passivhaus and aktivhaus
I was browsing Treehuger this morning, (I love this blog!) and there was a great story on a new 'aktivhaus' being built by the skylight window company, Velux. The story is a good comparison between an active solar house and a passive solar home, and we happen to have a passive solar home (although we don't have the 2-foot insulation) our home is heated in the winter by the sun. This treehugger story is good because it explains the difference and I don't think that many people even know about a passive solar home because it is not talked about much.
A passive solar house uses less technology with only the use of a 'heat recovery ventilator' or HRV because a 'passivhaus' is almost hermetically sealed and heavily insulated so you need a high powered ventilation system for the winter months to avoid moisture building up (because of bodily moisture, cooking moisture, and showering etc). A passive solar house depends on being well insulated and a home that is sited properly for optimal sun exposure.
I can explain a little bit what happens in our home; in the winter months, when the sun is low in the sky the sun shines pretty much into about half to three quarters of the house, it gets so warm that sometimes we have to open the windows on a crisp and sunny day even when it's below zero! We have shades that help insulate at night (but we keep it pretty cool at night in our home). On a true passive solar home you would have triple paned windows to help hold the heat in during the night hours. But our cement floor is also heated by the sun so our radiant heat has a jump-start. In the summer, when the sun is high in the sky our house stays cool and shady. We also have trees planted in the right places to keep certain areas (and kids outdoor play areas) with cool shade. We never have to use air conditioning, and just count on the cross-breeze from the windows.
It really depends on your individual home but you can look at how it's sited and possibly take some trees out or look at where you are placing your trees if you have a new home to make sure you are getting optimal use of the sun in your home.
Please take the time to read the story in Treehugger about the 'Akitivhaus' to get more information on the interesting technology that it takes to make a house work for you and using solar panels to heat your home and heat your water! just about off the grid...