Great Blog! I’ve been sifting through the information and you’ve been doing a great job documenting everything. As an architect, I’m always very curious what’s going on in my client’s head’s.

As a response to this post, we’ve been specifying radiant heat which seems to be the most comfortable heating system. In addition, we use an HRV or ERV to both supply constant fresh air, as well as temper the air from one area of the house to the other. This way, the temperature at the lower level of the house is very close to the upper level(s). In addition, we have been roughing in for a ductless mini split heat pump that can be fully installed at a later date. The heat pump is a very efficient way to both heat and cool a house. It’s ductless and is very efficient. Because we never really know exactly how much cooling we’ll need because comfort is alway relative to the specific occupant, this gives our client’s flexibility to tune their house to their own level of comfort. Another advantage of the heat pump is that you can quickly change the temperature in the air while the radiant system catches up. In addition to these measures, we do our best to design the house to not need any systems at all…ultimately, we hope our clients never need the heat pump.

Darin

Cost-wise, it’s probably at least $400 per square foot, and at about 7000 square feet, that’s $2.8m in construction costs plus maybe $1.4m in soft costs (using the 2/3rds 1/3rd rule), so that’s $4.2m. My math and estimates could obviously be off, but that’s many multiples beyond what I’m spending.

Still though… its a great, great example of the frontier of energy efficient luxury homes. If it costs that amount to build now, it will cost much less in 5-10 years.

Have a look at this house, similar orientation to yours: on the water with west facing glazing. They are using geothermal/radiant heating & cooling plus solar.

http://www.contemporist.com/2008/12/18/the-truro-residence-by-zeroenergy-design/

Rich

http://www.nytimes.com/slideshow/2008/11/25/greathomesanddestinations/1125-norway_5.html

I can take a simplified stab at this to get you started.

To calculate heat loss you need the U values and square feet of all external facing materials, windows, ceilings, walls, doors etc. The U value is BTUs lost per hr, per square foot (U=1/R). For a rough calculation you also need the temperature difference between the interior and exterior of the structure. You can use two figures, one for the cooling season, one for the heating season. This is very important, because heat transfer increases exponentially as the temperature difference increases. If the temperature is equal on both sides, no transfer, if it’s 30 degrees the transfer rate is obviously much higher.

There is also heat loss for ventilation (heat exchangers reduce this), door traffic, and voids in construction where different materials meet. This is where older homes perform poorly. Today with SIPs, spray foam etc you get a very tight structure so the heat loss in voids is minimal.

Now if you look at your windows, a quality triple pane Low E/Argon gas filled, fixed, window comes it at around R=5 or 6, U=1.7. Supposedly there is a krypton filled window that performs at an R=10, U=0.1 but it probably comes with a Superman price tag. A wall of SIP construction is rated around R=25, U=0.04, 4 to 5 times the performance of glass. Straw bale (I know, crazy idea) comes in at a massive R=48, U=0.02.

A couple other considerations:

• Think about the home’s performance in summer— it’s not just about heat gain from the sun—even with the shade down, there is substantial heat transfer through the windows putting more load on your cooling system.

• When you have a vaulted room heat moves quickly to the ceiling, forced air adds to the air movement, making it seem breezy so you end up increasing the temperature. Radiant heat travels slower, through you for a better comfort level. Unless you are on the couch, then you need a blanket or small gas insert, wood stove, etc. (It does tend to warm up the furniture though).

• If you spend more on a geothermal/radiant system, you may not get your money back through operating costs, but the house will have a higher resale value.

• If you can, check out homes with these different systems in the middle of winter to see what you prefer.

There are all kinds of tables online to plug in your numbers for heat transfer.

Hope this helps.