The term 'passive house' refers to an extremely high performing energy efficient home, in the sense that the heating and cooling is largely passive. To achieve this, homes have to be designed to take advantage of the free heat available from the sun, and heavily fortified with insulation to hang onto that precious heat.
Passive cooling comes from the insulation as well, in that not only does it stop heat from leaving your house in winter, it stops it from coming in during the summer.
The original certification program originates in Germany and the parameters of that program were specifically designed for that climate. The certification process has found its way to Canada, but without any changes to the performance requirements..
In Canada our bottom end temperatures can be much more extreme than those of Germany, and this is not reflected in the certification process. This can make achieving Passive House Certification here a far more costly undertaking, which could dissuade some from exploring it as an option, and likely be very disappointing to those who tried but didn't quite make it.
The main hurdle to certification is the maximum energy consumption of 15kWh per square metre per year in operation.There are some success stories, but to get to that point in Canada can require so much additional capital that the return on investment takes a serious beating. Your overall carbon footprint might be better if you settled for 16 or 17 kWh (still extremely high performance) and put that extra money into something like a Prius perhaps.
We stumbled upon one homeowner (or soon to be) who, in an attempt to build and certify to Passive House standards, has found the additional cost needed to squeeze the last bit of energy from the total modelled consumption quite prohibitive and decided to back off a bit. We found this interesting, and it's a good example of why we shouldn't look at any green building endeavour as an 'all or nothing' sort of thing.
Anyone can build a Certified Passive House when money is no object, but are they cost effective? We started to question that when we were designing the Damn Near Passive House.-Roy De Vries
Taken from the Damn Near Passive House blog, these are the objectives they had set out with:
- Design and build an affordable single family home that is highly energy efficient and environmentally sensitive.
- Assure that the house is designed to accommodate the ageing process.
- Complete the entire project on a reasonable budget that should accommodate many potential builders.
- Meet recognized PassivHaus standards for energy efficiency if proven to be cost efficient.
- Assemble a team of highly skilled journeyman trades craftsmen and women that appreciate the value of doing it right and want to participate.
- Work with suppliers in achieving our budget while maximizing awareness of how we selected their products in regards to merit and cost benefit analysis.
Within the realm of sustainaible building, most of us will have financial limits that we need to be realistic about. This does not mean that building an efficient home has to be a costly and selfless gesture, in fact it is quite the opposite. A high performing home will generally mean less money spent overall, not more. For more on that decision making process, have a look at the Damn Near Passive House blog.