Dana,
The bottom one is a classic house around here. The average US house looks much better at a much lower price (I think)

======================

In this post I want to write down a few weak spots of the passive design compared to a standard house.


One of the key design elements of a passive house seems to be a real open layout. Take advantage of the sun on the south side of the house and transfer the heat troughout the house. Tactically placed windows provide free cooling during cool summer nights.
jdebree wrote: "We have theorized that we could live in the basement if we couldn't afford the power bills"
If I couldn't pay my utility bills, I could just pick a room close all internal doors and only heat that room.

If someone owns a large piece of land a future proof passive house can be built because all landscaping factors are controlled by the owner. My guess is that many passive house owners don't have a lot of land. The for example have excelent solar gain on the south because they live near a ranch which a gigantic field on the south of the passive home. Then the rancher decides to build a huge stable blocking your sunlight.

The way I understand a passive house right now is that its perfect, but very delicate energy balance is easily disturbed.

When the heating in the house on the photo above breaks down they could just plug in a small electric heater and live in a small room until the heating is fixed. A passive house doesn't have that possibility because of it's open design.

Don't get me wrong, I've seen pictures of passive houses that outdo my house in many aspects. They looks better on the outside. More natural light. And a nice open design. But once the perfect balance gets disturbed....

Right now I'm looking at the foundation types.
Thermal mass is very important in a passive house. The outer walls can provide a lot of that mass if they aren't insulated on the inside. That's not a real problem because they can be insulated on the outside. But what's the use of R100 insulation on the outside if the wall and floor are a huge thermal bridge to the soil they stand on?

I've seen several designs that break that thermal bridge. They all involve insulation at strategic points. I'm wondering if insulation doesn't compress when putting a 2 or even 3 floor home on it. Without the thermal mass requirement things would be easy. Just build and add as much insullation on the inside as you like.


Note to self: figure out how to add pictures.

Posted By NewHoosier on 09 Aug 2014 01:10 AM
Right now I'm looking at the foundation types.
Thermal mass is very important in a passive house. The outer walls can provide a lot of that mass if they aren't insulated on the inside. That's not a real problem because they can be insulated on the outside. But what's the use of R100 insulation on the outside if the wall and floor are a huge thermal bridge to the soil they stand on?

I've seen several designs that break that thermal bridge. They all involve insulation at strategic points. I'm wondering if insulation doesn't compress when putting a 2 or even 3 floor home on it. Without the thermal mass requirement things would be easy. Just build and add as much insullation on the inside as you like.


Note to self: figure out how to add pictures.

The concrete slab doesn't carry any loads, the concrete footings carry the structural loads from the roof to the walls to the footings. The footings then disburse the loads into the soil surrounding them. The slab is just dead weight plus whatever you put on top of it (furniture, etc). Even so, Type 2 EPS can take some pretty heavy loads.

Lbear,

I can't find pictures similar to the ones in my book but this one will give you an impression.
http://www.level.org.nz/fileadmin/downloads/Passive_Design/LevelDiagram30.pdf
The wall is standing on the brown insulation. In this example it's just a wooden framing so not very heavy for a 1 floor house. It get's a bit heavier if there are more floors that need to be supported. Needless to say a concrete wall is far more heavy.

http://shegroovez.com/wp-content/uploads/2011/08/Slab-on-Grade-Insulation.png The floor rests on the ledge. A big point load I think. In this case the floor rests over the whole are on the ground beneath it. But not in all designs. I'm just wondering what load the insulation can take and what the Rvalue is. I'm also concerned about the structual strength. By putting a wall on piece on insulation the mechanical strength of the building gets less. ????

" way I understand a passive house right now is that its perfect, but very delicate energy balance is easily disturbed."
Actually, the beauty of the Passive House features is that they are not delicate but resilient. When you tighten the shell and follow PH concepts you end up with a home that works exceptionally well in most situations, sunny or not. Passive House is often confused with passive solar; similar terms, far different concepts.

The basic concepts produces reduced heating loads and increased resiliency whatever the method of construction, and whatever the design or orientation. Many builders are using basic PH concepts to build "net zero" homes that do not meet the stringent PH Certification requirements, but are a huge improvement over "standard" practices.

Posted By Bob I on 09 Aug 2014 08:45 AM
Passive House is often confused with passive solar; similar terms, far different concepts.

It seems I confuse those terms. For me it's a package deal. Solar + other things like good insulation. My bad

NewHoosier, I don't know if you are interpreting those diagrams properly. They both show the wall bearing directly on the concrete footing. There is no insulation between the load and the ground. And in the second diagram that is not a point load - they are showing a concrete slab on grade, not a grade beam.

Maybe so Jelly. I'm just looking for info here :-)

In the color picture I see a wall standing on DPC which is insulation AFAIK. The wall is indeed directly bearing on the foundation, but not part of it.

You are correct about the second drawing, but as I wrote I can't find an exact picture. I mean a concrete inaccesible crawl space of 1-2 feet high. The the floor has to rest on the ledge. So like the black and white picture with with the earth remove below the floor.

I just recently starting to think about thermal bridges. I'm now constantly looking for info.
The foundation types I found all have:
- Have no insulation at all
- Have some insulation but I wonder about compression and the R-value

It's very easy to fix by building a house as concrete cube (floor, walls and ceiling). Then insulate on the inside. The problem with that aproach is that the thermal mass is gone. Adding thick concrete internal walls could solve partly solve the problem at high cost. But then thermal bridging is introduced again agai because the inner walls have to stand on the concrete floor because I closed cell foam can't support a heavy wall.

Maybe I'm trying to solve something that's impossible to solve or already have been solved. At the very least I want to find the least imperfect solution....

I hope teh above makes some sense :-)

No, in that color diagram it is showing a bottom plate (the brown element with the X form), which in this case is lumber. The DPC is the thin broken line, which is there simply to isolate the lumber from the moisture of the concrete (it's probably only a couple millimeters thick).

In the black and white picture, if the earth were removed under the floor (like a crawl space) then it couldn't be built that way.

Understood Jelly.
Do you have suggestions for a crawl space? I don't like the concrete slab directly on the ground (thermal bridge)

You can build a suspended concrete floor. They use a special steel pan with ribs, and then pour concrete in it. Commercial buildings are done that way all of the time. You would want to insulate the underside very well, as the crawl space will be cool/cold.

Have you mostly lived on a slab floor? I grew up in an old colonial house in CT, then moved to FL for 30 years. In FL, everything is built on a slab. I find the slab floors to be rather tough on your feet and back. I've heard that professional dancers won't perform on a concrete floor for that reason. We decided that whatever we built in SC, it would have a suspended wood floor system. As it turned out with the slope of our land a walk-out basement was the path of least resistance. I'm not sure if maybe suspended concrete floors would have a little more give.

Currently I live in what's called a condo in the US (not sure). It has a suspended concrete floor.
My parents century old house had a wooden suspended floor. (1 fet crawlspace)
Currently the floor is simply a layer of plastic (old bags) with concrete poured over it. An air value horror :-0
But still it's a great house without a cold floor.
I think it greatly depends on the soil type and level of the water. It's always at 2-3 feet deep. Water sinks very fast. So it never wets the sand under the house.

yes of course a suspended concrete floor over a crawlspace can be built here, but not the way it was shown in that diagram.

I think what you live in currently would likely be called a "row house" in the US, but of course I haven't seen it!

Why are you leaving the Netherlands for Indiana? It must be a really good job or a lovely partner!

I know what's called now (suspended floor) that makes conversation easier. I don't really care what a foundation looks like. I'm trying to find a design that:
a] has no insulation on the inner walls, floor and ceiling to (more) create thermal mass
b] no thermal bridges to the outside to avoid heat/cold leaking in

That's all. The only reason I asked about a suspended floor was because I was (and still am) exploring options to remove all thermal bridges.

About me moving to the USA... It's a mix of things. No new job but retirement. Adventure. Doing other/better things with my life. Likely a spark of insanity too :-)
So much to sort out. USA as a country -space and people- is great. But the rest like healthcare, the way .gov handles things is far from ideal. Should I become a full American citizen or just live there with expat healthcare/insurance. We Dutchies have a pension that's consists of 2 parts. The part I paid myself and is based on the salary of my job. The other is a state pension everyone gets. No matter if you ever had a job or not. It's $1360/month. But the catch is that you get 2% of that for every year you are a Dutch citizen. So it costs me to move to the USA :-)

Anyway, a bit more on topic but still related to the above. Energy in the USA is dirt cheap but wouldn't be suprised that suddenly changes. The best guard about that is to minimize energy consumption. That's where this forum fits in. So far I learned a lot of things - thanks all - but I'm missing systems that combine things....
I can buy solar heating panels, wood stoves, HRVs, AC of all sorts etc etc. I want to tie them together into one big system. The following may be a bit over the top but it gives a good impression what I'm after.

a] Electric heating and cooling as a basis. It's the backbone of my house
b] Solar heat panels* that aren't sepearte unit blowing into my house but delivering their heat to system a
c] A wood stove (backup) that delivers heat to system a.
d] An HRV in the chimney of the woodstove. The HRV obviously feeds heat into system a
e] Grid tied solar PV.
f] A solar hot water system that delivers all spare heat to system a


*= I think they are great DIY projects if I can find the materials for cheap/free. I've seen a commercially availble panel that generates up to 10000 BTU/h (2.9 kWh). I'm fully aware about the magic advertising words 'up to' and they work only a few hours a day. IF I could build good performig panels for a low price I could aim for as much heat as I can possibly capture. Meaning my whole roof full of panels. During bitter cold all that heat might be needed instantly. During less cold days there may be excess heat. That's why I try to look at things over a 24 hour period. I don't want to blow the heat directly into my house, or directly pipe it to system a. I'm thinking of a massive high density concrete wall in the middle of the house. That way (excess) heat will be stored in that wall and can be used when the panels generate not enough output. Or maybe even simpler pipe the heat through a massive boiler. Hot water and a heat exchanger could add the heat to system a.


Thinking geothermal a bit I could pump well water through the same wall during the summer causing a cool(ing) surface...?

To summarize:
a] Tie as many energy sources into one system
b] Grab as much heat as possible and store it.
c] I need the brains of this forum to use solar heat as a way of cooling.

Posted By Dana1 on 07 Aug 2014 05:59 PM
There is no such thing as wind-cooling your house when the outdoor temperature in the middle of the night is 30C, with high outdoor humidity, which happens with some frequency in Indiana. Shading helps,

I agree 'cooling' with 30C is heating instead of cooling. If there are very few days wind-cooling can be used then there is no need to design to take advantage of it. But if the amount of cool summer nights is considerble then it may be a good thing to keep in mind?

Posted By Dana1 on 07 Aug 2014 05:59 PM
as does a sloped roof. With a sloped roof as the roof heats up convection causes the much hotter air at the roof surface to flow up the roof, bringing cooler air into it. With flat roofs there is no flow, just small localized convection loops as the super-heated air on the 60-70C roof bubbles up into the cooler air above, but it mixes with that air rather than being displaced by it. This is a HUGE difference, easily measured in the roof temperatures.

Just learned something new. I went for the flat roof for two reasons. Less surface area and easy access. I wanted to place my HVAC or mini-split on the roof (out of sight) but I was advised not doing so. The other reason was that I might place solar panels on the roof. I know the can also be placed on sloped roof but nothing beats access on a flat roof. When I use a sloped roof I might as well use a catherdral ceiling. (altough that increates area and volume) They look really great. The hot air moves to the highest point of the ceiling and there it could be easily 'collected' by my AC. I think air circulates great that way and it saves on ductwork for 'return' air. I'm not sure it's beneficial for a mini-split because if I understand that system correctly is hasn't and ductwork at all. In that case a big ceiling fan could be used in the heating season to blow the hot air back down. Causing a more even temperature (I think)

Okay first off your goals are very admirable. My own personal take on it is that the objective is to get the costs for heating and cooling the house as well as electrical consumption low enough that it’s a nonissue. In my own house my largest utility bill is my cell phone, and with my DSL line not far behind. My combined costs for electricity and heating are much less than that for communication. To me that defines reasonable efficiency.

There are many fancy and elaborate systems you can use to accomplish this, but you have 2 things working against you, cost and complexity. The other issue you face in the United States is that in general the workforce, that builds houses and installs HVAC systems is not as technically savvy, as it is in Europe. I was fortunate enough to see a friends house built in northern Germany and talk to the builder and some of the workers on site. That professional work force is very difficult to find here..
 
I think the list I previously wrote of the 10 or 11 things you want to include in the house still stands. But you can basically summarize it as build the house as small as you can, build it tight and really well insulated, add an HRV, use good windows, get the water management details correct, and be happy.

I think the other thing you have to wrap your head around is that a house is a system, not just a collection of parts. Changing one detail of the house often has ripple effects throughout.


Welcome to America
Eric

I agree Eric, the proposed system has ROI=never
At least not at the current (energy) price levels.
So I likely won't buy and solar equipment of any sort right now.
Maybe I start with a mini-split and later when the prices come down I buy PV panels to power that mini-split.
Here, what can roughly translated as, combination furnace, are very popular. Smalll 30 kWh wall mounted natural gas devices that provice both hot water and water based heating. Can be used for floor heating and wall based heaters. They last about 15 years and have a very good efficiency.

So it's more about being future proof that about wanting to install it right now. But to be future proof I need to make my home ready for other systems in the designing phase. I prefer to build a house and never do constuction work on it afterward. That includes ductwork. Just for heating that would. be simple. Waterbased radiant floors. The water can be heated in many ways. The only things that have to change are located in the utils room. Cooling is more difficult I'm afraid. But to be future proof I need some basic knowledge of systems. I could for example build a house/shell and insulate the ceiling and the add a false ceiling which leaves space for ductwork. But for that I need to know the sizes of the ductwork.

The workforce not being so techy scares me a bit. When I move to the US my time is worth nothing. So all construction work will be a hobby. I'm much slower than trained work crews but I'm 100% sure the quality of my work is very high. (just electical, waterpipes and water heating). But that's according to Dutch standards which vary greatly from US standards. Mayeb I won't even be connected to the grid if electric wasn't installed by a pro. Howver there is a chance all construction crews wil be free. But that's another story


As for the rest of your post, top quality insulation is at the very top of my list. A small house is no more that logical but I want a bit more than just enough to be honest. I want a few spare rooms for guests for example. Right now I'm figuring out a layout that takes most advantage of keeping those rooms mostly unconditioned. That sorta reduces the size of my house.

The lack of technical expertise, especially in my rural area makes me glad I am building my own house. They're still slapping together houses out of 2X4's, and putting the A/C ducts in the uninsulated attic. People around here think I'm a little crazy for building such a strong, well-insulated house. As you pointed out ROI= never. But I take a lot of satisfaction out of designing and building an efficient house. When there's a bad storm, i don't have to worry about the structure. It's going to take a lot to level an ICF house. We are already enjoying the small electric bills. More importantly is the overall comfort of the house, with the temperature being remarkably even and steady, despite only running one mini head at a time. Concrete houses of any kind are also extremely quiet, although usually the only 'noise' around here is birds.

As for your idea of cooling a wall with well water- it won't do anything for the humidity, and in fact may sweat from condensation during humid weather. When we lived in FL, the floors (concrete slab) would sweat when we had warm humid weather after a cold snap. Dehumidifying is a major feature of A/C, and my mini-splits have a dehumidifier mode which works well when it is humid, but too cool for A/C. You could cool the walls and run a dehumidifier, but it wouldn't be free. I'm not sure which uses more power- a dehumidifier, or a mini-split in dehumidify mode.

Yeah, condensation may be an issue. The idea wasn't to fully replace an AC but just lower the cost of operating it. Also being more flexible.
Does your mini-split automatically switch to dehumidifier mode?


My first plan was a flat roof but I took teh advise not to do so. The flat roof would have been of worry free concrete. All talk on this forum about moist, mold, barriers etc scares me a bit.
What I'm used to is this. Make wooden frame. Nail it shut with wood. nail battens on it. All unpainted/untreated wood. Put on tiles and as long as it doesn't leak it lasts a century.
Or just nail it shut with wood and put shingles on it. On the inside add insulation of your choice. But that's not posstible in Indiana?
I was thinking about the above, then add 9" closed cell foam on the inside. Optionally close it up with wood. Then add 1 feet lowered ceiling to create space for all sorts of pipes and wires

Combination Heat and hot water systems are readily available in the US and work well for energy efficient houses. The issue is of course that you need a separate system for AC. This is one of the reasons that forced air systems have become so popular in the US , I think they are about 90% of the new home heating market.

Based on your desire for a concrete structure, I would look hard at ICF construction for the shell Look at quadlock.com for examples, I think the R 38 TMO would make a nice wall with most of the foam on the outside so you could benefit from some of the thermal mass. There are other manufacturers of asymmetric blocks (more foam on the outside) so you will have choices.
If you really go with a well insulated house, along the lines I outlined previously, heating and cooling the house with a couple of small split AC units will work well and be quite efficient. You will want a cold weather specific model likely either Fujitsu, or Mitsubishi. If you Orient the roof so that it faces True(solar)south, and have the minimum number of obstructions on it, you can future proof it for solar.
As far as wanting a cathedral ceiling, I would recommend looking into scissor trusses for the roof. If you go this route, specify that you want an energy heel at least 8” so you can fully insulate. The other advantage of these is that you get a better roof pitch like 5/12 but the interior is 2.5/12 so the interior walls are not so high that there is a lot of unusable space.

If you wanted a reasonable cost manageable combo based on your stated desires and current US building capabilities
You could use ICF walls down to the footings, done with a brickledge, use brick for the exterior.
Slab on grade with 4” eps under the slab, roof done with 5/12/-2.5/12 scissor truss with an 8” energy heel and 2 ft overhangs. Sheath the underside of the truss with zip sheathing and tape the joints as your air barrier Plan on ~ r60 of cellulose in the ceiling. Pre install conduit for future solar PV
Add in high efficiency windows and you have a nice shell. Use high solar gain on the south side, and low solar gain on the other 3 sides. As far as the floor goes, either polish the concrete, or use a glue down cork flooring so it is a bit softer under foot. This gives more than enough thermal mass for a house.
The advantage of this setup is the interior walls are all non structural, so the floorplan can be anything you want.
For HVAC, use a couple of minisplits, plus a woodstove as a backup with an outside air source. Get the smallest woodstove you can find so you don’t cook yourself.
Learn to shower in cold water, while singing the national anthem and you are all set! Or for simplicity, install a single flat paneled solar water heater (glycol not drainback) with electric backup and an 80 gallon tank.
done