In the planning of a rural off grid home, or any energy efficient home, controlling electrical consumption should be a major design consideration.
Providing water, sewage, heating and lighting takes electricity. The trick is to keep the electrical and gas consumption to a minimum and with some sober thought and planning, this can be achieved cost effectively and relatively pain free.
Water is the most important element of any household. We can live for 30 days or more without food but only three to five without water.
The depth of the water well determines the amount of power required to lift the water, amount of usage will determine electrical consumption.
Sewage operation requires a pump in a sceptic tank with a field, or if building code and topography allows a lagoon, then gravity can be utilized and electrical consumption can be eliminated for this service.
Otherwise, energy use varies with the number of people in the household and the amount of water used; monitoring can control costs.
Heating and cooling can also be designed for minimal electrical consumption.
Facing the house to the south-southwest allows passive solar heat to be utilized in the cooler months of fall, winter and spring.
Correctly designed, the amount of roof overhang on a south facing deck will shade the windows from summer’s excessive heat but allow for direct sunshine to warm the interior in the winter.
Extra insulation in the attic and six- or eight-inch walls will greatly reduce furnace run time.
Heat supplements such as solar thermal panels and wood stoves operate with low electrical energy requirements. Solar thermal require circulator pumps to transfer the heat to where it is needed for either space or water heating.
Wood stoves with a high efficiency rating, placed in the correct position do not require extra fans for heat distribution.
Interestingly enough, burning wood introduces the same amount of carbon into the atmosphere, albeit at an elevated rate, as natural decay if it were to simply rot in the forest.
A tightly-built home with zero air leaks may keep the heat in but will render the air quality uncomfortable, if not dangerous to life.
Air exchangers can be either electrically powered or designed to use the convective circulation caused by a difference in temperatures to provide passive air exchange.
Passive air exchange for most circumstances is more than adequate; fan backup will ensure complete air exchange for those intense air quality situations.
Probably the most important consideration is actual construction of the home.
Size and complexity add greatly to heat and power requirements.
Simple is key, ideally four corners, one peak, shaded veranda, the KISS system incarnate.
For two-storey homes, same principal: a salt box type design.
With the design of the core structure maintained we can then add verandas and lean-to type add-ons for aesthetics. The old cold porch strategy of yesteryear utilized for energy savings.
In today’s world, do we really need huge amounts of living space given the world’s population versus resource ratio?
Lorne Oja is an energy consultant, power engineer and a partner in a company that installs solar panels, wind turbines and energy control products in Central Alberta. He built his first off-grid home in 2003 and is in the planning stage for his second. His column appears every second Friday in the Advocate. Contact him at: lorne@solartechnical.ca