MN Renovator 2012 Hypothetical new house
 

I'm living in a house I bought in the middle of 2010. I like the house and I've air sealed it pretty well and have a few more gaps that I know about that I'm taking care of this month. I got to thinking about what I'd do if I moved to another place to build a house.

When I do it all over again and eventually build a new place for myself instead of buying the mistakes made by builders and the original owners who chose the place and its location. I want to build it with similar thinking to the Alaska zero energy house but I won't need nearly as much insulation and realistically I don't think I need a huge hot water storage vessel to store summer heat through the entire course of the winter.

I'm thinking that I'd like to go with 12" dense pack cellulose in the above ground walls. I think I'd go with foam overhead and try to get close to R-75 as I can get overhead with a lighter colored metal roof and have livable space in the attic instead of lose that room to being an empty space, all glass larger than 2 feet per side would be on the south side of the house and enough thermal mass built in to do a decent job of slowing the big temperature swings between day and night.

I'd want to go with Fujitsu's 9k 26 SEER 12HSPF ductless minisplit unit installed with a very open upstairs floor plan with living/family room and kitchen upstairs with stairs in a non obstructive location at a corner of the house and bedrooms and theater room in the basement where the temperature stays more stable year round. By going with an open long throw floor plan one ductless minisplit can cover the entire space in regards to air flow.

I think that having a livable conditioned attic or at least accessible storage space and a finished and conditioned basement is key to making a small house work. I'd be looking for a interior floor size of 700sq ft or less, with a 700 sq ft size for each level, I could essentially have almost 2000sq ft of space, attic for suitable storage and bedroom expansion if wanted, kitchen and living space suitable for guests, and theater, office, and bedroom space downstairs with a bathroom on the main floor and basement. I would have the 9k minisplit be the only source of heat and cooling for the house. I think this would work because if my current house can handle staying the same temperature at -20f(-29c) using 26k BTU/hr when it had R11 fiberglass in the walls, plenty of infiltration, an unwrapped skylight, bad directional facing and big windows on the wrong sides of the house I'd imagine a house at 65% the volume and good design with plenty of thermal mass shouldn't need that much. An inside outside difference of 0f(-18c) and 70f(21c) inside is 20k with my current house. 65% of the foundation size as interior size would mathematically be 13k without factoring less windows and better positioned windows or increased insulation. Worst case I fire up a space heater, a toaster oven, a hair dryer, or snuggle in my bed with my heated mattress pad and watch TV on a cold night. 600sq ft floor space would save more and realistically its all I would need and I wouldn't even need the really attic if that complicated things too much but I think that wasting an attic would be wasting a great storage space that I currently use my basement for.

I'd have a small HRV and seal the house to the passive house 0.6 ACH50 standard when it is built, which I would imagine should be that difficult with a small house, a local builder at a 'green expo' said their houses are all 0.6 ACH50 blower door tested with R26 walls, R60 ceiling, and R20 foundation. He was talking about how it doesn't cost them that much to make these improvements over any other house and they average a 46 HERS while energy star requirements bring a HERS rating to 85.

I also had another radical idea, what if I built the house so the main floor was sunk in at the same level that a split-level lower floor is, that would save me from exterior heat and extreme cold exposure through the walls and I'd probably only really need 2x6 construction with less insulation. The house would look weird but if I was retired(not close enough to that yet though) and didn't need to commute to work then I could live far enough out in a rural area where there is farmland and I could have distance from the neighbors and rent the rest of the land to a neighboring farmer so it would look like I was just a farmer with a small house sunk 5 feet into the ground.

Am I way off base with my ideas for building a fairly efficient house? What do you think?

Instead of simply sinking the house 5' into the ground why not consider raising the grades around the house with a series of small terraces? That way, your front door can be at grade, and when you look out the windows you are not looking up. You will find it easier to damproof your foundation, easier to layout your perimeter footing drains, easier to layout your septic system grades, and your electrical meter (if so equipped) would be at a more conventional height. Also, you can choose to backfill the terraces with soils with good drainage characteristics, to help keep the house dry.
If and when you get to the more formal planning stages, my advice is to really study and understand all the systems and components that you want and need, so that when you are getting prices and proposals from contractors you can ask for specific things, such as the exact placement of pipes, vents/inlets, meter bases and so forth. If you don't specify these things, they will often be installed with no consideration for the next contractor's install- for instance a gas meter installed too close to your intended HRV inlet/outlet location. The actual installation crew will usually opt for the easiest/shortest route, and you really have to know what you want beforehand.
The other benefit to this kind of detailed planning is that you can take the site conditions such as sun and wind exposure, summer shade, and even landscaping into consideration, as to how they affect your mechanical systems.

I think that setup sounds pretty good. You didn't mention it but I imagine you'd also have a SHW setup for DHW.

I like the idea of sinking the house for additional insulation, but you wouldn't be able to get the southern window space (unless you dug out around it) that you could with a house above grade. You also may have water/ice issues with steps leading down to your front door.

A good idea is to build on the southern slope of a hill. That way you still have maximum solar gain from the exposed South, but the back and sides can be partially dug into the mountainside. IMO the soil isn't actually an insulator, but acts as thermal mass, reducing the temperature gradient through the (buried) walls during winter. You can get away with less insulation, but you have to make sure everything is protected against water. Also, building on the sunny side of a hill puts you in the windshadow of any chilly winds from the North.

Sounds like a decent design to me as well.
I'm a fan of saving money and energy on windows that don't open, sure you want enough windows that open that you get some cross ventilation, but having some pitcher windows that are triple pane can save a lot on window cost and they have fewer seals to leak.
I also got to check out the house that has the ground tempering of incoming fresh air via a ground loop of pex instead of using earth tubes, it's a slick system that takes care of the cooling needs of the house in the summer as well.
I worked for a number of years building straw bale houses and found that when working with other contractors that you have to assume that they are going to treat your project as a normal house so any details that might not be standard you need to be clear about and get in writing that they realize these details are there, we had issues with the footings for our walls being to narrower for a 20" thick straw wall, truss companies wanting to sell us trusses that didn't have space for R70 attic insulation and foundations that didn't have the amount of insulation that we specified.
In my own house and in others I've had to deal with insulation contractors that skimped on insulation in really extreme ways too.

I really like the idea of building up the soil around the house if you don't happen to own a south facing slope, I hate houses that you have to go up or down steps to get to the main floor/kitchen, 2-3 steps going up is ok, but hauling groceries in gets old and as you age it becomes more of an issue.

As long as the house is still imaginary...

The solar orientation should be primary, and then taking advantage of favorable site conditions. Everything already said about insulation is just great.

But a design feature that really intrigues me, that you don't see so much anymore is the idea of a 'core room'. I just made that term up, but the idea is a room that has rooms or hallways that surround it on all sides if possible, protecting it from extremes of weather.

I have one such room in my house, it has only one outside wall. The rest of the walls, and floor and ceiling, have a room on the other side. And this room is the warmest room in the winter, and the coolest room in the summer. It is also the quietest room at any time.. it is the best for taking a nap.

Another very handy idea is an actual, functioning pantry. My house had one that had been remodeled into a bathroom long before I moved in, and I didn't realize that it was ever a pantry until I removed the unnecessary bathroom... Then the logic of a small windowless room on the corner of the house that got the least sun, became clear.

In Oregon, 120 years ago, pantries were built into every house, for storing food, because you could not assume the uninterrupted availability of food.

120 years ago, in Oregon, people in the city planted nut and fruit trees around their houses, for the same reason.

I don't think it is unreasoning paranoia to think that we may live to see similar conditions again...

-AC_Hacker

herlichka, Sinking the house is probably a bad idea now that I think of it and Daox brought up the front door which I didn't think about. I don't think I'd raise grade. The thought was to reduce the need for insulation by having the ground shield the house against the temperature extremes. In the end, finding a builder to do this in an attractive way, or even a water-safe way may be extremely difficult.

Daox, I'm not sure if I would go with SHW. This summer I managed 4 therms of gas for two differnt months usage between the hot water and stove. I take showers and cook stuff so I'd imagine that if I had SHW, I'd actually have to use more water than I do for it to be worth it. I think that for the limited roof space that I'd rather have as much PV I can have up there which would have the added benefit of blocking sun from the roof which would be light in color and no asphalt shingles. I'm not looking to go with spendy panels to get higher output per panel but something on the affordable side from a reputable company who has a warranty worth something. It looks like a 2 to 3kw setup would balance my electrical usage but with more insulation and properly placed windows. I forgot to mention that I wanted a 2kw-3kw system. Ideally I'd probably put as much up there that I can fit, if somehow 4kw of panels managed to work, I'd be happy too if I'm on-grid and feed back and cash in the excess.

Piwoslaw, Soil might not be an insulator but the slab and walls of my basement are warmer than the upstairs of my house right now so I'd imagine that the soil temperature would save some energy in the winter and more energy in the summer since the exterior exposure wouldn't be the outside temperature. The solar gain is going to be whatever size glass I install. If the southern wall is 5 feet tall and the window is 4 feet tall and as wide as that side of the house then I'd imagine that there would be plenty of solar gain.

Ryland, I've found that the only weather I can open my windows in my climate is in the seasons where my electric bill is not dominated by the air conditioner because of the humidity. In the summer we sometimes get nice cool 60 degree nights but those are the nights where the dew point during the day was above the indoor temperature so opening the windows would raise the humidity quite a bit. I probably won't open windows too much and so a large picture window with two smaller side windows would probably do the trick. I've been reading that triple pane windows don't save much over double pane windows with a large enough gap because triple pane windows don't have a large enough gap between the panes to insulate as well as someone would think. I'll buy the windows based on the U-factor and in the end will probably get triple pane. I'm assuming triple pane doesn't affect the solar gain, does it? I want the southern windows to pull in the heat and in the summer have a proper overhang to block the sun. At the MN state fair this year there was a display showing passive house design, they used a ground tempering and since Minnesota needs it, the setup had a condenser to cool the incoming air. I think the building's entire air conditioning setup may have been to cool the incoming air exchange. What R value is a 20" straw bale wall assembly? I've been doing my own insulation in my house, and still working on a few details but I will be finished up once I can crawl in the 27" high upper attic without freezing. My current house has two steps to go up to get in. I like it because the ground level is the kitchen and living room and if I have someone over in a wheelchair it is much to not have to climb them up or down in a split-level house setting where the door greets you with a choice of stairs up and down. Some day I will convince my family to have grandma over at my place so we don't have to carry her up and down stairs. I could even make a simple plywood ramp too.

AC_Hacker, Most of what I saw about insulation was either learned searching for it, seeing it on the Building Science articles Building Science Information from this site, and quite of bit of the actual numbers and quantities came from members this site or a few of the energy auditors that are also in HVAC at the hvac-talk site. It just bugs me that I can't post there without my thread being closed because of their no DIY policy even though I wasn't saying anything about installing my own equipment. For what it's worth, this spring I'll be putting in a good half dozen or so fruit trees, 4 apple trees, 2 pear trees of different varieties. I never thought about nut trees, I don't know which ones would survive here but I'll take a look in spring. I like the idea of having food trees because they take nearly no effort once they are established to get food from them.

I like the idea of a 'core room' The problem with that idea is if the house is small, putting a room in the middle with no exterior walls might not really work. I think a good idea would be to have the master walk-in closet with a door seperating the outside from the inside and not intentionally conditioning that walk-in closet. I've seen zero energy houses that use a closed off area for entry ways that aren't conditioned and have the interior of those insulated from the outside as well as between that entry room and the outside. I don't think I need to go to that extreme since I don't ever leave the door open long at all and it adds sq ft and construction costs. If the inside is insulated enough such as 12" of cellulose I'd imagine its going to be quiet inside. Once I air sealed my bedroom I could crank my laptop volume as loud as it would go, which is fairly loud and couldn't tell there was music playing outside. I put the laptop downstairs where I hadn't air sealed yet and I could name the music that was playing on random. One thing I'd like to mention though is avoiding hallways. My plan is to not use them, if the house is designed without hallways and having the rooms on the outer walls then the only thing that resembles a hallway would be any stairs separating levels.

According to an environmental engineer who's house I worked on years back, you get enough more solar gain from non-low e glass on the south side of your house that the extra heat that you get makes up for the extra heat loss that you will see at night, if you then have insulated window shades you can close you can keep even more of that heat in then even the best window by it's self, if I was building the house from scratch I would install the outside insulated window shutters.

I like the idea of outside insulated window shutters, I'd imagine that having those on the front of a house would be considered an eyesore to many, along with awnings(which is why I'll have a carefully designed overhang). Hopefully I don't get angry picky neighbors when I build my next place. I've already got a neighbor who acts funny ever since he asked me about the 60 bags of cellulose insulation I had in my garage last year, apparently saving energy and money makes us all strange. Some tie it into their political assumptions too, which gets some people worked up now that elections are on everyones mind. I'm trying to think of how to add thermal mass to the house, in a design phase, I don't see why I wouldn't be able to 'build it in'. I figure the thermal mass should smooth out the excess heat and then let go of it when its cooler. I'm thinking of doing something other than having a 'Water jug masterpiece' for thermal mass. I think people who come over would look at me funny for that one.

I'll definitely have the insulated window shades, maybe a matching set to cover the wall containing the 'CulligaPicaso'.

A hydronic slab floor would certainly provide the mass you are looking for.

I saw a great article a few years back, in which a house was designed so that winter sun fell onto a substantial amount of the concrete floor, and the heat radiated out in the evening, along with heat from hot water in the slab.

I have a friend who built a very successful passive solar house near Portland Oregon, an area not known for its sunny winters. The house was long, East/West, and narrow, North/South. It had the usual overhang to shield against summer sun, was backed into an earth berm on the North side. Had an abundance of windows along its South face, an insulated concrete floor to store heat (no hydronics) and something like R-60 in the roof. It has a wood stove in the living room that supplies heat to the whole house... there's a free-standing stone wall behind the wood stove to capture and slowly release heat from the stove.

He says he burns a bit less than a cord of wood per year. That's his only heat, other than the sun.

A very pleasant house...

-AC_Hacker

"The house was long, East/West, and narrow, North/South. It had the usual overhang to shield against summer sun, was backed into an earth berm on the North side. Had an abundance of windows along its South face, an insulated concrete floor to store heat (no hydronics) and something like R-60 in the roof. It has a wood stove in the living room that supplies heat to the whole house... there's a free-standing stone wall behind the wood stove to capture and slowly release heat from the stove."

You seem to be describing what I'd build. A long east/west house with southern windows, overhang blocking summer sun, my original post was about having exterior of the house underground a bit, I'm thinking R75 roof.

The difference with mine is that I'd go with a ductless minisplit for heating and cooling instead of wood. I'd like to go all electric even though I love cooking with a gas stove(might go with propane for that). Reason why I'm not look at a gas furnace for a mostly passive house stems from my current experience from my 2150 sq ft house where 36% of my gas bill is connection fees, city franchise cost, etc. This house is not passive and has no south facing windows. Managed 31 therms($31) in our extremely mild December, warmest December I've ever experienced here. Natural gas total cost for 2011 was $350, fixed fees being $130 of that. Basically what I'm saying is that natural gas is expensive when you don't use any. In my current situation, I need enough heat to where going all electric doesn't make sense but for something mostly passive, it does. I'd probably use a space heater as my backup heat since I already own it, maybe turn the toaster oven on if I really need it, a hair dryer but I'm not looking to need 15k BTU, if I can manage to not freeze the pipes with a 5k BTU(standard 1500 watt space heater) or less I know I'm all set. I don't want to deal with wood, even if it is only a cord a season. Only needing a cord is amazing though, I suppose that's just a couple logs on the colder days.

I asked him if he would make any changes, and he said that he wished he'd put more insulation in the roof.

Just to keep things in perspective for you, the area where I live, has a Heating Degree Day rating of about 4,500. It looks like where you are, HDD is about 8,000. Our winters are fairly mild and direct sunshine is obscured by the clouds that blow over from the Pacific ocean. I'd imaging your winters are more of a challenge, and that you have more solar energy available.



I think mini-splits are great, I sure like mine.

However, I have been pursuing the practice of keeping multiple modes of heating & cooking, where possible. Although not as bad as it was, we still have power outages from time to time, and I'm always glad that my gas range still functions. I have a wood stove in the basement, too.

My gas demand water heater uses two D-cells as it's ignition source, so power outages don't affect it either. Once when we had a power outage, I went in and took a long hot shower by candle light, just because I could. It was a very practical luxury.

[QUOTE=MN Renovator;18850]...Basically what I'm saying is that natural gas is expensive when you don't use any...[QUOTE]

I'm with you on that one. I'm tempted to go propane for that reason. Most months, my gas use is less expensive than the fixed fees that are tacked on. But right now, the difference doesn't outweigh the cost & hassle of switching over.



Here's an interesting type of small heater, that is wall-mount and direct vent (combustion air in, exhaust gas out) and is very unobtrusive. Some brands of these are able to be retrofitted to run on either NG or LP gas. It has no pilot light (uses piezo), and uses no electricity to operate.

I think one of these should be in my kitchen.

-AC_Hacker

I was thinking an appropriately sized gas generator for the event of power outages. The largest load would be the water heater at 5kw since the heat pump would use less. I could go with a heat pump water heater instead but I'm not seeing it worth it unless the electrics have terrible insulation. The Honda inverters now go up to 5500 watts rated and run for 14 hours at 1/4 load off of a 4.5 gallon tank so I should be okay if I carry a decent amount of gas on hand. It might not be cheap or as ideal as using propane for water heating, clothes drying, or the stove but it eliminates the need for another fuel source, and propane is quite expensive to where I'd almost rather use a gasoline backup for the electric.

Earth berming was a popular direction in the 70's for energy conservation. I know people that built them. The fact that they are not still popular say a lot about their practicality. Two of the three have constant ongoing drainage problem and all three have humidity and possible mold issues(in MN). They are quiet and blend with the landscape. One even has a sod roof. But they need way more space and are more expensive per sq' that super insulated or passive design. I had planned to build one but didn't. People left the sod house concept behind for a reason.

I also don't see air/air HX as very effective in our cold winters. I think hydronic heat would be a better choice which gives you several choices on how to heat the water. Of the many "green" energy concepts that I have followed since the 70's I'm looking at the one that are still working out. Like passive solar(thermal mass), hydronic heat, super insulation, space conservation, indoor pollution control, EF appliances/lighting, PV generation, SDHW(location dependent), DIY knowledge/skills. Seen many great ideas flash, consuming peoples valuable money with no return possibly even threatening their very health(molds, raydon, contaminated water.

You have pointed out the potential problems with berming, but the problems can be overcome. I have a friend who lives in a bermed passive solar house, which is tucked into the side of a hill here in rainy Oregon. Proper drainage and damp-proofing was designed into the structure from the beginning. The house is dry and cozy and requires very little additional heat in the winter, and no A/C in the winter. So don't be too quick to toss the baby out with the bathwater.

There sure was a lot of activity in the 70's regarding energy efficiency, and a lot of good books written on the subject. I always keep an eye out when I'm in a used book store for 70's alternative energy books... I have amassed a fairly substantial vintage DIY alt-energy library.

But Drake, you are right, some of the ideas stood the test of time much better...

My Dad used to say it's much easier to have 20-20 vision when you're seeing things in the rear view mirror.

-AC

I don't see the issues with berming being that great considering that the house I live in is undergrade without any issues. It seems that as long as you build it with the same considerations as you would with having that bermed area being a basement, I'm not seeing the issue. I see houses all the time with walkout basements in the back of a house where the front of the house is flush with the ground or maybe a step or two above. That sort of house is effectively bermed. Of course the correct solar exposure is fairly critical. In the case of a house that I know of where the owner discussed energy bills, he says that the summer air conditioning is far higher than the winter heating due to almost all of the glass being on the south.

The more that I reading about passive house building and using glass to assist with heat in the winter, whether it is double pane, triple pane, or has a pile of films(won't name the brand name) the more than I'm leaning to having very little glazing when I build a new house. In the house I'm living now, I have the drapes shut pretty much all the time because the solar exposure is terrible in the winter because the big picture windows are not south facing enough for them to get much sun at all during the winter months. My house has about 4 square feet of southern glass and it's about the only glass that brings in a decent amount of light other than the skylight. The skylight is a nightmare though, when I moved in, it had drywall and sheathing and is directly exposed the attic and had water vapor streaks from shower humidity. In the winter this kind of glass lets out all your heat and in the summer it turns my bathroom into an oven. I have little use for the light considering that if its at night I have a single 430 lumen directional LED that does the job using 8 watts. I'm putting serious consideration into having that skylight removed when this house needs to have its roof replaced. It'll free up space for solar PV panels.

So basically my house is setup so that way in the winter I get little heat from the windows and in the summer my house is baking. I had the idea of installing a removable external sheet of polycarbonate plastic or acrylic and putting Gila film on it to block light in the summer but I found out how expensive those sheets were for the massive size of the picture bay window space(three windows). I think what I'll do instead is buy two patio door screens and fashion those into a removable frame to block light and add privacy. The faux wood blinds by Levolor that the previous owners installed are terrible, don't buy from that company or go with wood blinds, these things suck in the heat and reflect next to nothing. I've hit them with an IR scanner in the summer and had them at 110 degrees in a few spots with an indoor temperature at 74 with the a/c going. They are terrible and will be replaced with honeycomb cell shades in no color other than white.

My goal is to get the a/c heat load down to 1.5 tons, I currently have a 2 ton air conditioner and on a design temp day it will run continuously(as it should) and maintain a few degrees above the set point. On a cooler day I usually operate it so it will run in a single period without shutting it off so I can remove as much humidity as possible to make a higher temperature much more tolerable and its working well. The sun-facing windows with bugscreen over the outside should hopefully reduce the load below 1.5 tons and when I replace my equipment I can confidently ask for a 40k furnace and a 1.5 ton a/c.

The reason why I'm talking about my current house is because I can see all the mistakes of this one to avoid with the next one. It seems that even though I've got limited solar exposure I can manage to get my biggest winter heating bill down to $70($60 when subtracting fixed connection fees) in winter 2010/2011 and under $45 or $35 without fixed connection fees 50 therms Jan 2012 and 180 therms for the past 12 months. These are the highest bills for a house 2200sq ft. Granted I need to disclaim that I don't keep my house at 75 in the winter, I allow it to get as cold as I am comfortable living in, same goes for summer. It's too big for my uses but when I bought it, I was buying a house that fit the neighborhood that I want to live in. Happens to be this is a neighborhood mostly with families and not very many singles or couples so the idea was to buy a house that I could sell later on down the line. A future house would likely be in a college campus area where houses that are built under 1000sq ft for one or two people or maybe 2 people and a kid(I'm talking about the average demands of a family, not what I'd live in with 3 or 4 people). I'm willing to live in a small place even if it were a family of 4 but I won't build for a family of 4 when I'm single.

Back to the topic of glazing, I'm not seeing the advantages as far as cost/benefit goes when going beyond either a really good double pane with the appropriate air gap or triple pane windows with almost all of them on the south side of the house and keeping them sized small and using a fairly substantial amount of cellulose and of course appropriate air sealing. Going completely passive seems to have lost it favor for me after seeing a Duluth, MN project get denied the passivhaus standard because they couldn't make the .6 ach50 but were very close. That house is passive though even though it didn't meet the standard. My goal is to lose the $10.50 connection fee with the natural gas provider or whatever that fee is and having heating costs be under $126 in electricity with a combination of a 9k BTU/hr heat pump and resistance heat for when we get below 0f and that thing can't produce, or in case the heat pump decides to fail. I'm still sticking to my 5k BTU/hr design load goal at -20f. The actual heat design temp where I live is between -12 and -15f depending on where I check but I'm not far from an area north that seems to be -18f. With insulating to a 5k BTU/hr heat load at -20f I'm not seeing much reason to rely on the sun for heating and it seems to be a better plan for me to consider keeping the sun out during the summer. It seems passivhaus designed use an earth tube and a condenser to do the job. Earth tubes are expensive and it seems that more and more of the project I read about are not doing this. Instead of going completely passive, I'll skip some of the more expensive steps and goals of building the status and going with what works on my terms. Things like the ASHRAE ACH for a house are IMHO way too high. I've done the math, if my house was communicating that many air changes, I'd be frozen out of my house for how much heat I'm putting into it but I have a hard time believing that a little breathing, humidity, and human sweat are as terrible as people make them out to be. IMHO controlling humidity to prevent mold is a much bigger concern that any ventilation system in my area will only require much more air conditioning in the summer to pull the humidity back down so the dew point is below 50f to make the basement safe.

If I'm not mistaken, the ASHRAE standard for homes has been adjusted downward.

You might want to check that out...

-AC

The latest version of ASHRAE's manual that specifies ventilation or required infiltration prior to adding mechanical ventilation shows .35ACH prior to adding mechanical ventilation.

Personally, I'm on board with 15CFM for person. I think doing a bulk air exchange of that amount over the period of time during the day that is most favorable to the indoor temperature. Not to code, probably not officially recommended but anyone but I'd prefer it.

I've sketched out a few hypothetical houses myself. Maybe I'll make one of them into reality in a few years.

I was explaining the "tiny house" concept to a co-worker, and he told me about all the time he spends on his sailboat. In a boat, as in a tiny house, it's more about cubic feet than square feet. By utilizing the full height of a kitchen, having tall bookshelves (with electronics on the middle shelves, perhaps), and having a sleeping loft instead of a bedroom, you can get a lot more value out of each square foot. I see too many houses where there is nothing of utility on the top half of each floor. With a good floorplan and some efficient furniture, I wouldn't have a use for more than about 400ft².

The front yard is strictly for curb appeal. I'd place the house close to the street, and keep the small front yard looking good. There would be room for a few fruit trees in the front yard. I wonder how well a blueberry hedge would work. The street would be on the north side of the house, so that most of my windows would look out on the garden.

For me, the challenge is building a house that's far more efficient than a conventional house, but making it look very ordinary. The house has to look good from the street, and I'll have to make it look bigger than it is. Landscaping can help, as would 12" thick walls. I'd also use an attached garage to my advantage.

I want at least a two car garage, but I don't want two thirds of the front of the house to be garage doors. I like the idea of having the garage doors on the side of the house. I could add a large window with nice curtains to the side of the garage, to make it look like the house is bigger than it really is. This works especially well if I were to go with a "double deep" 2x2 car garage/lab. The garage would have concrete + epoxy floors, 2x4 construction with insulation behind OSB instead of drywall to keep costs and mantainence down. I would install an ordinary 45000BTU/hr furnace in the garage, to heat it quickly on demand. Maybe the south wall would be solar collectors for the house and DHW.

You should do the math on how much energy you use in the house vs. the car, and let us know how long a commute could get before cancelling out the savings.

I've always wondered, what drives recommendations for >R50 in the attic? Would it be different if you had a good heat-rejecting roof, such as one made of shiny metal, painted white, or covered in solar collectors?

I always thought the idea of more insulation in the roof came from the vented aspect of the roof increasing the surface heat conductivity of the insulation since there is air flow directly over it requiring more insulation while the walls are sheated and essentially have a layer over them. In the winter with the ceiling having the hottest air that supposedly you'd want more insulation there. Not to mention it's easy to load a whole bunch of loose fill cellulose up there. In my case it's about the only place I can add cellulose to my current house without tearing out drywall, which makes it a large and easy retrofit opportunity. As long as all air sealing opportunities aren't missed before loading a pile of treated paper up there, it's about one of the only options for adding R-value for most. In a new house R60 might be more than enough, depends upon the standards for energy use that someone is going after, I'll have to read those sections of my Manual J again and read the factors on heat loss through the attic versus the walls so I can make comments about what ASHRAE thinks.

I didn't intend to slander earth sheltering only point out it is being done and that detail to moisture control is very important, not inexpensive and doesn't fit every location. Humid summer areas challenge the design. Some of the best performing ones today are built with PWF lumber or ICF's.

Yeah, below grade moisture management is a b@&*c. I have to run a dehumidifier in the summer to keep my house safe. Insulation next to below grade masonry is a temperamental situation. It might be ok if you had R 40 on the outside of every concrete surface with proper capillary barriers and so forth. But at that rate you are in the same boat as people super insulating above grade. I'd love to live in such a house but I think it's a lot cheaper and easier to build a house on grade or retrofit an existing one. The retrofit is the easiest and most effective option but maybe not the cheapest.

Humidity control is necessary in any well insulated house located in a humid climate. We learned this when we built our house in 2002. When the outside temperature rose into the 80's or 90's and the dew point into the 70's, the inside temperature would stay in the low 70's and the inside turned into a swamp. We had a choice - get a dehumidifier or turn on the heat. We got the dehumidifier.

Above grade or below makes no difference - it's the indoor relative humidity. Mold happens when indoor relative humidity gets over 60%.

Your air conditioner is a dehumidifier. In Minnesota we got dew points well above the indoor temperature but as long as the air conditioner was used to bring the house down to a reasonable temperature, the humidity was plenty low. I managed to pull humidity down to 25% during the hottest weeks of the year and most weeks I'd have it in the low to mid 30's. If I let it get warmer, aka less use of the air conditioner I would have humidity in the 40's. I aimed to keep the dew point of the house below 50 degrees.

The success of an air conditioner dehumidifying your house is dependent on long cycle times, which becomes difficult when an HVAC contractor oversizes the A/C. If the blower speed is too high and the coil isn't cold enough to dehumidify the air, you have the same problem. Also if you don't have a well sealed house, you are letting humidity in, which seems to be the most likely scenario for you if you are having this problem but it is probably a combination of those issues.

The issue with dehumidifiers is that they essentially are an air conditioner with both the indoor and outdoor components inside, they leave you with a net gain of heat while drawing off moisture to a catch bucket or a drain. I made the mistake last year after reading on the hvac-talk forums that dehumidifiers were more efficient at removing humidity so I monitored my humidity and kept it at 40% but the dehum. never shut off to keep it there and burned 400watts to no end. The house was warm but the humidity level kept it comfortable enough. I ended up with the highest electric bill. I dehumidified my house using the air conditioner the following month when it was hotter and my electric bill was actually lower.

In the summer if you have issues with your humidity being that high, you should try letting the house get a little bit warm and try running your air conditioner in one cycle 4-8 hours long and tell me what happens to your humidity level. Running a long cycle will keep the a/c running its most efficient and remove the most humidity. These 30 minute cycles that some people have get rid of very little humidity.

This summer I'll be trying to use a 10.7 EER(energy star) 5k BTU/hr window A/C which is a higher EER than my current air conditioner's SEER(1986 unit) and will be in my bedroom where I want the most comfort, mostly for sleeping. If it can't keep up cooling the whole house, I will close the bedroom door and when it is overcooling the bedroom I'll open the door. If needed I'll cycle the furnace blower for a bit to suck the air around or use a few of my box fans. I got a good knack for working the 23k whole house unit last year to keep the humidity down and expect this unit if setup and used properly will do better and be cheaper.

You are not wrong that A/C dehumidifies but ideally I space that doesn't need cooling is the goal. A/C's do offer the advantage of keeping the heat removed outside of space over dehumidifiers. Is one more energy efficient?

An energy efficient house needs very little cooling. Our house has a one ton AC. The house also has zero shade.

During a heat wave where the daytime temperature stayed above 100 deg F all day, the AC only ran 58% of the time to maintain 79 F inside. That was not enough running to fully control the indoor humidity.

More typical summer weather has daytime temperatures in the 80's with dewpoints in the 60's and low 70's. Typically, when the outside temperature rises into the 80's, it's several days before we turn on the AC. Keeping the indoor dewpoint down below 60 deg F requires a dehumidifier.

They go make dehumidifiers that also have ventilation capability. It seems that type is also the most efficient dehumidifier, two birds with one stone there.