By Tracey Allen
I live on Prince Edward Island, Canada in what I call a passive solar house. Passive solar houses, sometimes referred to as “passivehaus”, have been around for quite a while and originated in Germany. A passive house is designed and built to allow sun to shine thorough the windows and heat the walls and floors which gradually release the heat into the house. The key factors in planning a passive solar home include positioning the house to capture the sun, careful selection of windows and strategic placement, and selection of flooring and wall materials that support the passive transfer of heat.
What I find most fascinating about our home is that we have no furnace to heat our house. So this means no oil, which makes our home a sustainable home.
ICF Wall Construction
While heating is important, equally important is what I call the “draft factor.” Most houses have drafts and the older the house the more drafts you will usually find. Since we were building new we had the option to decide on our wall construction. One of the major losses of heat is through leaks in your ‘envelope’ or your outside walls, and when the sun goes down on a passive home you don’t want to lose your heat. There are a number of construction techniques used to minimize this heat loss and one of them is insulated concrete forms (ICFs). Most ICFs are made of polystyrene foam and fit together like hollow Lego blocks. Once the walls are up, concrete is poured into the space between the insulating blocks.
Typically, homes with ICF wall construction go up faster than traditionally framed homes. Our own house was built in just 3.5 months, including a few unanticipated product shipment delays that impacted sub-contractor schedules. Our builder, an innovator in our Province, introduced ICF construction over 20 years ago. When other builders look to start offering ICF construction they consult our builder on the technique. Choosing a builder with this type of background gave us confidence to forward with the ICF construction. Although our builder had never built a passive solar house before, he was familiar with the principles; and the design provided by our architect was simple enough for him to follow.
Does Passive Solar Work?
We started the process by consulting with an architect since passive solar houses require some planning and are specific to the land and climate where you build. For that reason you really want to talk to the architect prior to purchasing the land and have him or her walk the land to be sure it is suitable.
Depending on what part of the world you live in, winds will be more prominent in one or more directions than another. For us, north and west winds dominate our winter. To protect us from these winds, we used an earth berming technique that uses the earth to stabilize the temperature in your home. I think of it as natural geothermal heating (and cooling). We used the earth-berming or placement of dirt up against the outside walls to add to the insulation value of our house. And again there is no mechanical device needed.
I did a lot of research on building techniques, passive solar, earth-berming and pretty well anything associated with sustainable building. However, even after talking to homeowners living in passive solar homes, I wondered – Will it work? Will I cook myself in the summer or freeze in the dead of winter?
Well, I’m happy to report passive solar does work. We moved into our new home July 20, 2012 and the entire, dry, hot summer our house was a nice 70F or 21C. I’m not sure if it was the ICF construction, the earth-berming or the nice eve on the house to block the sun or all three but the summer was comfortable and consistent in temperature.
Of course, in our neck of the woods, we joke that we have 2 months of summer and 10 months of winter. As fall approached we noticed the sun creeping into our house via our south facing windows and heating our house. We added insulated curtains to close when the sun went down to keep the heat minimize the heat loss. When we wake up in the morning the temperature is usually around 60F or 15C but as soon as the sun is up and shining the temperature in our house starts to climb. There are days we have to open the windows in January because otherwise it could get as warm as 90-95F or 30-32C indoors. When the sun doesn’t shine, yes the temperature can drop to 60F/15C, but so far no lower, and we are in full swing winter now. For those times we find 60F/15C a little too cool we put on a wood fire. To date we haven’t used a full cord of wood yet.
With the sun shining in, you might think there is a glare to deal with on your computer monitor for example. Again with a little planning and proper placement of your screen, this potential problem can be averted.
We are very happy with our house and can’t tell enough people how great passive, earth-berming, and ICF (insulated concrete forms) are, or how much we save in heating costs, reduced mechanical items to fix/replace, and how our house didn’t cost more than a conventional house to build!
Tracey Allen is the author of several books available at www.simplifyandsave.ca and lives in an earth-bermed, ICF, Passive Solar house in Prince Edward Island, Canada.