National Solar Tour
|
In late 2003, with the valuable expertise and assistance of Dennis Kelly and Nancy Cooney (AgStar Financial Services, Mankato, MN,(www.agstar.com), we were able to purchase our dream 40 acres in rural LeSueur county. During 2004 and early 2005, we built a driveway, seeded pastures and hay field, planted 400 trees (for a windbreak), built a 60 x 120 Morton pole building with attached 48 x 48 stable, put in fencing, drilled a well (Geib Well, Arlington, MN), dug in water lines and installed automatic waterers. We trenched in power lines, drainage lines, and a phone line. Randy Malkow (Minnesota Valley Excavating, Henderson, MN) designed and installed our septic system. Thank you, everyone!
Now we were finally ready to focus on the house!
In early 2005, with the help and guidance of Minneapolis architect, Richard Venberg, we began the process of designing and building our energy efficient dream home in rural LeSueur county.
Our priorities in design were (1) energy efficiency, and (2) handicapped access (one-story). Many options for heating the house were researched; initially a passive solar home, a geothermal heat pump was considered. The costs and difficulty of repairing a geothermal system steered us away from that technology. The next best idea was to switch from passive solar to active solar. With active solar you need a place to store the day’s excess heat, so that it can be released and utilized during the non-sunny time of day. This meant adding a basement to allow for water tanks. Neither of us really liked this idea as it meant adding stairs and a second level.
This option was developed for quite a while with breathtaking design input from Richard Venberg. We were close to a final design and the project was nearly a go until Bruce attended the Wisconsin Energy Fair with Ralph Jacobson of Innovative Power Systems of Minneapolis, (www.ips-solar.com) our solar/photo-voltaic consultant. At the fair, Bruce was introduced to Bob Ramlow, who has had great success using a subterranean sand bed for heat storage with active solar systems. Also during this time period, Richard Venberg reminded us of the Insulated Concrete Form called Rastra that he was impressed with. Our interest was tweaked when we learned that Rastra is made out of concrete and recycled polystyrene (styrofoam coffee cups and packaging peanuts). We viewed a DVD he provided, visited the company’s web site (www.rastra.com) and became instantly converted! Rastra is seven-times stronger than "conventional construction", has a initial R-value of approximately 38 (without adding extra insulation!), and is fire-proof! The Rastra walls will provide valuable thermal mass for maintaining a constant core temperature. We'd settled on a construction material, but we still hadn’t finalized on a floor plan.
We went back to the drawing board, removing the basement and adding additional length to the footprint to gain the necessary space for the control room on the main floor of the house. Additional space for water tanks was no longer needed, so the overall size was only increased a slight amount.
The 36 x 120 ft foundation provides a large southern exposure for passive solar gain. The roof has a lower section at 38 degrees to maximize exposure for future photovoltaic panels. Photo- voltaic panels convert sunlight to electricity. The highest level of the roof has a triangular section. The north-facing side contains roof windows for providing additional natural light into the homes interior. The solar panels will be mounted on the south-facing side. Where the two roof lines meet, a 2-foot wide walkway allows access to the solar panels or roof windows for maintenance and cleaning.
The 36 x 60 ft home area, will have a north and south entry, each with airlocks to minimize heat loss/gain and vaulted ceilings with access to the roof windows for natural ventilation. Although the Rastra will provide thermal mass, the flooring will be etched concrete or tile/stone to provide additional mass for storing the passive solar energy provided by the south-facing exposure. The home currently has a propane Takagi on-demand water heater for backup heating for those rare weeks when solar input alone does not maintain the sandbed target temps. The solar system, alone, should be able to keep the home at a comfortable temperature, provided the climate follows “normal weather patterns” for this latitude.
|
Future plans for a renewable-source backup heating system was realized in 2009 (2 years after moving in!) when we added a Tulikivi soapstone masonry furnace in the greatroom area. One 30-40 lb load of hardwood burns rapidly in the 4,400 lb soapstone unit. The combustion is extremely clean (exceeding Austria's stringent air-quality standards), while capturing and storing over 90% of the BTU's in the soapstone mass which is released gradually as radiant heat over approximately 18 hours. This backup heat source is the perfect complement to active solar, as it reduces heat loss from the sub-floor sand bed during the evening hours on the coldest winter nights. Our 2nd winter with the Tulikivi is half over and we've used only 1/4 cord of oak (since September 2008)! |
The 36 x 30 ft attached shop area will not have a backup heating system, but we’re hoping it is never needed anyway!
The remaining 36 x 30 ft space is a non-heated, but insulated (by the rastra) garage.
We are trying to do much of the construction ourselves, and have received help from Randy, Deb’s brother, Jack, Deb’s father, and Jim, Bruce's brother. Jack is a tireless worker (we can't keep up!) and continually motivates us to “Git ‘er Done!” Jack’s selfless devotion to the project during the fall and early winter of 2005 cannot be sufficiently repaid. Our THANKS does not seem enough… but “thanks, anyway, Dad” – we never could have gotten this far without your help and expertise.