "what" and "how" of our Passive House construction project, I think I should first discuss the "why?"
Truth be told, nearly two years ago when my wife, Lisa, and I decided to build our "dream house" I never had even heard of the term "Passive House" nor was I familiar with any other "green" building standards such as LEED or builder's challenge.
As it turned out, my wife--who operates a Pet Sitting business--had a client, named Jackie O'Neil, who built an extremely energy efficient home which was the first LEED Gold home in the US. Her home is classified as a net zero energy building (ZEB)--that is one that generates as much energy (ie; electricity) as it consumes.
The characteristics of the home are that it is well insulated, has a high degree of air-tightness, utilizes passive solar heat-gains during the winter while minimizing them in the summer, uses mechanical ventilation, and incorporates a grid-tie photo-voltaic (PV) system to generate electricity onsite whose excess generation capacity is sold back to the electric company, in a net metering configuration.
Although I had never seen the home or yet had the pleasure of getting to know Jackie, Lisa had shared with me her fascination with the home. So, on a couple of occasions I went along as she pet-sitted Jackie's four-legged companions and I, too, was intrigued by the unique design and the "positive feeling" of her home.
The timing for this couldn't have been better as Lisa and I were at the very earliest stages of conceiving what kind of home we wanted to build. Fortunately for us, Jackie was a most gracious hostess who allowed Lisa and I a close look at what she had achieved.
Having an engineering background, I was most impressed with the design elements of Jackie's home and the attention to every conceivable design detail and sensitivity to the environmental impact of its construction.
Having expressed an interest in building something similar, Jackie graciously offered her time to educate us in the (economic and quality-of-life) benefits of living in such a house. It was Jackie who introduced me to the concepts of passive solar heat generation, SIP construction, and mechanical ventilation, along with other energy efficient designs. Had it not been for Jackie's inspiring accomplishment (including building a second similar home for her sister), Lisa and I would have ended up building a conventional (energy inefficient) home.
What became one of the key driving forces in our project, was my desire to build a house that required little energy and would be inexpensive to heat and cool. Jackie had prepared a spreadsheet demonstrating the projected costs savings of many years, taking the long-term view.. And that spreadsheet was very compelling, indeed.
Key driving force #1: Long-term financial payback and near-term cash flow benefits
So I ran some calculations myself and came up with the following conclusion.
Taking into consideration the walkout basement of about 2300SF that total conditioned space in the house would be about 6700SF of treated floor space (TFA). Since the home was to be built in the North East that is predominately a heat loading environment, we figured a conventionally built home would require upwards of 8-10 tons of heating and/or cooling capacity (120,000 Btu).
Given the high cost of electricity in our area, we expected a total energy bill of about $8000 annually. And this would be with after-tax money. I figured by reducing our yearly heating and cooling demand by 90% we could potentially save about $7200 annually at current electricity rates. We also figured that the savings would improve as energy rates would only increase over time.
I assumed, being the first home that I designed and constructed that I was willing to tolerate an increased cost of the home could be as much as 30% more than the cost of conventional construction. As an example. let's assume the cost of construction for the "sticks and bricks" was projected to be somewhere in the neighborhood of $400,000 for a 4400 SF home, the additional costs for a PH design, could be as much as $120,000. Financing that additional cost over a 30-year period period, at a mortgage rate of 5% at the time we started building (in 2010), would amount to an increased monthly cost of the mortgage of nearly $650.
Since the interest expenses are front-loaded with the amortization schedule, we would benefit from being able to deduct the vast majority of our monthly P&I. So, beyond any "payback" over the years of ownership, I considered an immediate net improvement of cash-flow with the effective rate of return of our home investment to be greater than rates of return for other "safe investments," such as U.S treasuries or bank CDs.
Key driving force #2: Desire to Push the Outside of the Envelope
In the simplest terms, I wanted our construction project to be the equivalent of "walking on the moon." I wanted to explore what was actually possible using today's technology along with some of the sharpest minds out there.
I wanted to set an example for others, as Jackie did for us--knowing full well that I was very likely going to make mistakes that would add additional unforeseen construction costs, given that this was not only my first construction project, but one that had such ambitious objectives. I believe the "cost" of this education may potentially pay future dividends if I chose to build similar homes in the future as a "green" business.
In Europe, where the standard was originated by Dr. Wolfgang Feist of the Passivhaus Institut (PHI), there a scores of thousands of single-family homes, apartments, and commercial building conforming to the PH standard, with Germany (in particular) along with other European countries developing the most ambitious energy building standards the world has known.
Key driving force #3: Lead by Example
I wanted our home to be a luxury home--one that appeared like any other home (for the most part) and one that the energy efficiency design elements would be unseen by the untrained eye. I had seen other designs of passive houses and while I appreciated the concept of "form follows function," but I believe to encourage others to build energy efficient homes and to contribute to making them "mainstream" in the U.S. that such designs need to be aesthetically pleasing. Given the world-wide "glut" of new home construction, I figured that the new differentiator between new homes can and should be lower cost of ownership (through significant savings of energy consumption).
I believe, given the choice of purchasing one of two similarly appearing homes of equal or near-equal cost, that a prospective homeowner would choose the more energy efficient home. To me, it is a no-brainer. Since the increased construction costs of zero-energy homes in Europe have become essentially nil, I believe this is entirely possible here.
It is high-time that the U.S step up to the plate of energy and environmental good stewardship!
It doesn't matter what your views are of the environmental issues of our day--if long-term "global warming" is actually occurring and if it is, that it is a response to human activity, or if we can actually do anything to alter long-term climate change.
What matters is that it is the right thing to do, in any event! And I will take it one step further: energy independence and sustainability, I believe, are essential matters of national security!
If more and more building in the U.S would be built (or retrofitted) to save energy, we would reduce our disproportionate consumption of energy while becoming a better steward of our environment...I wanted to be a force for a positive change!
Key driving force #4: Historical Connection to 70's ZEB Design
Considering the alternative to LEED's requirements or Builder's Challenge.
At the outset, we had considered building our home to conform to LEED's building approaches and in fact, our home's location was close to another energy-efficiency first in Pennsylvania, the first LEED Platinum house in Limerick, Montgomery County, PA.
I think it very special that both LEED Gold and LEED Platinum homes are within several miles of each other! And when our home was completed, we added a Passive House to this distinguished list...all in a five mile radius! Pennsylvania is the Keystone state.
Having assembled a team of individuals who provided us with some rudimentary LEED building-design principles, we were inclined to build this way. Several weeks later, however, I talked with a builder, who had mentioned the term Passive House.
As an engineer, I immediately researched the topic and was attracted to this approach. The PassivHaus standard is merely one consisting of a few (key) energy performance requirements. It doesn't specify or mandate a path on how to actually achieve them--leaving the home builder with a vast array of choices. This has its good points and potentially "bad" points (for those unfamiliar with the approaches that work.)
While LEED provides a building "checklist" and awards "points" toward LEED certification, Passive House does not. It is purely a building performance standard, in fact, the most aggressive and hard to achieve standard yet developed.
Closely examining the Limerick house, I learned that the home employed double-hung windows, one of the most energy inefficient window designs. Additionally it employed a lot of mechanical systems, such as four heat pumps, including a geothermal unit.
While the home is certainly a very impressive accomplishment, to be sure, the Passive House approach appealed to me more. In my opinion, the best systems are no systems. And Passive House, by its very nature, encourages building that eliminates or reduces the need for active systems. For example, heating and cooling system capacities can be significantly reduced--to the point that the need for geothermal systems may be eliminated for smaller more "elegant" (simple) systems.
I recalled during my time as an undergraduate of Rensselaer Polytechnic Institute, some thirty years ago, that an administrative building was built to use only passive heating in the cold climate of upstate New York and that the original impetus for designing "zero energy" buildings occurred during the 1970s, in the wake of the oil crisis. Unfortunately that "movement" was short-lived as energy prices returned to normal after the crisis abated.
Key driving force #5: Occupant Comfort & Health
My research of PassivHaus construction are such homes are far more comfortable to live in than a conventionally built home.
House temperatures tend to be extremely consistent from room to room, floor to floor--there is little or no "stacking" that occurs. Breathable air quality is also purported to be noticeably better as well. In other words, a Passive House just feels better to live in. (I recall Jackie's home, mentioned earlier in our blog).
Key driving force #6: Independence from Public Infrastructure
Ever since 9/11, in particular, and other world catastrophic events--man made and natural--since that time, I have thought about issues of national security as well as individual security.
I believe as our societies evolve as more inter-connected and hence inter-dependent, the systemic systems that enable this become even more critical (and vulnerable) to perturbation and as such, individuals that rely on such infrastructure, are becoming increasingly vulnerable.
In light of this new reality, I wanted to help ensure my wife's and I security and independence from reliance on these systems as much as possible.
Fortunately for us, we have an onsite well and septic system, which provides a level of independence from municipal water and sewer systems.
By building a Passive House, I hope to minimize impact, in the event of a systemic failure of the electrical grid. Since such a home has far less demand requirements for electricity than a conventional home, I believe this is achievable. If we were to include a grid-tie system that can be disconnected from the grid, we should be able to generate enough power to supply our needs without the reliance of an electrical utility.
Lisa and I are also expecting to harvest some of our own fruits and vegetables, as well.
So, the choice was obvious for me, Passive House was the way to go. Ultimately, I believe, the most compelling designs for the future will incorporate the most sensible elements of each of the "green" building standards. At this point in time, the PH standard has yet to be recognized by our government agencies as a viable standard, at least to the extent that LEED is. But, I hope this will change in time.
To put the PH movement in the U.S. in its proper context, PHI only recognizes a handful of homes as conforming to their standard compared to the many thousands of certified LEED projects. Clearly, there is work to be done on this front, but like any grassroots project, it can done brick by brick--one home at a time.