Geos homes are designed with Passive House concepts in mind. The Passive House Alliance defines the Passive House as “both a building energy performance standard and a set of design and construction principles used to achieve that standard. The Passive House standard is the most stringent building energy standard in the world: buildings that meet the standard use 80 percent less energy than conventional equivalent buildings, and provide superior air quality and comfort.
“It is a systems-based design strategy that carefully models and balances a comprehensive set of factors including heat emissions from appliances and occupants to keep the building at comfortable and consistent indoor temperatures throughout the heating and cooling seasons. Continuous mechanical ventilation of fresh filtered air, assures superb air quality.”
While Passive Homes are some of the most energy efficient homes available, Geos strives to keep affordability in mind while still reaching the ultimate goal of net-zero energy, and therefore will not be certified as Passive Homes. Certain parts of the Passive House standard will be met — such as the extreme air tightness levels of 0.6 ACH50 — but other parts of the standard are not economical when taking into account the constantly falling price of solar PV. Instead, all homes will be certified by the RESNET Home Energy Rating System or HERS. A HERS score of zero is a net-zero energy home while a HERS score of 100 is a typical built-to-code home.
At Geos we first design with perfect orientation, window sizes, and window overhangs, because good design is much cheaper than overbuilding. Then we optimize the building envelope (insulation, windows, air tightness) to the cost of the solar PV system. For instance, if it costs an extra $4000 to add an additional R10 of insulation to our walls, we look at how much energy could be saved by that upgrade. We found that simply spending an extra $500 for more solar PV will give us the equivalent energy to what the extra wall insulation would save. In that instance, we spend the money on the PV and save the homeowner $3500 in up-front construction cost, while still meeting our goal of net-zero energy.