The finished home

Here are some photos of the Zero Energy Ready Home.  Once the weather warms up a bit more we’ll paint the front porch columns white and install the landscaping.

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Note the 24 inch overhangs to keep water away from the foundation.  The stone beds under the eaves hide a french drain system that diverts water to the backyard area.  This also eliminates the need for gutters, which means less maintenance for the owners.  Also notice the slightly inclined sidewalk and roll-in entry door to make the home friendly to those with disabilities.  Both the front and back doors on the home have this feature.

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The view when you enter the home shows the open layout, where the kitchen, dining area, and living room blend as one space.  This is a blank canvas for the homeowners to create a place for their family with lots of natural light.  The flooring is a vinyl plank floor that is easily cleaned and does not off-gas chemical odors.

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The cabinetry and counter tops for the home were built by inmates at a prison facility in Ionia, Michigan.  This “Prison Build” program provides job training for inmates nearing the end of their sentences, and helps provide Habitat with affordable, high quality cabinetry.  All of the cabinet boxes are plywood, not particleboard, and all stains and finishes are water-based, ensuring no toxic compounds enter the air of the home.

The appliances were provided by Whirlpool’s gift in kind program.  Whirlpool donates a refrigerator and range for every Habitat home built in the U.S.

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A look at the entrances to the laundry room and bath, and the three bedrooms.  We paint all walls, ceilings, and trim with a high quality low-VOC primer and paint.  The homeowners can add color if they wish once they move in.

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The bath cabinets and counter, also made by the Prison Build program.  The bathroom of this home is large enough to have a five foot diameter turning circle for a wheelchair, and although accessibility features like grab bars were not installed, wood blocking was installed in the walls to accommodate their installation later.  The plumbing for the sink also comes out of the wall, not the floor, so that in the future a wall-mounted sink could be installed to make the bath ADA compliant.

 

 

Water heating

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In the Zero Energy Ready Home we chose to use a Navien tankless ultra-condensing water heater, model NPE-180S.  We found it to be the most efficient natural gas water heater we could find at a decent price.  In fact, the unit with the flush valve kit included only cost about $400 more than a standard power-vent tank water heater.  It also has a 15 year warranty on the heat exchanger, whereas a power-vent model only has a 6 or 9 year warranty on the tank.  Also, even the best power vent water heaters are only about 70% efficient, so 30% of the energy created when the gas is burned goes right out the exhaust and is wasted.  The Navien unit has an incredible energy factor of .97, meaning that almost 100% of the gas burned goes directly to heating the water.

The unit draws its own combustion air from outside, not extracting heated air from the home like other models.  And the best part of the tankless unit is that it only comes on when hot water is called for.  Any other time of day it is off and using virtually no power (except the LED read-out), unlike a tank heater that must occasionally turn on to maintain the temperature of the water in the tank.  To find out more about the water heater we used, follow this link:

http://us.navien.com/Product/Page1/Details/NPE-180S?Category=NPE-S%20series

 

House complete!

We’re finally done!  The home looks great, and is already performing better than expected.  We are anxiously awaiting the Home Energy Rating Score (HERS) and other stats, which we will share as soon as they available.  Some preliminary data is showing a HERS below 50, with total annual operating costs under $900.  This is more than 50% more efficient than the 2006 energy code.  There is no cross-reference yet from the HERS to the newest (2015) energy code, but the home is at least 10-15% more energy efficient than that code, which went into effect only a few weeks ago.  The image below shows the HERS scale.

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Other preliminary data that we have so far is showing that heating will represent less than 25% of the home’s energy usage, and water heating only about 15%.  The largest energy usage of the home is the lights and appliances.  We installed all LED lights and Energy Star appliances, so there isn’t much more we can do to reduce that number.  It just shows how little energy the home itself costs to run by being built with energy conservation in mind.

Another benefit of the tight, well insulated home is comfort.  I was in the home doing a final inspection of the work and filling out paperwork last week for about an hour.  In that time the furnace never came on, and it was 25 degrees outside.  The thermostat read 64 degrees, but I was comfortable in short sleeves because there was absolutely no draft.  Since air movement in a home can lead to a significant difference in how a temperature feels to us, that 64 degrees felt just fine.

As part of our final testing of the home by our third-party energy rater, a blower door test was performed to test the air-tightness of the home.  A fan and frame are placed in an entry door and the fan is turned on to blow outwards, which simulates a 20 mph wind on all sides of the home.  Anywhere air can leak into the home is tested with a smoke stick, and in this home we almost couldn’t find any visible leakage whatsoever.   The cubic feet per minute (cfm) of air moving through the fan to maintain a certain vacuum pressure in the home gives you the leakage of the home.  For those of you interested in numbers, the home tested at just over 200 cfm at a negative pressure of 50 Pascals.  This was our best test on any home to date by far.  The image below shows a standard blower door (not from our home).

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For those of you who are more visual, a standard existing home has an air leakage that represents a small window being left open year-round, and a newer home something the size of a doggy-door, or maybe a mail slot.  Our home’s air leakage could be represented by a 1-1/4″ diameter hole.   Since air leakage accounts for about 40% of a home’s energy loss, all of this results in very low energy bills and operating costs for our homeowners, now and even more in the future as energy prices inevitably rise.

We’ll be holding a dedication ceremony this coming Sunday for the family, volunteers, and community, and the family should be moving in sometime toward the end of the month.

Stay tuned for more information as the final results come in from our rater!

 

Windows

In this home we chose to install Pella 250 series windows with triple pane glass, argon gas, and low-E coating.  The triple pane glass is about 50% more energy efficient than the double pane Energy Star rated windows we used to install (the new windows are still Energy star rated, just better).  The U-factor of the glass in the windows we used is 0.20, compared to an Energy Star window with a U-factor of about 0.30 – 0.35.  Since the U-factor is the inverse of the R-value (one divided by the U-factor), the windows in our home are R-5, or the equivalent of 1″ foam insulation.

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The windows also have argon gas inserted between the panes of glass.  Since argon is a very heavy gas (much heavier than air), it slows down the “convective looping” between the panes.  This is heat that is lost in the winter when air or other gas picks up heat from the inside pane and then “loops” in the space and gives off the heat to the outside pane.   The reverse is true in hot months, when the gas between the panes slows down the heat transfer from the outside in.

The low emissivity, or Low-E, coating on the glass acts to control solar heat gain into the home.  The special coating reflects solar rays in the summer when the sun is high in the sky and at a sharp angle to the glass.  In the winter, the angle of sunlight is lower, and the coating lets the rays in.  This helps the home gain some heat in the winter and keep the heat out in the summer.  Yet another example of the home saving energy without mechanical means.

One comment I often hear is that the materials we use, especially the windows, are expensive, and therefore drive up the cost of the home.  The Pella triple pane windows on this home cost about $2700, whereas a set of double pane windows (which are 33% less efficient) would have been closer to $1900.  Yes, we spent about $800 more for the better windows, but amortized over a 30 year mortgage, this will cost the homeowners an additional $2.22 per month, a small price to pay for superior performance and comfort.  And windows are an integral part of the home that aren’t changed out every 10-15 years like a water heater or appliances.  They should last 50 years or more, so doing it better from the start makes sense.

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The last step in installing windows (and doors) is applying the flashing, or materials that keep water out of the building around the windows.  This has to be done absolutely perfectly or there is the potential for water to leak into the building and cause major damage.  This is a step often done improperly in homes even to this day,and something we take very seriously, since the consequences can be hundreds to thousands of dollars in damage down the road.  Vinyl siding keeps most of the water away from the house wrap but not all, and changes in weather can also cause moisture to collect behind the siding.  If this flashing isn’t done right,  you won’t know until you start seeing evidence inside the home, and by that time  the damage to the sheathing, framing, drywall, etc. is pretty severe.  You can see in the photo above how we used Dow Weathermate flashing tape (blue) around the sides and top of the window, then overlapped the house wrap (light blue) to create a drainage surface that keeps water out.  If you’ve done your flashings right, in theory, you could never install siding and water would still not get in.  An added benefit to all of this flashing is that it helps air-seal the home, which is another way to prevent heat loss.  The home works as a system, and all parts are related.

Wall Insulation

Once all of the trades were roughed in and inspected and framing was inspected, we began the insulation in the exterior walls.  We ran into a bit of a challenge with this home when it came to choosing and installing the insulation we would use.  We prefer dense-packed cellulose over fiberglass insulation because it performs better due to the way it slows down air flow in the wall cavities.  When you slow down the movement of air inside the walls, you greatly slow down heat loss by convection (loss of heat from air to a solid, like drywall and wall sheathing).  Fiberglass is not a bad product, but it lets air flow through it fairly easily (think of a cheap furnace filter; made of fiberglass).  So we chose dense-packed cellulose.

Note: we could have used a damp-spray cellulose material, but we have found in the past that the foam sheathing does not allow the insulation to sufficiently dry, leaving wet areas of insulation in the walls.  Even with dehumidifiers running in a home for two weeks the insulation still has a moisture content that makes us nervous.  With a tight, high-performance home, moisture in the walls is a very bad thing, and can lead to mold issues down the road.  We also had the option of damp sprayed fiberglass, but again we were concerned about added moisture into the structure.

The trouble came when we discovered that the staggered stud walls that we had built, although excellent at heat loss prevention, made it significantly more challenging to insulate than a standard framed wall.  Generally with cellulose, the material is blown into each stud cavity under pressure, causing the insulation to fill the cavity nice and tight.  By building the staggered stud walls, the stud cavities are no longer enclosed, but rather open to the next cavity, and the next, and so on.  It becomes impossible to create any pressure and pack the insulation in.  See the photo below that illustrates our dilemma:

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Help came from Mark Lee of Better World Builders here in Kalamazoo.  His company does very high quality energy improvement work, and is acting as our insulation contractor on the ZERH project.  Mark came up with a way of using a fabric material (made for this purpose), stapled to the sides of the studs, to create enclosed cavities that would accept the dense-packed insulation.  His crew did a great job of installing the material, filling the insulation tightly around all of the framing, wires, electrical boxes, and other items in the walls.  The photos below show the fabric in place in the walls:

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With the 2 inches of dense foam on the exterior walls as sheathing and the dense-packed cellulose inside the walls, we end up with an R-value of about 32, or about 78% better than the 2012 energy code, which won’t be adopted here in Michigan until early next year.  This should insure energy savings and a comfortable living space for the life of the home.

 

 

 

Plumbing and water savings

We gave some very careful thought to the plumbing in the Kalamazoo ZEHR home, as we do with any new home we build.   Every home we build incorporates water-saving fixtures rated by the EPA WaterSense label.  These fixtures use less than typical plumbing fixtures, and can reduce the water usage (and therefore water costs) of the homeowners, as well as have obvious environmental benefits through the use of less clean water.  From our experiences these fixtures perform as well as standard fixtures and don’t typically cost any more to buy.  The image below is found on WaterSense labeled products:

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Aside from the efficient fixtures, we are also trying to design the plumbing supply lines in the home to be as efficient as well.  In most homes, water lines are typically run as 3/4 inch mains, which then reduce before the fixtures to 1/2 inch pipe.  These pipes are WAY over sized for the amount of water required by almost every fixture in a home.  Most shutoff valves under a sink or toilet have an opening of less than 3/8 of an inch, so why make the pipes any bigger?

Also, locations where the water is used, such as kitchen, baths, and laundry, can be spread all over the home, making long runs of pipe to each room.  It is amazing how much water pipes can hold.  A 50 foot long run of 1/2 inch pipe holds about 1/2 gallon of water, while a 3/4 inch pipe holds over double that at 1.15 gallons.  With all of the long runs, twists, and turns in a standard plumbing system, it is easy to have 50′ of pipe or more to many fixtures.  So reducing the size of pipes carrying water can reduce the amount of water standing in the lines.

So, why does this matter?

All of this comes into play when using hot water.  When you turn on a faucet to wash your hands or wash dishes,  you often have to wait from several  seconds to sometime more than a minute before the cold water sitting in the pipes is pushed out and hot water arrives.  We’ve all experienced this at some point.  During this time, anywhere from several cups to a few gallons of nice, clean, potable water goes right down the drain.  This may not seem much, but added up many hundreds of times over a year can lead to thousands of gallons of wasted water.  This is both a waste of water and money.  Here in Michigan we are extraordinarily blessed to be surrounded by fresh water, but water still takes massive amounts of resources to process and clean for human use, so we think treating it wisely is good for all of us.

In our home we “clustered” the rooms so that the locations of water use were as close to the water heater as possible.  The water heater (a tank-less hybrid) will be placed in a closet adjoining both the bathtub and laundry room so that there is less than 6 feet of pipe to each.  The bathroom sink is just across the room, with maybe 12 feet of pipe to the fixture.  The longest run is to the kitchen sink, which is about 25 feet at most.

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Also, we had our plumber run what is called a manifold, or “home run” system of piping.  Instead of the typical “trunk and branch system”, which uses larger pipes as the main line, then reduces to smaller lines as it gets near fixtures, we went from a very short section 3/4 inch pipe directly to a series of 1/2 inch lines right away, so each fixture has its own “home run” line (we wanted to go with even smaller lines, like 3/8 inch or even 1/4 inch, but fittings are hard to find, plumbers don’t have tools to work with them, and current plumbing code may not allow it).

This greatly reduces the amount of water wasted before hot water arrives, and also the time waiting for that hot water.  In fact, we did some calculations of the amount of water held by the pipes, and it turns out that the amount of water contained in the ENTIRE hot water supply system (not including the water heater itself) is less than 1/2 gallon!  The picture below shows a typical trunk and branch plumbing system:

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This illustration below shows a manifold, or “home run” plumbing system like we used in our home:

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(these images are not ours, but were gathered from a Fine Homebuilding article online)

Another advantage of this system is that there aren’t fittings in the walls and floors to reduce pipe size.  The only connections are at the start and finish of the lines, so a future leak is easy to find.  The photo below shows the manifolds our plumber installed, which splits the water to each fixture:

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To the right is the main water line and shutoff valve, which feeds all of the other lines.  The larger lines reduce to smaller, dedicated lines via the black manifolds.  As you can see, almost all of the fittings are in this small utility room, so if there is a leak, it will be here and accessible to fix.  The water heater will hang on the wall above.  Immediately to the right is the bathtub/shower and to the left is the laundry.

Lastly, another step we took to save hot water was to insulate the lines where they ran under the slab floor so that they do not lose much of their heat to the ground.  This conserves heat between uses, so even less water is wasted waiting for hot water.  In the end, we hope to have designed a system that will conserve water as well as cut costs of living for the homeowners.

To find out more about the EPA WaterSense label, go to:

www.epa.gov/watersense