Lessons Learned

I thought I would share my experience with the Passive House (PH) design system, and relate how it works with LEED.  I had been enamored with PH for some time as a rigorous energy design system.  Having many years of experience in construction and being reasonably computer savvy, I ordered the PH software about six months before I began construction, thinking I could work through the logic and design my own home. 

I gave up after six months of trying to deconstruct the logic and hired John Semmelhack of Think Little.  As it turned out, John is the chair of the Technical Development committee for Passive House US (PHIUS).  He is familiar with a number of the different energy modeling software applications, and was able to complete the modeling on our home in about one day.  With his facility in performing the calculations, I have no reason to attempt to learn the software as I can rely on his expertise.

Though John was able to get our design to comply with the PH requirements of less than 0.6 Air Changes per Hour (ACH), and 4.75 kBTU/(ft²yr), the cost of achieving that exceeded our budget.  The primary driver of that cost was the building geometry.  Since a primary objective was to build a barrier free home, we designed it all to be on one level.  This meant that the ratio of exterior wall and roof area to the floor area was not optimal for thermal design.  It was more important to us to have the barrier free design that to meet the PH requirements, though we came very close.  We exceeded the air infiltration requirements by getting down to 0.44 ACH, but only got down to 7.20 kBTU/(ft²yr).  The only changes we made from the original PH design was to reduce the thickness of the perimeter walls from 22” to 19”, and specify a window that was not quite as high performing as the one that would attain the PH rating. 

The savings allowed us to purchase a ground source heat pump which performs both heating and cooling for us.  Due to the efficiency of the thermal envelope, the heat pump we purchased was the smallest one made, and we are only using half of that capacity.  If the next owner chooses to finish the attic, the heat pump will be more than adequate to the task.  As we get older, our thermal comfort will become more and more important, and having this thermal control will be a benefit.  I also work out of our home, and my productivity is tied to my thermal comfort.  The PH design did not include any cooling, so this was ultimately a good choice for us for the long term. 

There is some tension between the advocates of Passive House and LEED, though there need not be.  Passive house is strictly a building energy model that deals with the energy efficiency of the home.  It operates beautifully within the Energy and Atmosphere section of LEED to maximize energy efficiency.  However it does not deal with any of the other environmental best practices described by LEED.  LEED is more holistic as an environmental standard, considering other tangential energy inputs such as the energy costs of commuting to the site and material delivery.  However LEED does not mandate the strict energy requirements of Passive House. 

My goal in implementing Passive House standards was to develop a return on investment that would pay for all of the energy costs of the building for the lifetime of the building (which I hope to be 100 to 200 years) within the first 5 to 10 years.  We implemented the most energy efficient envelope, appliances, and alternative energy sources we could afford in a coordinated effort to achieve that goal.  Time will tell what the actual return will be. 

Things we would do differently:

The dual stud wall was designed to eliminate thermal bridging.  With the 4” of rigid insulation on the outside, we do not have any thermal bridging, so we had some added labor for the wall construction.  Constructing the walls out of 2x10 material would have simplified the erection process, but the materials would have cost about $500 more. 

I would have been more adamant about the concrete sealer.  Due to poor communication on my part, the material we have is like a hard shellac.  It scratches easily, and in the space of a couple of years is going to look terrible.  At 9:00 every night our two cats start chasing each other around the house.  When they try to get traction on the smooth floors they look like Willey E. Coyote spinning his legs and they leave scratch marks on the finish as they skid to a stop.  What I had wanted was a concrete hardener which would have served roughly the same purpose, but not have been as shiny.  This would look like the concrete floors you see in most of the large box retailers like Home Depot.  We could apply a wax to it to prevent staining and would produce the same polished finish.

I wish we had thought of the cedar shake shingle as a siding material earlier.  We committed a lot in labor and material cost for the installation of the plaster lath.  The cedar looks much better than the stucco would have, and the whole house sits much better on the site for the change in materials.  In hindsight, the stucco would have been a boring finish. 

Things we love: 

We love the clear span concrete in the basement.  Not having a beam and columns in the basement provides a lot of options for use.  We had designed the basement for use as a storm shelter, storage, and mechanical room, but it is going to take on a more prominent role at some future date. 

We love the concrete floors.  The finish notwithstanding, cleaning the floors is a breeze.  About five minutes with a dust mop cleans the whole house, then a little bit of damp mopping here and there periodically as needed.  We do have some area rugs for color, comfort, and acoustics in a few areas, and we need to drag out the vacuum for those, but it only takes about another five minutes to finish the vacuuming.

We love the Serious windows.  These are extruded fiberglass windows, and have a somewhat commercial storefront design to them.  They perfectly frame the views we had hoped to capture, and the thermal comfort is superb.  We have tested the temperature at the window ledge at one degree of difference from the center of the home when the outside temperature was 50^o F lower. 

We love not having any drafts.  After living in homes that were over 100 years old for the last 30 years, we have had no complaints about drafty conditions.  Even though there is a lot of glass, the thermal efficiency of the window does not even generate any noticeable convection to cause any discomfort.

We love the radiant floor heating and cooling.  Warm toes make a great difference in thermal comfort, and we really enjoy the even heat that is distributed throughout the house without the air currents of a forced air system.  The same goes for the cooling.  This summer was especially hot, and we could feel the coolness radiate from the floor.  After working outside installing the siding this summer it was a welcome relief to come in and recover on the cool floors.

We love the Energy Recovery Ventilator.  We had some issues with the installation.  We had some testing done to see if it was delivering the proper amount of air, and found that it was short about 30%.  When the power failed once during the summer, we felt as if we were suffocating within about 8 hours from lack of oxygen.  We had installed flexible ductwork in the basement to the ERV, which is not as efficient as metal ductwork.  When we changed it to the metal ductwork, we were able to operate the fan speed on the low setting and feel just as comfortable as we felt previously when it was operating on the high setting. 

We love our yard.  We opted not to have a lawn and enjoy nature right up to the edge of the house.  We installed a six foot gravel rainwater collector around the perimeter of the home to hold back the vegetation, and planted a no mow native plant species for the first 20’, then planted prairie grasses over the rest of the disturbed areas of the site.  Some of the grasses are designed to attract wildlife, and one is designed to be shallow rooted wildflowers for over the drainfield.  Though we have not experienced a full year of growth, and it takes about three years for a prairie to mature, we are really looking forward to seeing this develop.

The rainwater harvesting system is something I wanted to do to test the economic efficiency of the technology.  I knew the economics would be marginal for our use as we only intended to irrigate the garden.  I did however really want to eliminate the need to clean out gutters on this tree lined site as we get older, and this presented itself as a solution.  We normally get 36” of rainfall in this region which is more than enough for any native plant life.  This year we experienced a drought that lasted nearly 8 weeks, and our cistern ran dry.  The next 8 weeks we had rainfall every few days and required no irrigation.  The right mix of capacity and need seems to be a function of rolling the dice. 

Done…ish

The solar panels are finally operational.  The power company finally recovered enough from assisting the clean up efforts after Hurricane Sandy, and came to install the new meters.  The existing meter needed to be removed, and a new dual meter box installed.  The meter box required a new feed from the solar panels, and then new meters were installed.  This all occurred over the space of a day.  We were without power for about four hours while the wiring was done. 

 

The panels were powered up at noon on Monday, and produced 2,000 watts (2kW) of electricity under a hazy sky.  On Tuesday the sky was heavily overcast, and the day’s production was 3kW.  This is what is recorded on the supply side meter.  I do not yet know if this is the net consumption for the home, or if it is just the raw number for production.  I should know when I get my next utility bill. The two electric meters, phone interface, and generator interface are shown in the picture below.

Nights have been getting down into the low to mid 20’s (F), and days have been in the upper 40’s.  On sunny days we have been getting at least a 4 to 5 degree boost in temperature from the sun warming the slabs on the south side.  One modification I would like to make to the mechanical system is to be able to circulate the water in the radiant floor heating system when the sun is out to re-distribute the heat from the south side throughout the house.  This should be easily done with the small 1/10^th hp pump which is already in the loop and a thermostat that samples the temperature on the south side. 

That completes that last major project on the house that makes us fully operational.  Now we have a number of smaller initiatives that we will implement over the next year or two to finish up.  These are more in the nature of a honey-do list than construction. 

A relatively significant project on the wish list is a monitoring system that would provide data tracking for the major energy using devices that we can web host.  We already have some limited ability with our HVAC equipment to do data tracking, but this does not provide a comprehensive look at energy consumption.

 

Last week we had our Green Rater Michael Holcomb of Home Inspector General do his final review of our project.  We went through the checklist and tentatively came up with 105 points on the LEED Homes rating scale.  We needed 88 points to reach the highest rating of Platinum.  The new version of LEED Homes (V4) that has just been released in pilot form has raised the bar significantly, and we plan to see how well we perform in the new rating system.  Our expectation is that we will just barely achieve the Platinum level designation.  All of this is subject to the final review by USGBC National. 

Installing the Solar Panels

The solar panels are finally installed waiting only to be wired up and tied to the electrical panel.  Forty panels arrived about three weeks ago coiled up in two large boxes.  The panels are 15 ½” wide by 18’ long, each providing 144 watts of power for a total power generating capacity of 5,760 watts, or 5.67 kW of output.  Each panel has two wires leading from the top end which fasten to the adjacent panel.  We can wire up to four panels together for a total of ten 576 watt series to be wired back to the main panel.

The main panel (cleverly called the converter) converts the solar energy which produces Direct Current (DC power) into Alternating Current (AC power) which is what almost every home and business uses.  Once the power has been converted, it will feed the house electrical panel for use in the home.  If the solar panels produce more power than the home requires, the excess power effectively runs the meter backwards, selling the power back to the power company.  When the generated solar power is insufficient (nighttime), we purchase power back from the power company.

We had the good fortune to be the recipients of an EARP grant from our regional power company Consumers Energy.  State law mandates that the utilities will produce 15% of their grid power with alternative energy sources by 2015.  One of the methods of attaining the goal is to allow people like me to contribute to the grid.  The grant process will pay me a higher than market rate for the power I contribute to the electrical grid, and in return I only have to pay the normal retail rate for the power I consume.  This helps pay for the installation of the alternative energy infrastructure I install.  

The installation of the panels requires a good deal of preparation.  We installed a standing seam metal roof in anticipation of using the UniSolar thin film solar panel.  UniSolar is unfortunately one of the casualties of the economy, but we did obtain the panels prior to their dissolution.  The metal roof had to be power washed, then rubbed down twice with isopropyl alcohol to remove all of the dirt, bugs, and bird doo.  It was amazing how much dirt accumulated in only nine months.  My shoulders complained for several days after each cleaning. The solar panel has a self adhesive backing with a plastic film release sheet which is peeled away before it is adhered to the metal roofing. 

The adhesive is extremely sticky, and would have required a supreme effort to remove had it been installed incorrectly.  The installation temperature required that the ambient temperature of the roof material be between 50 and 80 degrees Fahrenheit.  Below 50 degrees, the adhesive would not stick evenly, and above 80 degrees, it was impossible to remove the release sheet.  We typically had either frost or dew on the roof until about 9:00 am when the sun got high enough.  After 10:00 am, the sun would warm up the black solar panels beyond the 80 degree mark stopping the installation until after 4:00 pm.  This allowed us to install four to six panels per day depending on the weather. 

Remaining to be completed is the final wiring, installing the converter panel, and replacing the electrical meter.  I expect the wiring to be done this week, and hopefully we will be operational in the next two weeks.  I do not have any monitoring equipment installed, and have not figured out what I will do yet.  If there is anyone out there with experience in monitoring equipment let me know. 

After nearly 40 years working in construction, I finally broke down and purchased a fall protection harness.  The roof is extremely steep and slippery.  Though I never felt the need for it once I got the scaffold set up, it was reassuring to have it on just in case.  I know my wife felt better about it. 

Water treatment has been an ongoing issue.  We finally took the least cost alternative and put in a water softener.  This goes went everything I had wanted to do for water treatment, but is within our budget.  Perhaps some time in the future we can upgrade.  We do have a slightly salty taste to our water now which we are working on, but we have noticed less mineral accretion on the faucets, and the sulfurous smell is gone. 

So far we have not had the heat on though temperatures have been down to the 30's at night for several weeks.  Now that the sun is low in the southern sky, the solar gains have warmed the home up enough to last all night with only a couple of degrees lost.  One sunny day it got up to 80 degrees inside dropping down to 78 by the next morning.  The outside temperature was in the mid 30’s during the night.  I had to open the windows the next day to keep the house from overheating.

 

Our turtles never did hatch, so we can only surmise that the critters found the eggs and dug them up.  Bow hunting deer season has started, and the hunters have been stirring up the deer.  One nice size 8 point buck which had been visiting our yard all summer has been declared off limits by our neighbors who hunt.  They want to let him grow up another year.  Judy had taken to calling him Bucky, but I started calling him Dumby, a bit more reflective of his intellectual capabilities.  He was either very arrogant, or had no clue about self preservation.  He was often seen grazing in the ditch at the side of the road, oblivious to passing cars. 

 

 

We did have a nice flock of turkeys amble through the back yard.  They were slowly pecking their way through the grass as I maneuvered from window to window taking pictures as they wandered around the yard.  All was fine until the cat jumped up on the window ledge and spooked them all.  They certainly are pre-historic looking creatures.

 

The woodchucks have started hibernating, and the hummingbirds are gone for the season.  We got a lot of enjoyment from them as they chased each other around the house.  The garden was spectacular.  We just put everything to bed, building a large compost pile, and picking any remaining fruit.  We made a large batch of green tomato salsa which turned out pretty good, and had some that night on baked chicken.  A few runty ears of corn remained, which appeared to have been enjoyed by the local racoons after Judy threw the ears over the garden fence.  We think we have a better garden plan for next year which includes greater diversity of plant material, canning, freezing, and donations to the local food bank.

The yard furniture has been packed away, and the video camera has been taken down, restoring the view out the front window.  The only major project remaining is painting the basement stairwell.  The basement is done, but there are still a lot of little miscellaneous items to clean up that we should be able to get done over the winter.  Paint touch up, a few drawers need adjustment, some hardware on the large pocket doors, and a little more sanding on the kitchen countertop are among the remaining projects.

Over the next year, I will periodically update you on how the home is performing, a project that would be facilitated if I had come to grips with the design of any monitoring equipment. 

All in all it is beginning to feel like home. 

Siding progress

It has been a while since my last posting as there has not been much to report.  I have been slowly installing the cedar shakes one by one.  Three sides of the house are complete now with just a gable end remaining.  The trim is painted with two coats of paint before it is installed, then one more after it is up and the nail holes are filled and joints caulked. 

The seed we planted for the yard did not do very well with the drought conditions.  Hopefully it will come back in the spring.  I have mowed a 10 – 15’ wide area around the house to keep the weeds down so that they don’t compete with what grass seed is growing.  In February I will plant some white clover in the frost.  The clover will fill in the blank spots in the grass where crabgrass likes to grow, is a nice forage crop for deer, and is attractive to bees.  

 

 

The warm weather gave us a chance to try out the radiant cooling system, and we were very pleased with the effect, though not with the electric bill.  With all of the sunshine we have had this summer, the solar panels would have been nice to have.  We are still waiting for the revised pricing to arrive for the solar panels since UniSolar went out of business.

 

The critters seem to have made peace with us.  There is a small herd of four does that occasionally browse their way through the yard, and this nice little 8 point buck that has been spurned by the herd.   

We have a number of hummingbirds that chase each other around the house with the buzzing of their wings making a Doppler effect as they zip by. You feel certain to be impaled by an errant bird shaped missile.

The garden just took over.  The tomatoes if stretched to full height would be about 8’ tall.  They have toppled their cages over, and have made passage through the garden impossible.  We harvested the largest zucchini I have ever seen at about 16” long.   

The pumpkin vine is over 30’ long with two pumpkins.  One is about 18” long and beginning to turn orange, and the other is hanging through the fence at nibbling height for the deer and is about the size of a cantaloupe.  The deer graze the pumpkin foliage down flush with the fence nearly every morning.   

Cedar shaking it

We have been experiencing a six week drought and the irrigation cistern has run dry.  Though we have the well water available, we are definitely rethinking the irrigation strategy to include drip irrigation for the garden.   

The Summer Solstice has come and gone, but we wanted to demonstrate the intent of the shading design in these photos.  We have some small amount of daylight that streams in the northern windows in the early morning in a couple of areas, but is blocked by trees in the late afternoon.  We have two west facing windows that we shade with shutters in the late afternoon as needed much to the dismay of the cat.  As you can see, the eaves block the sunshine right at the window sill at the peak of summer at solar noon on the south side.  Click this link to see the You Tube 3D animation we did in the design phase.

 

We started installing the siding last week which involved adding a layer of 5/8” plywood sheathing over the foam insulation.  I asked JA Schmitt Construction to give me a hand with the gable ends as they are the largest expanses, over 20’ high, and at least a two person job to install the plywood.  We have completed the plywood around most of the home, and have completed the shingles on the west elevation.  The remaining shingles are all straight runs at ground level which I should be able to manage on my own.  




We opted to install the shingles around the corner using a method called the "Boston Weave" rather than install corner posts.  The method is a little more labor intensive, but is more in keeping with the craftsman period.  Rae selected the perfect paint color to tie the roof and shingles together, and Judy has taken the week off to paint the trim.  The colors and materials reside comfortably on the landscape. 



The heat in the upper 90’s has been oppressive, and we have had to knock off early to recover.  We have been able to experiment a bit with the geothermal radiant floor cooling.  The first day we turned it on, we had very high humidity, and we could see the outline of the radiant tubing on the floor from the dew that condensed on the concrete slab.  That was quickly remedied by turning on the dehumidifier, which has been running nearly nonstop for the last week.  We had purchased two dehumidifiers, but one of them is in the repair shop.  We have been struggling to keep the humidity in the low to mid 50% range. 

The Heat Recovery Ventilator (HRV) has been bringing in fresh air, but it has brought in the very humid hot air for exchange with the exhaust air.  The continuous addition of the humid air from outside in addition to any moisture we generate from our activities indoors does affect our comfort level.   

The current energy and water use in the house will not be reflective of typical use.  We knew that we would be doing a protracted period of dehumidification to extract the water content of the concrete and the insulation.  This is a very energy intensive proposition.  Our May and June energy bills averaged about 500 Kwh (about $80).  Our design energy budget was 439 Kwh/month.   Both months should have been below the energy budget particularly as we had unseasonably warm weather this spring.  We would anticipate higher energy use than the budget in the winter months as we heat the place.   

Establishing the lawn has required extensive watering, and we have had no assistance from mother nature.  In May we had not yet seeded and our average daily water use per person was 40 gallons.  In June we applied over 10,000 gallons to the yard to make it viable raising our average daily use per person to 197 gallons.  Fortunately, next year irrigating the lawn will not be necessary.  The only cost to us for this added irrigation is in the electricity to run the pump.  We have not yet decided on a water treatment system, though we know we need to do something soon.   

The garden has grown explosively after only having been planted for three weeks.  The tomato plants are waist high, the corn is knee high, the squash is taking over the garden.  We harvested our first zucchini and baked it into zucchini bread, and we have a lot of tomatoes starting.   

 











 



We have two woodchucks which have been named Sylvia and Jack.  It is apparently common knowledge among our Iowa kinfolk that woodchucks climb trees.  We have seen both Sylvia and Jack in these 20’ tall shrubs happily grazing on the leaves.  This is Jack distinguished by his more scraggly tail.  Of course we are guessing at their gender.  We will be as surprised as you if Jack should have a litter of woodchips one day.