We particularly enjoy these types of questions, read on for the questions and answers.

[From the client]

“I hope this is not too premature.  We have been looking at kitchen
appliances and plumbing fixtures.  We are starting to figure out what
we want and don’t want and are narrowing our choices down.  Some
technical questions have come up that depending on the answers could
direct us in different directions.”

Q. We prefer cooking with gas and know that gas produces moisture.  How would this affect the air environment of a passive house?

A. Cooking with gas works just fine in a PH.  The act of passing the fresh incoming air across the heat exchanger within our Heat Recovery Ventilation (HRV) system tends to reduce the relative humidity level in the home.  There is a small pipe at the bottom of the HRV that delivers condensation water to a drain.

In some climates, this drying effect is actually a problem, and in those cases we would choose an Energy Recovery Ventilation (ERV) system instead of an HRV.  ERV’s manage humidity in addition to performing the heat exchange function of an HRV.  However, in the pacific northwest, the ambient humidity and the action of the HRV act together to keep the indoor relative humidity at a level that is recommended for humans.  Because enough air to completely fill the house is brought into the home through the HRV every three hours or so, cooking with gas has little impact.

Q.  Cooking with either gas or electric produces lots of heat as well. In a passive house how comfortable will the kitchen be in the summer?

A. In a regular house, when it comes to dealing with cooking heat during the summer months, you can open windows and doors as needed.  That’s what you will do in a passive house as well.  Additionally, you can turn the HRV up to the high setting, using a booster switch that will be installed in your kitchen.  This will bring fresh air into the entire house as needed.

If it is too hot outside to gain some relief by opening windows or running the HRV, you will be no worse off than you would be in any house.  But living in a PH reduces the effect of high outdoor temperatures during those hot afternoons.  In the summer, you can open things up at night and close them up during the day.  Because the home is super-insulated, chances are that your home will be cooler than the house next door is on a summer afternoon.  There will be days when you are enjoying your indoor temps and you don’t want to cook indoors and warm things up.  But in a PH, you will have a better chance of avoiding having this be the case.

Q.  Today we were introduced to the idea of induction cooking stove tops as a way to reduce the problems of moisture and heat. Do you have any thoughts on this?  We are both not drawn to that style of cooking, but thought maybe we should consider it.

A. Some of our PH owners selected the induction cooktops.  They are pretty neat!  If you are attracted to the low energy use, fast cooking times, and the fact that the surface of the cooktop does not really get hot, an induction cooktop may be for you.

Some of our PH owners cook with gas. They have reported no issues specific to this approach.  So, don’t avoid gas cooking if that’s what your prefer.

Q.  When we were at Albert Lee in Tacoma we discussed the concept of recirculating vent hoods like you showed us in the two houses we viewed with you.  The salesman there gave us the low down on them and seem to be not as efficient at removing the heat, moisture, smells, grease as a regular vent hood that exhausts to the outside.  We have concerns about this technology and would like to understand better how the heat exchanger is going to take care of the recirculated air from such a vent hood?

A. I think it’s generally true that a recirculating range hood will not be as effective as one that is vented to the outside of the home.  But when you have an HRV in your home, this is not a problem.  The range hood is there to collect heavy steam and the grease that is in the air right above the cooktop.  The HRV deals with everything else – minor cooking smells, moderate increase in humidity, etc.

It’s important to remember that the HRV is is moving a lot of fresh air into the entire home, and that this approach works well.  Here is an analogy: If you have a pool in the yard that is full of water that is never cleaned, you will be really picky about keeping impurities out of the water.  But if the pool has a stream running into and out of it all the time, the flow of water from the stream will keep the water in the pool clean, even if impurities are introduced occasionally.  I hope this analogy applies for you!

Q.  Like wise we are still concerned about the amount of moisture released by showers and cooking and how this will be evacuated from the house.

A. We will install booster switches in the kitchen and the bathrooms that you can use to turn the ventilation system up to the high setting.

Summary:

Current ventilation code requires fans that are rated to remove 50 cubic feet per minute be installed in bathrooms.  In actual practice, most fans in bathrooms today don’t move the amount of air that they are rated for.  But we turn on those fans and they do the job if they are not too crummy!  The typical owner of a regular home never knows how much air is being moved by the exhaust fan.

When you buy a PH from The Artisans Group, after the home is completed, Randy and an experienced Engineer will show up to test the ventilation system.  We spend two hours, and use specialized equipment, to measure air flow at various flow settings on the HRV (low, medium, high, etc.)  We check the air flow at every single ventilation register in the home, and take the time to adjust the system until it is offering air flow rates that are consistent with our design goals for the home. After you are in the home, if something goes awry, or you don’t see the results that you want when you are cooking or showering, we will want to know about it!  We will come back and adjust things until everything is groovy.

[editors note] We received an email from a reader who made some noteworthy observations regarding the efficiency ratings of gas vs. induction cooking~40% to 85-95% respectfully. Also worth mentioning is gas is not a renewable resource. Good points!

That’s what I’m talkin’ about.

With help from the United States Energy Information Administration, we’ve calculated projections related to the cost of heating our latest Passive House project, Le Jardin located in West Olympia:

The cost of electricity used to heat this home is only $85 per year!

How is it possible to lower your heating bill this much? It’s pretty simple, really. Here is a list of how we do it:

1. Super Insulate your home. How much insulation is needed will vary with the exact climate where you are building.  We don’t want to buy and install insulation that is unnecessary.  But if the home is designed with a focus on insulating to the correct level to achieve really meaningful savings on your energy bill, investing in extra insulation will pay off very quickly.

2. Build with really good Doors and Windows. There are new and better windows coming onto the market all the time.  However, most windows that simply meet code are still poor performers, energy-wise.  These windows also tend to block the heat of the sun as they become better at insulating against heat loss.  The trick for homes in the Pacific Northwest is to select windows that have really high insulating values AND a high capacity to let the sun’s heat come through.  It sounds contrary, but modern window technology offers this magic mix – you just need to know what to ask for.

3. Use excellent Air Sealing techniques during construction of your home. Most homes that exist today are leaky!  New homes that meet current energy codes will be tighter.  But to really make an impact on your energy bill, you want a home that is built air-tight.  This level of air sealing is not expensive or difficult to achieve during the construction of a home.  But it does require exacting focus on the part of the home’s designers and builders.  Simply squirting caulk and spray foam into a typical home during construction will not get the job done!

4. Install a highly efficient ventilation system. Most homeowners pay their energy bills so they can heat their home, only to turn around and dump the air they just paid to heat outside each time they turn on an exhaust fan in the bathroom or kitchen.  Of course we need fresh and healthy air in our homes, but the money-saving move here is to ventilate your home with a small system that uses the warmth found in the stale air that is being exhausted, to heat the fresh air that is coming in.  Heat Recovery Ventilation systems or HRV’s have been around for a while, and the better systems will retain over 85% of the heat energy from stale air as it is exhausted from your home.  The best part of this approach is that homes which use good HRV’s have consistent temperatures throughout the whole house and always have excellent indoor air quality – quiet, constant circulation of clean air through good filters means that your entire home will be super comfortable and always feel fresh.

5. Most important:  use the Passive House Planning Package (PHPP) software when designing your home. If you simply target the above 1 through 4 without careful planning first, you can create a home that is unnecessarily expensive, and it may be uncomfortable to live in. We are trained to use the world’s best energy modeling software, the PHPP, in all of our work.  What this means to you is that we can do cost/benefit analyses to drive the cost of building your home down, while ensuring that your energy use will be fantastically low!  Best of all, we know your finished home will be unusually comfortable, even before we build it!

Performing these five steps will add up to very impressive savings! There will be no cash spent on large heating systems; and geothermal heat pumps or whole-house radiant floors are overkill with our homes. Exotic, complicated, and maintenance-heavy mechanical systems do not need to be purchased or installed to create an energy-efficient home.

Simple and effective, and comfortable for $1.63 per week. Nice!

References:

www.eia.gov

www.eia.doe.gov/neic/experts/heatcalc.xls

www.passivehouse.us/

[Reader Question]

My husband and I are considering building/remodeling a home in the next three years. The idea of a passive house appeals to us strongly. As we think about the future, we’re wondering whether a custom passive house is a realistic choice for our family.

Right now, our ideal would be a home around 1800-2300 square feet in the Seattle area. Our budget by then will be in the range of $500-600K for land and construction. Our question is whether we are out of our league, hoping to build a house of that size on that kind of budget.

More generally, what recommended reading would you suggest for people in our position, considering building in the somewhat-near future? Books, blogs or magazines about design, architecture, or green building? Any suggestions would be welcome.

Thank you for your time.

[Reply from Randy Foster, president | The Artisans Group]
Thanks so much for contacting us.  The brief answer to questions about the cost of a Passive House (PH) is that I think it is quite feasible to build a PH within the budget that you have described.  Of course, the big variable will be the cost of land.

The cost of a PH is not really that much higher than any other custom home.  The PH approach is based in spending money on the home’s thermal envelope (windows, insulation, doors, etc), and not spending money on heating and other energy-related systems that can be really expensive in other green approaches.  The cost increases and the savings largely cancel each other out.

The idea that I’m trying to highlight is that PH is a cost-conscious way to design and build a home.  I did not arrive at building Passive Houses through my sensibilities as an environmentalist. Though, this method is good for the environment and for society as well, which are huge bonuses.  But my earliest attraction to the paradigm is rooted in managing financial risk by limiting exposure to rising energy prices.  PH is fiscally smart.

So… I can get off of the soap box now and offer some price ranges for Passive Houses that we are currently designing and/or building:

• $150/sf for a really cool semi-modern-styled home, 1,100 sf, with modest selections of roofing, siding, flooring, cabinets, etc.

• $170/sf for an “elegant farmhouse”, 1,700 sf, with an attached garage and carport.

• $210/sf for a waterfront modern home, 1,500 square feet, with selections that are more exciting, from a design point of view.

Each of these examples illustrates a home that is perhaps a bit smaller than the home I understand you are considering.  That’s good news!  Creating a super-energy-efficient home tends to be easier and more cost-effective as the size of the home increases.

There is a tremendous amount of high quality information available on PH. Specifically, there are a couple of excellent books that will give you a solid understanding of the method itself and which feature PH projects around the country:

•Homes for a Changing Climate Passive Houses in the U.S. by Katrin Klingenberg, Mike Kernagis, Mary James

•Recreating the American Home: The Passive House Approach by Mary James

Thank you for your interest!

Meanwhile, he’s decided on his siding and reports:

Wood is not Wood

The JEWEL BOX  |  FREAS RESIDENCE

This 1137 sf Passive House is a gem of understated modern design.  Located just outside the city limits of Olympia, it dances lightly on a sloped and wooded site.  The approach of the house is recessed into the earth, creating a sense of shelter and compression at the entry process, contrasting elegantly with the cantilevered glass box that is the great room and the back of the structure.

The floor to ceiling Pazen™ glazing in the great room faces the wooded area to the South, Puget Sound to the West (active shading required), and The Olympic Mountains to the North.  The interior partition walls are treated with finished plywood and only extend to a 7’ height, with glass wrapping around the “mechanical core” for privacy. 

This small but flexible design is engineered to have a second story added to it in the future should family needs expand. The second structure on the site is a large woodworking and metal shop with a carport on the front for the client’s needs as sculptor and artist.

This stunningly austere design proves the Passive House approach can be applied to any project program regardless of exposure, size, and lifestyle needs.  In the case of this “Jewel Box” less is certainly more . . .

In addition to the testing required by the Passive House Institute US (PHIUS) which verifies compliance with the Passive House performance characteristics, there will be additional testing on our houses by the Washington State University Energy Program. We are now partnered with them under the Building America Program, which is an industry-driven research program sponsored by the US Department of Energy. The program was “designed to accelerate the development and adoption of advanced building energy technologies”. They will be collecting performance data from our Passive Houses over time which will add to their knowledge of cost-effective energy innovations in the building industry. This, of course, leads to a broader base of knowledge that informs how we will all build in the future.

The benefits of the Building America Program to the homeowner is:

• Reduced costs—Building America homes use less energy which translates into large reductions in utility bills
• Improved comfort—Building America homes are constructed to reduce temperature fluctuations and room-to-room variations
• Higher quality—Building America homes utilize strategies and materials that improve the overall structure and operation
• Durability—Building America homes are designed to resist long term degradation caused by weather and age
• Environmental sustainability—Building America homes save energy and reduce pollution.

There’s quite a lot of great information on their site.

We’ll keep you posted as results come in!

What controls the humidity level inside a passive house?

There are two types of ventilation systems available that are being used in Passive Houses.  One is a heat recovery ventilation system (HRV), the other is an energy recovery ventilation system (ERV).   The difference between the two is that an ERV manages moisture as well as heat while delivering fresh air into the home.  With both systems, incoming fresh air receives heat from the stale air that is being exhausted.  With an ERV, moisture in the air is exchanged as well.  The Artisans Group is specifying ERV’s in all of the Passive Houses that we build.

Does/Can the fresh air system filter the air?

Yes.  The HRV/ERV industry is quite mature, and the industry did not develop exclusively for Passive House.  The basic provision behind the success of the industry is that of excellent indoor air quality.  Moving relatively low volumes of air through highly effective filters is a great way to improve air quality.

In my case, I have a spouse that can be quite sensitive to pollen in the spring.  Can the fresh air system be configured to remove dust and pollen from the air?

Filters that are designed to meet the specific needs of all Passive House occupants can be integrated into these systems.  HEPA, electronic, and other high-efficiency filtration systems work well with the ERV’s that we install.

Thanks readers for engaging with us, we enjoy hearing from you!

Read on to learn about why vaulted ceilings can be miserable in older homes yet work so nicely in a Passive House:

Comfort in a home is determined by many subjective variables, however what makes a home ‘thermally comfortable’ is well known.  Below are the four comfort measures, that, when in balance make for a very enjoyable living space:

•    Air Temperature
•    Temperature of surrounding surfaces (ie walls, windows)
•    Speed of air (draft)
•    Humidity

Let’s say in our typical home, we set the thermostat to 72°F to keep the chill off, anything much lower than that often feels chilly. Then we look at the temperature of surrounding surfaces, inefficient windows, doors and walls will be cooler or cold to the touch. When the heated 72°F air hits those colder surfaces interesting things happen.  One thing is that cold air is heavier than warm air, as the heated air cools off on the cold surfaces, it sinks. So, imagine the heated air coming from the furnace is lighter than cold air, it stays ‘high’ up in a room until it starts to cool off on those cold surfaces, it starts to sink, while being replaced by more light, heated furnace air, and so it goes. In older homes this movement of air would be called a… draft. In many older homes, when combined with air leakage this looping of air can actually feel breezy. It’s very uncomfortable.

Then there is humidity. This makes things even more interesting in our quest for comfort.  High humidity levels play a big part in why 72°F doesn’t always feel warm enough in our older homes.  For example, imagine a winter day in Colorado, at 28°F with low humidity levels, you might actually ski in a long sleeve t-shirt and be very comfortable. While, the same day in Olympia, WA at 50°F with humidity levels above 45% will have you drinking tea in your hot tub.

The other juicy thing about unbalanced humidity in your home is that it can cause loads of condensation on cold windows and walls resulting in serious deterioration and mold issues. Not good.

In a Certified Passive House, we don’t have inefficient, cold windows, doors and walls and we have no air leakage. With super insulation and critically efficient windows and doors, we avoid all that looping of sinking cold air and rising warm air… no draft! The temperature at the vault peak will be within a couple degrees of what it is at floor level. Given that, there is no need to crank up the heat to 72°F to overcome all that air movement found in an older home, in a Passive House 65°F feels exactly like 65°F no matter where you are in the room!

In our Passive Houses, those comfortable, ambient temperatures combine with a fresh air delivery system for a delightful synergy of human comfort, efficiency and durable structure. Passive Houses are so simple and work so well. Pretty cool.