It was a long road, but the house is complete, and we've been living here for two years.
Last year's temperature and power-monitoring data has also enabled me to simplify my heating system and get even more efficiency from the W-W Ground Source Heat Pump. It's working well this winter.
Here are some things that did NOT get into the final design.
Here are some basic numbers for my final design: (Download Plan in PDF form)
A key aspect of my design is that it still strongly Earth Sheltered. This means that a large portion of the surfaces that are normally exposed to the elements are actually protected by the earth. Rather than providing extra insulation, earth sheltering actually provides a moderate temperature buffer between the house and the environment. In a predominantly cold climate like Deep Creek, this means that even if the outside temperate is minus 10 degrees F, the earth sheltered walls are only exposed to a mild 50 Deg F. The reduced temperature differential in these conditions effectively cuts the heat loss by a factor of 4. My design uses a combination of earth penetration, and earth berming to achieve a high degree of earth sheltering. The diagram on the right shows how this works. The house footprint is essentially cut into the side on the hill, and the excavated soil is used to back-fill both side walls. The blue lines show the rainwater runoff before and after the construction.
OK, so lets see how well the passive solar will work. The basic
principal is that in Summer the eaves shade the windows from the high sun, and
in Winter the low sun enters the house unrestricted. To test this theory,
I setup my CAD program to generate a series of sun positions during a mid-summer
day, and a mid-winter day. I then took the images that it created, and turned
them into two animations. To say the least, the results were fantastic.
Take a look. Remember that the windows face South, so the sun starts at
the right of the image and moves over the top to the left. The shadows
show up as lighter sections of green exterior.
From these two simulations, we can see that proper orientation and shading can drastically reduce Summer cooling loads, and Winter heating loads. The 6" concrete slab floor acts as a thermal storage device during the day (slowly rising in temperature), and gives off the heat at night. 60,000 BTU of solar gain is predicted on a sunny winter day.
Geothermal Heating and cooling.
In addition to using the earth to shelter the house, the earth is also used as a constant temperature source/sink for a Geothermal Exchange HVAC system. An extensive ground water loop is used to feed two Ground Source Heat Pumps. One heat pump generates hot water for Domestic use (showers etc) and to heat the radiant slab. The other heat pump is used to heat or cool ducted air. In addition to this efficient heating/cooling system, a passive heat exchanger is used on a continuous flow ventilation system to reclaim energy from exhaust air. The system is diagrammed below.
For pictures of the actual installation, visit the Equipment Room page.
This site is all about building a cool, energy efficient house, that makes maximum use of earth sheltered design, passive solar heating and cooling, geothermal exchange energy management, and right sizing of the house for it's designated use. The home's placement is on a south-facing hillside in Deep Creek Lake, Maryland. This site describes the design process, the technologies used and the expected results. We also have a comprehensive Links Page for anyone who is also interested in designing a similar project.