I have been studying passive house ideas and standards for a while now and want to know if anyone here had built a home that meets the standard. A home that I finished early this spring is out performing expectations and if it continues will surpass the standard by about 60%. From all of the information I have gathered a passive house should use < 120Kwh/sqm annually. Here is how the house I built is performing to date. The house is 1976/sqft or 183.5/sqm. So if I am correct the house to meet passive house standards should use about 22,000 Kwh's of electrical energy annualy, 120Kwhr'sX183.5 Sqm's. The house is all electric so measuring energy is simple just read the meter. Passive solar windows (water filled) a SIP's envelope, HRV, electric hot water heater, Geothermal heat pump supplying an insulated radiant slab on grade and lots of attention to air sealing and thermal bridging. To date the house has been occupied for 7 months and has used 6,015 Kwhr's of electricity, a large amount of this used for cooling. If the energy modeling numbers hold true the total annual energy consumption should be around 12,000 Kwhrs maybe as high as 14,000 but I doubt it will get any higher than that. Does this mean that it will have surpassed the passive house standard? I'm not sure but 22,000 Kwhrs for a 1,976 sq.ft house seems like a lot. Can anyone elaborate on the total annual energy use to meet passive house standards? The house cost about $135/sqft to build, not including the cost of the water filled windows still in prototype design. here is a link to the passvie house institute that I got my numbers from. http://www.passivehouse.us/passiveHouse/PassiveHouseInfo.html

   While all of my focus has been on the energy efficiency and consumption of the house the homeowner takes another view. While she loves the fact that the homes energy cost is 1/2 of what her previous 1,300 sq/ft home used. Her real pleasure has been in how comfortable the indoor environment is in air quality and how quite the house is. here is a link to the house, it doesn't look like most passive houses I have seen but is performing better than expected.
http://www.eebt.org/Open-house.html


Tom Pittsley
ecobuilder@aol.com
www.eebt.org

I haven't used SIPCRETE, looks interesting but very labor intensive. For the SIP's I use R-Control, 6-1/2" panels  1/2"osb/5-1/2"EPS/1/2"osb, available locally for around $4 sq/ft, R-24.3 for all exterior walls. At a minimum 10-1/4" SIP's for the ceiling or roof R-40.

       So you really think passive house standards are easy to achieve in a cost effective way? I'd be interested in here about projects people have actually completed that have met the passive house standards for total energy use. Then I would like to here about the products and methods used to achieve it. Please don't post endorsments for products unless you are telling us how it was used in a house that has met the passive house standards. The benchmark being that the total house energy was less than 120 kWh/m2/year

Example:a house measuring 2,000 sq/ft or 185.8 sq/m   should use less than 22,296 kWh/year. While most houses don't use electrcity  for all  there energy the numbers can be converted from any source to a kWh here is a good energy converter tool to say convert LPG to kWh's 1gallon of LPG= 28kWh of elctrical energy at 100% efficiency. For me the end result for total energy use is the most accurate way to determine if the house should meet the standards, not just the individual requirements for measure. I myself have not had the opprotunity to use the PPHP energy modeling software and I'd be interested in finding out just how accurate it is when comparing it to actual homes the have monitored and compare the results from the model to the actual total energy used.

Then the hard part, HOW MUCH DID IT COST TO REACH THE STANDARD? $/sq/ft please
The house I completed in March 09 cost $135/sq/ft to build, and to date is outperforming the energy models by about 30% below the passive house standard. This winter will be true test, I'll keep track of it and post the info here.

Performance Characteristics of a passive house

1. • Airtight building shell ≤ 0.6 ACH @ 50 pascal pressure, measured by blower-door test.
   

2. • Annual heat requirement ≤ 15 kWh/m2/year (4.75 kBtu/sf/yr)

1. • Primary Energy ≤ 120 kWh/m2/year (38.1 kBtu/sf/yr)
   

In addition, the following are recommendations, varying with climate:

1. • Window u-value ≤ 0.8 W/m2/K  

2. • Ventilation system with heat recovery with ≥ 75%  

   efficiency with low electric consumption @  0.45 Wh/m3

1. • Thermal Bridge Free Construction ≤ 0.01 W/mK
   
   
   
   
   Tom Pittsley                                                                                            ecobuilder@aol.com                                                                                                      www.eebt.org

Tom: I have been a lurker for a short while on this site; hence, this is my first post. I should like to say that I am most impressed with your projects. Moreover I have learned quite a bit by reading your posts. Keep up the good work! Job well done! My wife and I are contemplating building a house here in south central New Mexico that would incorporate some, if not all, passive house standards. I plan to continue reading and surfing sites like this one to learn as much as possible. Congratulations on your work. I bet that the house you built beats the Passive House standards. Regards, Steve

Very impressive, Tom. I especially like the liquid filled windows. I can only hope my next house performs like your example!

Great info!! I was not aware of the liquid filled windows. My home is built with 6" aluminum clad sips with radiant heated concrete floors. I did use a thermal blanket under the pex tubing. The hot water for the floors is furnished by 6 -4x8 solar panels flowing into a 1,000 gal insulated tank. The fresh air supply system is 500' of 8" perforated pipe buried 6' underground and that incoming air stays above 64º in winter and below 76º in the summer. The house is total electric using a 4 ton high efficiency heat pump for cooling and backup heat. Windows are LowE insulated (46 of em) The main glassed areas are South facing. Total square ft is 3675 and I have averaged around 18,000 kwh per year for the past 4 years.

Bravo reddirt!! Where are you located? As you know climate has a lot to say about how well passive solar/energy efficiency can be utuilized. I am building these in Massachusetts with 6,000 heating degree days and 600 cooling degree days anually. Focusing on ways to minimize heat loss and ways to maximize winter solar energy more so than cooling.

I have people talk about bringing in fresh air through underground tubes, but have yet to converse with anyone that has first hand knowledge of such a system. How much did it cost to install 500' of pipe 6' underground? Does it use a blower for moving the air through the tubes? and if so what size? Have you had any issues with moisture present in the tubes and if not how did you accomplish keeping water out? These are some of the question a doubting Thomas would ask. I love the idea but have others more knowledgable than myself discourage me from attempting it.
What was the cost of the solar hot water system? Would assume somewhere in the $5-6,000 range if you did it yourself.

The water filled windows were a prototype of a window system being developed by the VP of reasearch and development for Hunter Douglas. Wendell Colson, has been developing shades for them for over 30years and was the inventor of the original honeycomb insulate window shades. His newest version of the windows does not contain water but a gel substance for capturing the solar energy, less problems with containing water and maintaining clearity. It is amazing at how well they work and his new version looks more like a tall casement window, 2' wide and 7' tall. Very heavy windows about 250lbs/lnft.

Tom Pittsley
ecobuilder@aol.com
www.eebt.org

Tom, The PH standard only has three requirements, but there are some caveats.

1) < 15 kWh/m2/year heating energy use (4.75 kBtu/sf/yr)
2) < 0.6 ACH50 air tightness
3) < 120 kWh/m2/year total SOURCE energy use (38.1 kBtu/sf/yr)

There are several issues that complicate these measurements.

First, the floor area is measured according to the German Treated Floor Area. This is SF measured Inside Face of Wall, no interior walls or staircases, and storage and basements at 40%. This can make a US house as measured by a real estate agent 25% smaller right off the line, and make hitting /SF targets all the more difficult.

Next, the 120 kWH / m2 / yr is Source Energy, as measured at the power plant. Depending on where you get your power from this can be 3x the energy you use in your house because of inefficiencies in line losses and power plants.

If you use all off-site generated energy, this would be only 40 kWH / m2 / yr allowable. If you generate all your electricity on site, your losses will be much less.

Lastly, the air volume for the ACH50 test is measured as if you filled the house up with water, poured it out and measured it. No interior partitions, floors, etc. Pure interior air volume of house considered.

So, it's worth checking your numbers again, it's a very tough standard to hit in a northern climate... We haven't done it yet, but are getting closer project by project.

Is there information on the water filled windows. What happens to these windows when they freeze? How long will the fluid stay inside the glazing system and how does it effect the thermal characteristics of the whole window? Seems like convective and conductive heat transfer would be much greater.

In MA the latent cooling loads are way too high for earth tube to be an optimal cooling method.  . For ventilation air tempering in the winter & shoulder seasons it'll be OK.

Subsoil temps in MA are in the 50s, but the summertime dew points are typically in the low 60s, and frequently hit the 70s during warm spells. November-March the average dew points are in the 40s, during, which time condensation & mold from earth-tempering the ventilation isn't a problem.  But it is guaranteed to have condensation and very high RH conditions most of the time from May-September, presenting serious mold growth potential on any organic matter (pollen, dust, whatever) that finds it's way into the tube. It needs to be constructed at a reasonable drain angle (a few degrees of slope) and have a condensation drain/disposal system designed-in, and it should be smooth-bore to avoid trapping/stagnating water & organic matter.

With a good filter and active dessicant-wheel (ERV) heat recovery ventilation you might get away with it, but as a passive solar-chimney or venturi stack flue/wind driven device, fuggedaboudit.  (From the Rockies & westward it can probably work though.)  PassivHaus earth tube air tempering was developed in/for northern Europe, where 60F+ dew points are rare & brief.  They've now moved on to dual-core HRV, which is probably what makes the most sense in MA from both a cost/benefit and hazard point of view.

The cost of DIY solar hot water will vary dramatically by the total DHW load.  Small systems in MA can run ~$7-9K, installed, and provide 60%+ solar fractions to DHW-frugal families of 4 (or a single DHW-pig), but you won't be fillin' the spa with it very often.  I assume they're making a profit, so yeah, $5-6k for a minimalist system is doable. If you're willing to forgo tub-baths and shower instead on not-so-sunny days/seasons you can boost that solar fraction considerably (into the 80s) with a drainwater heat recovery heat exchanger.  (I wouldn't do solar HW without it.  For $500-700 in hardwater DWHR returns over 50% of the heat in a 2.5gpm or lower flow shower.  Showers represent 40% of the "typical" hot water use in the US, but 50-60% for showering-only families.  DWHR is far cheaper than the additional solar goods necessary to support the load without it. The size of both the storage and panel area can be reduced by ~20-30%.)

I'm sorry I'm new here...

Slowly reading through posts to find more info on 'green' building...

What am I missing here??? I'm looking at the kWH usage standards for these passive buildings and am very confused...  The OP stated his client's 2,000 square foot home, all electric, has consumed 6,000 kWH in 7 months... But we have a 3,000 square foot 'passive solar' house, all electric that consumes between 5,500-6,000 kWH/year (between 400-600 kWH/year) 

This seems much lower than the passive home requirements above. I don't get it??? I must be misunderstanding or calculating something wrong...

BTW, I can't imagine using much more electricity than we use. We have all the stuff... computer, tv, microwave, dishwasher, electric range/oven... (we do hang most of our laundry to dry, but end up using the dryer every couple weeks) One thing is that we use the wood stove for 90% of our heating needs (only using baseboard heat on the odd occasion).

Also number 2: anyone happen to know the heat equivalent BTU of 1/2 cord of wood? Just curious because this is our yearly consumption....

Lastly number 3: we had an air blower test which showed 1,600 CFM.  How does this compare to the ≤ 0.6 ACH @ 50 pascal pressure, measured by blower-door test? So confused

Methinks maybe...

Lemme 'splain ya then...

kwh & btus, therms, gallons of oil, cords of wood are all convertible by constants, the PassiveHouse standard just states it all in kwh, but let's play the heating portion in BTUs, since that how fuels are usually rated in the US. 

Square meters and square feet are also convertible by a constant, and it's close enough to 11ft^2/m^2 that we'll just call it 11 to keep it simple.

so...3000 square feet is about 273M^2.

To meet PassiveHouse standard your heating/cooling energy (converted to kwh) can be no more than 15kwh/m x 273m, or 4095kwh, which (at 3413BTU/kwh) is ~14,000,000 BTUs. 

A cord of wood is between 15,000,000-25,000,000 BTUs, you're burning half a cord call it 10,000,000 BTUs.  Assuming it's burned in a 70% AFUE wood stove your heating-energy use (not counting the 30% that went up the flue) is 7,000,000 BTUs, or...

...0.5x the PassiveHouse standard for heating/cooling (not bad!)

Converting that back to kwh/meter you gets you:

 ~7.5kwh/m used, or

~11kwh/m source-fuel on your heating/cooling.

Assuming 6000kwh/year on the electric bill, that's 6000kwh/300m=20kwh/m.  For your total energy use/meter, add that to the 7.5kwh/m heating energy you get 27.5kwh/m or..

0.65x the PassiveHouse standard (still not bad!)

Source-kwh refers to the energy burned at the power plant/heating-system to deliver the energy to the structure.  Your heating system source energy is known, but what went into the powerplant isn't.  If your local grid is primarily fossil-fired, it's about 3x what showed up on your electric bill.  If it's mostly hydro it's about 1.1-1.2x the bill. Nukes, beats me- I'd have to look it up, but the vast majority of the energy in a nuke plant goes into the cooling towers.  Assuming you live on gas & coal fired local grid, that 6000kwh/year is ~18,000 source-fuel kwh.

Divided by 300m^2 gives you 60kwh/m, which fully half the total. Add the 11kwh/m source-energy from the heating, you're still in there with 72kwh/m-source

or 0.6x the PassiveHouse standard. (Terrific!)

As for the ACH #s, assuming an average ceiling height of 9 feet (could be higher, could be lower), 3000' of house is 27,000cubic feet.  1600cfm is (1600cfm x 60min/hr) 96000cubic feet/hr, so your ACH is ~96000/270000=

3.56ACH (or ~6x the standard.) 

You could tighten the place up and use less heating fuel, but the active ventilation that would then be required would add a bit to your power use. (Less total energy than that saved in heating though- it's still a net-win, but at what cost? From a cost effectiveness point of view going super-tight may not be worth it in your case.)

So, what your saying is that, if my utility is efficient then it is easy to meet the standard, if not then it's much tougher. So does the source energy figure factor in things like how much energy is used to pump the oil out of the ground, refine it, transport it half way around the world, offload it and then transport it again before you burn it in your home? How do you know exactly where your energy is coming from? I have the Plymouth nuclear power plant less than 20 miles away does some or all of my energy come from there? Solar cells are at best 20% efficient how does that factor in? Does anyone really know how efficient the utility companies are? With the network of grids can you really tell where your energy comes from and how efficient it is? I don't think so.
So if my utlity is 50% efficient the home will meet the standard but if it's only 30% efficient then it doesn't? This seems illogical to my left handed right brain way of thinking. IMHO the only number that should be considered is the energy consumed by the home, weather it be by oil, gas, LPG, electricity or solar. However you factor it the goal is to reduce the total energy demands on the home to a point where you don't need much energy, UTILITY INEFFICIENCIES BE DAMNED!!!

Tom Pittsley
ecobuilder@aol.com
www.eebt.org

So the PH standards don't take in to account the heating degree-days at the location? If not I can't imagine how you would get near those numbers anywhere "up north" without 2 feet on exterior insulation. Seems to me it should take in to account the ccd and hdd somehow. Unless they just set the standard and you try your darndest to hit it.

I'm not saying it, the PassivHaus Institute is.  But if you think those questions are unanswerable, think differently!

There are methods of determining fairly precise answers to all of those questions.  Just 'cuz it's complicated enough that it can't be hacked on the back of a napkin doesn't make it unknowable.  Even if the details are constantly evolving and obscure to the ratepayer doesn't mean that it isn't all tracked and accounted for- most of it IS tracked and accounted for.


BTW: NO utility is 50% efficient from fuel to load, so you can rule that out of the "if"...

If you have an issue with the PassivHaus Institut paying attention to source fuel efficiency take it up with them (or start your own standard). But if you rule out source fuel issue complete, you end up with the preposterous notion that electrical resistance heating is identical to or better than high efficiency gas-fired or wood heating, despite the fact that the impact per delivered BTU in most US regions is easily 3x as great in terms of carbon emissions, let alone the other environmental costs.

Yes, there really IS a difference between on-site solar thermal and coal fired electricity delivered at 28% total grid efficiency to the load.   (Who knew? )

In your native MA, natural gas is something like a third to half of the total electricity production, but the amount varies from utility to utility.  Heating your house with electricity on an all gas-fired grid burns ~3x as much fuel as if you'd heated the place with a condensing gas furnace or boiler.  How is that not relevant?

OTOH, how is it not relevant that the same electricity generated in a coal fired plant of identical thermal efficiency pours twice as much carbon into the air? (Which ISN'T accounted for in the PassivHaus standard.)

The total load is important, but so are sources.  Of course, the lower you make the load, the less relevant the sources become.  The PassivHaus standard isn't counting carbon grams or fuel source pollution, envirnmental costs from fuel extraction, etc only source-fuel BTUs, which is already a huge oversimplification of the real environmental impact, and fairly easy to account for.

It's true that it's much easier/cheaper to meet the standard in Berkeley CA than it is in Duluth MN, yet both have been implemented. (I'm not holding out for seeing one Whitehorse Yukon any time soon though. :-) )  There are examples in colder mountainous parts of Austria too. Whether it's cost effective depends... 

In Green Bay it really only takes about a foot of exterior insulation, not two, provided you've addressed all thermal bridging and heat loss to the ground reasonably, and have window area under control. The glazed area fraction is huge- more important than additional insulation thickness.  Once you're at R30+ clear-wall values, air leakage and glazing losses dominate the heat loss/gain. Cutting the window area 30% makes a bigger difference than bumping the wall insulation up to R50, etc.

The PassivHaus was conceived as a standard for Germany/western Europe, and there are many issues & practices that can work there that just plain don't in other climates. (eg. Earth-tube pre-conditioning of ventilation air was popular in German PassivHauzen, but sucks as a method in hot-humid climates.) But their energy modeling software it pretty good, with reasonable correlation between the model projections and measured reality.

We have the minimum window size in most of our rooms except the living space facing south. It amazed me when they forced us to increase window size when we were trying to build an energy efficient house. As you said it seems so silly to me that you can have a wall space of 100 sq feet and are worried about it being R30, then throw in a 10sq ft R2 space in it. I would think 90% of the heat loss is the windows in our house. We have 2x6 exterior walls that are foamed for 2 inches, then bat for 4, then 1 inch of pink foam over the studs (the electricians didn't like us), than sheet rock. Of course you throw a window in there and...

I have no idea what R value our windows really are, they are Anderson 400 series with storms on all of them, but I am guessing that is our biggest loss in winter.

RE: Passive House
One of the PH goals is to help pay for the energy upgrades by eliminating the central heating, so I would assume that anyone who needs a geothermal heat pump system (30-60K?) wouldn't be anywhere near the standards. I worked on plans for a 3500 Sf house, not quite to PH standards, but well insulated - we were figuring two minisplits for heat & AC.

Incidentally, in regards to this question "So the PH standards don't take in to account the heating degree-days at the location?" That is incorrect. Detailed climate data for the building site is one of the first things you input into the program. And yes, it will work in higher latitudes.
Bob I
PH Consultant

Sure it can even work 15000HDD locations, but from a cost-effectiveness POV compared to buying a fossil burner is much harder than at more temperate climes. 

For 5000HDD it's pretty easy, and in-between it's, well, somewhere in-between...

RE: PH at higher latitudes
Well, we really don't know yet but we will soon. Last year there were 14 PH consultants, now there are around 200. This is an indication of the level of interest in PH, so I anticipate the number of PH projects in the US will rapidly increase. Since PH doesn't specify insulation type or building design, there will be quite a variety. I anticipate modeling a currect project in PH in the next few weeks, so I should have a better idea after that.
Bob