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Occupant Behavior Makes a Difference

Or, when is a Passivhaus not a Passivhaus?

Posted on Mar 9 2012 by Martin Holladay

Energy experts often repeat the cliché, “There’s no such thing as a zero-energy home — just zero-energy homeowners.” Energy monitoring data from two well-publicized Massachusetts homes — the so-called Montague Urban Homestead house in Turners Falls and the home of Matt and Laura Beaton in Shrewsbury — prove the cliché to be true.

Energy-use data for the two homes were shared in a presentation by Mike Duclos and Paul Panish at the Better Buildings by Design conference in Burlington, Vermont, on February 8, 2012. Duclos and Panish are energy consultants at the DEAP Energy Group in Newton, Mass.

The first of the two houses, the Montague house, is owned by Tina Clarke and Doug Stephens. It has won at least two awards: the $25,000 Massachusetts Zero Energy Challenge, and NESEA’s $10,000 Zero Energy prize. Energy-use data from the Montague house show that the homeowners used far less energy than predicted by energy models.

The other house discussed by Duclos and Panish, Matt Beaton’s house in Shrewsbury, is the first certified Passivhaus in Massachusetts. Energy use data from the Beaton house show that the homeowners used far more energy than predicted.

The key factor in both cases was occupant behavior.

The Montague house

The Montague house was built by Bick Corsa with help from the homeowners. Construction was completed in 2009.

Here’s a snapshot of the house:

  • Size: 1,152 square feet
  • Number of bedrooms: 3
  • Foundation: slab on grade
  • Foundation insulation: 6 in. XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation. (R-30) on 5 sides of the slab
  • Wall construction: Two rows of 2x4 studs
  • Wall insulation: R-42 dense-packed cellulose
  • Attic construction: Vented unconditioned attic
  • Attic floor insulation: R-100 cellulose
  • Windows: Thermotech Fiberglass windows with orientation-specific triple glazingWhen referring to windows or doors, the transparent or translucent layer that transmits light. High-performance glazing may include multiple layers of glass or plastic, low-e coatings, and low-conductivity gas fill.; south glazing is U-0.23 and 0.44 SHGCSolar heat gain coefficient. The fraction of solar gain admitted through a window, expressed as a number between 0 and 1.; interior R-6 insulated shutters
  • Winter design temperatureReasonably expected minimum (or maximum) temperature for a particular area; used to size heating and cooling equipment. Often, design temperatures are further defined as the X% temperature, meaning that it is the temperature that is exceeded X% of the time (for example, the 1% design temperature is that temperature that is exceeded, on average, 1% of the time, or 87.6 hours of the year).: -5°F
  • Design heating load: 7,500 Btu/h
  • Space heat: Fujitsi 9RLQ ductless minisplit air-source heat pumpHeat pump that relies on outside air as the heat source and heat sink; not as effective in cold climates as ground-source heat pumps. rated at 9,000 Btu/h
  • Domestic hot water: 2 4’x8’ flat-plate solar collectors with an 80-gallon storage tank; backup provided by a Tempra 24 on-demand electric resistance water heater.
  • Mechanical ventilation: Lifebreath HRV(HRV). Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger; a similar device, an energy-recovery ventilator, also transfers water vapor. HRVs recover 50% to 80% of the heat in exhausted air. In hot climates, the function is reversed so that the cooler inside air reduces the temperature of the incoming hot air.
  • PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow. system: 4.94 kW
  • Refrigerator: Ultra-low-energy Sundanzer chest refrigerator uses only 34 kwh/year
  • Cost: About $200,000

Energy modeling (using REMrate software) predicted that the homeowners would consume 5,479 kWh of electricity per year; in fact they used only 1,959 kWh — that is, only 36% of the projected usage. Average consumption was 163 kWh per month.

The home’s PV array produced 4,892 kWh during the first year — two and a half times as much electricity as the owners consumed.

Of course, there is no secret to low energy use. We all know how to do it: don’t use much hot water, only turn on a light when you really need to, and keep the thermostat low. (Clarke and Stephens reportedly kept the thermostat at 60°F when they were home, and turned off the heating system when they weren’t home.)

After all, the owners had a strong motivation to keep their electricity usage low: they were aiming to win two cash prizes worth $35,000. They succeeded — in part because their modest home has an excellent envelope and extremely efficient HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. equipment, but mostly because they were focused like a laser on energy conservation.

Mike Duclos summed up the situation this way: “These are not normal users.”

Matt and Laura Beaton's house

Matt and Laura Beaton moved into their new home, the first certified Passivhaus in Massachusetts, in 2011. Since Matt Beaton owns a construction company, he is the builder as well as the owner. The architect was Mark Yanowitz, and the Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. consultant was Paul Panish.

Here’s a snapshot of the house:

  • Size: 3,399 sq. ft.
  • Basement slab insulation: R-41
  • Basement wall insulation: R-51
  • Above-grade wall construction: Double wall construction with 2x6 inner wall and 14-inch-thick I-stud outer wall
  • Above-grade wall insulation: R-65 cellulose
  • Ceiling insulation: R-126 cellulose
  • Windows: Accurate Dorwin windows with orientation-specific triple glazing; center-of-glazing specs: south windows U-0.16, SHGC = 0.64; remaining windows U-0.13, SHGC = 0.55
  • Space heat: Mitsubishi MXZ-3A30NA ductless minisplit air-source heat pump with 2 indoor heads
  • Domestic hot water: 2 4’x8’ flat-plate solar collectors with an 80-gallon storage tank and electric resistance backup
  • Mechanical ventilation: UltimateAir RecoupAerator 200DX ERVEnergy-recovery ventilator. The part of a balanced ventilation system that captures water vapor and heat from one airstream to condition another. In cold climates, water vapor captured from the outgoing airstream by ERVs can humidify incoming air. In hot-humid climates, ERVs can help maintain (but not reduce) the interior relative humidity as outside air is conditioned by the ERV.
  • Air leakage rate: 0.44 ach50

According to Panish, who has been monitoring the home's energy use, the owners are using much more energy than predicted. “There is higher than expected cooling demand,” said Panish. “High internal loads are adding to the cooling loads. The default value for internal loads according to the PHPP software is 621 watts continuous, but the actual internal loads at this house are 1,061 watts continuous.”

The data were a surprise to Panish. “Something unexpected is going on,” he said. “Plug loads are sky high.”

It didn’t take long to figure out what was driving the high energy bills. “There is a very large plasma TV, plus a second TV on the porch,” said Panish. “There is a DVR. The two TVs and the DVR use 600 watts when they're on and 100 watts when they are off, and the TVs are on for an average of 6 hours per day. The loads for entertainment and computers are high. There is an old freezer in the basement. There is a basement dehumidifier. The lighting load is 600% of what was predicted. It seems as if all the lights in the house are left on all the time.”

After delving into the data, Panish reached a few conclusions. “You’ve probably seen a bell curve showing energy used by a range of Passivhaus homeowners,” said Panish. “Well, this family is at the high end of the bell curve. They are concerned about energy use, but their concern doesn’t get reflected in their behavior. The implication was that once they built the house with the good envelope, the job was done. But the job was not done.”

The bell curve will never go away

There are several points to be gleaned from the monitoring data from these two houses:

  • Although both of these houses have excellent thermal envelopes and very efficient HVAC equipment, the occupants of the Beaton house used more than 7 times as much electricity as the occupants of the Montague Urban Homestead. (Of course, the Beaton house is 3 times as big as the Montague Urban Homestead).
  • No matter what kind of house you live in, you can achieve significant energy savings by following your grandmother’s advice: turn down the thermostat, close the door, turn out the light, and don’t leave the faucet running.
  • It’s possible for occupants of a Passivhaus to use a lot of energy; the Beaton family uses 14,744 kWh of electricity per year. (The national average residential use in 2009 was 11,040 kWh per household; of course, unlike the Beatons, most of these homes also used significant quantities of natural gas, propane, or fuel oil in addition to electricity.)
  • When occupants of a Passivhaus use more energy for lighting and appliances than expected, there is one positive side effect: the waste heat from the humming appliances reduces the heating load.
  • The default values for plug loads provided in the PHPP software may make sense for the typical German family, but they are probably too low for the typical American family.

Last week’s blog: “The High Cost of Deep-Energy Retrofits.”

Tags: , , , , ,

Image Credits:

  1. Matt Beaton
  2. Paul Panish

Mar 9, 2012 4:38 PM ET

by Eric Sandeen

Continuous 1kW load in a Passivhaus? The mind boggles. :) Having chosen a passivhaus, I guess I would have expected occupants to be more savvy about energy. LED TV vs. Plasma, for starters? And I'm a little surprised that the entertainment center wasn't on a switched outlet or something?

I'm starting to think more and more that the always on / continuous load is one of the very first things to look at in an energy audit, speaking as an outsider to all this. :)

Mar 9, 2012 7:56 PM ET

Ah, the human factor.
by James Morgan

No engineering that away.

Mar 10, 2012 9:13 AM ET

Renewable Electricity
by shane claflin

It sounds like the Beatons would be good candidates for a PV system.

Mar 10, 2012 9:42 AM ET

effect of monitoring
by 5C8rvfuWev

In the discussions here on the use of monitoring to measure building performance, I've wondered if "knowing" would impact behavior .... if seeing the effect of my behavior on load and cumulative use ... and cost ... would be a nagging reminder to change what I do.

Is there any plan to go back to these folks' houses later on ... to see if the Beatons adjust in some meaningful way ... or if the residents of the Montague house tire of their disciplined usage and find a different comfort range. Did Duclos or Parish mention follow up, Martin?

Mar 10, 2012 10:17 AM ET

I dunno
by Keith Gustafson

Their 'bad' behavior still uses a lot less total energy than many of us [hand raised]

Mar 10, 2012 10:27 AM ET

similar range
by Dan Kolbert

We've seen similar ranges in our small sample of new houses. Obviously good design and careful construction is important, but strong buy-in by occupants is critical. Yes, they're going to use less power living large in a Passive House than in an Energy Star house, but if their energy consumption gets publicized as the norm for high performance homes, it is hardly good advertising for the importance of the work.

Mar 10, 2012 10:44 AM ET

Response to Keith
by James Morgan

Their 'bad' behavior still uses a lot less total energy than many of us [hand raised]

Good point. Of course this does point out that homeowner behavior constitutes a major variable to cost/benefit projections. A dramatic rise in future energy costs (an even bigger variable) would perhaps get the homeowners attention and improve their energy habits. So it all might even out. And at the very least they now have better options than most of us.

Mar 10, 2012 6:50 PM ET

that means beaton house
by mike eliason

that means beaton house missed the mark on performing as a passivhaus. the worst case they could have done energy-wise was 14,015kWh/a. for me, this further cements the notion that we should be striving to adopt the energy consumption of the germans or swiss, instead of trying to adopt PHPP/passive house to the average american's horrible consumption.

Mar 10, 2012 9:11 PM ET

by Keith Gustafson

If one buys a Nissan Leaf one loses ones certification?

You can lead a horse to water..............

Mar 10, 2012 11:12 PM ET

Initial construction costs also have weight.
by deniz bilge

How much did the Beaton's house cost? I wouldn't be surprised if it cashed in around $350/ft--a huge investment for, in my opinion, not much more than status and conversation. I can't see the payback being worth it... Given that the Montague house is basically a double 2x4 home with great attention to insulation detail, ornamented with renewable energy and fiberglass windows, the $174/foot is still a high cost (not by much, but still high) in my opinion. Kudos to the Montagues for conservative energy use practices, but I think that getting a home in the $125/ft range is do-able. At about $50/ft more than traditional energy star home building, I can see payback, but not for a while... I'm building a 3400 sq ft --a pretty good house (attention to insulation, but not dedicated to it-....R-10 below basement slab, R-30 walls, R 45 roof in southern NJ)--home using icf, concrete, steel, for just under $50/ft...Granted, I'm doing 85% solo, but still doing it....Careful shopping, doing the research & design yourself, and flexible plans are a big part of the secret.
I think it's more important to compare the performance of the house to its cost per ft because that's pretty much the bottom line. Energy consumption can always be offset by energy production, but the cost of energy efficiency must be able to realistically be pay for itself in savings within a reasonable amount of time (in my opinion, no more than 7 yrs).

Mar 10, 2012 11:28 PM ET

by Dan Kolbert

Why 7 years? If you've got a 30 year mortgage, and financing the cost of energy upgrades is less than the savings from those upgrades, isn't that a good deal? Saving you $ from day 1?

Mar 11, 2012 6:14 AM ET

Edited Mar 14, 2012 6:13 AM ET.

Response to Joe W
by Martin Holladay

Studies of the effects of real-time energy use monitors with displays in the kitchen or living room have generally shown that the installation of such monitors results in energy savings, but the degree of the savings and the longevity of the effect are in some dispute. Read more here: Home Dashboards Help Reduce Energy Use.

Q. "Is there any plan to go back to these folks' houses later on, to see if the Beatons adjust in some meaningful way, or if the residents of the Montague house tire of their disciplined usage and find a different comfort range?"

A. I'm not sure; I can check with the researchers. But I think focusing on these two families misses the point. We could all write different endings to this particular drama: the Montague residents could either become extreme Luddites, and set their thermostats at 42°F -- or perhaps they could discover a new, energy-intensive hobby, like art welding. Perhaps Matt Beaton will fall off his donkey on the road to Damascus, and resolve to cut his energy use in half -- or perhaps he could install a huge conditioned wine cellar in this basement.

What I'm saying is, the personal dramas of these families is not the point. The point is that this bell-curve phenomenon exists, and the range is very large. I think we should keep that point in mind when determining whether Passivhaus obsessiveness -- Is it 0.6 ach50 or 0.7 ach50? -- makes any sense.

Mar 11, 2012 4:32 PM ET

Edited Mar 11, 2012 6:22 PM ET.

Response to Martin Holladay
by albert rooks


"What I'm saying is, the personal dramas of these families is not the point." Thanks - Well said.

"I think we should keep that point in mind when determining whether Passivhaus obsessiveness -- Is it 0.6 ach50 or 0.7 ach50? -- makes any sense."

We (green building industry) are good at envelopes but aren't really effective at changing occupant behavior. Just because part of the problem is beyond our scope of effective influence, let's not loose the energy in "normalizing" major strides in envelope design and practices.

It's American "obsessiveness" that get's an awful lot done in this world. I don't think it's time to "relax" our obsessiveness, curiosity, or expectation that "getting good" at "getting tight" is a realistic or worthwhile goal.

As businesses we do have to "fit the market", so "pretty good" is as important as "Passivhaus". But lets not pretend that "obsession" and the "pressure to improve" are not necessary and valuable.

Mar 11, 2012 6:08 PM ET

re Martin
by 5C8rvfuWev

No, certainly the point reaches a million miles beyond the two families. I was hoping that someone was measuring and monitoring and was seeing that some people -- some being the important word -- were able to learn from their needless overindulgences.

Such growth doesn't seem to me to be particularly technical but it does seem to fit the behavior of an adult.

Back to the regularly scheduled programing.

Mar 12, 2012 6:02 AM ET

Edited Mar 12, 2012 6:03 AM ET.

Response to Albert Rooks
by Martin Holladay

You wrote, "I don't think it's time to relax our obsessiveness, curiosity, or expectation that getting good at getting tight is a realistic or worthwhile goal."

I'm all in favor of air tightness and thick insulation, but I'm skeptical of the value of PHPP modeling, an exercise that requires many hours of expensive labor.

At the recent NESEA conference in Boston, Alan Gibson of GO Logic in Maine presented monitoring data on the so-called GO Home Passivhaus. During the period from November 2010 to November 2011, here's how the 6,947 kWh broke down: Lights and plug loads, 64%; ERV, 14%; Space heating, 12%; kitchen appliances, 12%. (During this time frame, there was no domestic hot water use because the house was used as an office.)

During a subsequent four-month period of monitoring, after a family had moved in, the percentages were a little different: Lights and plug loads, 28%; Kitchen appliances, 24%; Domestic hot water, 23%; ERV, 15%; Space heating, 11%.

Albert, as you can see, it's great to build a tight envelope and install lots of insulation. But we don't need to spend days filling out PHPP spreadsheets, because space heating isn't a problem.

It's all about the plug loads, which means it's all about occupant behavior.

Mar 12, 2012 4:09 PM ET

Plug Loads, Plug Loads
by Dan Whitmore

Yep, plug loads are undoubtedly a huge driver in building energy use today and will be moving forward. When I look at the Beaton House or the GO Logic Home though, I see a building that's ready for the future. Not just for short-term bragging rights (with award money!) of having the most efficient residents' behavior. We are continuing to detail our buildings for the near future yet hoping to utilize them for 50+ years.

If inefficient appliances, devices, plasma TVs, 15mpg SUVs and the like aren't confined to the obsolete heap in the closer future, in my mind all this work will be a sideshow. So, I'm working on the premise that in a generation or two, society will have at it's disposal much lower-energy using fixtures. The infrastructure we are constructing though will be there for the long-haul and needs to be crafted with the best design we can when we create it.

Sure it takes a few hours to run a building through the PHPP (or a thorough modeling program), but I can tell you clearly that it allows informed choices regarding where to put the additional effort during construction. Where can we best spend the additional $ on these structures? (Insulation in the roof, wall, sub-slab, foundation; windows - solar heat gain, U-values of frames, glazing, sizing, orientation (doors too); ventilation system efficiencies; building orientation; envelope shape; the mechanical systems...) The list is VERY long yet it can be optimized, for initial installation cost as well as long-term usage. Only relying on prescriptive measures doesn't account for the intricacies of building for optimal performance. That said, I don't see every individual project going through extensive modeling, though many, especially unique ones and larger ones, will benefit. As the tools become easier and more widely used, however, I personally hope that in that next generation it will be standard practice.

So, with the hope that nearly all structures built or significantly retrofitted are looking for the 50-100+ year return, I think it's another tragic case of American short-sightedness that we stop short of where they could be for fear of engaging a relatively small effort.

Mar 12, 2012 4:41 PM ET

Edited Mar 12, 2012 5:05 PM ET.

Response to Dan Whitmore
by Martin Holladay

Many builders have known for years what a "pretty good house" looks like in their climate zone. Here in Vermont, smart builders have (for many years) been building rectangular 2-story buildings without bump-outs, with the long orientation east-west, and built with attention to air sealing, with the following insulation levels: R-15 or R-20 basement walls, R-30 or R-40 above-grade walls, and R-60 attic floors. We've been installing orientation-specific triple glazing, with about half of the glass area on the south side, and very little or no glazing on the north.

Many builders have been building this way for 20 years -- without PHPP. And you know what? The difference between this house and a house with a $3,000 Passive House consultant is less than one plasma TV. Furthermore, the difference can be in either direction -- because many wealthy homeowners who can afford to hire a Passive House consultant use more gadgets than the frugal Vermonters who make do without consultants.

I'm convinced that experienced builders and designers can learn the difference between an energy-hog building and a well-designed building without thermal bridges or nosebleeds -- and that a good builder or designer can develop a gut reaction to design suggestions.

For example, when I first saw Katrin Klingenberg's Smith house, my first reaction -- one I think would be shared by any builder who designed passive solar homes in the 1970s and early 1980s -- was, "this house is going to overheat in March and October." Although the house went through the PHPP process, it apparently didn't go through the process of vetting by an experienced builder.

Klingenberg later had to install a trellis to keep the sun out of her house during the swing seasons and the summer.

I think that it would be great if architects had to play around with PHPP in architecture school. (Hopefully they'll use a version of PHPP that does a better job of predicting overheating.) Then, if we're lucky, architects might graduate with a well-developed sense of what a good building looks like.

Mar 12, 2012 6:30 PM ET

As an experienced builder, I
by Dan Whitmore

As an experienced builder, I find it very rewarding to be able to use modern modeling tools to test my 'gut reactions' before the nails fly. Some were right some were wrong. But now I don't need to depend on notoriously subjective occupant behavior/feedback, as your article demonstrates very well, to determine how what has already been built may perform.

Certainly for reputable, forward thinking builders a $3000 additional fee may not be necessary (though for a standard SF house that seems to be a number out of an over-sized hat - including all rating and certification, maybe?) However, watching 3 new places go up right nearby me and seeing them receive Built Green 4 Star Ratings (4 out of 5 possible, which didn't come free, I assure you) while putting together a basically energy-code building makes me very disappointed. Now the developer is selling them for about $550K in the low-rent part of Seattle? Seems like it would have been money very well spent convincing reticent individuals on what is a good path/goal to work with.

Re the trellis on the Smith House, my recollection is that was planned from the beginning, installation just waited until feasible.

Mar 12, 2012 10:37 PM ET

Edited Mar 12, 2012 10:43 PM ET.

My first passive solar SIPs
by Richard Patterman

My first passive solar SIPs house sold to a couple that bought it because of the view, floor plan and schools. They drove a SUV and had jet skis and snowmobiles, no bikes or skis. The monitored results were very disappointing!

What we can do is well thought out electrical switching and lighting so at least the occupant has the option to manage use.

Often thought meters or monitors that had readouts in flashing $Amounts$, might help.
Or maybe an electric meter that you had to feed with quarters and you could only buy 20 kWh at a time.

At some point in the life of the buildings we are building today, energy costs will be high enough that IT WILL MATTER!!!

Mar 13, 2012 5:47 AM ET

Edited Mar 13, 2012 5:50 AM ET.

Response to Dan Whitmore
by Martin Holladay

You wrote, "As an experienced builder, I find it very rewarding to be able to use modern modeling tools to test my 'gut reactions' before the nails fly. Some were right some were wrong."

I don't doubt what you are saying. I'm saying something else: that the BTU difference between the two alternatives that might fool an experienced builder like you are so small that they fall into the category I call "misplaced accuracy."

You are worried about the PHPP subtleties -- by definition, subtleties that are so small that your gut is wrong -- and then the occupants move in with all their stuff from WalMart, and plug everything in. Space heating is 15% of energy use, and plug loads might be 55%. So why were you sweating over PHPP?

You wrote, "I don't need to depend on notoriously subjective occupant behavior/feedback." I don't depend on feedback monitors either, because the occupants will do what the occupants will do. These monitors might help a little, and they can't hurt, but the real motivator is the price of energy. That's why we need to lobby our legislators for carbon taxes.

Mar 13, 2012 8:49 AM ET

Edited Mar 13, 2012 8:50 AM ET.

Response to Richard Patterman
by Martin Holladay

Good points.

You wrote, "I often thought that meters or monitors that had readouts in flashing $Amounts$, might help. Or maybe an electric meter that you had to feed with quarters and you could only buy 20 kWh at a time."

Both gadgets exist. If you want an energy-use monitor with an indoor display calibrated in dollars, you can choose The Energy Detective monitor or the PowerCost monitor.

Prepaid electrical meters are manufactured by several South African companies. They are usually installed in low-income neighborhoods; residents can't use electricity until the electronic meter is loaded with a payment. (These meters generally don't accept coins, however; they usually require some type of electronic funds transfer.) When you use up all of the electricity that you have already paid for, your house goes dark.

As you can imagine, these meters have colonial overtones, and are often viewed unfavorably in low-income neighborhoods.

For more information on prepaid electric meters, see:
Battle brewing over prepaid electric meters

A distributor of prepaid electric meters

Prepaid electric meters in India

Oklahoma utilities are eager to test prepaid electric meters

Mar 13, 2012 12:06 PM ET

Richard, Martin,loving the
by aj builder, Upstate NY Zone 6a

Richard, Martin,loving the banter, points,info and all in the last few posts.

Mar 15, 2012 10:06 AM ET

Response to Martin Holladay re: value of modeling
by albert rooks


You're certainly not going to let any "program" off with a "pass". Good. We are all forced to do our work better when we have to prove project performance, value and our own biases.

If I'm following you correctly it seems that you are questioning the value of taking the extra step of modeling the project with the PHPP because these cases illustrate that it could be a wasted effort due to:

Marginal performance gains vs cost of modeling.

Potential fall/spring over heating due to using solar gain to meet demand criteria

Moderate gains wiped out: "the occupants move in with all their stuff from WalMart, and plug everything in. Space heating is 15% of energy use, and plug loads might be 55%."

I agree with your skepticism.

Sometimes it would not make sense to model a project in PHPP: Simple straight forward projects where the clients are not interested in approaching or meeting the Passive House standard do not make sense. However, it seems to me that when the site is less optimal with poor solar access or other issues, then modeling with the PHPP can bring a level of accuracy that is extremely useful... If one chooses to use it, and regardless of a desire for PH certification.

The potential overheating question seems to nag at you... It's kept coming back to me over the last year too. Sure, increasing glazing to meet the heating demand is a tool that helps the designer meet the demand criteria. Sure it can be misjudged, or in fact mis-used. I don't think that you can blame the PHPP for overheating anymore that you can blame a saw for lost fingers. Its depends on who's hands the tool is in. And even when it's in good hands, mistakes happen. -Ouy! I'd certainly lean towards a little F/S overheating right now... In the Pacific Northwest it's been endless grey rainy days. I'd like more glazing, more light. The "seasonal affective disorder" has set it and it sucks.. At least too much glazing can be fixed with a little shading...

As to the Occupants: Well that is a least the one bright spot. They can change their behavior. That's the one thing in this whole scenario that can change (other than shading). Once the building envelop is done, it's done. Let's not relax skills or expense just because occupant behavior is out of our control.

Mar 15, 2012 10:18 AM ET

Keeping everything in perspective
by Martin Holladay

I agree with most of your points. Most homes don't need PHPP modeling, but the occasional modeling exercise is useful to keep a designer on his or her toes.

As we chase those last decimal points and save those last few BTUs -- at a price per BTU that rises steeply the deeper we dig -- we need to keep everything in perspective. To me, the fact that domestic hot water use and plug loads dominate usage mean that we need to focus on those items. Our nitpicking about small envelope details is a historical legacy from the 1970s; it's time to move on.

Mar 15, 2012 10:57 AM ET

Reply to Martin
by Cathy Rust

"I'm convinced that experienced builders and designers can learn the difference between an energy-hog building and a well-designed building without thermal bridges or nosebleeds -- and that a good builder or designer can develop a gut reaction to design suggestions."

Martin, I couldn't agree with you more! In theory, builders probably don't need to get very expensive passive house designation when they seal a building properly. However, what I've found is that there are many builders out there who build on spec. and don't really care how tight a building envelope is but are more concerned about their profit margins. A certification, whether LEED Gold or Platinum or Passivehaus, lets a prospective buyer know the building has been built to high energy efficient standards because it has passed certain minimum requirements as determined by an independent third party.
As many excellent and reputable builders as there are out there, there are unfortunately just as many who've gotten into the business to make a fast buck, and since a consumer buys a house only a few times in his or her lifetime, they're not going to necessarily be able to ferret out the good builders from the not so good. A certification gives them the confidence to know they're buying a well-made house.
I know this is off-topic, but I thought I'd chime in. Re occupant behaviour, as mentioned, the simplest way to get people to conserve is through price hikes. Simple, but effective -- just ask the Europeans.

Mar 15, 2012 12:08 PM ET

Cost of House #2
by Jason Burk

Can somebody knowledgeable throw us bone as to the cost of House #2? A rough number perhaps? It completely takes away from the relativity of the comparison, at least on one level which I truly desire to know!

Mar 15, 2012 3:02 PM ET

occupant behavior
by Greg Duncan

If occupant behavior is unpredictable, that's all the more reason to build the best envelope and HVAC system possible. It isn't my role to judge the future occupants of the buildings I design. In many cases I don't know who they will be.

Why sweat space heating if it's only 15% of the total energy use? Because that's what I can control as an architect. I can't tell the future residents that they aren't allowed to have a DVR or a home office.

Mar 15, 2012 3:10 PM ET

Edited Mar 15, 2012 3:22 PM ET.

educating occupants is part of our job
by David Butler

In recent years, my work (which is 100% new construction) has shifted from builders to homeowners. This has allowed me to attack occupant behavior. I spend a significant amount of time talking to clients about dhw and plug loads. Each person and family is obviously different, but in all cases it's important for the homeowner to have a sense of the relative impact of envelope loads compared to DHW and appliance/plug loads. In particular, those who do care about modifying their behavior need to have a better sense of where their efforts will pay off the most.

I encourage clients to purchase a couple of Kill-A-Watt modules. Some folks are more curious than others, but those who embrace this type of energy sleuthing typically find it to be "eye-opening" and are more successful in reducing overall energy consumption.

As Martin points out in his follow-up replies, when you consider the already low cost of heating and cooling a home that gets all the basics right, it doesn't make a lot of sense to pile R125 insulation in the attic or seal the house to sub-1.0 ACH50.

Regarding the Beaton windows... the relatively high-gain windows (shgc 0.55) on the non-south windows jumped out at me. Not surprising that cooling loads are higher than predicted, and it's not just the internal loads that are the culprit. This could easily have been avoided. What would really be interesting (for the Beaton house) is how much of their annual energy load is attributed to heating and cooling.

In my experience, and in my opinion, PH doesn't do a great job of addressing cooling loads (see my comments here).

David Butler

Mar 15, 2012 3:13 PM ET

Controlling what we can
by Geoff Briggs

It may be true that “There’s no such thing as a zero-energy home — just zero-energy homeowners" but in all but the mildest climates you cannot be a zero-energy homeowner without a very well performing home. That will only be more true going forward. As designers and builders of quality structures we want our buildings to outlive the average, hopefully but a factor of two. So we are obligated to build to the highest standards available today. And while we'd all love to educate all of the future occupants of our buildings in the ways of low impact living, realistically we can only influence a few of them. So we control what we can control and give currant and future occupants the tools they need.

It's great to hear that most builders in Vermont can build to near Passive House levels without modeling, or probably even plans for that matter, but if you look around this country you will not find this the norm. Code minimum with no site specific features. Certifications like Passive House offer buyers confidence, builders an opportunity to differentiate their product, and regulators and utilities valuable planning tools. If PHPP under-reports average plug load usage, or is unduly cumbersome or time consuming, that's a problem with the modeler, not a reason not to perform energy (or daylight, or ventilation) modeling.

Mar 15, 2012 4:51 PM ET

Response to Geoff Briggs
by Martin Holladay

You wrote, "It's great to hear that most builders in Vermont can build to near Passive House levels without modeling."

Not most builders, alas -- but a small subset of builders who pay attention to energy efficiency and superinsulation.

Mar 16, 2012 1:09 AM ET

Occupants need a new level of choices
by albert rooks

What irks me most is the wasted energy.

Changing behavior for an occupant is probably challenging. It's one thing to argue with a teenager about leaving lights on and taking shorter showers. I can understand that people get attached to their comforts and are resistant to change.

However, the stuff that really frustrates me are the phantom loads. I've got the usual array off electron sucking gadgets: and no real way to control the loads unless I unplug them. Sometimes I do and sometimes I forget. And I actually care about the issue. I could just imagine getting the "blank stare" from those who really don't understand the level of consumption going on and don't care enough to make it a priority.

Does it make sense to try a new approach? Why not run the wall circuits like we do our heat?

Put all room outlet circuits through a programable module just like a programable thermostat:

Just like programing a thermostat to turn the heat down while your a sleep or away, it could turn off the wall circuits during the same periods: Off goes the cable box, Plasma TV, phone,computer/printer transformers... Program out the periods where no one gets any comfort or benefit out of these loads.

I used to think that we should be adding "kill switches" to each room, but now I've moved on to looking at the whole system. It's not really that complicated to imagine a scenario where there is a line voltage relay system at the panel location that is controlling each (most?) room outlet circuits. The whole system can be programed by the occupants. A further backup could be in each room that is a simple override that when pushed will enable the rooms circuits (for like when you get up in the middle of the night). The room overrides could be done cheaply by low voltage rather than line voltage since they are controlling a relay system.

The point is that so far all of the suggestions require occupants to think, make decisions, and act. Something they probably don't want to do. If we can automate the shutdown of phantom loads like we rollback temps, it would probably work.

Has anyone had experience with curbing phantom loads other than just adding switched plug strips? Could this be a realistic solution? There's gotta be more solutions that can be developed.

Mar 16, 2012 4:15 AM ET

Response to Jason Burk
by Martin Holladay

Q. "Can somebody knowledgeable throw us bone as to the cost of House #2? A rough number perhaps?"

A. As far as I can tell, the construction cost of this house has not been made public. But it's safe to estimate that it cost more than $100 a square foot, and probably cost less than $200 a square foot. That would put the construction cost somewhere in the range of $340,000 to $680,000.

Mar 16, 2012 4:18 AM ET

Response to Greg Duncan
by Martin Holladay

Q. "Why sweat space heating if it's only 15% of the total energy use? Because that's what I can control as an architect."

A. Fair enough. But if you are facing a tough decision at the design stage and need to determine whether an expensive envelope measure is worth it -- a change that might save 7% of the heating cost -- it's important to remember that this represents only 1% of the energy use of the home.

Mar 16, 2012 4:21 AM ET

Response to Albert Rooks
by Martin Holladay

As someone who has lived off-grid for 30 years, I think there are two basic approaches to the problem of electronic devices with high phantom loads:

1. Buy as few of these devices as possible.

2. Put them on plug strips.

Really, it's not that hard. Of course, I don't have an automatic garage door opener, a digital video recorder, or a doorbell with a 24-hour transformer. But it sure saves the batteries from getting run down in the winter.

Mar 16, 2012 8:26 AM ET

It would take 10 cents worth
by Keith Gustafson

It would take 10 cents worth of hardware to turn every wall wart from a .5 watt standby draw to a 0 watt. It is 10 more cents than they want to spend. Similarly tvs etc could change from constantly drawing to charging a battery and monitoring it

On positive thing I have seen is the proliferation of usb chargers, meaning you can migrate toward one power strip if you choose

Mar 16, 2012 1:33 PM ET

vampire loads
by David Butler

@Albert, the scheme you described, using programmable relays, would cost far more than the energy saved in a lifetime. Actually, this type of system has been around for decades (based on GE RR-7 relay modules), and was at one time used by "home automation" pioneers. But unless a house is wired specifically with this in mind, killing an entire circuit to control plug loads would also disable lights. Not to mention having to reset all the clocks in electronic devices, as very few have b/u batteries.

As Keith pointed out, it costs very little to build devices with low standby power requirements. In fact, there's actually been a *lot* of activity in recent years aimed at reducing standby power in electronic devices (DoE and industry groups, see this). Great progress has been made, especially with TV's and set-top boxes, among the worst offenders. For example, my 8-yr-old satellite DVR consumes 50W whether it's on or off, but according to this table, the average is less than half of that with current models.

Computers are easy. Virtually all desktop computers sold in the last decade have standby or sleep mode (assuming user uses this feature). And laptops have had excellent power management since the beginning.

The key is to identify which devices are the biggest culprits in your home and focus on those, rather than trying to control everything. And there's plenty of information on the Internet to help folks make wise purchase decisions. Awareness & education are the key.

Mar 16, 2012 3:44 PM ET

Get rid of the "zero"
by Neil Porter

The article starts: "Energy experts often repeat the cliché, “There’s no such thing as a zero-energy home — just zero-energy homeowners.”"

Actually there is no such thing as either.

It's too bad someone coined such an incorrect term as "zero-energy home". A lot of energy went into the materials and construction of the home. Energy is expended daily in every home regardless how efficient it is and even if it produces its own energy by solar, wind or water. Energy comes into the home from the sun and the people that live in the home.

Likewise there are no "zero-energy homeowners". Every person uses energy.

Even the term "net-zero-energy home" is neither accurate nor a clear term to the average person not deeply immersed in green buildings and living.

Can't someone come up with an accurate and easily understandable term? Get rid of the "zero" because that is definitely out of place. My first thought is "energy-self-reliant home".

Also, most seem perfectly satisfied if a home merely produces as much energy every year as it consumes each year and totally ignore the embodied energy and materials. If someone wants to boast, shouldn't they also strive to produce the embodied energy in their home too? Perhaps we could give them 50 years.

Mar 16, 2012 4:30 PM ET

by Neil Porter

Dan Kolbert

Why 7 years? If you've got a 30 year mortgage, and financing the cost of energy upgrades is less than the savings from those upgrades, isn't that a good deal? Saving you $ from day 1?"

Payback and saving (meaning spending less) money are nice things when it happens. However, I think the green movement shot itself in the foot by talking about payback so much. There is no payback for many things that we should do to protect the environment and our health. Because the idea of payback has become so imbedded in so many people's minds, they refuse to consider green things that "aren't worth it" financially. The irony is, that virtually all of our consumption has absolutely no payback and no one balks about buying a TV, or fancy car or any of the many other things we buy. They are not investments, they are expenditures for consumables - things that eventually wear out and their materials and embodied energy are consumed.

We need to promote an attitude that finds it desirable to spend money for things that are truly good for the health of the Earth and the people, animals and plants that live on it. I lived in Germany for 29 years and personally experienced the media promoting a green attitude and the populace in general accepting that new way of thinking. Wednesday afternoons and Saturday mornings the village recycling center had a line of cars bringing things there to be recycled. When I left the country in 2002 all of the trash receptacles in the Frankfurt airport consisted of three containers: one for paper, one for recyclables and one for garbage. And the people knew what belonged where and discarded their things in the correct containers.

Passivhaus is not the only green concept that we can learn from the Germans. Our village of 3,000 started requiring rain-water harvesting for all new homes. Wind and solar energy were promoted by the government so that Germany was the world leader in installed systems until recently. Every recyclable product has a small fee as part of the price to cover the cost of recycling and an emblem to signify that. The railroads are promoted as a much more efficient method of transportation than long-distance trucking. In general, the populace is intelligent and understands and accepts the logic of the various attitudes and behaviors. What has been accomplished in Germany could also be accomplished in the United States. We have started in the right direction but there needs to be a greater public emphasis on green thinking and living.

Mar 16, 2012 4:35 PM ET

Monitor before building
by Neil Porter

As this article makes clear, modeling a building's design is not sufficient to ensure low energy use.

Perhaps people’s lives should be monitored before designing and building a house for them. If they have had a big TV going six hours a day until now, that isn’t going to change in a new home.

Mar 16, 2012 5:36 PM ET

Phantom loads
by Neil Porter

albert rooks:

"Has anyone had experience with curbing phantom loads other than just adding switched plug strips? Could this be a realistic solution? There's gotta be more solutions that can be developed."

I've used switched plug strips to shut off all the electronics at my desk but they are probably often hidden behind the desk to keep all the power supplies and cables out of the way and out of sight. Inconvenience means that they stay on all the time. If you knew ahead of time where those things would be located you could connect one outlet to a switch by the room's light switch. But what if you charge your phone by the computer during the night? Disconnecting that outlet would not only disconnect all the computer hardware but also the phone charger. When I lived in Germany I made my own power strip with about eight outlets and each had a separate labeled switch.

I bought a Kill A Watt at Home Depot and have had my HTC Evo 3D phone charger plugged in for 41 hours. I usually leave my phone on the charger when I'm at home so that it's always fully charged. Looking at the Kill A Watt display I noticed that it draws 2.5 - 5 watts when the display is on. 1.5 watts when the display is off. 0 watts when the phone is unplugged from the charger but the charger is still connected to the Kill A Watt. So, this HTC charger has no phantom load. Total cost for the year it has calculated at $0.86. A charger for another device that is fully charged is drawing 0 watts. So some manufacturers are designing chargers with no phantom load when not actually charging. My laptop is using 30-35 watts while using it.

It was also mentioned: "It's one thing to argue with a teenager about leaving lights on and taking shorter showers."

I would suggest some understanding of teenagers' developing sexuality in this context. This could be their only place of total privacy to experience this part of their being. Unless you prefer them to find a girlfriend or boyfriend. But that could be far more costly. By the way, my 58-year-old partner very much enjoys the pulsating shower head I gave her two years ago. I would suggest that you add a bit more hot water to your list of essentials for a happy life and stop complaining to the kids.

Mar 16, 2012 5:44 PM ET

Response to Neil Porter
by Martin Holladay

Thanks for the smile -- and the reminder that there is more to life than energy conservation.

Mar 16, 2012 10:19 PM ET

Stat Down???????
by gene batema

Any idiot can turn-down the stat to 60 and off when not at home, and save energy. Did they buy hoodies and Carhartts with the savings. I spent 2 days with no power last week because of a power line failure and it was not fun-- had to turn on the gas stove a couple of times to heat up a bit. I, like other people need 68-70 F. to stay comfortable and 66 F. while in bed. I hope Carhartts are not the new sleepwear fashion.

Gene Batema,
Licensed Michigan GC.

Mar 17, 2012 5:57 AM ET

Response to Gene Batema
by Martin Holladay

As noted in the article, “These are not normal users.” Their habits were described, not advocated.

Mar 18, 2012 5:21 AM ET

Response to David: Kill the Vampires.
by albert rooks


Thanks for the reply,

I think the problem is bigger, and getting bigger as we go:

Yes the trend is forcing industry to make devices with lower standy loads. But the number of household devices with a standby mode (and load) are increasing.

For you and I, some of the loads can be controlled by power strips, but for most of the country, it's not a practical solution. Most of the US is not aware or care enough about the issue to act on it. Even if they were, they don't have a practical way of controlling the loads. The average house has too many devices that are too spread out. Add children into the mix of daily life and I'm sure it becomes more challenging.

I wish I could believe that most of the US would make it part of their daily routine to turn off the loads that are not needed to be in standby when the household is asleep or away. There are really too many to control individually: Garage door systems, Internet modem, wireless router(s), entertainment centers with cable/sat box, TV, Stereo, wireless network printers, Kids laptops, Gameboxes.... The list seems to get longer every year. All of them constantly drawing.

That list represents all of the electronic stuff that is on it's way out of big box retailers and into an American home seven days a week. I don't know, but I don't think that the buyers are concerned about the in-use plug loads, let alone the standby loads.

Yes, I'm reaching back to the "home automation days" in thinking of introducing new control measures for the circuits that supply these things. These days it would be far easier in new construction: Lighting and plug load circuits are already separated, We don't have to use the old magnetic relays, surely there are now ways of managing multiple line voltage circuits without significant loads.

The question came up because of the contrast in the two households here, and that this week I'm working with our regional Passive House Association (Passive House Northwest) writing proposals for consideration in this round of Washington State Energy Code cycle. For the code cycle all we are trying to do at this point is defend and support the ICC 2012 improvements. It just got me to thinking about all of those constant loads that are wasted in an empty or sleeping households.

Perhaps it's time to return to some of those original "home automation" idea's. I think plug load circuit automation integrated into the developing new home "systems" has something to offer.

Mar 18, 2012 5:36 AM ET

Response to Neil: Those darn kids.
by albert rooks

"I would suggest that you add a bit more hot water to your list of essentials for a happy life and stop complaining to the kids."


We raised 4 kids through the teen years and all are grown up and on their way in life. My statement was based on my experience on the difficulty of talking about resource conservation to a teenager. Some take to it easily while others understand it, but have a difficult time maintaing awareness of it. I agree that it's a balance, but I do see talking about consumption and limits as an important part of parenting.

Mar 18, 2012 2:45 PM ET

Albert, I think you are
by aj builder, Upstate NY Zone 6a

Albert, I think you are looking for phantom solutions to absurdity.

I have lots of phantom loads and their total power is minuscule compared to any other load.

Lastly, industry is rapidly solving all this with well designed newer products every day that goes by. Moors law is working wonderfully.

Mar 19, 2012 7:07 AM ET

Ultimately the culture is more important than the science
by Robert McClellan

In "Is Efficiency Sufficient?" (prepared for the European Council for an Energy Efficient Economy (eceee) with funding from the European Climate Foundation and the U.S. Environmental Protection Agency’s ENERGY STAR Program), Chis Calwell notes that we've successfully increased efficiency, but energy loads are increasing. We could start a Manhattan project for efficiency, but unless we have a serious cultural shift in our approach not only to energy but to material, we will continue our trend to increased energy consumption.

The elephant in the living room is, well, the living room! When I was growing up we had a huge black & white TV in the living room. The lights dimmed when it came on, it took two and a half minutes to warm up and baked the paint off the shelf above it. But we turned it on a half hour a day (well, an hour on Sundays, for “Lassie” and “Walt Disney Presents,” the show before the “Wide World of Color”).

Free market capitalism runs on gains not reductions. If we are to rely on the market for solutions, there must be some real economic gain for reduction that is greater than cost reduction. In today’s world that would mean a sliding scale for energy that is opposite of what we have now: paying less per kWh for electricity if you use less rather than less if you use more. This certainly isn’t the “natural” order of free market, the free market relies on scarcity to increase price across the board. In Europe, they’ve increased the cost of energy “artificially” through taxes, acknowledging that the free market is severely short-sighted. In this country our gasoline taxes are going down as percentage of the cost because they are levied per gallon rather than per dollar.

To a large extent this is also biological. Natural selection has favored those in our species that have amassed wealth, first in the form of stored food, now in the form of a much broader array of material—TVs, automobiles, computers, weapons, etc.—but the future of the status quo, if not the species, relies on cooperation. Perhaps if we can get our big brains to override our reptilian ones in this regard, we’ll be able to turn around. Otherwise we may be in for the most Malthusian of population curves.

Whenever I write something like this I ask myself, “How in the world does this help?” I’m not sure. I’m a “glass half full” kind of guy. I’ve seen this kind of trend before and often it ends with an abrupt shift when there is some kind of catalytic event. So I remain optimistic that a catalytic event will preclude an apocalyptic one.

Mar 19, 2012 8:08 AM ET

Response to Robert McClellan
by Martin Holladay

You wrote, "In "Is Efficiency Sufficient?" (prepared for the European Council for an Energy Efficient Economy (eceee) with funding from the European Climate Foundation and the U.S. Environmental Protection Agency’s ENERGY STAR Program), Chis Calwell notes that we've successfully increased efficiency, but energy loads are increasing."

In 2009, I wrote two blogs on that topic:

Getting More Efficient, But Using More Energy

The Jevons Paradox

Mar 19, 2012 8:09 AM ET

Response to Robert McClellan
by Martin Holladay

You wrote, “In ‘Is Efficiency Sufficient?’ ... Chis Calwell notes that we've successfully increased efficiency, but energy loads are increasing.”

In 2009, I wrote two blogs on that topic:

Getting More Efficient, But Using More Energy

The Jevons Paradox

Mar 19, 2012 1:26 PM ET

Edited Mar 19, 2012 2:33 PM ET.

phantom loads
by Tim Rowledge

I've used the Insteon system ( in my new house with considerable success. It can substitute for already installed switches/outlets/etc if you have an existing house. It needs no central control device, though it can do cleverer things with one; which can be anything from an old PC or Mac to a sophisticated special purpose unit. Plug a power strip into one of the plug-in relays and you can turn it on/off by remote control and or timer. Have a button by your bed to turn off everything with one press.

I spent approx $2500 for the entire thing. I didn't need to worry about any traveller wires for 3-way switching - and anyway my stairwell lights have ended up with effectively 6-way, so imagine the fun of hard-wiring that! Since insteon uses the power lines as the main transmission means (though there are wireless backups as well) you only have to make sure you have all three wires at each location.

I should add that the simplest possible insteon network is two devices talking to each other to do a three-way switch. Or perhaps a wireless IR detector talking to a switch to turn on lights.

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