These criteria are achieved through intelligent principles of passive design (methods that don’t require mechanical or active intervention such as orientation, window placement, optimizing solar gain) and implementation of the following detailing strategies: reducing thermal bridges, high performance windows, ventilation with heat recovery, quality insulation, airtight construction, heat cycle appropriate vapour control.
The above numbers and strategies are an example of criteria required for PassiveHouse Certification (“PassiveBuilding” or PassiveHaus). This can be extended to achieve NetZero by limiting the total energy consumed on site and providing for local provision of required energy.
As a home-owner or builder, certification may not be required or even under consideration, nor necessarily these levels of performance, but having the tools to evaluate possible geometries in conjunction with different wall assemblies, factoring in material costs, labour costs, and running costs over the life of the building is a powerful tool to have at your disposal.
If a homeowner plans on living in their renovation for 20 yrs and a single thoughtful detail potentially reduces their energy cost by $10000 alone over that 20 yrs, it certainly makes sense to capitalize on that logic wherever possible. By the same token, a heat recovery system is virtually meaningless if the construction detailing is not conceived from the same perspective. A high-efficiency heating system is helpful but limited if the rate of heat loss is no better than mediocre. If the construction is fundamentally flawed, it will require redoing in less than 20 yrs. as opposed to more than 50 yrs. if performance driven. And still more, all of these facts are nothing compared with the immeasurable value of simply living in an uncompromisingly comfortable and healthy environment.
To be sure, the range of human activities in a living space, no less than the predispositions of different body-types would already imply that no single formula could account for the range required by such subjective criteria as comfort. At least one would think. Yet unless wearing a parka indoors when it is -20ºC outdoors, an occupant walking into a room with a large plate glass window and naturally drawn to the window with its view, will turn around to face the room and involuntarily step several feet further into the room. This natural behaviour is cause by the immediate chill felt upon turning. The chill results from the temperature differential between the warm air at the centre of the room and the cold radiating from the cold glass surface.
In standard Canadian construction (typical Ux values of
, a 1 sq. inch of total leakage area will permit approximately 30 litres water to be transported due to air leakage over 1 heating season (21ºC @ 40%rh interior). This in conjunction with any other flaw or compromising condition would result in condensation within the wall resulting in premature decay, mold, rot or other conditions. These flaws do not necessarily point to contractor installation, but just as often to poor design or inadequate planning for localized climate conditions.
Sustainable.design employs best practices planning, optimizing and verifying at every design stage and every building stage. By combining building information modelling with energy modelling, there are no surprises — for the contractor or the client.