Passive House design relies on a set of integrated design principles. Each element of the design is precisely quantified and entered into a modeling program we are trained to use called the Passive House Planning Package (PHPP). The result calculates and establishes the building’s “energy balance.” The energy balance is the relationship between the energy “losses” thru transmission (the building structure and, windows) and ventilation (minimized air leakage, the fresh air system), the free “gains” from windows and people and equipment in the building, and the final fraction of heating and cooling to make up the modest difference. This is the secret sauce that produces the buildings remarkable performance and all the benefits that come it.

Here’s an overview of the design and construction principles that this home depends on, guided by the analysis provided by the PHPP:

FORM AND ORIENTATION The house is a simple two story 28′ x 44′ rectangular form to assure an optimum surface to volume ratio to conserve energy (a coffee cup rather than a soup bowl!). The building is oriented 14 degrees from true south to relate to desired site features while allowing the south facing windows to capture solar energy. The garage and front porch are skewed 15 degrees to add architectural interest and there is a screen porch to the east; each of these features are deliberately separated from the buildings thermal envelope.

SUPER INSULATION The insulation levels of walls, ceiling and foundation are tuned to the local climate to levels that assure a stable, draft free interior without noticeably cold wall or window surfaces while minimizing transmission losses (this has a lot to do with THERMAL COMFORT). This home is built with a “sandwich wall”: a double stud 12″ wall with dense pack cellulose in the two 2×4, 24″ on center exterior walls and foam panels in the 5″ center (think one cup inside another).

THERMAL BRIDGE FREE CONSTRUCTION Careful attention to construction details is required to assure that energy is not transferred thru building materials via “thermal bridges” (think cup holder).  Wall junctions at corners, floors, and roofs are calculated to assure they are not bleeding energy.

AIR TIGHT CONSTRUCTION Rigorous attention to the sealing of all potential sources of air leakage in the building and intermediate testing to remediate any leakage discovered during construction allow us to gain control of these potential ventilation losses – an essential component of our “energy balance” equation. Like a lid on a coffee cup, and unlike the way many homes are built, precious energy is not lost thru leakage.

NET-GAIN HIGH PERFORMANCE WINDOWS Triple glazed Tilt-Turn windows from Germany assure that the net performance of all the windows is gaining more energy than they are losing on an annual basis. Windows are sized and located to achieve gains from the south and minimize losses to the north, east, and west. In a sense, the windows are providing some of the energy we have traditionally depended on our mechanical system to provide. Shading is carefully designed into the architecture to protect against overheating. Sorry, my coffee cup metaphor comes up short regarding the contribution windows make!

BALANCED VENTILATION While less efficient homes get by with the natural leakage in their construction, homes this tight benefit from the control of constant fresh air provided by a highly efficient Zehnder heat recovery ventilation system. While natural ventilation is uncontrolled and is the source of considerable heat loss, this balanced system recovers most of the heat from the steady and balanced flow of air it is designed to regulate, allowing the home to constantly breathe. This is one source of a Passive House’s dependable comfort and healthy indoor environment.

AIR SOURCE HEAT PUMPS The peak heat load for this house could be served with about 12′ of electric baseboard heat (or maybe two hair dryers). To have the option of cooling we are using Mitsubishi ducted mini-split air source heat pumps. Regular electric heat provides one unit of output for each unit of input – a watt for a watt (like a see-saw).  If we shift the center of that see-saw a kid can lift an adult, in other words one unit (input) can lift several more units (output). We call this factor the coefficient of performance (COP) and our heat pump has a COP of appx. 2.5 – for each watt we consume we get 2.5 watts out. We are using energy more effectively. In addition, the fans use efficient motors that move the air run smoothly from low to high, not just one on/off level (imagine trying to drive a car like that).

DOMESTIC HOT WATER While all the strategies we employ to reduce the energy demand for the house dramatically reduce the heat load, providing hot water for the family becomes an increasingly large proportion of our energy use. We entertained many of the strategies for providing hot water efficiently including solar thermal(drainback), heat pump water heaters, tankless systems, and even a heat exchanger using the existing well (not deep enough). Our client became intrigued with the design of a DIY system using a large storage tank, a coil of PEX tubing for heat exchange, and electric tankless backup. He is also planning on constructing his own collector to be located behind the garage. Sorta old school! Another strategy we plan to employ is a drainwater heat recovery system which uses the hot water coming down the drain from showers to pre heat the hot water being created so serve the shower.

LIGHTING AND PLUG LOADS House lighting will use LED and CFL light sources in nearly all the fixtures. The most energy efficient appliances have been selected, including an induction range. The rest comes down to the client’s use of TV’s and computers and other plug in devices and how they are able to moderate the use of those devices.

PHOTOVOLTAIC SYSTEM On the main roof of the house we will be installing a 10.4 Killowatt array of photovoltaic modules that will allow the home to produce as much energy as it consumes – including the anticipated use of an electric vehicle! This positions this project to be a strong competitor in the Zero Energy Challenge sponsored by the Connecticut Energy Efficiency Fund.

SEE PASSIVE HOUSE PRINCIPLES IN A FAMILIAR FORM (click bottom right to see full screen)

It’s said that “There’s no such thing as a zero-energy home — just zero-energy homeowners.” It’s also said that “there is no accounting for human behavior,” but actually there is. Take a look at this graph of actual energy use in buildings designed to use very little energy.

You’d think that people who choose to live in these homes would use their remarkable design to use the little energy they were designed for. Instead people use up to 50% more AND as little as 50% less than that. The curves in these graphs appear over and over when these studies are done in all kinds of buildings. Why is that?

This is actually a whole field of study, not just about energy in buildings but for health, fitness, travel, even hotel laundry – anything where people make choices. And in each case patterns emerge that could be summed up as:

* People need to understand what they are using; so some form of monitoring helps reveal that
* People need to recognize their habits and behavior patterns; if you don’t notice you’re unlikely to change
* Once aware, it helps to have a plan, and even better to share that plan with your family or others
* It never hurts to have a prompt, something that reminds you to stay on your path
* If everyone else is doing it, it quickly becomes second nature to do it too. Cultural norms matter.
* The better the feedback, the better able you are to adjust (try filling a bathtub without being able to feel the temperature out of the faucet)

When it comes to energy in your home, a good place to begin is this do it yourself energy audit called the Home Energy Saver. Perhaps recognizing that YOU actually make more difference in how much energy your home uses than otherwise significant but less effective actions like replacing windows or caulking leaks (not that these shouldn’t be part of an overall energy saving portfolio) will motivate you to get aquainted with your energy use.

There are also a range of tools that fit different parts of the prescription for gaining leverage thru “good” behavior. Some of these attempt to provide direct and immediate feedback, along with long range analysis to show how you are doing over time. These “energy dashboards” are sort of like having a coach or teacher tracking your progress.

At the other end of the spectrum are the things we know but have forgotten. Things as simple as turning off the lights or hanging clothes to dry outside. Some of these may be new habits to learn while others require planning and observation. Like the transition to eating clean whole foods or establishing a regimen that keeps our body fit and flexible, you start where you are and, determined to make a difference, head forward one choice at a time.

This wonderful video pretty much sums it up:

A few weeks before most of Connecticut lost power last October I was sitting in my car waiting to turn into our office when I heard screeching tires behind me and looked up in time to see a car who hadn’t seen me, smash into me, pushing me into the car I was waiting behind. I was stunned, but not physically injured (seat belt), and only in the days that followed did I come to learn how a trauma like this would subtly effect me in the months to come as I slowly recovered (I was ultimately diagnosed as having a concussion).

In that October storm we all lived thru a seismic change in our daily lives and most of us developed a profound new understanding and appreciation for the role that readily available energy plays in our daily lives. I joined the digital refugees, hunting down libraries or coffee shops where we could charge our phones and computers and get a working WiFi connection to check our email – then home to sleep in the cold dark house. This uninvited event drew people together even as it unsettled our lives. It revealed surprising lessons about what truly matters.

Two days before my father Arthur’s 88th Valentines Day birthday he died the comfortable death we all hope for: at the end of a long, full, and accomplished life, at home, safe and comfortable, without tubes or monitors, and with time to spend with those he loved. In the service we held to remember his life I recalled that the hole left is also a whole profoundly felt. As anyone who has experienced a loss knows, it settles into you on its own terms and what rises from it can be as rich as it is sad.

A week ago our dog Zeke was hit full on by a car in front of our house, nearly died, and is rather miraculously regaining his body functions, including the repair of a nasty leg fracture and neurologic damage that will only slowly return the use of his limbs. Worrying about him, his chance for recovery, and now patiently nursing him to health is providing a visceral relationship with the trauma he endured and the body’s ability to heal.

Nearly three years ago, along with the rest of the housing industry, Wolfworks had to confront a market that could not support our staff and overhead – there was no work. We had some design work, but it progressed cautiously and it was nearly a year before we were building again. Needless to say, as it was for all in our industry, this was challenging.

Trauma, by definition, is the result of some unexpected force that upsets our familiar relationships with the world, the body, the home, the community, the business we live with and in. In time we recover, but to what? Recent studies reveal this surprising answer: Growth: Personal. Professional. Family. Community.

And this idea comes with what I think is a useful name: Post Traumatic Growth! We adapt. And we grow.

Post traumatic growth demonstrates the resilience of the body, the spirit, the people, and the communities that experience seismic changes in some dimension of their once familiar world. Across this spectrum, as often as not, the trauma makes way for something new to emerge that can be fuller, richer, deeper and more engaged than what preceded the event. Communities recovering from natural disasters, soldiers returning from war with lost limbs and lost comrades, and most immediately me and my dog recovering from car accidents, the loss of my father, and the changes in our industry; each offers the opportunity to respond to the event with a renewed sense of possibility and potential. I’m not saying its easy, far from it. Just that, as they say, “from the ashes…”

Wolfworks’ post traumatic growth took place as we quickly came to understand that how we design and build, and the guidance we provide to the clients we serve, needed to acknowledge not just the economic challenges we faced, but the environmental and cultural challenges we will experience as we face the end of cheap energy, the limits to non-renewable resources, and disturbances to ours climate.

The good news is that as we embraced this reality, as we grew and learned and changed, we realized that what we could design and build was remarkably better in nearly every way than what we knew before. The ways we know to build now are safer, simpler, healthier, more comfortable, durable, and are miserly in their use of energy. Best of all, we now know how to create homes that are contributing to the solution, rather than adding to the problem. So we have adapted and we have grown, and as a result of our “post traumatic growth” we are better equipped to guide you.

This winter nature did its own energy audit of our homes and produced striking graphs in the form of icicles hanging from our roof eaves. Of course I am talking about the ice dams you saw on houses everywhere this winter. It was interesting to “read” these graphs and try to understand just what they revealed about the ways our homes lose heat, which is exactly what an ice dam reveals.

The most immediate thing nature’s audit reveals is the weak edge where the wall meets the roof. When we see ice dams we know that this junction is not thick enough to have enough insulation to keep the roof cold. We insulate to slow the transfer of heat to cold – the more insulation, the slower the transfer and the longer we retain the heat where we want it – inside! Too little insulation and the heat leaves the building and warms the roof above the wall, melting the snow which freezes along the edge building up a “dam” that forces the melted snow back into the house.

Aggravating this condition is the concentration of wood across the top of the wall and where the frame of the ceiling and roof come together there. Lots of wood offers the heat in the building a “bridge” to the outside, again warming the roof and creating the conditions that form the ice dams. You can also see this effect when there is a dusting of snow on a roof and the outline of the (warm) rafters can be observed, another graph from nature’s energy audit. We call these “thermal bridges” and we have been building them into houses for hundreds of years.

Speaking of which, hundreds of years back houses weren’t kept warm enough for these conditions to occur. It was easy to identify unoccupied homes this winter because the snow sat like a pillow on the cold roof because there was little or no heat on inside. That or a frugal homeowner wearing a hat and sweaters! With mechanical heating systems we keep our homes warm enough and insulate and air seal them poorly enough to cause this problem.

Which brings us to this. Our homes are generally poorly air sealed, so that warm air inside the house is leaving it along these very same edges. Couple this with gaps inside our walls and warm light fixtures at our ceilings and we have unwittingly installed what is effectively a radiator to warm the roof and melt the snow.

With nature’s energy audit revealing the symptoms of this endemic problem in our homes how do we target our efforts to stop the waste that is causing the problem, or at the very least, prevent the leaks when these conditions occur. There are two actions to take. The best, though often the more difficult, is to eliminate air leakage and improve insulation and reduce thermal bridges. Probably the best way to do this is to add thickness to the roof, often a difficult or aesthetically challenging proposition. But it can be done and the benefit will be a more comfortable home that uses less energy.

The other action, which should be done on every home that cannot improve its insulation, is to install an impenetrable barrier beneath the roof shingles, usually referred to as “ice and water shield.” Any time you replace a roof this should be done, and may even be done 3-4 feet up a roof that may not need the whole roof replaced. This however, is a band aid. You will still be wasting energy and the ice dams will still form, it just won’t leak into the house.

While we still learn a lot from the diagnostic equipment available today, knowing how to read the clues that natural processes reveal can make it abundantly clear that our homes are not working.

Over time this stuff accrues. Our lives and needs change. We gain mates and raise families and try new styles and take on new activities and more stuff comes with each. And sooner or later the time comes to give or throw or store it all away. First to make way for more. Later to just be able to live with less.

I know this because I have visited hundreds of homes and been in their attics, basements, and garages, poked around their closets and cabinets, and helped people think about how to live in a better relationship with this river of stuff.

In his wonderful book “How Buildings Learn” Stewart Brand explains that our homes are nested in parts that exist at different rates of change. From the site (the most permanent) thru the skin, the structure, the services, and the space we arrive finally at the most transient – our stuff (he illustrates this nicely with photos of a room over time – run your own mental animation of a room you know!).

Sometimes it helps to just be aware of what is at work. Once aware, we can think about how to manage, if not control, this tide. In the difficult ordeal of dealing with several family estates I learned this valuable guidance from a helpful and experienced woman hired to help with the decision making (and that is the critical part).

• We would look at each item and decide:
• Do we keep this because it has a use or meaning?
• Do we give to someone we’d like to have it or who would use it?
• Is it worth trying to sell (auction, tag sale, ebay, etc.)?
• Can we donate it to a worthy cause?

…and if none of the above, we throw it away or recycle it.

If done before being stowed away for years, this simple exercise would clear most of the stuff that instead resides in most attics and basements. And then there is this example:

Our Resource Coordinator Janet was explaining her ten year old daughter’s quandary before a field trip to the Science Center last week. “Can I buy something at the gift shop she asked?” Janet said she could, but that she should look at the checklist before making a purchase with her own money. I asked Janet about this checklist, and she brought it in (printed on a business card so you can keep it with you):

• Do I already have something like this?
• Can I reuse of fix up my old ones?
• Can I rent one, borrow one, or share one with a friend?
• Is this made to last a long time?
• When I’m done with it, can I resue or recycle what’s left?
• Can I reuse or recycle the package it comes in?

What a good mom!

She also reminded her daughter that Christmas was coming and she might get something she liked as a gift. “Oh mom” she said, “I knew you would say that!”

She ended up coming home with a venus fly trap.

FOR MORE ON THE RELATIONSHIP BETWEEN OUR STUFF AND OUR WORLD

In this wintry season, who isn’t thinking about what’s required to be comfortable in our homes?

Not too hot and not too cold, the ability to provide thermal comfort is one of the most important functions of a building, which you might think of as your third “skin”. Optimal thermal comfort requires the heat loss of the human body to be in balance with its heat production. This is similar to the relationship between an activity (e.g. sleeping, running…) and clothes – our second skin.

The conditions that maintain this thermal balance in a building are:

• air temperature
• the temperature of the surrounding surfaces ( the “radiant temperature”)
• air speed and turbulence
• humidity of the air
• presence of dust in the air

To feel good, a range of combinations create a “comfort field” in which:

• the air is not too humid
• air speeds remain within established limits
• the difference between radiant and air temperature remains small
• the difference of the radiant temperature in different directions (between your body and adjacent surfaces) remains small
• room air temperature stratification between head and feet is small
• the percieved temperature varies less than 1.5°F within the living area
• the air is clean

Maintaining these conditions are the domain of two important building systems:

• the building envelope, which includes the walls, floors, and roof or ceilings that enclose the building, and any penetrations of that enclosure for doors, windows, chimneys, vents, etc. plus the accumulated air leakage created by gaps in the structure and;
• the mechanical systems that provide supplemental heating, sometimes cooling, and any controlled ventilation.

We have mostly built, and live and work in, buildings that favored control over these conditions thru the use of mechanical systems like boilers and furnaces. Due to an accumulation of shortcomings in the building envelope and mechanical system we are often required to tolerate conditions outside the comfort field. To overcome our discomfort we may rely on additional fans, heaters, humidifiers, etc. to establish a local comfort zone. Or we may put on a coat – or switch to shorts!

By making integrated improvements to the building envelope and mechanical systems we can provide a more dependable comfort field. These improvements allow us to acquire greater control over each of the factors that determine comfort. The effect, while scientifically quantifiable, is ultimately valued for its quality:

We can be considerably and consistently more comfortable in our homes.

WATCH THIS SLIDESHOW TO BETTER UNDERSTAND HOW THIS WORKS!

Choose “Menu” at the bottom left and select “Full Screen” to View the Show.

• Replacing your windows
• Weatherstripping and caulking
• Heating system replacements, tune ups, and filter changes
• Floor insulation or basement duct sealing
• Water heater replacements and tankless gas water heaters
• Small behavior changes: cleaning fridge coils, closing drapes at night, cooking with lids on pots, changing furnace filters frequently

After all, don’t ads and well meaning “green guides” recommend many of these actions and seem to suggest they offer big energy savings? Wouldn’t it be worthwhile to understand which actions were the most worthwhile, even if they aren’t so obvious or aggressively promoted?

Thanks to decades of research on tens of thousands of home energy retrofit projects across the country independent energy expert Michael Blasnik DOES know better. He has studied how much energy each of these actions actually saves and the answer is decidedly(and sometimes counterintuitively): not much!

So what does make a difference? Here’s what Michael knows (and we’d all do well to pay attention to). Notice there are no solar panels of expensive technology involved, just the proven actions that help us use less to begin with.

INSULATE

Adding or increasing insulation makes an important difference. The less there is to begin with, the greater the difference. The first place to insulate or add insulation, is the attic, then the walls, then the foundation. But insulation alone is not enough we also need to…

AIR SEAL

Our homes have lots of leaks. We lose lots of energy through these leaks. Though we imagine the leaks to be where we can feel them, like around doors and windows, the really important ones are generally in places we can’t see, so don’t think about. Air sealing in attics (around pipes, chimneys, gaps in framing, etc.) and along the edge where your house sits on its foundation can be the most important and effective places to seal. As Michael says, “effective air sealing is often the largest unexploited savings.”

THERMOSTATS

When we’re not at home it can make a meaningful difference to manage the temperature in our absence, a few degrees cooler in heating season or warmer when cooling can add up without any impact on our comfort. Learn to use a setback thermostat. If you don’t have one, install one.

DUCTWORK IN ATTICS OR CRAWLSPACES

If your home has ductwork and it runs through spaces that are closer to outside temperature than inside, sealing them so they are not leaking air and insulating them so they do not lose the energy they are transferring makes an important difference.

OLD HEATING SYSTEM REPLACEMENT

If you have an old system that has a low efficiency and is being replaced with a new high efficiency system the difference does matter. No matter what, always choose a high efficiency system, and do all you can to reduce the amount of energy it will need to provide by insulating and air sealing first. In the energy world, we always advise: “Reduce, then Produce.”

HOT WATER

Understanding that things that need to be heated use the most energy, determine how to use less hot water. Fix leaks (this makes a BIG difference). Use the most efficient clothes and dishwashers, and use cycles that work with cold water.  Use low flow showerheads.

USE LESS ELECTRICITY

Replace (and don’t save) an inefficient refrigerator or dryer. Wherever possible use fluorescent of LED lighting. Use motion detectors or a timer for outside lighting. Unplug stuff that draws energy when not in use (use plug strips). Try a clothes line. I advocate getting a power monitor so you can see how much energy your house is using at any given time. You’ll notice that lights are left on (I know, you think you turn them off but this tells the tale) or the difference it makes when equipment is disconnected, and hopefully so will the whole family.

Like any diet – and let’s face it, we could all use to lose less energy – its important to know which actions will actually make a difference in reaching our goal. Thanks to Michael’s dedication to understanding how our homes really use energy we can focus our attention where it matters most.

Visit our PRODUCTS page to see some of the tools available to manage each of these domains of household energy use.

Over time we have found ways to thicken that layer of protection. We count on that protective boundary to contain the heat our bodies generate. We build fires next, in pits first and fireplaces next and ultimately in boilers and furnaces. Understanding the effort it takes to gather and fuel that fire, or to pay to sustain it, we gain interest in preserving the effect; in sustaining the comfort we derive as long as possible, with less effort to gather the fuel – or pay for it.

The thickness of that shell, the thermal boundary that we rely on to contain the heat, has been growing slowly over the course of my building career. Following generations of hollow walls, filling that narrow framework with insulation became standard practice. In the eighties we began increasing the thickness of the walls by two inches; an idea that was considered radical at first eventually became the norm.

We now face energy and environmental realities that require us to treat our ration of energy with much greater reverence. The age of abundant cheap energy is nearing its end. Fortunately we have a provocatively simple option. Thicken the walls and use dramatically less energy to provide what turns out to be substantially better comfort.

Here’s why.

Not only do thicker walls with more insulation require substantially less energy to provide comfort, when we take equal care to reduce air leakage the investment we make in heating that space is not suddenly exhausted thru what have historically been hundreds of air leaks in the typical home.

Thick walls, constructed without leaks, end up producing a home that is not only more energy efficient, it is healthier, more durable, comfortable, and stable than any home we have ever lived in.

How great is that!

1 1/2" thick, this "Economy" Insulation once offered false hope of saving energy

We’re working on a house that had this “economy” insulation in its walls. Measuring an inch and a half in thickness, this insulation was doing next to nothing to preserve energy or provide comfort in this home. In the course of a remodel that is now underway we have turned the tide. We have “thickened” the building envelope in every way we know how, and we expect this home to use half the energy it once did as a result. We’re saving energy. Inch by inch!