kimchi & kraut

Passive House + Net Zero Energy + Permaculture Yard

Tag Archives: green building in illinois

Our Energy Bills

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The Logic Behind the Effort and Added Cost of Passive House

Passive House, as a building strategy, requires meticulous air sealing, along with ample amounts of insulation, carefully placed to eliminate or reduce the impact of thermal bridges through the building envelope. Once the air barrier of the building has been established, it requires mechanical ventilation to meet IAQ needs, along with high performance windows and doors to avoid undermining all of the air sealing and insulation.

Air sealing, water proofing, and thermal elements come together around a high performance window.

All of these elements together, if successfully managed and implemented, should achieve a building that requires significantly less energy to operate and maintain at comfortable temperatures than any conventionally built structure of similar size and shape.

The Visitor enjoying some early morning solar heat gain through our kitchen window.

With a ‘conservation first’ approach (i.e. extensive air sealing and insulation), the goal is to reduce total heating and cooling demand as much as reasonably possible (while maximizing occupant comfort), with the possibility of adding renewables like solar or wind as mostly an afterthought to further reduce, or eliminate entirely, the remaining energy demand of the structure. It also typically means going all electric, so in our case it meant no natural gas (the normal fuel source in our area for a furnace and a hot water tank).

So far, our 11 panel 2.9 kW system has been averaging between 3,500-4,000 kWh of solar production per year.

A Passive House structure, by design, should use significantly less energy than any conventionally built counterpart of similar size and shape. This includes lighting (normally assumes only LED fixtures will be used) and other plug-in loads (e.g. Energy Star appliances), as well as hot water (typically a heat pump hot water tank, or a newer product like Sanden or Chiltrix).

Unfortunately, these loads are relatively ‘baked-in’, even for an existing, conventionally built home. For instance, a hundred year old home could switch all of their light fixtures to LED bulbs, replace old appliances with new Energy Star rated models, and change out a gas-fired or a conventional electric hot water tank to a high-efficiency heat pump model. In effect, they’d have pretty much the same reduction in energy use as a brand new certified Passive House of similar size and layout for these particular sources of energy demand. As a result, the real opportunities for driving down energy use in a Passive House are in the heating and cooling loads (mainly due, of course, to the extensive air sealing and insulation levels).

On most days the 15,000 Btu head in our kitchen and family room handles all of the heating and AC needs for our entire house. We have two additional heads in our bedrooms (9k and 6k Btu respectively), but they’re rarely used apart from the coldest and hottest days of the year.

Although there has been some moving of the goal posts as the Passive House programs have evolved over time, they remain challenging targets to meet.

Here are the current PHI requirements according to Passipedia: Passive House Checklist

In the case of PHIUS, the requirements have gone through several iterations, for instance, PHIUS+ 2015, PHIUS+ 2018, and most recently a fairly dramatic change to a prescriptive track to seek certification with far less onerous levels of paperwork and data collection required.

Overall, regardless of which model is pursued, PHI or PHIUS, the intent is to dramatically reduce the overall energy use of buildings by emphasizing the importance of air sealing, insulating to levels that exceed current code requirements (in most cases), along with quantifying things like thermal bridges, heating and cooling demand, and peak heating and cooling demand. The issue of energy demand or energy use is further complicated by the distinction made between Primary/Source and Site Energy.

Additionally, there’s been a growing consensus regarding the need to incorporate renewables in these building strategies, both in terms of financial feasibility and in terms of further reducing (or even canceling out altogether) net energy demand. And while it’s true that Net Zero is fairly straightforward to achieve (assuming needlessly large PV arrays are not utilized as a short-cut), it does require a commitment to meticulous air sealing and quantities of insulation that, along with the in-depth energy modeling, unavoidably add cost to any construction budget.

Zehnder ERV, Rheem HPHW tank, radon pipe with fan, and battery back-up sump pump. Elements that support proper moisture management, IAQ, and HVAC needs.

The opportunity for significant energy reduction also correlates with the size of the project. Because of form factor ratios, the larger the project (assuming a compact form is mostly maintained) the more energy a structure stands to conserve. This is why larger institutional, multi-family projects, or corporate-sized projects stand to be the biggest winners when it comes to the purported benefits associated with Passive House energy conservation.

Outdoor heat pump compressor after the snow, but before the worst of the 2019 Polar Vortex.

If executed properly, low energy demand will mean considerable financial savings. These savings are cumulative, year after year, rather than just a one-off initial price break, with the added potential to increase should energy costs go up.

In addition, there is the potential for less upfront expenditures for HVAC equipment (less heating and AC demand — at least in theory — means smaller and more cost-effective equipment required). In our case, in climate zone 5, where we get cold, dry winters and hot, humid summers, this didn’t prove to be the case. Combining the cost of our heat pump and ERV reflected roughly what we would’ve paid had we built a conventional home with a high efficiency gas furnace with a humidifier attached (fairly typical system in our area). Either way, it would constitute roughly a $20,000 expenditure for a house under 2,000 square feet. The level of indoor comfort, however, should be vastly different between a conventional and a Passive House build.

Even though occupant behavior can derail some of these projected performance outcomes, assuming that homeowners or tenants are reasonably educated on the best way to enjoy and benefit from the Passive House details, especially the HVAC systems (normally this means commissioning units and then mostly leaving them alone in terms of settings), this should not be a stumbling block for most builds.

While all of this becomes more challenging with a smaller, more compact build like our 1,500 square foot single-family home, the possibility of significantly lowering energy demand is no less real, along with the cost savings. Not to mention the level of occupant comfort, which I personally feel is the main selling point of the Passive House building principles.

Some Background Information on Our Home

A quick summary of our build would include our blower door score of 0.2 ACH@50 (106 cfm@50), along with the following R-values for the structure:

R-16 Below the basement slab

R-20 Exterior of the basement foundation

R-40 Exterior walls

R-80 Attic

In 2019, our first full year of occupancy, with three of us (my wife, daughter, and myself) we had a total of just over 11,000 kWh of energy use. This included lighting, all other plug-in electricity demands (appliances, TV, computers, charging cell phones etc.), along with our HPHW tank and all of our heating and AC needs. It also included countless hours of power tool usage as I finished up interior trim, doors, along with some shelving and storage projects after we moved in. Record low temps during a Polar Vortex event in late January and into early February added to the total as well.

For 2020, a substantial increase in overall energy use might have been the expectation after the outbreak of COVID-19. Yet even after subsequent stay-at-home guidelines that began for us in March, we actually ended up at 10,446 kWh, a slightly lower annual number compared to the previous year. This lower total happened even with all three of us being home most of the time, with no breaks even for vacation time, outdoor activities that require some travel, or normal visits to family out of town.

If there’s a payoff in pursuing Passive House, it has to be in the combination of lower energy costs and increased occupant comfort when compared to a similar, conventionally built home or structure.

This lower number was in keeping with our usage during our first nine months (April-December, 2018). If the Polar Vortex was an anomaly (everyone hopes that it was), then most years going forward should be around 9,500-10,500 kWh for total annual demand. In part we think going over 11,000 kWH our first full year reflects just how significant a colder than normal winter can be on overall energy use in a Passive House, not to mention heating demand more generally (whether it’s a Passive House or not).

Moreover, for a family of three and a structure of this size with similar performance specs, it seems to suggest that our 3-4,000 kWh of annual usage per person is mostly ‘baked-in’. Meaning, in terms of occupant behavior, there’s not much we could do to further lower these numbers. Perhaps we could take fewer showers, cook less at home (stove and dishwasher), do less laundry, only ‘live’ from dawn to dusk (to avoid using artificial lighting at night), not do any woodworking or other DIY projects (use power tools off site?), and heat the home to only 60º F in the winter and cool to only 85º F in the summer. Obviously, these would be rather extreme measures to chase after the last final few kWh of energy use and, arguably, it wouldn’t be particularly meaningful apart from bragging rights should we end up with a lower annual total.

After all, it’s fair to ask what’s the point of the air sealing, insulation, and triple pane Passive House windows and doors, if it doesn’t produce a much more comfortable day-to-day living experience for those living inside the home or building? If simply chasing energy use were the main objective, reducing it no matter the consequences, then removing all the windows and doors and replacing them with continuous R-40 walls would be a good place to start, but hardly worth considering for obvious reasons. If there’s a payoff in pursuing Passive House, it has to be in the combination of lower energy costs and increased occupant comfort when compared to a similar, conventionally built home or structure.

In terms of unexpected surprises, really the only unanticipated energy use was the need for dehumidification on the hottest and most humid summer days of the year.

After our first summer in 2018, when part of the excess humidity was likely due to new construction moisture present inside the structure, we’ve been averaging about 30-40 days a summer, including a few random days in spring and fall, when the dehumidifiers are running intermittently. We set the units to 50% relative humidity, but normally they shut off around 55% based on gauges placed around the house. We try to keep the house under 60% RH. The risk for mold increases above 60%, but it’s mainly at that point when humidity levels make us feel noticeably uncomfortable.

Also, we didn’t think about the energy use associated with power tools for woodworking and arts and crafts projects. Without tracking it, we can only guess that it represents a few hundred kWh a year, rather than something in the thousands. We’ve been doing plenty of projects around the house our first three years, but still far less than what a full-time woodworking company would require. Even so, along with the potential for a EV charger, it’s something to think about when designing a new home or retrofitting an older one, especially if renewables are part of the equation and you’re trying to establish likely annual demand.

Actual Energy Use: Demand and Costs

The breakdown is as follows:

Based on our first 2.5 years in the house, we can expect 10-11,000 kWh of total energy use per year. Again, for some context, this is for a family of three, in a 1,500 square foot single story home that has a full basement.

In our first full year, 2019, we exceeded 11,000 kWh mainly due to the Polar Vortex. Compared to our first winter, along with numbers for this current season, it looks like the Polar Vortex added nearly 1,000 kWh of demand above a more typical January – March time period.

Over the course of our first 2.5 years (our first year was April-December), the numbers have been surprisingly consistent across seasons and month-to-month, regardless of our level of activity in the home (e.g. guests staying over, vacations away from the home, power tool use, etc.).

For instance, even in our first June, back in 2018, when the house was still drying out from new construction related moisture, and we felt compelled to start using two dehumidifiers to control excessive humidity (one in the kitchen and one in the basement), total energy use for the month was 616 kWh.

The following June, in 2019, we ended up with an even higher number, at 786 kWh of demand.

For June of this year, even with stay-at-home restrictions for COVID-19 in place, so a reasonable expectation might be for still yet higher demand, we actually ended up at a lower 605 kWh of use.

On a side note, it’s probably reasonable to assume COVID-19 had some impact on overall energy use for 2020, but after going through the numbers, it just seems unlikely that it contributed more than 500-1,000 kWh to our annual usage. We should have a better idea of its full impact once winter is over.

Presumably, without a granular study of day-to-day conditions, including day and night temperatures, along with relative humidity data, not to mention minor fluctuations in how we used the AC or how much laundry we were doing over these same three periods, it’s hard to explain this deviation with any level of certainty. Suffice it to say, we can expect June usage to normally be in the 600-800 kWh range. Obviously, a June in the future that experiences a heat wave like the one Chicago experienced in 1995 would likely drive the final number well over 800 kWh, but hopefully that remains a singular event rather than a more normal June.

In other words, even in a year where the weather remains milder than normal for a full 12 months, and we’re all exceedingly busy and rarely at home, our total energy use for the year, at best, will likely still end up in the 9,000-10,000 kWh range. And even if there was just one person living here, it’s hard to imagine they could keep total energy usage much below 4-5,000 kWh on an annual basis since so much of the demand is ‘baked-in’, as previously noted above.

Here is the monthly breakdown of energy use for the first full year we were in the home for 2019:

January: 1,738 kWh (includes 2019 Polar Vortex; following January was only 1,374 kWh)

February: 1483 kWh (the following year was 1,237 kWh)

March: 837 kWh (following year was 561 kWh — clearly a bitterly cold winter)

April: 681 kWh

May: 473 kWh

June: 786 kWh

July: 612 kWh

August: 608 kWh

September: 630 kWh

October: 812 kWh

November: 1,166 kWh

December: 1,237 kWh

Total energy use for 2019 was 11,063 kWh.

In this same period, our solar panels produced 3,863 kWh, so net demand for the year was 7,200 kWh (this requires some math using the billing statements from our utility company and the Enphase Enlighten solar app).

Our monthly bills for electricity in 2019 totaled: $1,075.89.

Because of our SRECs, which for us totaled $848 for the year (paid via quarterly checks), our net energy costs for 2019 were $227.89 (an average of $18.99 per month).

For comparison, numbers for 2020 were: 10,446 kWh of demand, while solar production for the same time period was 3,675 kWh, for a net energy demand of 6,771 kWh.

After SREC payments (again, totaling $848 for the year), our net total cost for 2020 was $189.36 (an average of $15.78 per month).

The SREC payments (these are based on a 5 year contract) reduced our annual cost by $848 each year, with a net average cost for our first two years of just $208.63 per year for all of our energy needs (a roughly $17.39 per month average).

Without any solar panels or SRECs, our electric bill would be roughly just under $1,500 per year based on current rates. By way of comparison, a new code-built home of the same size would likely pay more than twice this amount — an older home still more, assuming less air tightness and insulation, combined with a less efficient gas furnace for HVAC and domestic hot water.

It’s worth noting that as building codes tighten up their performance metrics, the difference in total energy demand between code-built and Passive House homes should continue to shrink. This assumes, however, that any number of ‘ifs’ are successfully overcome. For example, if air leakage is accurately measured (is there enforcement should the structure fail?). If a proper Manual J has been completed. If HVAC ducts are sized, installed, air sealed, and insulated properly. If insulation has been properly installed in appropriate quantities throughout the exterior walls and roof. If thermal bridges are avoided. If moisture (bulk and water vapor) is appropriately addressed and managed. This is a lot to get right, and it’s easy to get any number of things wrong, even with inspections and third party verification.

As pointed out earlier, since we’ve moved in we haven’t aggressively pursued trying to lower our energy demand. Instead, our approach has been to live ‘normally’, enjoying the benefits of the air sealing, insulation, and our HVAC set-up. We set and mostly forget our heat pump at 70º F in winter, 75º F in summer, in order to try and better understand ‘real world’ energy demand in a tight, well insulated and appropriately ventilated home of our size.

Hopefully some of this information can benefit others in the planning stages of their own Passive House, or Pretty Good House project. Moreover, in addition to WUFI analysis and PHPP, BEopt is another modeling option for figuring out energy demand and cost-effective design elements for a structure (new or old). The new calculator from PHIUS would also be a good place to start: PHIUS+ 2021

For anyone who wants an easy, initial test of their current home’s energy efficiency (EUI), a calculator like this one may be helpful: Energy Smart

Numbers for Heating and Cooling

In spring and fall when there’s less demand for heating or AC, our baseline monthly energy usage is below 500 kWh (this has been fairly consistent over the course of our 2.5 years in the home, even during COVID-19 when the three of us were home most of the time).

If this low demand could be maintained for much of the year, as it is in milder regions of the country like in parts of California, our annual usage could be cut by more than half (it wouldn’t require R-40 walls or R-80 attics to achieve either). Moreover, in these more temperate regions of the country with reduced insulation needs, and therefore less demand on HVAC systems, ‘green’ building programs like Passive House and Net Zero become even more attractive since they’re far more cost effective and easier to achieve.

In our case, summer months typically run about 600-800 kWh of actual usage, dependent on the number of days above 82º F when we typically find that we need to turn on the AC. Even on these days we will turn it off if there’s a sufficient drop in outdoor temps overnight, which allows us to open the windows (dependent on outdoor humidity or rain).

It might be worth noting that even though we thought we’d regularly open our windows whenever the weather was remotely nice, this hasn’t turned out to be the case. Between having to monitor indoor humidity levels, and the ability of our ERV to deliver continuous filtered fresh air (it’s shocking how quickly our fresh air supply filter turns black — within a month or two at the most), apart from the few days a year when the weather is perfect for opening windows, they mostly just stay shut. Much like Jim Gaffigan’s quip on seasons here in the Midwest, “Spring, that’s a fun day,” because the weather tends to be so mercurial there just aren’t that many days or nights when we feel comfortable leaving the windows open for extended periods of time.

On the plus side, it’s not uncommon for us to wait until there are 2-3 successive days where temperatures rise above 82º F before we feel the need to turn on the AC. In other words, there is some truth to the idea that Passive House buildings take some time to heat up or cool down based on outdoor conditions, although this can be quickly undermined by an ERV/HRV that’s set on high or in boost mode for long periods of the day (lots of cooking or showering, particularly relevant in the case of larger families, would make this a necessity) .

“Heating and cooling energy – that which is most reflective of the efforts of the design and construction process – is a small percentage of the total energy usage. As Andy Shapiro says, there is no such thing as a net zero house, only net zero families. Occupant choice matters hugely.”

—Marc Rosenbaum‘s report on South Mountain Company’s Eliakim Net Zero Energy Project

During the heart of winter, our total energy demand is in the range of 1,000-1,500 kWh per month. Even in January of 2019, with a Polar Vortex event, our bill still managed to stay below 2,000 kWh for the month. During this same week, however, we saw minimal benefit from our solar panels since they were covered by several inches of snow during the sunniest (and coldest) parts of the billing period.

These elevated kWh numbers during winter reflect just how much harder our Mitsubishi heat pump system has to work in order to maintain indoor comfort because of the Delta T between outdoor and indoor temperatures. And we can hear the difference: while in summer the system is virtually silent, in winter, especially as temps head towards zero, we can hear the compressor outdoors working to keep up. Compare this to summers: 75º F indoors vs. 95-100º F outside on the hottest days of the year, even though it’s significantly cooler for most of the summer, thus helping to explain the lower overall energy demand for AC usage in comparison to heating demand.

Cooling, unlike the demand for heating, is relatively comparable to what it would be in a conventional new build. In summer, the Passive House ‘thermos-like’ structure is mostly a hindrance rather than a benefit to keeping the interior comfortable. All the ‘free’ sources of heat in winter, e.g. south-facing windows on sunny days, body heat from the occupants, heat given off by computers, TVs, appliances, and even LED lights or our heat pump dryer, either thankfully don’t exist (in the case of south-facing glass because of sufficient overhangs) or they actively contribute (however small in some cases) to the overall cooling load.

In addition, because cooling loads are relatively low, and the efficiency of the mini-split heat pump is so high, even as the multiple indoor heads have no issue maintaining comfortable temperatures (we rarely notice the system — wall units or outdoor compressor — running in summer), it leaves us with a latent load that we need to address with two stand-alone dehumidifiers, indirectly adding to the overall cooling load.

So of our roughly 10-11,000 kWh per year of total demand, without an actual energy use monitor like TED on our main panel to establish exact numbers (a review of similar product options: here), it looks like just over 3,000 kWh is used for heating, with another 800-1,000 kWh used for cooling needs (at least in a typical year). In years where there’s a significant Polar Vortex event, or should a summer in the future experience an extended heat wave, then our numbers for heating and cooling are likely to hit 5-6,000 kWh of demand. With climate change, these numbers are invariably going to fluctuate or even grow depending on just how severe weather patterns become over the ensuing years and even decades.

Notes on Designing a Heat Pump System for Passive House

An issue worth considering, especially for those in the design stages of a build, is the added efficiency of a 1:1 set-up for heat pumps, meaning one outdoor compressor for each distribution head indoors (or air handler). There appears to be a growing consensus that this layout will offer added efficiency because of improved modulation over what has been a more typical set-up, like ours, which is a multi-zone system that has multiple distribution heads on a single compressor. It’s hard to imagine, at least in our case, that this impact could be more than a few hundred kWh per year, but worth exploring when having someone do a Manual J and S.

Additionally, we haven’t experienced any issues with the distribution heads in the two bedrooms (9k & 6k Btu’s respectively), either for heating or cooling, although concerns about the effectiveness of these undersized units in smaller bedrooms often comes up in discussions on how best to design and layout a heat pump system on Green Building Advisor.

When designing our system, I don’t remember this issue of 1:1 vs. multi-zone heat pump set-ups being discussed in any of the information I was able to hunt down, either in Passive House related books, or even online resources. I also didn’t come across discussion of the need for active, separate dehumidification while designing our build in 2016. These are just two examples demonstrating that Passive House is still actively evolving as a ‘green’ building program (potential overheating in winter and shoulder seasons would be a third example).

A cautionary tale for designers, as well as building owners, to guard against hubris as the construction drawings develop or when the details are finally executed on a construction job site. Other issues may arise with Passive House builds in the coming years, so it’s worth considering potential unintended consequences before finalizing details. Today’s solution may be someone’s costly headache tomorrow.

Additional Solar Panels to Achieve Net Zero?

Based on what we’ve been paying for energy in these first 2.5 years, we don’t feel compelled to add more solar panels at this time. Should the SREC’s dramatically fall in value with a new contract, or disappear altogether, it might encourage us, at that point, to purchase more panels for the roof. But even so, at less than $90 per month, even without the SREC’s, it makes our energy bills a relatively painless expenditure (roughly equivalent to one nice restaurant dinner for the three of us, or still less than what we pay on a monthly basis for things like coffee, breakfast cereals, and milk). Put another way, averaging around 3,500 kWh per person of demand, whether with or without the solar panels and our SRECs payments, our monthly energy bill is typically cheaper than a single visit to the grocery store.

Because of the effort and money expended upfront for air sealing and insulation, all while trying to carefully manage window placement and HVAC layout successfully, we’ve managed to whittle our energy costs down to something highly affordable and resistant to significant cost increases. This should remain true, regardless of what’s happening in the market in terms of prices for natural gas, coal, or nuclear power (i.e. the major sources of power in our region, here in the Midwest). Worst case scenario, we add additional solar panels to get to Net Zero or even Net Positive in order to cancel out what remains of our monthly energy bill. This would require an additional 7-8,000 kWh of annual solar production, or roughly three times what our current system produces.

In our specific case as a household — averaging between 3,500-4,000 kWh of solar production per year (this amounts to nearly 40% of our annual demand), combined with SRECs — we nearly end up at Net Zero, at least in terms of total cash spent for energy (arguably the most important — maybe the only — metric that homeowners ultimately care about; whether it’s the total cost to build a new home, or in terms of the annual energy bill). As a result, there’s not much financial incentive to purchase additional solar panels to achieve absolute zero energy consumption (this is in site energy terms only). The fact that this all comes with a house that’s extremely comfortable and quiet to live in, regardless of season or room, makes our home only that much more valuable to us.

Passive House + Net Zero?

In addition to designing for Passive House, there is the question of Net Zero or even Net Positive buildings. While Passive House strategies eliminate a significant portion of overall demand by requiring a significant outlay of upfront funds for air sealing and insulation, once this pill has been swallowed, it’s normally cost-effective to incorporate renewable energy of some kind to cancel out the expense of the remaining energy bill.

A quick side note: An excellent resource, one that I found only as our build was coming to an end, is William Maclay’s book The New Net Zero. It contains a wealth of information, but, in particular, many specific construction details vividly illustrated. This is especially valuable for DIY builders, or even seasoned professionals, when evaluating all the possible elements of roof-wall-foundation assemblies.

Also worth noting, if this approach (Passive House + Net Zero) were adopted on a national level, including renovations, it would eliminate a large portion of aggregate energy demand, thus having a meaningful impact on greenhouse gas emissions and global climate change (up to 40% for construction and existing buildings).

Based on what we know at the moment, a combination of approaches — including Passive House building principles, Zero Carbon goals, and the use of renewables — could be the way out of the climate crisis over the long haul. In addition, if adopted as part of building codes, it could mean properly training the next generation of tradespeople (like European-style apprenticeship models, thereby also improving the build quality) while also being a tremendously effective jobs program.

Beyond Net Zero, or even Net Positive, in regards to energy demand, there is increasing awareness about carbon emissions more generally, and the variety of ways to radically reduce or sequester it, including the choice of building materials (for new construction or retrofit projects) or even how we decide to landscape our yards.

Passive House Cost Premium

Unfortunately, due to relatively inexpensive utility rates here in the Midwest, even though Passive House (or Pretty Good House) offers a significant reduction in energy costs if done well, when considered as a percentage of household income the numbers may appear much less impactful or motivating when faced with line items in a build budget for things like air sealing and levels of insulation that far exceed building code requirements.

In our case, the annual energy savings compared to something code-built would likely be in the $2-3,000 range. Fairly significant, but if the purchase price of the home is $500,000 – 1,000,000+ (fairly typical here in the Chicago suburbs for new construction) then even a $100,000 savings over the course of a 30 year mortgage may not convince someone to move beyond conventional construction practices (particularly if they have their heart set on a long list of high-end finishes and appliances). The upfront costs associated with meticulous air sealing and added levels of insulation — if not viewed as an investment in build quality — will likely appear frivolous to the average consumer.

“One of the issues we face here is the fact that energy is cheap, like most things in the Midwest. We don’t have the financial burden placed on us that the coasts do—real estate-wise and energy-wise. So there is not much enthusiasm around green building on a financial level; it’s almost always an ethical issue. The people who are interested want to do a good thing for the environment, as opposed to saving money on their utility bills. Another thing is that people are accustomed to discomfort—we have drastic and frequent temperature swings. It’s really humid in the summer and freezing in the winters, when drafty windows are just accepted. They are used [to] it, so it is hard to sell them on high-performance windows to be more comfortable; or taking measures to keep a basement from being wet—they just aren’t concerned about it. There’s a complacency that we fight against; there’s not enough financial gain to incentivize making upgrades.” — Travis Brungardt, GBA Q&A

Looking solely at upfront costs is likely to discourage most prospective homebuyers from pursuing Passive House (or even Pretty Good House in many cases), whereas looking at the cost of ownership, including the cost of monthly utilities, produces a more accurate comparison (note, however, this assumes the homeowner can stay put for at least the next twenty to thirty years).

A cost of ownership calculation should also acknowledge less maintenance costs year-to-year since, if the structure is detailed well, it should experience far fewer issues (none ideally), especially damage caused by bulk water intrusion, mold, or even air leakage. Granted, it may take a decade or more before this kind of damage is found in a conventional home, but when it is, it’s rarely (if ever) inexpensive to properly correct.

Hard Choices

As a culture, we have been in a similar place before. One quick example would be automotive engineering applied to car safety. In terms of perspective, if you get the balance between cost and safety wrong when evaluating value, then seat belts, air bags, and better designed bumpers might seem like misspent dollars.

“Nader argued that Detroit willfully neglected advances in auto safety, like roll bars and seat belts, to keep costs down… But using [seatbelts] was strictly voluntary. And many Americans didn’t want to.”

— Daniel Ackerman, Before Facemasks, Americans Went to War over Seat Belts

In a similar vein, the American consumer has been taught by the market, realtors, and builders to believe cost per square foot is the gold standard of value. As a consequence, little emphasis is placed on building science basics such as air tightness, proper moisture management, thermal performance, or indoor air quality. In layman’s terms, this means the average American home is leaky, parts of it have likely been damaged by bulk water or mold, and it’s uncomfortable in terms of indoor temperatures and humidity, all while delivering subpar air quality to its occupants.

In terms of quality construction and ‘green’ building (Passive House or not), the hard truth is there really is no free lunch (not even renting: rentcafe). Quality, of any kind — finishes, proper moisture management, occupant comfort, even reduced energy bills — has its price, but only those who recognize its value will be willing to pay for it.

Regardless, as homeowners we either pay upfront for the air sealing and insulation, along with high performance HVAC for better IAQ, or we pay monthly (and perpetually) in the form of higher energy bills (this normally comes with less occupant comfort) and far inferior IAQ. Either way, the money is going to be spent, it’s just a question of when (upfront vs. long term month-to-month) and for what (air sealing and insulation vs. mediocre systems and underwhelming outcomes that require costly maintenance over time).

As with car safety in the past, depending on one’s point of view, the answer to these kinds of construction and homeownership options are either obvious or nonsensical. Nevertheless, regardless of the path taken — conventional construction or some version of high performance — no one’s wallet will remain closed for long.

Flooring: 3/4″ Hardwood

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Hardwood vs. Carpet

In our previous home we made the decision not to use any carpet. Not only did we prefer the look of combining tile (for wet areas) with hardwood (living areas and bedrooms), we also knew these surfaces would be easier to keep clean than carpeting. Although I grew up in two homes that both had mostly wall-to-wall carpeting, it was only after having to rip up several rooms of carpet that I realized just how much dirt and general detritus gets trapped below the surface.

There does seem to be an element of generational change (some would argue even social class) involved in this choice between carpet and hardwood. For example, my parents, who grew up on farms in the 1940’s without carpet, were shocked that we preferred hardwood flooring since having wall-to-wall carpeting was a big deal for them when they moved to Chicago in the late 1950’s. To them, hardwood flooring signified the outdated past while carpeting was the future.

Having lived with both, I don’t think I’d ever choose to go back to carpet. In addition to being much more visually interesting, I find hardwood flooring not just easier to keep clean but much easier to fix or repair should damage occur.

Which species of wood?

For our last house we went with pre-finished 3/4″ x 5 1/4″ wide plank Australian Cypress. Even though we loved the look of the Australian Cypress, it was more expensive than other species and it seemed to dent more easily than its Janka hardness score would suggest.

Oak is, by far, the most popular wood species for flooring, seen in countless stain color variations, but we wanted to try something with more natural color variation from one board to another.

For our new home we knew we still wanted to go with only hardwood and tile, even though there are now more eco-friendly and sustainable carpet options. We also knew we’d have to utilize a low or no VOC finish for the wood flooring in order to maintain a high level of indoor air quality.

Another option to consider is engineered vs. 3/4″ solid hardwood flooring. Because of the additional wear layer, and because I’d previously worked with a solid hardwood in my last house, we opted for the 3/4″ solid.

Also, since we went with a prefinished hardwood last time, this time we decided to try a traditional install, meaning sanded and finished in place.

The only real gripe we had with the pre-finished flooring in our last house was the beveled edge between boards, creating grooves that can trap dirt. Also, we felt it was slightly less visually appealing than a traditionally finished floor. Nevertheless, we would consider pre-finished flooring to be a viable option, especially if you’re having to work under severe time constraints and you need a room or whole house completed quickly.

3/4″ x 4″ Hickory

After considering various wood species, we settled on Hickory since it can look similar to the Australian Cypress, while its Janka hardness score is slightly higher, giving us some added durability. It’s also harvested and shipped from within the US, so it cuts down on shipping costs and total embodied carbon emissions.

Looking around locally, including our local Floor & Decor, I could only find manufacturers who packaged their flooring in boxes of shorter boards (the longest boards typically in the 4′-7′ range). Using shorter boards tends to produce a choppy look, reminiscent of a brick running bond pattern.

Online the options seemed much better, although shipping costs had to be factored in. It was also difficult to find the color variation we were after since much of the Hickory that’s available would be classified as clear or select (NWFA). In the end, we used Countryplank, ordering their Old Growth Hickory in random lengths (2′-10′).

After initially receiving someone else’s order in an entirely different species, Mark from Countryplank quickly took care of the problem and got my correct flooring to me the following week. Once it showed up on site, the boys were back to help me carry it in the house — as always, many thanks to them for helping us out with the grunt work.

unloading wood flooring
Smitty and Ricky helping us unload the truck.

Of course when the flooring was being delivered it turned out to be one of the coldest days of the year with plenty of snow around. Thankfully, with the guys helping us, it went pretty quick.

Installation

Before installing the Australian Cypress in my last house, I used a book from Don Bollinger as a helpful how-to guide. The book came with a video companion, which I’ve since lost, but much of the footage has shown up on YouTube:

And there are many other helpful videos available as well:

After clearing a room of tools and other construction related items, I set to work prepping the Advantech subfloor.

family rm b4 wood floor
Setting up to prep the family room subfloor.

Although the Advantech is said to resist moisture better than other OSB or plywood subflooring, because of the delay in construction after firing our pair of GC’s, the sheets of Advantech saw more exposure from the weather than is ideal.

Nevertheless, apart from having to grind and sand down some edges that had expanded due to moisture, the Advantech held up incredibly well. In addition, since the framers used nails to fasten it to the floor joists I went through each room adding decking screws to help stiffen the floor even more.

Once this was done, I was able to put down some red rosin paper. In my last house I had used 15# roofing felt, but since it’s embedded with asphalt I decided, for the sake of indoor air quality, that the red rosin paper was the better option. Rather than using it to control moisture, it’s mainly helpful in keeping a neater workspace as the flooring goes down.

mbr red rosin
Red rosin paper going down in the master bedroom.

With all of the red rosin paper down, it was time to bring in the tools and to start arranging piles of wood flooring based on length and color. As I unwrapped each pile of boards I went looking for the longest and darkest boards, making sure to have them nearby as I tried to use the longest boards first, and then be selective about how to place the darkest and most attractive pieces. When all the rooms were complete, I wanted the leftovers to be mostly shorter and lighter colored pieces.

family rm prepped 4 wood
Family room prepped for hardwood flooring.

The only other major decision before beginning to install the flooring was orientation. Most homes utilize the longest wall in a space as a guide, installing the wood parallel to this wall. Ideally this would also mean the flooring runs straight from the front door entry area to the back of the house in bowling alley fashion. This assumes the floor joists are perpendicular to the direction of the wood flooring. In our last home, and in our current Passive House, we could have oriented the hardwood flooring in this ‘straight’ pattern, but after trying and loving a diagonal pattern in our last home we knew we wanted to stick with this angled pattern. The only significant downside to the diagonal pattern is additional cuts are necessary so, therefore, more wood is required.

family rm wood going down
Arranging pieces before getting started.

The use of spline pieces, or split tongue, was helpful when making a change of direction, or establishing the border where the hardwood flooring met the tile in the kitchen, utility room, entry, and bathrooms.

kitchen outside corner w: router
Finishing up the family room. Note the shorter pieces of spline on the tile, and the router used to make a connection between the main pieces and the wood border next to the kitchen tile.

When I needed to create a groove I used a groove bit with the Bosch router before gluing and installing a section of spline. This was especially helpful where the wood met up with tile and I needed to first create a border piece.

First, using a table saw I would cut off the tongue side of the board, facing this side towards the tile. Now with the groove side exposed I could cut to length the piece I needed to butt up against this border piece against the tile. Once it was cut to length I could use the router to make a groove on the end that would be in contact with the border. With the border piece and the field piece now having grooves it was easy to add the spline in between, making for a tight, durable connection between these two pieces with some wood glue.

family rm mostly done
Done with the family room and ready to head towards the front door.

The diagonal pattern also means that the flooring nailer runs out of room before you get to the wall because of the angle involved. For these last few inches I utilized a trim nail gun, shooting into the tongue and face nailing a couple of nails at the outside edge. Even though these nails are significantly weaker than the flooring nails, we haven’t experienced any gapping or other issues at the perimeter of our walls. This may be due to the fact that we don’t see wide swings in the levels of indoor humidity (typically the house stays within 30-55% relative humidity; most of the year hovering around 40%) because of the air tightness and high levels of insulation required of a Passive House.

It probably also explains the lack of floor squeaks. When there are wide swings in outdoor humidity we sometimes get a couple of ‘pops’ from the wood flooring itself, but we’ve never had an issue with the floor joists/Advantech connection squeaking. In our last home, a conventionally built tract home, similar changes in humidity made our wood floors sound like they were in a hundred year old farmhouse, popping with almost every step until the humidity and the wood itself had a chance to stabilize.

One of the best tool purchases for the entire build was this Powernail ‘persuader’. Whether at walls, or out in the field, this tool works exceptionally well at closing unsightly gaps that would otherwise need to be filled with wood filler.

powernail persuader
The Powernail ensured a much tighter floor installation.

And the Powernail was an excellent guide for identifying bad boards — if it couldn’t close gaps on a particular board, it meant that board shouldn’t be used.

For spots or areas that would need some extra attention during sanding, I marked these with a pencil, either with an X or a circle.

marks for xtra sanding
Spots requiring careful sanding marked with X’s or circles.

Before sanding I also went around applying wood filler to all of the nail holes, any voids in the many knots, and to any remaining gaps between boards (mostly where the ends butt together). For the deepest voids in the knots I made two passes with the wood filler, sanding in between coats. In the end this produced a much smoother finish.

I found the Timbermate brand online, and was pleasantly surprised at how easy it was to work with and how well it’s performed over time. I started out with half a dozen different colors, but eventually narrowed this down to just two colors: Beech/Pine and Chestnut. In effect, these two colors spanned the wide variation in color from light to darker boards.

Although it claims to be zero VOC, it does have a distinct and slightly funky smell as it comes out of the jar. This odor completely disappeared once it was sanded down and the floors were sealed with tung oil. The Timbermate is also very easy to sand smooth.

wood putty for floors

Sanding the Floors

Thankfully, the flooring didn’t require a lot of sanding, nowhere near the amount typical in strip oak flooring. Overall, the flooring did seem to be precision milled and I ended up with very few completely unusable boards.

not much sanding
This was about as bad as it got. Most boards came together much better than this.

I could’ve rented a traditional floor sander and edger, but after reading about Festool’s orbital sander and then a similar sander from Bosch, I decided to try the Bosch out and see what it could do. I started in a smaller room, my daughter’s bedroom, just to see how long it would take to do a room-sized amount of sanding. Starting with 40 grit for the worst areas, I slowly worked my way through increasing grits, ending at 150 for a smooth finish ready for tung oil.

Since I was able to work through the various grits in just over an hour, I decided to keep using the Bosch sander for the duration of our project. Again, if I was sanding conventional oak strip flooring purchased from a big box store, I definitely would’ve rented the normal sander/edger combo.

bosch sander
Bosch orbital sander.

Since I was installing and finishing room by room (we had a lot of construction ‘stuff’ to maneuver around, but that we wanted to keep onsite), renting the equipment, in addition to being more expensive, would’ve meant a lot of back and forth between home and the tool rental center. Also, once the flooring was done, I still owned an excellent sander. It’s easily the best sander — palm or orbital — I’ve ever owned. The lack of vibration compared to comparable sanders makes working with the Bosch a real pleasure.

bosch sander ready to go
Utility room ready to be sanded.

Hooked up to a shop vac with a HEPA filter, the sanding dust was kept to a bare minimum, making the house pleasant to work in, regardless of the amount of sanding just completed.

Just before starting the wood floors my Fein shop vacuum died on me. I picked up a Ridgid brand vacuum from Home Depot mainly because it was the quickest option, fully expecting to be disappointed by its performance. To my surprise, it worked even better than the Fein vacuum and at a much lower price point.

rigid vacuum
I was surprised how well this Ridgid vacuum effectively contained the sanding dust.

Once the floors had been sanded down, it was finally time to start finishing with tung oil.

wood entry tile
Front entry transitioning to hardwood flooring.

Finishing the Floors with Tung Oil

Before we started the tung oil we made sure to tape edges where the wood met tile, mainly to keep clean-up to a minimum, but to also protect the grout from being darkened by the tung oil.

wood tile tape b4 tung
Utility room ready for tung oil.

Real Milk Paint, the company I purchased the tung oil from, has an excellent how-to video on doing wood floors:

We used close to a 50/50 mix of tung oil and citrus solvent, with just slightly more citrus solvent added to encourage deeper penetration of the tung oil.

My ‘helpers’ enjoyed doing the first coat with me in each room since there was such a dramatic color change as the tung oil initially went down. The tung oil really makes the grain and all the color variation in the wood really come to life.

First, we brushed in from the perimeter edges several inches, before rolling the rest of the floor with a lambswool roller connected to a paint stick. We were careful to not get too far ahead of the roller with the cutting in, hoping to avoid any ‘flashing’ that could show up where these areas meet up once the floor was completely dry.

family rm 1st coat
Anita brushing in the edges before rolling out the remainder of the floor.

It was always exciting to watch this dramatic transition from light and dusty to amber, dark, and stunning.

starting in br closet tung
Beast helping me start in her bedroom closet.
tung oiling s's br
Making our way across her bedroom floor.

Close-up of the hickory as the tung oil is applied:

dry tung
Dramatic change in color as the tung oil is applied.

Making progress across the family room floor:

dry tung family rm
First coat of tung oil going down in the family room.

Once the floor had a full coat of tung oil applied, we waited about 45 minutes before looking for areas where the oil had completely soaked in — this was especially pronounced around the many knots in the wood.

kitchen wet stay wet
Family room coated with tung oil.

After waiting an additional 45 minutes, we hit these ‘dry’ spots again. Once another 45 minutes were up we then wiped down the floors with cotton rags, available in 20 pound boxes from a local paint store.

s's br just tung oiled
Floor rolled, waiting for the tung oil to soak in.

Typically the floors were completely dry within 24 hours, but sometimes we waited one more day before repeating the same process a second and final time.

br entry after tung
Following morning after first application of tung oil.

After two separate days of applying the tung oil in this way, the floor was finally finished and I was ready to move on to the next room.

s's br after tung
2nd bedroom ready for baseboard.

It does take quite a few rags to wipe the floors down properly. It’s also worth noting that we were extremely careful once we were done to dispose of the rags responsibly in order to avoid a fire from the oil-soaked rags — a more common occurrence than most people realize.

final wipe down in mbr
Anita doing a final wipe down in the master bedroom.

In fact, when we thought we were done wiping, we’d go back one last time, walking the floor with rags under our shoes to get the last bit of tung oil that was inevitably still oozing up out of the hickory.

kitchen family rm after 1st ct tung
Family room ready for second day of tung oil application.

Here’s a close-up after the first coat color change next to the kitchen tile. We really like the contrast between the warmth of the wood and the cool gray of the tile:

kitchen wood connection after tung
Family room meets kitchen tile.

We also used this tung oil process on our basement stairs, which had hickory treads, along with a landing covered in hickory installed diagonally like the rest of the flooring.

Paul, from Signature Stairs, was the salesperson for our basement stairs. He made measuring and ordering what we wanted very easy, and he even took the time to stop by right after the stairs were installed and immediately took care of a minor touch-up for us. We’ve been extremely happy with the stairs. In fact, they were so well built we’ve yet to have even a single squeak, which, when compared to our last home, is extremely impressive.

base stair steps after tung

Because of the amount of variation in the wood, it was a lot of fun playing around with how best to show off the darker pieces. I always tried to keep in mind where furniture would end up, saving the most dramatic pieces for those areas that would remain out in the open and highly visible.

mbr b4 tung
Master bedroom ready to be sanded.

And it was always exciting to see the transformation from unfinished to very rich looking as the colors in the wood popped after the application of the tung oil.

mbr after tung
Master bedroom after tung oil.

We really love the color variation from one board to another. The range of colors and textures in the grain is stunningly beautiful. Visually the floors run the gamut from what looks like pine, walnut, tropical hardwood, oak, maple, birdseye maple, some boards with insect damage and staining, to of course clear hickory. This wide variety of colors and textures celebrates the full breadth of what the wood has to offer (as opposed to just clear grade), and it nicely adds to our overall Urban Rustic and wabi sabi design aesthetic for the house.

Here are some close-ups of individual boards showing this wide variation in looks:

tropical
Some of the darker boards look like walnut.
orange w: insect
A few boards had this insect or worm hole damage, including some attractive streaking.
lighter almost pine
Waves reminiscent of end grain Douglas fir.
light w: staining
There were several boards with this dark streaking over a much lighter background, as if the wood had been exposed to fire.
brown light red
The darker colors ranged from this walnut brown (at left) to a much redder, almost exotic tropical hardwood color (on the right).
lightest
The darker pieces were nicely balanced by many other lighter, more natural toned boards.
close-up knot w: staining
Even the knots themselves can be quite dramatic in terms of colors and smoky looking swirls.
beetle pine
There were even a couple of boards that look very much like beetle kill pine.

The orientation of the flooring was installed going with the main direction of foot traffic so that it feels like you’re almost always moving with the pattern in the floor rather than against it. In order to maintain this feeling throughout the house, it required changing direction in a couple of areas, for instance, where the kitchen and family room transition to the bedrooms. In these areas I used a transition piece in the door jamb of each bedroom to mark the change in direction.

mbr cu floor color variation
Master bedroom complete. Ready to change direction into the family room.

When the flooring changes direction it makes for a dramatic visual accent as the contrasting angles meet up. Below is the same area shown above, now with the family room flooring installed (but unfinished) next to the tung oiled master bedroom flooring:

family rm mbr wd flr meet
Change in direction from the family room (on the left) to the master bedroom (on the right).

Living with Oil-finished Hardwood Flooring

The tung oil finish is definitely softer and more prone to damage when it is first put down than a floor covered in a clear coat would be. After move-in day, I definitely noticed some scuff marks but no major damage. Since then, the tung oil finish has been holding up well.

Granted, we take our shoes off when entering the house, which definitely helps to keep dust and dirt under control, particularly the grit that can scratch wood floors. It also helps that we keep all food and drink in the kitchen. But this would’ve also held true had we gone with a clear coat finish on the wood, so there was no change in our behavior required from our last house to this one.

There’s only been a couple of times that a significant scratch or dent required getting out the Timbermate wood filler, the orbital sander, and the tung oil. In these cases, it was much easier to repair these relatively small spots than it otherwise would’ve been had the same damage occurred under a clear coat.

Overall, the main advantage a natural oil finish has over any clear coat is the amount of texture in the wood grain that’s allowed to come through (especially when viewed on an angle), combined with a matte finish, so the wood tends to look much more natural and warmer looking than it would if covered by multiple coats of clear finish.

mbr bath wood transition
Transition between master bath and master bedroom.

Nevertheless, I don’t think I would use an oil finish if we had a large dog, or if we preferred to keep our shoes on all the time. Under those circumstances, I’m guessing you’d have to commit to an annual spot sanding and tung oil application, at least in high traffic areas, to keep up with the damage so that it didn’t become too unsightly.

Hickory meeting kitchen tile.

Whether using a natural oil finish, or a more common clear coat, it’s worth exploring the options, including coming up with a few sample boards just to make sure you’ll be happy with the final look. A website like Green Building Supply is especially helpful in this regard, as they offer several brands of each kind of finish in low or no VOC products.

finished floor variation

It’s also worth noting that the initial wide contrast between the lightest and darkest boards has mellowed over time, so although the contrast is still evident it’s not quite as dramatic as it once was when the tung oil was first applied. Even so, we’re extremely happy with how our wood floors have turned out, and we have no regrets in terms of our choice of wood species or the use of an oil finish.